The current design for AP pass-through does not support making dynamic
changes to the AP matrix of a running guest resulting in a few
deficiencies this patch series is intended to mitigate:
1. Adapters, domains and control domains can not be added to or removed
from a running guest. In order to modify a guest's AP configuration,
the guest must be terminated; only then can AP resources be assigned
to or unassigned from the guest's matrix mdev. The new AP
configuration becomes available to the guest when it is subsequently
restarted.
2. The AP bus's /sys/bus/ap/apmask and /sys/bus/ap/aqmask interfaces can
be modified by a root user without any restrictions. A change to
either mask can result in AP queue devices being unbound from the
vfio_ap device driver and bound to a zcrypt device driver even if a
guest is using the queues, thus giving the host access to the guest's
private crypto data and vice versa.
3. The APQNs derived from the Cartesian product of the APIDs of the
adapters and APQIs of the domains assigned to a matrix mdev must
reference an AP queue device bound to the vfio_ap device driver. The
AP architecture allows assignment of AP resources that are not
available to the system, so this artificial restriction is not
compliant with the architecture.
4. The AP configuration profile can be dynamically changed for the linux
host after a KVM guest is started. For example, a new domain can be
dynamically added to the configuration profile via the SE or an HMC
connected to a DPM enabled lpar. Likewise, AP adapters can be
dynamically configured (online state) and deconfigured (standby state)
using the SE, an SCLP command or an HMC connected to a DPM enabled
lpar. This can result in inadvertent sharing of AP queues between the
guest and host.
5. A root user can manually unbind an AP queue device representing a
queue in use by a KVM guest via the vfio_ap device driver's sysfs
unbind attribute. In this case, the guest will be using a queue that
is not bound to the driver which violates the device model.
This patch series introduces the following changes to the current design
to alleviate the shortcomings described above as well as to implement
more of the AP architecture:
1. A root user will be prevented from making edits to the AP bus's
/sys/bus/ap/apmask or /sys/bus/ap/aqmask if the change would transfer
ownership of an APQN from the vfio_ap device driver to a zcrypt driver
while the APQN is assigned to a matrix mdev.
2. Allow a root user to hot plug/unplug AP adapters, domains and control
domains for a KVM guest using the matrix mdev via its sysfs
assign/unassign attributes.
4. Allow assignment of an AP adapter or domain to a matrix mdev even if
it results in assignment of an APQN that does not reference an AP
queue device bound to the vfio_ap device driver, as long as the APQN
is not reserved for use by the default zcrypt drivers (also known as
over-provisioning of AP resources). Allowing over-provisioning of AP
resources better models the architecture which does not preclude
assigning AP resources that are not yet available in the system. Such
APQNs, however, will not be assigned to the guest using the matrix
mdev; only APQNs referencing AP queue devices bound to the vfio_ap
device driver will actually get assigned to the guest.
5. Handle dynamic changes to the AP device model.
1. Rationale for changes to AP bus's apmask/aqmask interfaces:
----------------------------------------------------------
Due to the extremely sensitive nature of cryptographic data, it is
imperative that great care be taken to ensure that such data is secured.
Allowing a root user, either inadvertently or maliciously, to configure
these masks such that a queue is shared between the host and a guest is
not only avoidable, it is advisable. It was suggested that this scenario
is better handled in user space with management software, but that does
not preclude a malicious administrator from using the sysfs interfaces
to gain access to a guest's crypto data. It was also suggested that this
scenario could be avoided by taking access to the adapter away from the
guest and zeroing out the queues prior to the vfio_ap driver releasing the
device; however, stealing an adapter in use from a guest as a by-product
of an operation is bad and will likely cause problems for the guest
unnecessarily. It was decided that the most effective solution with the
least number of negative side effects is to prevent the situation at the
source.
2. Rationale for hot plug/unplug using matrix mdev sysfs interfaces:
----------------------------------------------------------------
Allowing a user to hot plug/unplug AP resources using the matrix mdev
sysfs interfaces circumvents the need to terminate the guest in order to
modify its AP configuration. Allowing dynamic configuration makes
reconfiguring a guest's AP matrix much less disruptive.
3. Rationale for allowing over-provisioning of AP resources:
-----------------------------------------------------------
Allowing assignment of AP resources to a matrix mdev and ultimately to a
guest better models the AP architecture. The architecture does not
preclude assignment of unavailable AP resources. If a queue subsequently
becomes available while a guest using the matrix mdev to which its APQN
is assigned, the guest will be given access to it. If an APQN
is dynamically unassigned from the underlying host system, it will
automatically become unavailable to the guest.
Change log v17-v18:
------------------
* Added a new document, Documentation/s390/vfio-ap-locking.rst to describe
the locking design for this series. This included a patch for adding the
new doc to the MAITAINERS file for the VFIO AP maintainers.
* Added Reviewed-by for Halil in patch 6
* Restore filtering in the queue remove callback. (Halil)
* Added patch s390/vfio-ap: hot unplug of AP devices when mdev removed to
unplug all AP devices from the guest when the mdev is removed.
* Split patch 9 (s390/vfio-ap: allow hot plug/unplug of AP resources using
mdev device) into xx patches:
- allow hot plug/unplug of AP devices when assigned/unassigned
* Replaced v17 patch 08/15, s390/vfio-ap: keep track of active guests with
s390/vfio-ap: introduce new mutex to control access to the KVM pointer.
No longer tracking guests with a list of struct ap_guest objects. Added a
global mutex called kvm_lock which must be held whenever the kvm->lock is
taken. (Halil)
* Changed signature of the filtering function to limit the APQNs
examined. This change resulted in a cascade of changes to patches 5, 8
and 12. (Halil)
* Removed v17 patch 01/15 (s390/vfio-ap: Set pqap hook when vfio_ap module
is loaded). (Halil, Jason).
* Split patch 14 (notify drivers on config changed and scan complete
callbacks) into two patches: One to make the AP bus changes and the other
to implement the callbacks in the vfio_ap device driver. This was done
to facilitate merging the AP bus changes separately from the vfio_ap
driver changes. (Harald)
* Removed check of driver flags in the __verify_card_reservations and
__verify_queue_reservations functions in ap_bus.c to balance the
weighting between the default and vfio_ap drivers. (Harald)
Tony Krowiak (17):
s390/ap: driver callback to indicate resource in use
s390/ap: notify drivers on config changed and scan complete callbacks
s390/vfio-ap: use new AP bus interface to search for queue devices
s390/vfio-ap: move probe and remove callbacks to vfio_ap_ops.c
s390/vfio-ap: manage link between queue struct and matrix mdev
s390/vfio-ap: introduce shadow APCB
s390/vfio-ap: refresh guest's APCB by filtering APQNs assigned to mdev
s390/vfio-ap: allow assignment of unavailable AP queues to mdev device
s390/vfio-ap: introduce new mutex to control access to the KVM pointer
s390/vfio-ap: allow hot plug/unplug of AP devices when
assigned/unassigned
s390/vfio-ap: hot plug/unplug of AP devices when probed/removed
s390/vfio-ap: reset queues after adapter/domain unassignment
s390/vfio-ap: implement in-use callback for vfio_ap driver
s390/vfio-ap: sysfs attribute to display the guest's matrix
s390/vfio-ap: handle config changed and scan complete notification
s390/vfio-ap: update docs to include dynamic config support
s390/Docs: new doc describing lock usage by the vfio_ap device driver
MAINTAINERS: pick up all vfio_ap docs for VFIO AP maintainers
Documentation/s390/vfio-ap-locking.rst | 389 +++++++
Documentation/s390/vfio-ap.rst | 492 ++++++---
MAINTAINERS | 2 +-
drivers/s390/crypto/ap_bus.c | 226 +++-
drivers/s390/crypto/ap_bus.h | 16 +
drivers/s390/crypto/vfio_ap_drv.c | 71 +-
drivers/s390/crypto/vfio_ap_ops.c | 1347 ++++++++++++++++++------
drivers/s390/crypto/vfio_ap_private.h | 57 +-
8 files changed, 2058 insertions(+), 542 deletions(-)
create mode 100644 Documentation/s390/vfio-ap-locking.rst
--
2.31.1
The vfio_ap device driver registers for notification when the pointer to
the KVM object for a guest is set. Recall that the KVM lock (kvm->lock)
mutex must be taken outside of the matrix_dev->lock mutex to prevent the
reporting by lockdep of a circular locking dependency (a.k.a., a lockdep
splat):
* see commit 0cc00c8d4050 ("Fix circular lockdep when setting/clearing
crypto masks")
* see commit 86956e70761b ("replace open coded locks for
VFIO_GROUP_NOTIFY_SET_KVM notification")
With the introduction of support for hot plugging/unplugging AP devices
passed through to a KVM guest, a new guests_lock mutex is introduced to
ensure the proper locking order is maintained:
struct ap_matrix_dev {
...
struct mutex guests_lock;
...
}
The matrix_dev->guests_lock controls access to the matrix_mdev instances
that hold the state for AP devices that have been passed through to a
KVM guest. This lock must be held:
1. To control access to the KVM pointer (matrix_mdev->kvm) while the
vfio_ap device driver is using it to plug/unplug AP devices passed
through to the KVM guest.
2. To add matrix_mdev instances to or remove them from
matrix_dev->mdev_list. This is necessary to ensure the proper locking
order when the list is iterated to find an ap_matrix_mdev instance for
the purpose of plugging/unplugging AP devices passed through to a KVM
guest; for example, when a queue device is bound to (probe callback) or
removed from (remove callback) the vfio_ap device driver.
For example, when a queue device is removed from the vfio_ap device
driver, if the adapter is passed through to a KVM guest, it will have to
be unplugged. Since the vfio_ap device driver only knows the APQN of the
queue device when it is removed, in order to figure out whether the
adapter is passed through, the matrix_mdev object to which the queue is
assigned will have to be found. Its KVM pointer (matrix_mdev->kvm) can
then be used to determine if the mediated device is passed through
(matrix_mdev->kvm != NULL) and if so, to unplug the adapter.
In addition to introducing the matrix_mdev->guests_lock mutex, the
matrix_dev->lock mutex is being renamed to matrix_dev->mdevs_lock to
better reflect its purpose, which is to control access to the state of the
mediated devices under the control of the vfio_ap device driver.
It is not necessary to take the matrix_dev->guests_lock to access the KVM
pointer if the pointer is not used to plug/unplug AP devices; however, in
this case, the matrix_dev->mdevs_lock must be held in order to access the
KVM pointer since it set and cleared under the protection of the
mdevs_lock.
A case in point is the function that handles interception of the PQAP(AQIC)
instruction sub-function by the host. This handler needs to access the KVM
pointer, but only for the purposes of setting or clearing IRQ resources, so
only the matrix_dev->mdevs_lock needs to be held.
The proper locking order must be maintained whenever plugging/unplugging
AP devices passed through to a KVM guest under the control of the vfio_ap
device driver:
matrix_dev->guests_lock
matrix_mdev->kvm->lock
matrix_dev->mdevs_lock
Signed-off-by: Tony Krowiak <[email protected]>
---
drivers/s390/crypto/vfio_ap_drv.c | 7 ++-
drivers/s390/crypto/vfio_ap_ops.c | 81 +++++++++++++++------------
drivers/s390/crypto/vfio_ap_private.h | 17 ++++--
3 files changed, 61 insertions(+), 44 deletions(-)
diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index 5013a5531171..e8f3540ebfda 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -68,7 +68,7 @@ static ssize_t status_show(struct device *dev,
struct ap_matrix_mdev *matrix_mdev;
struct ap_device *apdev = to_ap_dev(dev);
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->guests_lock);
q = dev_get_drvdata(&apdev->device);
matrix_mdev = vfio_ap_mdev_for_queue(q);
@@ -84,7 +84,7 @@ static ssize_t status_show(struct device *dev,
AP_QUEUE_UNASSIGNED);
}
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->guests_lock);
return nchars;
}
@@ -155,8 +155,9 @@ static int vfio_ap_matrix_dev_create(void)
goto matrix_alloc_err;
}
- mutex_init(&matrix_dev->lock);
+ mutex_init(&matrix_dev->mdevs_lock);
INIT_LIST_HEAD(&matrix_dev->mdev_list);
+ mutex_init(&matrix_dev->guests_lock);
dev_set_name(&matrix_dev->device, "%s", VFIO_AP_DEV_NAME);
matrix_dev->device.parent = root_device;
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index f2b98f347f9f..623a4b38676d 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -278,7 +278,7 @@ static int handle_pqap(struct kvm_vcpu *vcpu)
return -EOPNOTSUPP;
apqn = vcpu->run->s.regs.gprs[0] & 0xffff;
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
if (!vcpu->kvm->arch.crypto.pqap_hook)
goto out_unlock;
@@ -305,7 +305,7 @@ static int handle_pqap(struct kvm_vcpu *vcpu)
out_unlock:
memcpy(&vcpu->run->s.regs.gprs[1], &qstatus, sizeof(qstatus));
vcpu->run->s.regs.gprs[1] >>= 32;
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
return 0;
}
@@ -396,9 +396,9 @@ static int vfio_ap_mdev_probe(struct mdev_device *mdev)
vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb);
hash_init(matrix_mdev->qtable.queues);
mdev_set_drvdata(mdev, matrix_mdev);
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->guests_lock);
list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->guests_lock);
ret = vfio_register_emulated_iommu_dev(&matrix_mdev->vdev);
if (ret)
@@ -407,9 +407,9 @@ static int vfio_ap_mdev_probe(struct mdev_device *mdev)
return 0;
err_list:
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->guests_lock);
list_del(&matrix_mdev->node);
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->guests_lock);
vfio_uninit_group_dev(&matrix_mdev->vdev);
kfree(matrix_mdev);
err_dec_available:
@@ -472,11 +472,11 @@ static void vfio_ap_mdev_remove(struct mdev_device *mdev)
vfio_unregister_group_dev(&matrix_mdev->vdev);
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
vfio_ap_mdev_reset_queues(matrix_mdev);
vfio_ap_mdev_unlink_fr_queues(matrix_mdev);
list_del(&matrix_mdev->node);
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
vfio_uninit_group_dev(&matrix_mdev->vdev);
kfree(matrix_mdev);
atomic_inc(&matrix_dev->available_instances);
@@ -652,7 +652,8 @@ static ssize_t assign_adapter_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->guests_lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
/* If the KVM guest is running, disallow assignment of adapter */
if (matrix_mdev->kvm) {
@@ -683,7 +684,8 @@ static ssize_t assign_adapter_store(struct device *dev,
vfio_ap_mdev_filter_matrix(apm, matrix_mdev->matrix.aqm, matrix_mdev);
ret = count;
done:
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
+ mutex_unlock(&matrix_dev->guests_lock);
return ret;
}
@@ -726,7 +728,7 @@ static ssize_t unassign_adapter_store(struct device *dev,
unsigned long apid;
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
/* If the KVM guest is running, disallow unassignment of adapter */
if (matrix_mdev->kvm) {
@@ -751,7 +753,7 @@ static ssize_t unassign_adapter_store(struct device *dev,
ret = count;
done:
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
return ret;
}
static DEVICE_ATTR_WO(unassign_adapter);
@@ -806,7 +808,8 @@ static ssize_t assign_domain_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
unsigned long max_apqi = matrix_mdev->matrix.aqm_max;
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->guests_lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
/* If the KVM guest is running, disallow assignment of domain */
if (matrix_mdev->kvm) {
@@ -836,7 +839,8 @@ static ssize_t assign_domain_store(struct device *dev,
vfio_ap_mdev_filter_matrix(matrix_mdev->matrix.apm, aqm, matrix_mdev);
ret = count;
done:
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
+ mutex_unlock(&matrix_dev->guests_lock);
return ret;
}
@@ -879,7 +883,7 @@ static ssize_t unassign_domain_store(struct device *dev,
unsigned long apqi;
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
/* If the KVM guest is running, disallow unassignment of domain */
if (matrix_mdev->kvm) {
@@ -905,7 +909,7 @@ static ssize_t unassign_domain_store(struct device *dev,
ret = count;
done:
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
return ret;
}
static DEVICE_ATTR_WO(unassign_domain);
@@ -932,7 +936,7 @@ static ssize_t assign_control_domain_store(struct device *dev,
unsigned long id;
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
/* If the KVM guest is running, disallow assignment of control domain */
if (matrix_mdev->kvm) {
@@ -958,7 +962,7 @@ static ssize_t assign_control_domain_store(struct device *dev,
vfio_ap_mdev_filter_cdoms(matrix_mdev);
ret = count;
done:
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
return ret;
}
static DEVICE_ATTR_WO(assign_control_domain);
@@ -986,7 +990,7 @@ static ssize_t unassign_control_domain_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
unsigned long max_domid = matrix_mdev->matrix.adm_max;
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
/* If a KVM guest is running, disallow unassignment of control domain */
if (matrix_mdev->kvm) {
@@ -1009,7 +1013,7 @@ static ssize_t unassign_control_domain_store(struct device *dev,
ret = count;
done:
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
return ret;
}
static DEVICE_ATTR_WO(unassign_control_domain);
@@ -1025,13 +1029,13 @@ static ssize_t control_domains_show(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
unsigned long max_domid = matrix_mdev->matrix.adm_max;
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
for_each_set_bit_inv(id, matrix_mdev->matrix.adm, max_domid + 1) {
n = sprintf(bufpos, "%04lx\n", id);
bufpos += n;
nchars += n;
}
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
return nchars;
}
@@ -1054,7 +1058,7 @@ static ssize_t matrix_show(struct device *dev, struct device_attribute *attr,
apid1 = find_first_bit_inv(matrix_mdev->matrix.apm, napm_bits);
apqi1 = find_first_bit_inv(matrix_mdev->matrix.aqm, naqm_bits);
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
if ((apid1 < napm_bits) && (apqi1 < naqm_bits)) {
for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, napm_bits) {
@@ -1080,7 +1084,7 @@ static ssize_t matrix_show(struct device *dev, struct device_attribute *attr,
}
}
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
return nchars;
}
@@ -1134,13 +1138,15 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev,
kvm->arch.crypto.pqap_hook = &matrix_mdev->pqap_hook;
up_write(&kvm->arch.crypto.pqap_hook_rwsem);
+ mutex_lock(&matrix_dev->guests_lock);
mutex_lock(&kvm->lock);
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
list_for_each_entry(m, &matrix_dev->mdev_list, node) {
if (m != matrix_mdev && m->kvm == kvm) {
+ mutex_unlock(&matrix_dev->mdevs_lock);
mutex_unlock(&kvm->lock);
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->guests_lock);
return -EPERM;
}
}
@@ -1151,8 +1157,9 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev,
matrix_mdev->shadow_apcb.aqm,
matrix_mdev->shadow_apcb.adm);
+ mutex_unlock(&matrix_dev->mdevs_lock);
mutex_unlock(&kvm->lock);
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->guests_lock);
}
return 0;
@@ -1210,16 +1217,18 @@ static void vfio_ap_mdev_unset_kvm(struct ap_matrix_mdev *matrix_mdev,
kvm->arch.crypto.pqap_hook = NULL;
up_write(&kvm->arch.crypto.pqap_hook_rwsem);
+ mutex_lock(&matrix_dev->guests_lock);
mutex_lock(&kvm->lock);
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
kvm_arch_crypto_clear_masks(kvm);
vfio_ap_mdev_reset_queues(matrix_mdev);
kvm_put_kvm(kvm);
matrix_mdev->kvm = NULL;
+ mutex_unlock(&matrix_dev->mdevs_lock);
mutex_unlock(&kvm->lock);
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->guests_lock);
}
}
@@ -1396,7 +1405,7 @@ static ssize_t vfio_ap_mdev_ioctl(struct vfio_device *vdev,
container_of(vdev, struct ap_matrix_mdev, vdev);
int ret;
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
switch (cmd) {
case VFIO_DEVICE_GET_INFO:
ret = vfio_ap_mdev_get_device_info(arg);
@@ -1408,7 +1417,7 @@ static ssize_t vfio_ap_mdev_ioctl(struct vfio_device *vdev,
ret = -EOPNOTSUPP;
break;
}
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
return ret;
}
@@ -1493,7 +1502,8 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
if (!q)
return -ENOMEM;
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->guests_lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
q->apqn = to_ap_queue(&apdev->device)->qid;
q->saved_isc = VFIO_AP_ISC_INVALID;
vfio_ap_queue_link_mdev(q);
@@ -1504,7 +1514,8 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
q->matrix_mdev);
}
dev_set_drvdata(&apdev->device, q);
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
+ mutex_unlock(&matrix_dev->guests_lock);
return 0;
}
@@ -1514,7 +1525,7 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
unsigned long apid;
struct vfio_ap_queue *q;
- mutex_lock(&matrix_dev->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
q = dev_get_drvdata(&apdev->device);
if (q->matrix_mdev) {
@@ -1528,5 +1539,5 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
vfio_ap_mdev_reset_queue(q, 1);
dev_set_drvdata(&apdev->device, NULL);
kfree(q);
- mutex_unlock(&matrix_dev->lock);
+ mutex_unlock(&matrix_dev->mdevs_lock);
}
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index fa11a7e91e24..7e82a72d2083 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -33,20 +33,25 @@
* @available_instances: number of mediated matrix devices that can be created
* @info: the struct containing the output from the PQAP(QCI) instruction
* @mdev_list: the list of mediated matrix devices created
- * @lock: mutex for locking the AP matrix device. This lock will be
- * taken every time we fiddle with state managed by the vfio_ap
- * driver, be it using @mdev_list or writing the state of a
- * single ap_matrix_mdev device. It's quite coarse but we don't
- * expect much contention.
+ * @mdevs_lock: mutex for locking the ap_matrix_mdev devices under the control
+ * of the vfio_ap device driver. This lock will be taken every time
+ * we fiddle with state of an ap_matrix_mdev device. It's quite
+ * coarse but we don't expect much contention.
* @vfio_ap_drv: the vfio_ap device driver
+ * @guests_lock: mutex for controlling access to a guest that is using AP
+ * devices passed through by the vfio_ap device driver. This lock
+ * will be taken when the AP devices are plugged into or unplugged
+ * from a guest, and when an ap_matrix_mdev device is added to or
+ * removed from @mdev_list or the list is iterated.
*/
struct ap_matrix_dev {
struct device device;
atomic_t available_instances;
struct ap_config_info info;
struct list_head mdev_list;
- struct mutex lock;
+ struct mutex mdevs_lock;
struct ap_driver *vfio_ap_drv;
+ struct mutex guests_lock;
};
extern struct ap_matrix_dev *matrix_dev;
--
2.31.1
Introduces a new driver callback to prevent a root user from re-assigning
the APQN of a queue that is in use by a non-default host device driver to
a default host device driver and vice versa. The callback will be invoked
whenever a change to the AP bus's sysfs apmask or aqmask attributes would
result in one or more APQNs being re-assigned. If the callback responds
in the affirmative for any driver queried, the change to the apmask or
aqmask will be rejected with a device busy error.
For this patch, only non-default drivers will be queried. Currently,
there is only one non-default driver, the vfio_ap device driver. The
vfio_ap device driver facilitates pass-through of an AP queue to a
guest. The idea here is that a guest may be administered by a different
sysadmin than the host and we don't want AP resources to unexpectedly
disappear from a guest's AP configuration (i.e., adapters and domains
assigned to the matrix mdev). This will enforce the proper procedure for
removing AP resources intended for guest usage which is to
first unassign them from the matrix mdev, then unbind them from the
vfio_ap device driver.
Signed-off-by: Tony Krowiak <[email protected]>
Reviewed-by: Harald Freudenberger <[email protected]>
Reviewed-by: Halil Pasic <[email protected]>
---
drivers/s390/crypto/ap_bus.c | 145 ++++++++++++++++++++++++++++++++---
drivers/s390/crypto/ap_bus.h | 4 +
2 files changed, 139 insertions(+), 10 deletions(-)
diff --git a/drivers/s390/crypto/ap_bus.c b/drivers/s390/crypto/ap_bus.c
index 1986243f9cd3..d71d2d2c341f 100644
--- a/drivers/s390/crypto/ap_bus.c
+++ b/drivers/s390/crypto/ap_bus.c
@@ -36,6 +36,7 @@
#include <linux/mod_devicetable.h>
#include <linux/debugfs.h>
#include <linux/ctype.h>
+#include <linux/module.h>
#include "ap_bus.h"
#include "ap_debug.h"
@@ -1067,6 +1068,23 @@ static int modify_bitmap(const char *str, unsigned long *bitmap, int bits)
return 0;
}
+static int ap_parse_bitmap_str(const char *str, unsigned long *bitmap, int bits,
+ unsigned long *newmap)
+{
+ unsigned long size;
+ int rc;
+
+ size = BITS_TO_LONGS(bits) * sizeof(unsigned long);
+ if (*str == '+' || *str == '-') {
+ memcpy(newmap, bitmap, size);
+ rc = modify_bitmap(str, newmap, bits);
+ } else {
+ memset(newmap, 0, size);
+ rc = hex2bitmap(str, newmap, bits);
+ }
+ return rc;
+}
+
int ap_parse_mask_str(const char *str,
unsigned long *bitmap, int bits,
struct mutex *lock)
@@ -1086,14 +1104,7 @@ int ap_parse_mask_str(const char *str,
kfree(newmap);
return -ERESTARTSYS;
}
-
- if (*str == '+' || *str == '-') {
- memcpy(newmap, bitmap, size);
- rc = modify_bitmap(str, newmap, bits);
- } else {
- memset(newmap, 0, size);
- rc = hex2bitmap(str, newmap, bits);
- }
+ rc = ap_parse_bitmap_str(str, bitmap, bits, newmap);
if (rc == 0)
memcpy(bitmap, newmap, size);
mutex_unlock(lock);
@@ -1286,12 +1297,69 @@ static ssize_t apmask_show(struct bus_type *bus, char *buf)
return rc;
}
+static int __verify_card_reservations(struct device_driver *drv, void *data)
+{
+ int rc = 0;
+ struct ap_driver *ap_drv = to_ap_drv(drv);
+ unsigned long *newapm = (unsigned long *)data;
+
+ /*
+ * increase the driver's module refcounter to be sure it is not
+ * going away when we invoke the callback function.
+ */
+ if (!try_module_get(drv->owner))
+ return 0;
+
+ if (ap_drv->in_use) {
+ rc = ap_drv->in_use(newapm, ap_perms.aqm);
+ if (rc)
+ rc = -EBUSY;
+ }
+
+ /* release the driver's module */
+ module_put(drv->owner);
+
+ return rc;
+}
+
+static int apmask_commit(unsigned long *newapm)
+{
+ int rc;
+ unsigned long reserved[BITS_TO_LONGS(AP_DEVICES)];
+
+ /*
+ * Check if any bits in the apmask have been set which will
+ * result in queues being removed from non-default drivers
+ */
+ if (bitmap_andnot(reserved, newapm, ap_perms.apm, AP_DEVICES)) {
+ rc = bus_for_each_drv(&ap_bus_type, NULL, reserved,
+ __verify_card_reservations);
+ if (rc)
+ return rc;
+ }
+
+ memcpy(ap_perms.apm, newapm, APMASKSIZE);
+
+ return 0;
+}
+
static ssize_t apmask_store(struct bus_type *bus, const char *buf,
size_t count)
{
int rc;
+ DECLARE_BITMAP(newapm, AP_DEVICES);
+
+ if (mutex_lock_interruptible(&ap_perms_mutex))
+ return -ERESTARTSYS;
- rc = ap_parse_mask_str(buf, ap_perms.apm, AP_DEVICES, &ap_perms_mutex);
+ rc = ap_parse_bitmap_str(buf, ap_perms.apm, AP_DEVICES, newapm);
+ if (rc)
+ goto done;
+
+ rc = apmask_commit(newapm);
+
+done:
+ mutex_unlock(&ap_perms_mutex);
if (rc)
return rc;
@@ -1317,12 +1385,69 @@ static ssize_t aqmask_show(struct bus_type *bus, char *buf)
return rc;
}
+static int __verify_queue_reservations(struct device_driver *drv, void *data)
+{
+ int rc = 0;
+ struct ap_driver *ap_drv = to_ap_drv(drv);
+ unsigned long *newaqm = (unsigned long *)data;
+
+ /*
+ * increase the driver's module refcounter to be sure it is not
+ * going away when we invoke the callback function.
+ */
+ if (!try_module_get(drv->owner))
+ return 0;
+
+ if (ap_drv->in_use) {
+ rc = ap_drv->in_use(ap_perms.apm, newaqm);
+ if (rc)
+ return -EBUSY;
+ }
+
+ /* release the driver's module */
+ module_put(drv->owner);
+
+ return rc;
+}
+
+static int aqmask_commit(unsigned long *newaqm)
+{
+ int rc;
+ unsigned long reserved[BITS_TO_LONGS(AP_DOMAINS)];
+
+ /*
+ * Check if any bits in the aqmask have been set which will
+ * result in queues being removed from non-default drivers
+ */
+ if (bitmap_andnot(reserved, newaqm, ap_perms.aqm, AP_DOMAINS)) {
+ rc = bus_for_each_drv(&ap_bus_type, NULL, reserved,
+ __verify_queue_reservations);
+ if (rc)
+ return rc;
+ }
+
+ memcpy(ap_perms.aqm, newaqm, AQMASKSIZE);
+
+ return 0;
+}
+
static ssize_t aqmask_store(struct bus_type *bus, const char *buf,
size_t count)
{
int rc;
+ DECLARE_BITMAP(newaqm, AP_DOMAINS);
- rc = ap_parse_mask_str(buf, ap_perms.aqm, AP_DOMAINS, &ap_perms_mutex);
+ if (mutex_lock_interruptible(&ap_perms_mutex))
+ return -ERESTARTSYS;
+
+ rc = ap_parse_bitmap_str(buf, ap_perms.aqm, AP_DOMAINS, newaqm);
+ if (rc)
+ goto done;
+
+ rc = aqmask_commit(newaqm);
+
+done:
+ mutex_unlock(&ap_perms_mutex);
if (rc)
return rc;
diff --git a/drivers/s390/crypto/ap_bus.h b/drivers/s390/crypto/ap_bus.h
index 95b577754b35..67c1bef60ad5 100644
--- a/drivers/s390/crypto/ap_bus.h
+++ b/drivers/s390/crypto/ap_bus.h
@@ -142,6 +142,7 @@ struct ap_driver {
int (*probe)(struct ap_device *);
void (*remove)(struct ap_device *);
+ int (*in_use)(unsigned long *apm, unsigned long *aqm);
};
#define to_ap_drv(x) container_of((x), struct ap_driver, driver)
@@ -289,6 +290,9 @@ void ap_queue_init_state(struct ap_queue *aq);
struct ap_card *ap_card_create(int id, int queue_depth, int raw_type,
int comp_type, unsigned int functions, int ml);
+#define APMASKSIZE (BITS_TO_LONGS(AP_DEVICES) * sizeof(unsigned long))
+#define AQMASKSIZE (BITS_TO_LONGS(AP_DOMAINS) * sizeof(unsigned long))
+
struct ap_perms {
unsigned long ioctlm[BITS_TO_LONGS(AP_IOCTLS)];
unsigned long apm[BITS_TO_LONGS(AP_DEVICES)];
--
2.31.1
Update the documentation in vfio-ap.rst to include information about the
AP dynamic configuration support (e.g., hot plug of adapters, domains
and control domains via the matrix mediated device's sysfs assignment
attributes). This patch also makes a few minor tweaks to make corrections
and clarifications.
Signed-off-by: Tony Krowiak <[email protected]>
---
Documentation/s390/vfio-ap.rst | 492 +++++++++++++++++++++++----------
1 file changed, 346 insertions(+), 146 deletions(-)
diff --git a/Documentation/s390/vfio-ap.rst b/Documentation/s390/vfio-ap.rst
index f57ae621f33e..f4b8748ab9a8 100644
--- a/Documentation/s390/vfio-ap.rst
+++ b/Documentation/s390/vfio-ap.rst
@@ -123,27 +123,24 @@ Let's now take a look at how AP instructions executed on a guest are interpreted
by the hardware.
A satellite control block called the Crypto Control Block (CRYCB) is attached to
-our main hardware virtualization control block. The CRYCB contains three fields
-to identify the adapters, usage domains and control domains assigned to the KVM
-guest:
+our main hardware virtualization control block. The CRYCB contains an AP Control
+Block (APCB) that has three fields to identify the adapters, usage domains and
+control domains assigned to the KVM guest:
* The AP Mask (APM) field is a bit mask that identifies the AP adapters assigned
- to the KVM guest. Each bit in the mask, from left to right (i.e. from most
- significant to least significant bit in big endian order), corresponds to
+ to the KVM guest. Each bit in the mask, from left to right, corresponds to
an APID from 0-255. If a bit is set, the corresponding adapter is valid for
use by the KVM guest.
* The AP Queue Mask (AQM) field is a bit mask identifying the AP usage domains
- assigned to the KVM guest. Each bit in the mask, from left to right (i.e. from
- most significant to least significant bit in big endian order), corresponds to
- an AP queue index (APQI) from 0-255. If a bit is set, the corresponding queue
- is valid for use by the KVM guest.
+ assigned to the KVM guest. Each bit in the mask, from left to right,
+ corresponds to an AP queue index (APQI) from 0-255. If a bit is set, the
+ corresponding queue is valid for use by the KVM guest.
* The AP Domain Mask field is a bit mask that identifies the AP control domains
assigned to the KVM guest. The ADM bit mask controls which domains can be
changed by an AP command-request message sent to a usage domain from the
- guest. Each bit in the mask, from left to right (i.e. from most significant to
- least significant bit in big endian order), corresponds to a domain from
+ guest. Each bit in the mask, from left to right, corresponds to a domain from
0-255. If a bit is set, the corresponding domain can be modified by an AP
command-request message sent to a usage domain.
@@ -151,10 +148,10 @@ If you recall from the description of an AP Queue, AP instructions include
an APQN to identify the AP queue to which an AP command-request message is to be
sent (NQAP and PQAP instructions), or from which a command-reply message is to
be received (DQAP instruction). The validity of an APQN is defined by the matrix
-calculated from the APM and AQM; it is the cross product of all assigned adapter
-numbers (APM) with all assigned queue indexes (AQM). For example, if adapters 1
-and 2 and usage domains 5 and 6 are assigned to a guest, the APQNs (1,5), (1,6),
-(2,5) and (2,6) will be valid for the guest.
+calculated from the APM and AQM; it is the Cartesian product of all assigned
+adapter numbers (APM) with all assigned queue indexes (AQM). For example, if
+adapters 1 and 2 and usage domains 5 and 6 are assigned to a guest, the APQNs
+(1,5), (1,6), (2,5) and (2,6) will be valid for the guest.
The APQNs can provide secure key functionality - i.e., a private key is stored
on the adapter card for each of its domains - so each APQN must be assigned to
@@ -192,7 +189,7 @@ The design introduces three new objects:
1. AP matrix device
2. VFIO AP device driver (vfio_ap.ko)
-3. VFIO AP mediated matrix pass-through device
+3. VFIO AP mediated pass-through device
The VFIO AP device driver
-------------------------
@@ -200,12 +197,13 @@ The VFIO AP (vfio_ap) device driver serves the following purposes:
1. Provides the interfaces to secure APQNs for exclusive use of KVM guests.
-2. Sets up the VFIO mediated device interfaces to manage a mediated matrix
+2. Sets up the VFIO mediated device interfaces to manage a vfio_ap mediated
device and creates the sysfs interfaces for assigning adapters, usage
domains, and control domains comprising the matrix for a KVM guest.
-3. Configures the APM, AQM and ADM in the CRYCB referenced by a KVM guest's
- SIE state description to grant the guest access to a matrix of AP devices
+3. Configures the APM, AQM and ADM in the APCB contained in the CRYCB referenced
+ by a KVM guest's SIE state description to grant the guest access to a matrix
+ of AP devices
Reserve APQNs for exclusive use of KVM guests
---------------------------------------------
@@ -235,10 +233,10 @@ reserved::
| | 8 probe | |
+--------^---------+ +--^--^------------+
6 edit | | |
- apmask | +-----------------------------+ | 9 mdev create
+ apmask | +-----------------------------+ | 11 mdev create
aqmask | | 1 modprobe |
+--------+-----+---+ +----------------+-+ +----------------+
- | | | |8 create | mediated |
+ | | | |10 create| mediated |
| admin | | VFIO device core |---------> matrix |
| + | | | device |
+------+-+---------+ +--------^---------+ +--------^-------+
@@ -246,14 +244,14 @@ reserved::
| | 9 create vfio_ap-passthrough | |
| +------------------------------+ |
+-------------------------------------------------------------+
- 10 assign adapter/domain/control domain
+ 12 assign adapter/domain/control domain
The process for reserving an AP queue for use by a KVM guest is:
1. The administrator loads the vfio_ap device driver
2. The vfio-ap driver during its initialization will register a single 'matrix'
device with the device core. This will serve as the parent device for
- all mediated matrix devices used to configure an AP matrix for a guest.
+ all vfio_ap mediated devices used to configure an AP matrix for a guest.
3. The /sys/devices/vfio_ap/matrix device is created by the device core
4. The vfio_ap device driver will register with the AP bus for AP queue devices
of type 10 and higher (CEX4 and newer). The driver will provide the vfio_ap
@@ -269,24 +267,24 @@ The process for reserving an AP queue for use by a KVM guest is:
default zcrypt cex4queue driver.
8. The AP bus probes the vfio_ap device driver to bind the queues reserved for
it.
-9. The administrator creates a passthrough type mediated matrix device to be
+9. The administrator creates a passthrough type vfio_ap mediated device to be
used by a guest
10. The administrator assigns the adapters, usage domains and control domains
to be exclusively used by a guest.
Set up the VFIO mediated device interfaces
------------------------------------------
-The VFIO AP device driver utilizes the common interface of the VFIO mediated
+The VFIO AP device driver utilizes the common interfaces of the VFIO mediated
device core driver to:
-* Register an AP mediated bus driver to add a mediated matrix device to and
+* Register an AP mediated bus driver to add a vfio_ap mediated device to and
remove it from a VFIO group.
-* Create and destroy a mediated matrix device
-* Add a mediated matrix device to and remove it from the AP mediated bus driver
-* Add a mediated matrix device to and remove it from an IOMMU group
+* Create and destroy a vfio_ap mediated device
+* Add a vfio_ap mediated device to and remove it from the AP mediated bus driver
+* Add a vfio_ap mediated device to and remove it from an IOMMU group
The following high-level block diagram shows the main components and interfaces
-of the VFIO AP mediated matrix device driver::
+of the VFIO AP mediated device driver::
+-------------+
| |
@@ -343,7 +341,7 @@ matrix device.
* device_api:
the mediated device type's API
* available_instances:
- the number of mediated matrix passthrough devices
+ the number of vfio_ap mediated passthrough devices
that can be created
* device_api:
specifies the VFIO API
@@ -351,29 +349,37 @@ matrix device.
This attribute group identifies the user-defined sysfs attributes of the
mediated device. When a device is registered with the VFIO mediated device
framework, the sysfs attribute files identified in the 'mdev_attr_groups'
- structure will be created in the mediated matrix device's directory. The
- sysfs attributes for a mediated matrix device are:
+ structure will be created in the vfio_ap mediated device's directory. The
+ sysfs attributes for a vfio_ap mediated device are:
assign_adapter / unassign_adapter:
Write-only attributes for assigning/unassigning an AP adapter to/from the
- mediated matrix device. To assign/unassign an adapter, the APID of the
- adapter is echoed to the respective attribute file.
+ vfio_ap mediated device. To assign/unassign an adapter, the APID of the
+ adapter is echoed into the respective attribute file.
assign_domain / unassign_domain:
Write-only attributes for assigning/unassigning an AP usage domain to/from
- the mediated matrix device. To assign/unassign a domain, the domain
- number of the usage domain is echoed to the respective attribute
+ the vfio_ap mediated device. To assign/unassign a domain, the domain
+ number of the usage domain is echoed into the respective attribute
file.
matrix:
- A read-only file for displaying the APQNs derived from the cross product
- of the adapter and domain numbers assigned to the mediated matrix device.
+ A read-only file for displaying the APQNs derived from the Cartesian
+ product of the adapter and domain numbers assigned to the vfio_ap mediated
+ device.
+ guest_matrix:
+ A read-only file for displaying the APQNs derived from the Cartesian
+ product of the adapter and domain numbers assigned to the APM and AQM
+ fields respectively of the KVM guest's CRYCB. This may differ from the
+ the APQNs assigned to the vfio_ap mediated device if any APQN does not
+ reference a queue device bound to the vfio_ap device driver (i.e., the
+ queue is not in the host's AP configuration).
assign_control_domain / unassign_control_domain:
Write-only attributes for assigning/unassigning an AP control domain
- to/from the mediated matrix device. To assign/unassign a control domain,
- the ID of the domain to be assigned/unassigned is echoed to the respective
- attribute file.
+ to/from the vfio_ap mediated device. To assign/unassign a control domain,
+ the ID of the domain to be assigned/unassigned is echoed into the
+ respective attribute file.
control_domains:
A read-only file for displaying the control domain numbers assigned to the
- mediated matrix device.
+ vfio_ap mediated device.
* functions:
@@ -383,45 +389,75 @@ matrix device.
* Store the reference to the KVM structure for the guest using the mdev
* Store the AP matrix configuration for the adapters, domains, and control
domains assigned via the corresponding sysfs attributes files
+ * Store the AP matrix configuration for the adapters, domains and control
+ domains available to a guest. A guest may not be provided access to APQNs
+ referencing queue devices that do not exist, or are not bound to the
+ vfio_ap device driver.
remove:
- deallocates the mediated matrix device's ap_matrix_mdev structure. This will
- be allowed only if a running guest is not using the mdev.
+ deallocates the vfio_ap mediated device's ap_matrix_mdev structure.
+ This will be allowed only if a running guest is not using the mdev.
* callback interfaces
- open:
+ open_device:
The vfio_ap driver uses this callback to register a
- VFIO_GROUP_NOTIFY_SET_KVM notifier callback function for the mdev matrix
- device. The open is invoked when QEMU connects the VFIO iommu group
- for the mdev matrix device to the MDEV bus. Access to the KVM structure used
- to configure the KVM guest is provided via this callback. The KVM structure,
- is used to configure the guest's access to the AP matrix defined via the
- mediated matrix device's sysfs attribute files.
- release:
+ VFIO_GROUP_NOTIFY_SET_KVM notifier callback function for the matrix mdev
+ devices. The open_device callback is invoked by userspace to connect the
+ VFIO iommu group for the matrix mdev device to the MDEV bus. Access to the
+ KVM structure used to configure the KVM guest is provided via this callback.
+ The KVM structure, is used to configure the guest's access to the AP matrix
+ defined via the vfio_ap mediated device's sysfs attribute files.
+
+ close_device:
unregisters the VFIO_GROUP_NOTIFY_SET_KVM notifier callback function for the
- mdev matrix device and deconfigures the guest's AP matrix.
+ matrix mdev device and deconfigures the guest's AP matrix.
-Configure the APM, AQM and ADM in the CRYCB
--------------------------------------------
-Configuring the AP matrix for a KVM guest will be performed when the
+ ioctl:
+ this callback handles the VFIO_DEVICE_GET_INFO and VFIO_DEVICE_RESET ioctls
+ defined by the vfio framework.
+
+Configure the guest's AP resources
+----------------------------------
+Configuring the AP resources for a KVM guest will be performed when the
VFIO_GROUP_NOTIFY_SET_KVM notifier callback is invoked. The notifier
-function is called when QEMU connects to KVM. The guest's AP matrix is
-configured via it's CRYCB by:
+function is called when userspace connects to KVM. The guest's AP resources are
+configured via it's APCB by:
* Setting the bits in the APM corresponding to the APIDs assigned to the
- mediated matrix device via its 'assign_adapter' interface.
+ vfio_ap mediated device via its 'assign_adapter' interface.
* Setting the bits in the AQM corresponding to the domains assigned to the
- mediated matrix device via its 'assign_domain' interface.
+ vfio_ap mediated device via its 'assign_domain' interface.
* Setting the bits in the ADM corresponding to the domain dIDs assigned to the
- mediated matrix device via its 'assign_control_domains' interface.
+ vfio_ap mediated device via its 'assign_control_domains' interface.
+
+The linux device model precludes passing a device through to a KVM guest that
+is not bound to the device driver facilitating its pass-through. Consequently,
+an APQN that does not reference a queue device bound to the vfio_ap device
+driver will not be assigned to a KVM guest's matrix. The AP architecture,
+however, does not provide a means to filter individual APQNs from the guest's
+matrix, so the adapters, domains and control domains assigned to vfio_ap
+mediated device via its sysfs 'assign_adapter', 'assign_domain' and
+'assign_control_domain' interfaces will be filtered before providing the AP
+configuration to a guest:
+
+* The APIDs of the adapters, the APQIs of the domains and the domain numbers of
+ the control domains assigned to the matrix mdev that are not also assigned to
+ the host's AP configuration will be filtered.
+
+* Each APQN derived from the Cartesian product of the APIDs and APQIs assigned
+ to the vfio_ap mdev is examined and if any one of them does not reference a
+ queue device bound to the vfio_ap device driver, the adapter will not be
+ plugged into the guest (i.e., the bit corresponding to its APID will not be
+ set in the APM of the guest's APCB).
The CPU model features for AP
-----------------------------
-The AP stack relies on the presence of the AP instructions as well as two
-facilities: The AP Facilities Test (APFT) facility; and the AP Query
-Configuration Information (QCI) facility. These features/facilities are made
-available to a KVM guest via the following CPU model features:
+The AP stack relies on the presence of the AP instructions as well as three
+facilities: The AP Facilities Test (APFT) facility; the AP Query
+Configuration Information (QCI) facility; and the AP Queue Interruption Control
+facility. These features/facilities are made available to a KVM guest via the
+following CPU model features:
1. ap: Indicates whether the AP instructions are installed on the guest. This
feature will be enabled by KVM only if the AP instructions are installed
@@ -435,24 +471,28 @@ available to a KVM guest via the following CPU model features:
can be made available to the guest only if it is available on the host (i.e.,
facility bit 12 is set).
+4. apqi: Indicates AP Queue Interruption Control faclity is available on the
+ guest. This facility can be made available to the guest only if it is
+ available on the host (i.e., facility bit 65 is set).
+
Note: If the user chooses to specify a CPU model different than the 'host'
model to QEMU, the CPU model features and facilities need to be turned on
explicitly; for example::
- /usr/bin/qemu-system-s390x ... -cpu z13,ap=on,apqci=on,apft=on
+ /usr/bin/qemu-system-s390x ... -cpu z13,ap=on,apqci=on,apft=on,apqi=on
A guest can be precluded from using AP features/facilities by turning them off
explicitly; for example::
- /usr/bin/qemu-system-s390x ... -cpu host,ap=off,apqci=off,apft=off
+ /usr/bin/qemu-system-s390x ... -cpu host,ap=off,apqci=off,apft=off,apqi=off
Note: If the APFT facility is turned off (apft=off) for the guest, the guest
-will not see any AP devices. The zcrypt device drivers that register for type 10
-and newer AP devices - i.e., the cex4card and cex4queue device drivers - need
-the APFT facility to ascertain the facilities installed on a given AP device. If
-the APFT facility is not installed on the guest, then the probe of device
-drivers will fail since only type 10 and newer devices can be configured for
-guest use.
+will not see any AP devices. The zcrypt device drivers on the guest that
+register for type 10 and newer AP devices - i.e., the cex4card and cex4queue
+device drivers - need the APFT facility to ascertain the facilities installed on
+a given AP device. If the APFT facility is not installed on the guest, then no
+adapter or domain devices will get created by the AP bus running on the
+guest because only type 10 and newer devices can be configured for guest use.
Example
=======
@@ -471,7 +511,7 @@ CARD.DOMAIN TYPE MODE
05.00ab CEX5C CCA-Coproc
06 CEX5A Accelerator
06.0004 CEX5A Accelerator
-06.00ab CEX5C CCA-Coproc
+06.00ab CEX5A Accelerator
=========== ===== ============
Guest2
@@ -479,9 +519,9 @@ Guest2
=========== ===== ============
CARD.DOMAIN TYPE MODE
=========== ===== ============
-05 CEX5A Accelerator
-05.0047 CEX5A Accelerator
-05.00ff CEX5A Accelerator
+05 CEX5C CCA-Coproc
+05.0047 CEX5C CCA-Coproc
+05.00ff CEX5C CCA-Coproc
=========== ===== ============
Guest3
@@ -529,40 +569,56 @@ These are the steps:
2. Secure the AP queues to be used by the three guests so that the host can not
access them. To secure them, there are two sysfs files that specify
- bitmasks marking a subset of the APQN range as 'usable by the default AP
- queue device drivers' or 'not usable by the default device drivers' and thus
- available for use by the vfio_ap device driver'. The location of the sysfs
- files containing the masks are::
+ bitmasks marking a subset of the APQN range as usable only by the default AP
+ queue device drivers. All remaining APQNs are available for use by
+ any other device driver. The vfio_ap device driver is currently the only
+ non-default device driver. The location of the sysfs files containing the
+ masks are::
/sys/bus/ap/apmask
/sys/bus/ap/aqmask
The 'apmask' is a 256-bit mask that identifies a set of AP adapter IDs
- (APID). Each bit in the mask, from left to right (i.e., from most significant
- to least significant bit in big endian order), corresponds to an APID from
- 0-255. If a bit is set, the APID is marked as usable only by the default AP
- queue device drivers; otherwise, the APID is usable by the vfio_ap
- device driver.
+ (APID). Each bit in the mask, from left to right, corresponds to an APID from
+ 0-255. If a bit is set, the APID belongs to the subset of APQNs marked as
+ available only to the default AP queue device drivers.
The 'aqmask' is a 256-bit mask that identifies a set of AP queue indexes
- (APQI). Each bit in the mask, from left to right (i.e., from most significant
- to least significant bit in big endian order), corresponds to an APQI from
- 0-255. If a bit is set, the APQI is marked as usable only by the default AP
- queue device drivers; otherwise, the APQI is usable by the vfio_ap device
- driver.
+ (APQI). Each bit in the mask, from left to right, corresponds to an APQI from
+ 0-255. If a bit is set, the APQI belongs to the subset of APQNs marked as
+ available only to the default AP queue device drivers.
+
+ The Cartesian product of the APIDs corresponding to the bits set in the
+ apmask and the APQIs corresponding to the bits set in the aqmask comprise
+ the subset of APQNs that can be used only by the host default device drivers.
+ All other APQNs are available to the non-default device drivers such as the
+ vfio_ap driver.
+
+ Take, for example, the following masks::
+
+ apmask:
+ 0x7d00000000000000000000000000000000000000000000000000000000000000
- Take, for example, the following mask::
+ aqmask:
+ 0x8000000000000000000000000000000000000000000000000000000000000000
- 0x7dffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
+ The masks indicate:
- It indicates:
+ * Adapters 1, 2, 3, 4, 5, and 7 are available for use by the host default
+ device drivers.
- 1, 2, 3, 4, 5, and 7-255 belong to the default drivers' pool, and 0 and 6
- belong to the vfio_ap device driver's pool.
+ * Domain 0 is available for use by the host default device drivers
+
+ * The subset of APQNs available for use only by the default host device
+ drivers are:
+
+ (1,0), (2,0), (3,0), (4.0), (5,0) and (7,0)
+
+ * All other APQNs are available for use by the non-default device drivers.
The APQN of each AP queue device assigned to the linux host is checked by the
- AP bus against the set of APQNs derived from the cross product of APIDs
- and APQIs marked as usable only by the default AP queue device drivers. If a
+ AP bus against the set of APQNs derived from the Cartesian product of APIDs
+ and APQIs marked as available to the default AP queue device drivers. If a
match is detected, only the default AP queue device drivers will be probed;
otherwise, the vfio_ap device driver will be probed.
@@ -579,8 +635,7 @@ These are the steps:
0x4100000000000000000000000000000000000000000000000000000000000000
- Keep in mind that the mask reads from left to right (i.e., most
- significant to least significant bit in big endian order), so the mask
+ Keep in mind that the mask reads from left to right, so the mask
above identifies device numbers 1 and 7 (01000001).
If the string is longer than the mask, the operation is terminated with
@@ -626,11 +681,22 @@ These are the steps:
default drivers pool: adapter 0-15, domain 1
alternate drivers pool: adapter 16-255, domains 0, 2-255
+ Note ***:
+ Changing a mask such that one or more APQNs will be taken from a vfio_ap
+ mediated device (see below) will fail with an error (EBUSY). A message
+ is logged to the kernel ring buffer which can be viewed with the 'dmesg'
+ command. The output identifies each APQN flagged as 'in use' and identifies
+ the vfio_ap mediated device to which it is assigned; for example:
+
+ Userspace may not re-assign queue 05.0054 already assigned to 62177883-f1bb-47f0-914d-32a22e3a8804
+ Userspace may not re-assign queue 04.0054 already assigned to cef03c3c-903d-4ecc-9a83-40694cb8aee4
+
Securing the APQNs for our example
----------------------------------
To secure the AP queues 05.0004, 05.0047, 05.00ab, 05.00ff, 06.0004, 06.0047,
06.00ab, and 06.00ff for use by the vfio_ap device driver, the corresponding
- APQNs can either be removed from the default masks::
+ APQNs can be removed from the default masks using either of the following
+ commands::
echo -5,-6 > /sys/bus/ap/apmask
@@ -683,7 +749,7 @@ Securing the APQNs for our example
/sys/devices/vfio_ap/matrix/
--- [mdev_supported_types]
- ------ [vfio_ap-passthrough] (passthrough mediated matrix device type)
+ ------ [vfio_ap-passthrough] (passthrough vfio_ap mediated device type)
--------- create
--------- [devices]
@@ -734,6 +800,9 @@ Securing the APQNs for our example
----------------unassign_control_domain
----------------unassign_domain
+ Note *****: The vfio_ap mdevs do not persist across reboots unless the
+ mdevctl tool is used to create and persist them.
+
4. The administrator now needs to configure the matrixes for the mediated
devices $uuid1 (for Guest1), $uuid2 (for Guest2) and $uuid3 (for Guest3).
@@ -755,6 +824,10 @@ Securing the APQNs for our example
cat matrix
+ To display the matrix that is or will be assigned to Guest1::
+
+ cat guest_matrix
+
This is how the matrix is configured for Guest2::
echo 5 > assign_adapter
@@ -774,17 +847,24 @@ Securing the APQNs for our example
higher than the maximum is specified, the operation will terminate with
an error (ENODEV).
- * All APQNs that can be derived from the adapter ID and the IDs of
- the previously assigned domains must be bound to the vfio_ap device
- driver. If no domains have yet been assigned, then there must be at least
- one APQN with the specified APID bound to the vfio_ap driver. If no such
- APQNs are bound to the driver, the operation will terminate with an
- error (EADDRNOTAVAIL).
+ Note: The maximum adapter number can be obtained via the sysfs
+ /sys/bus/ap/ap_max_adapter_id attribute file.
+
+ * Each APQN derived from the Cartesian product of the APID of the adapter
+ being assigned and the APQIs of the domains previously assigned:
- No APQN that can be derived from the adapter ID and the IDs of the
- previously assigned domains can be assigned to another mediated matrix
- device. If an APQN is assigned to another mediated matrix device, the
- operation will terminate with an error (EADDRINUSE).
+ - Must only be available to the vfio_ap device driver as specified in the
+ sysfs /sys/bus/ap/apmask and /sys/bus/ap/aqmask attribute files. If even
+ one APQN is reserved for use by the host device driver, the operation
+ will terminate with an error (EADDRNOTAVAIL).
+
+ - Must NOT be assigned to another vfio_ap mediated device. If even one APQN
+ is assigned to another vfio_ap mediated device, the operation will
+ terminate with an error (EBUSY).
+
+ - Must NOT be assigned while the sysfs /sys/bus/ap/apmask and
+ sys/bus/ap/aqmask attribute files are being edited or the operation may
+ terminate with an error (EBUSY).
In order to successfully assign a domain:
@@ -793,41 +873,50 @@ Securing the APQNs for our example
higher than the maximum is specified, the operation will terminate with
an error (ENODEV).
- * All APQNs that can be derived from the domain ID and the IDs of
- the previously assigned adapters must be bound to the vfio_ap device
- driver. If no domains have yet been assigned, then there must be at least
- one APQN with the specified APQI bound to the vfio_ap driver. If no such
- APQNs are bound to the driver, the operation will terminate with an
- error (EADDRNOTAVAIL).
+ Note: The maximum domain number can be obtained via the sysfs
+ /sys/bus/ap/ap_max_domain_id attribute file.
+
+ * Each APQN derived from the Cartesian product of the APQI of the domain
+ being assigned and the APIDs of the adapters previously assigned:
- No APQN that can be derived from the domain ID and the IDs of the
- previously assigned adapters can be assigned to another mediated matrix
- device. If an APQN is assigned to another mediated matrix device, the
- operation will terminate with an error (EADDRINUSE).
+ - Must only be available to the vfio_ap device driver as specified in the
+ sysfs /sys/bus/ap/apmask and /sys/bus/ap/aqmask attribute files. If even
+ one APQN is reserved for use by the host device driver, the operation
+ will terminate with an error (EADDRNOTAVAIL).
- In order to successfully assign a control domain, the domain number
- specified must represent a value from 0 up to the maximum domain number
- configured for the system. If a control domain number higher than the maximum
- is specified, the operation will terminate with an error (ENODEV).
+ - Must NOT be assigned to another vfio_ap mediated device. If even one APQN
+ is assigned to another vfio_ap mediated device, the operation will
+ terminate with an error (EBUSY).
+
+ - Must NOT be assigned while the sysfs /sys/bus/ap/apmask and
+ sys/bus/ap/aqmask attribute files are being edited or the operation may
+ terminate with an error (EBUSY).
+
+ In order to successfully assign a control domain:
+
+ * The domain number specified must represent a value from 0 up to the maximum
+ domain number configured for the system. If a control domain number higher
+ than the maximum is specified, the operation will terminate with an
+ error (ENODEV).
5. Start Guest1::
- /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on \
+ /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on,apqi=on \
-device vfio-ap,sysfsdev=/sys/devices/vfio_ap/matrix/$uuid1 ...
7. Start Guest2::
- /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on \
+ /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on,apqi=on \
-device vfio-ap,sysfsdev=/sys/devices/vfio_ap/matrix/$uuid2 ...
7. Start Guest3::
- /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on \
+ /usr/bin/qemu-system-s390x ... -cpu host,ap=on,apqci=on,apft=on,apqi=on \
-device vfio-ap,sysfsdev=/sys/devices/vfio_ap/matrix/$uuid3 ...
-When the guest is shut down, the mediated matrix devices may be removed.
+When the guest is shut down, the vfio_ap mediated devices may be removed.
-Using our example again, to remove the mediated matrix device $uuid1::
+Using our example again, to remove the vfio_ap mediated device $uuid1::
/sys/devices/vfio_ap/matrix/
--- [mdev_supported_types]
@@ -840,26 +929,137 @@ Using our example again, to remove the mediated matrix device $uuid1::
echo 1 > remove
-This will remove all of the mdev matrix device's sysfs structures including
-the mdev device itself. To recreate and reconfigure the mdev matrix device,
+This will remove all of the matrix mdev device's sysfs structures including
+the mdev device itself. To recreate and reconfigure the matrix mdev device,
all of the steps starting with step 3 will have to be performed again. Note
-that the remove will fail if a guest using the mdev is still running.
+that the remove will fail if a guest using the vfio_ap mdev is still running.
-It is not necessary to remove an mdev matrix device, but one may want to
+It is not necessary to remove a vfio_ap mdev, but one may want to
remove it if no guest will use it during the remaining lifetime of the linux
-host. If the mdev matrix device is removed, one may want to also reconfigure
+host. If the vfio_ap mdev is removed, one may want to also reconfigure
the pool of adapters and queues reserved for use by the default drivers.
+Hot plug/unplug support:
+================
+An adapter, domain or control domain may be hot plugged into a running KVM
+guest by assigning it to the vfio_ap mediated device being used by the guest if
+the following conditions are met:
+
+* The adapter, domain or control domain must also be assigned to the host's
+ AP configuration.
+
+* Each APQN derived from the Cartesian product comprised of the APID of the
+ adapter being assigned and the APQIs of the domains assigned must reference a
+ queue device bound to the vfio_ap device driver.
+
+* To hot plug a domain, each APQN derived from the Cartesian product
+ comprised of the APQI of the domain being assigned and the APIDs of the
+ adapters assigned must reference a queue device bound to the vfio_ap device
+ driver.
+
+An adapter, domain or control domain may be hot unplugged from a running KVM
+guest by unassigning it from the vfio_ap mediated device being used by the
+guest.
+
+Over-provisioning of AP queues for a KVM guest:
+==============================================
+Over-provisioning is defined herein as the assignment of adapters or domains to
+a vfio_ap mediated device that do not reference AP devices in the host's AP
+configuration. The idea here is that when the adapter or domain becomes
+available, it will be automatically hot-plugged into the KVM guest using
+the vfio_ap mediated device to which it is assigned as long as each new APQN
+resulting from plugging it in references a queue device bound to the vfio_ap
+device driver.
+
Limitations
===========
-* The KVM/kernel interfaces do not provide a way to prevent restoring an APQN
- to the default drivers pool of a queue that is still assigned to a mediated
- device in use by a guest. It is incumbent upon the administrator to
- ensure there is no mediated device in use by a guest to which the APQN is
- assigned lest the host be given access to the private data of the AP queue
- device such as a private key configured specifically for the guest.
+Live guest migration is not supported for guests using AP devices without
+intervention by a system administrator. Before a KVM guest can be migrated,
+the vfio_ap mediated device must be removed. Unfortunately, it can not be
+removed manually (i.e., echo 1 > /sys/devices/vfio_ap/matrix/$UUID/remove) while
+the mdev is in use by a KVM guest. If the guest is being emulated by QEMU,
+its mdev can be hot unplugged from the guest in one of two ways:
+
+1. If the KVM guest was started with libvirt, you can hot unplug the mdev via
+ the following commands:
+
+ virsh detach-device <guestname> <path-to-device-xml>
+
+ For example, to hot unplug mdev 62177883-f1bb-47f0-914d-32a22e3a8804 from
+ the guest named 'my-guest':
+
+ virsh detach-device my-guest ~/config/my-guest-hostdev.xml
+
+ The contents of my-guest-hostdev.xml:
+
+ <hostdev mode='subsystem' type='mdev' managed='no' model='vfio-ap'>
+ <source>
+ <address uuid='62177883-f1bb-47f0-914d-32a22e3a8804'/>
+ </source>
+ </hostdev>
+
+
+ virsh qemu-monitor-command <guest-name> --hmp "device-del <device-id>"
+
+ For example, to hot unplug the vfio_ap mediated device identified on the
+ qemu command line with 'id=hostdev0' from the guest named 'my-guest':
+
+ virsh qemu-monitor-command my-guest --hmp "device_del hostdev0"
+
+2. A vfio_ap mediated device can be hot unplugged by attaching the qemu monitor
+ to the guest and using the following qemu monitor command:
+
+ (QEMU) device-del id=<device-id>
+
+ For example, to hot unplug the vfio_ap mediated device that was specified
+ on the qemu command line with 'id=hostdev0' when the guest was started:
+
+ (QEMU) device-del id=hostdev0
+
+After live migration of the KVM guest completes, an AP configuration can be
+restored to the KVM guest by hot plugging a vfio_ap mediated device on the target
+system into the guest in one of two ways:
+
+1. If the KVM guest was started with libvirt, you can hot plug a matrix mediated
+ device into the guest via the following virsh commands:
+
+ virsh attach-device <guestname> <path-to-device-xml>
+
+ For example, to hot plug mdev 62177883-f1bb-47f0-914d-32a22e3a8804 into
+ the guest named 'my-guest':
+
+ virsh attach-device my-guest ~/config/my-guest-hostdev.xml
+
+ The contents of my-guest-hostdev.xml:
+
+ <hostdev mode='subsystem' type='mdev' managed='no' model='vfio-ap'>
+ <source>
+ <address uuid='62177883-f1bb-47f0-914d-32a22e3a8804'/>
+ </source>
+ </hostdev>
+
+
+ virsh qemu-monitor-command <guest-name> --hmp \
+ "device_add vfio-ap,sysfsdev=<path-to-mdev>,id=<device-id>"
+
+ For example, to hot plug the vfio_ap mediated device
+ 62177883-f1bb-47f0-914d-32a22e3a8804 into the guest named 'my-guest' with
+ device-id hostdev0:
+
+ virsh qemu-monitor-command my-guest --hmp \
+ "device_add vfio-ap,\
+ sysfsdev=/sys/devices/vfio_ap/matrix/62177883-f1bb-47f0-914d-32a22e3a8804,\
+ id=hostdev0"
+
+2. A vfio_ap mediated device can be hot plugged by attaching the qemu monitor
+ to the guest and using the following qemu monitor command:
+
+ (qemu) device_add "vfio-ap,sysfsdev=<path-to-mdev>,id=<device-id>"
-* Dynamically modifying the AP matrix for a running guest (which would amount to
- hot(un)plug of AP devices for the guest) is currently not supported
+ For example, to plug the vfio_ap mediated device
+ 62177883-f1bb-47f0-914d-32a22e3a8804 into the guest with the device-id
+ hostdev0:
-* Live guest migration is not supported for guests using AP devices.
+ (QEMU) device-add "vfio-ap,\
+ sysfsdev=/sys/devices/vfio_ap/matrix/62177883-f1bb-47f0-914d-32a22e3a8804,\
+ id=hostdev0"
--
2.31.1
Let's move the probe and remove callbacks into the vfio_ap_ops.c
file to keep all code related to managing queues in a single file. This
way, all functions related to queue management can be removed from the
vfio_ap_private.h header file defining the public interfaces for the
vfio_ap device driver.
Signed-off-by: Tony Krowiak <[email protected]>
Reviewed-by: Halil Pasic <[email protected]>
---
drivers/s390/crypto/vfio_ap_drv.c | 59 +--------------------------
drivers/s390/crypto/vfio_ap_ops.c | 31 +++++++++++++-
drivers/s390/crypto/vfio_ap_private.h | 5 ++-
3 files changed, 34 insertions(+), 61 deletions(-)
diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index e043ae236630..5013a5531171 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -100,64 +100,9 @@ static const struct attribute_group vfio_queue_attr_group = {
.attrs = vfio_queue_attrs,
};
-/**
- * vfio_ap_queue_dev_probe: Allocate a vfio_ap_queue structure and associate it
- * with the device as driver_data.
- *
- * @apdev: the AP device being probed
- *
- * Return: returns 0 if the probe succeeded; otherwise, returns an error if
- * storage could not be allocated for a vfio_ap_queue object or the
- * sysfs 'status' attribute could not be created for the queue device.
- */
-static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
-{
- int ret;
- struct vfio_ap_queue *q;
-
- q = kzalloc(sizeof(*q), GFP_KERNEL);
- if (!q)
- return -ENOMEM;
-
- mutex_lock(&matrix_dev->lock);
- dev_set_drvdata(&apdev->device, q);
- q->apqn = to_ap_queue(&apdev->device)->qid;
- q->saved_isc = VFIO_AP_ISC_INVALID;
-
- ret = sysfs_create_group(&apdev->device.kobj, &vfio_queue_attr_group);
- if (ret) {
- dev_set_drvdata(&apdev->device, NULL);
- kfree(q);
- }
-
- mutex_unlock(&matrix_dev->lock);
-
- return ret;
-}
-
-/**
- * vfio_ap_queue_dev_remove: Free the associated vfio_ap_queue structure.
- *
- * @apdev: the AP device being removed
- *
- * Takes the matrix lock to avoid actions on this device while doing the remove.
- */
-static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
-{
- struct vfio_ap_queue *q;
-
- mutex_lock(&matrix_dev->lock);
- sysfs_remove_group(&apdev->device.kobj, &vfio_queue_attr_group);
- q = dev_get_drvdata(&apdev->device);
- vfio_ap_mdev_reset_queue(q, 1);
- dev_set_drvdata(&apdev->device, NULL);
- kfree(q);
- mutex_unlock(&matrix_dev->lock);
-}
-
static struct ap_driver vfio_ap_drv = {
- .probe = vfio_ap_queue_dev_probe,
- .remove = vfio_ap_queue_dev_remove,
+ .probe = vfio_ap_mdev_probe_queue,
+ .remove = vfio_ap_mdev_remove_queue,
.ids = ap_queue_ids,
};
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 2b6b61719cce..c963443873e1 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -1201,8 +1201,7 @@ static struct vfio_ap_queue *vfio_ap_find_queue(int apqn)
return q;
}
-int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q,
- unsigned int retry)
+static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q, unsigned int retry)
{
struct ap_queue_status status;
int ret;
@@ -1411,3 +1410,31 @@ void vfio_ap_mdev_unregister(void)
mdev_unregister_device(&matrix_dev->device);
mdev_unregister_driver(&vfio_ap_matrix_driver);
}
+
+int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
+{
+ struct vfio_ap_queue *q;
+
+ q = kzalloc(sizeof(*q), GFP_KERNEL);
+ if (!q)
+ return -ENOMEM;
+ mutex_lock(&matrix_dev->lock);
+ q->apqn = to_ap_queue(&apdev->device)->qid;
+ q->saved_isc = VFIO_AP_ISC_INVALID;
+ dev_set_drvdata(&apdev->device, q);
+ mutex_unlock(&matrix_dev->lock);
+
+ return 0;
+}
+
+void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
+{
+ struct vfio_ap_queue *q;
+
+ mutex_lock(&matrix_dev->lock);
+ q = dev_get_drvdata(&apdev->device);
+ vfio_ap_mdev_reset_queue(q, 1);
+ dev_set_drvdata(&apdev->device, NULL);
+ kfree(q);
+ mutex_unlock(&matrix_dev->lock);
+}
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 648fcaf8104a..3cade25a1620 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -119,7 +119,8 @@ struct vfio_ap_queue {
int vfio_ap_mdev_register(void);
void vfio_ap_mdev_unregister(void);
-int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q,
- unsigned int retry);
+
+int vfio_ap_mdev_probe_queue(struct ap_device *queue);
+void vfio_ap_mdev_remove_queue(struct ap_device *queue);
#endif /* _VFIO_AP_PRIVATE_H_ */
--
2.31.1
Refresh the guest's APCB by filtering the APQNs assigned to the matrix mdev
that do not reference an AP queue device bound to the vfio_ap device
driver. The mdev's APQNs will be filtered according to the following rules:
* The APID of each adapter and the APQI of each domain that is not in the
host's AP configuration is filtered out.
* The APID of each adapter comprising an APQN that does not reference a
queue device bound to the vfio_ap device driver is filtered. The APQNs
are derived from the Cartesian product of the APID of each adapter and
APQI of each domain assigned to the mdev.
The control domains that are not assigned to the host's AP configuration
will also be filtered before assigning them to the guest's APCB.
Signed-off-by: Tony Krowiak <[email protected]>
---
drivers/s390/crypto/vfio_ap_ops.c | 96 ++++++++++++++++++++++++++++++-
1 file changed, 93 insertions(+), 3 deletions(-)
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 4b676a55f203..b67b2f0faeea 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -317,6 +317,63 @@ static void vfio_ap_matrix_init(struct ap_config_info *info,
matrix->adm_max = info->apxa ? info->Nd : 15;
}
+static void vfio_ap_mdev_filter_cdoms(struct ap_matrix_mdev *matrix_mdev)
+{
+ bitmap_and(matrix_mdev->shadow_apcb.adm, matrix_mdev->matrix.adm,
+ (unsigned long *)matrix_dev->info.adm, AP_DOMAINS);
+}
+
+/*
+ * vfio_ap_mdev_filter_matrix - copy the mdev's AP configuration to the KVM
+ * guest's APCB then filter the APIDs that do not
+ * comprise at least one APQN that references a
+ * queue device bound to the vfio_ap device driver.
+ *
+ * @matrix_mdev: the mdev whose AP configuration is to be filtered.
+ */
+static void vfio_ap_mdev_filter_matrix(unsigned long *apm, unsigned long *aqm,
+ struct ap_matrix_mdev *matrix_mdev)
+{
+ int ret;
+ unsigned long apid, apqi, apqn;
+
+ ret = ap_qci(&matrix_dev->info);
+ if (ret)
+ return;
+
+ vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb);
+
+ /*
+ * Copy the adapters, domains and control domains to the shadow_apcb
+ * from the matrix mdev, but only those that are assigned to the host's
+ * AP configuration.
+ */
+ bitmap_and(matrix_mdev->shadow_apcb.apm, matrix_mdev->matrix.apm,
+ (unsigned long *)matrix_dev->info.apm, AP_DEVICES);
+ bitmap_and(matrix_mdev->shadow_apcb.aqm, matrix_mdev->matrix.aqm,
+ (unsigned long *)matrix_dev->info.aqm, AP_DOMAINS);
+
+ for_each_set_bit_inv(apid, apm, AP_DEVICES) {
+ for_each_set_bit_inv(apqi, aqm, AP_DOMAINS) {
+ /*
+ * If the APQN is not bound to the vfio_ap device
+ * driver, then we can't assign it to the guest's
+ * AP configuration. The AP architecture won't
+ * allow filtering of a single APQN, so let's filter
+ * the APID since an adapter represents a physical
+ * hardware device.
+ */
+ apqn = AP_MKQID(apid, apqi);
+
+ if (!vfio_ap_mdev_get_queue(matrix_mdev, apqn)) {
+ clear_bit_inv(apid,
+ matrix_mdev->shadow_apcb.apm);
+ break;
+ }
+ }
+ }
+}
+
static int vfio_ap_mdev_probe(struct mdev_device *mdev)
{
struct ap_matrix_mdev *matrix_mdev;
@@ -672,6 +729,8 @@ static ssize_t assign_adapter_store(struct device *dev,
{
int ret;
unsigned long apid;
+ DECLARE_BITMAP(apm, AP_DEVICES);
+
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
mutex_lock(&matrix_dev->lock);
@@ -701,12 +760,15 @@ static ssize_t assign_adapter_store(struct device *dev,
goto done;
set_bit_inv(apid, matrix_mdev->matrix.apm);
+ memset(apm, 0, sizeof(apm));
+ set_bit_inv(apid, apm);
ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev);
if (ret)
goto share_err;
vfio_ap_mdev_link_adapter(matrix_mdev, apid);
+ vfio_ap_mdev_filter_matrix(apm, matrix_mdev->matrix.aqm, matrix_mdev);
ret = count;
goto done;
@@ -775,6 +837,10 @@ static ssize_t unassign_adapter_store(struct device *dev,
clear_bit_inv((unsigned long)apid, matrix_mdev->matrix.apm);
vfio_ap_mdev_unlink_adapter(matrix_mdev, apid);
+
+ if (test_bit_inv(apid, matrix_mdev->shadow_apcb.apm))
+ clear_bit_inv(apid, matrix_mdev->shadow_apcb.apm);
+
ret = count;
done:
mutex_unlock(&matrix_dev->lock);
@@ -848,6 +914,7 @@ static ssize_t assign_domain_store(struct device *dev,
{
int ret;
unsigned long apqi;
+ DECLARE_BITMAP(aqm, AP_DOMAINS);
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
unsigned long max_apqi = matrix_mdev->matrix.aqm_max;
@@ -872,12 +939,15 @@ static ssize_t assign_domain_store(struct device *dev,
goto done;
set_bit_inv(apqi, matrix_mdev->matrix.aqm);
+ memset(aqm, 0, sizeof(aqm));
+ set_bit_inv(apqi, aqm);
ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev);
if (ret)
goto share_err;
vfio_ap_mdev_link_domain(matrix_mdev, apqi);
+ vfio_ap_mdev_filter_matrix(matrix_mdev->matrix.apm, aqm, matrix_mdev);
ret = count;
goto done;
@@ -946,6 +1016,10 @@ static ssize_t unassign_domain_store(struct device *dev,
clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm);
vfio_ap_mdev_unlink_domain(matrix_mdev, apqi);
+
+ if (test_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm))
+ clear_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm);
+
ret = count;
done:
@@ -999,6 +1073,7 @@ static ssize_t assign_control_domain_store(struct device *dev,
* number of control domains that can be assigned.
*/
set_bit_inv(id, matrix_mdev->matrix.adm);
+ vfio_ap_mdev_filter_cdoms(matrix_mdev);
ret = count;
done:
mutex_unlock(&matrix_dev->lock);
@@ -1046,6 +1121,10 @@ static ssize_t unassign_control_domain_store(struct device *dev,
}
clear_bit_inv(domid, matrix_mdev->matrix.adm);
+
+ if (test_bit_inv(domid, matrix_mdev->shadow_apcb.adm))
+ clear_bit_inv(domid, matrix_mdev->shadow_apcb.adm);
+
ret = count;
done:
mutex_unlock(&matrix_dev->lock);
@@ -1186,8 +1265,6 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev,
kvm_get_kvm(kvm);
matrix_mdev->kvm = kvm;
- memcpy(&matrix_mdev->shadow_apcb, &matrix_mdev->matrix,
- sizeof(struct ap_matrix));
kvm_arch_crypto_set_masks(kvm, matrix_mdev->shadow_apcb.apm,
matrix_mdev->shadow_apcb.aqm,
matrix_mdev->shadow_apcb.adm);
@@ -1528,6 +1605,7 @@ static void vfio_ap_queue_link_mdev(struct vfio_ap_queue *q)
int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
{
struct vfio_ap_queue *q;
+ DECLARE_BITMAP(apm, AP_DEVICES);
q = kzalloc(sizeof(*q), GFP_KERNEL);
if (!q)
@@ -1537,6 +1615,12 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
q->apqn = to_ap_queue(&apdev->device)->qid;
q->saved_isc = VFIO_AP_ISC_INVALID;
vfio_ap_queue_link_mdev(q);
+ if (q->matrix_mdev) {
+ memset(apm, 0, sizeof(apm));
+ set_bit_inv(AP_QID_CARD(q->apqn), apm);
+ vfio_ap_mdev_filter_matrix(apm, q->matrix_mdev->matrix.aqm,
+ q->matrix_mdev);
+ }
dev_set_drvdata(&apdev->device, q);
mutex_unlock(&matrix_dev->lock);
@@ -1545,14 +1629,20 @@ int vfio_ap_mdev_probe_queue(struct ap_device *apdev)
void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
{
+ unsigned long apid;
struct vfio_ap_queue *q;
mutex_lock(&matrix_dev->lock);
q = dev_get_drvdata(&apdev->device);
- if (q->matrix_mdev)
+ if (q->matrix_mdev) {
vfio_ap_unlink_queue_fr_mdev(q);
+ apid = AP_QID_CARD(q->apqn);
+ if (test_bit_inv(apid, q->matrix_mdev->shadow_apcb.apm))
+ clear_bit_inv(apid, q->matrix_mdev->shadow_apcb.apm);
+ }
+
vfio_ap_mdev_reset_queue(q, 1);
dev_set_drvdata(&apdev->device, NULL);
kfree(q);
--
2.31.1
The APCB is a field within the CRYCB that provides the AP configuration
to a KVM guest. Let's introduce a shadow copy of the KVM guest's APCB and
maintain it for the lifespan of the guest.
The shadow APCB serves the following purposes:
1. The shadow APCB can be maintained even when the mediated device is not
currently in use by a KVM guest. Since the mediated device's AP
configuration is filtered to ensure that no AP queues are passed through
to the KVM guest that are not bound to the vfio_ap device driver or
available to the host, the mediated device's AP configuration may differ
from the guest's. Having a shadow of a guest's APCB allows us to provide
a sysfs interface to view the guest's APCB even if the mediated device
is not currently passed through to a KVM guest. This can aid in
problem determination when the guest is unexpectedly missing AP
resources.
2. If filtering was done in-place for the real APCB, the guest could pick
up a transient state. Doing the filtering on a shadow and transferring
the AP configuration to the real APCB after the guest is started or when
AP resources are assigned to or unassigned from the mediated device, or
when the host configuration changes, the guest's AP configuration will
never be in a transient state.
Signed-off-by: Tony Krowiak <[email protected]>
Reviewed-by: Halil Pasic <[email protected]>
---
drivers/s390/crypto/vfio_ap_ops.c | 10 ++++++----
drivers/s390/crypto/vfio_ap_private.h | 2 ++
2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index aa838ed47406..4b676a55f203 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -336,6 +336,7 @@ static int vfio_ap_mdev_probe(struct mdev_device *mdev)
matrix_mdev->mdev = mdev;
vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);
matrix_mdev->pqap_hook = handle_pqap;
+ vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb);
hash_init(matrix_mdev->qtable.queues);
mdev_set_drvdata(mdev, matrix_mdev);
mutex_lock(&matrix_dev->lock);
@@ -1185,10 +1186,11 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev,
kvm_get_kvm(kvm);
matrix_mdev->kvm = kvm;
- kvm_arch_crypto_set_masks(kvm,
- matrix_mdev->matrix.apm,
- matrix_mdev->matrix.aqm,
- matrix_mdev->matrix.adm);
+ memcpy(&matrix_mdev->shadow_apcb, &matrix_mdev->matrix,
+ sizeof(struct ap_matrix));
+ kvm_arch_crypto_set_masks(kvm, matrix_mdev->shadow_apcb.apm,
+ matrix_mdev->shadow_apcb.aqm,
+ matrix_mdev->shadow_apcb.adm);
mutex_unlock(&kvm->lock);
mutex_unlock(&matrix_dev->lock);
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index aea6a8b854b3..fa11a7e91e24 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -91,6 +91,7 @@ struct ap_queue_table {
* @node: allows the ap_matrix_mdev struct to be added to a list
* @matrix: the adapters, usage domains and control domains assigned to the
* mediated matrix device.
+ * @shadow_apcb: the shadow copy of the APCB field of the KVM guest's CRYCB
* @group_notifier: notifier block used for specifying callback function for
* handling the VFIO_GROUP_NOTIFY_SET_KVM event
* @iommu_notifier: notifier block used for specifying callback function for
@@ -105,6 +106,7 @@ struct ap_matrix_mdev {
struct vfio_device vdev;
struct list_head node;
struct ap_matrix matrix;
+ struct ap_matrix shadow_apcb;
struct notifier_block group_notifier;
struct notifier_block iommu_notifier;
struct kvm *kvm;
--
2.31.1
Let's implement the callback to indicate when an APQN
is in use by the vfio_ap device driver. The callback is
invoked whenever a change to the apmask or aqmask would
result in one or more queue devices being removed from the driver. The
vfio_ap device driver will indicate a resource is in use
if the APQN of any of the queue devices to be removed are assigned to
any of the matrix mdevs under the driver's control.
There is potential for a deadlock condition between the matrix_dev->lock
used to lock the matrix device during assignment of adapters and domains
and the ap_perms_mutex locked by the AP bus when changes are made to the
sysfs apmask/aqmask attributes.
The AP Perms lock controls access to the objects that store the adapter
numbers (ap_perms) and domain numbers (aq_perms) for the sysfs
/sys/bus/ap/apmask and /sys/bus/ap/aqmask attributes. These attributes
identify which queues are reserved for the zcrypt default device drivers.
Before allowing a bit to be removed from either mask, the AP bus must check
with the vfio_ap device driver to verify that none of the queues are
assigned to any of its mediated devices.
The apmask/aqmask attributes can be written or read at any time from
userspace, so care must be taken to prevent a deadlock with asynchronous
operations that might be taking place in the vfio_ap device driver. For
example, consider the following:
1. A system administrator assigns an adapter to a mediated device under the
control of the vfio_ap device driver. The driver will need to first take
the matrix_dev->guests_lock to potentially hot plug the adapter into
the KVM guest.
2. At the same time, a system administrator sets a bit in the sysfs
/sys/bus/ap/ap_mask attribute. To complete the operation, the AP bus
must:
a. Take the ap_perms_mutex lock to update the object storing the values
for the /sys/bus/ap/ap_mask attribute.
b. Call the vfio_ap device driver's in-use callback to verify that the
queues now being reserved for the default zcrypt drivers are not
assigned to a mediated device owned by the vfio_ap device driver. To
do the verification, the in-use callback function takes the
matrix_dev->guests_lock, but has to wait because it is already held
by the operation in 1 above.
3. The vfio_ap device driver calls an AP bus function to verify that the
new queues resulting from the assignment of the adapter in step 1 are
not reserved for the default zcrypt device driver. This AP bus function
tries to take the ap_perms_mutex lock but gets stuck waiting for the
waiting for the lock due to step 2a above.
Consequently, we have the following deadlock situation:
matrix_dev->lock locked (1)
ap_perms_mutex lock locked (2a)
Waiting for matrix_dev->lock (2b) which is currently held (1)
Waiting for ap_perms_mutex lock (3) which is currently held (2a)
To prevent this deadlock scenario, the in-use callback will use
mutex_trylock to take the matrix_dev->guests_lock and if the lock can not
be obtained, will return -EBUSY from the function.
Signed-off-by: Tony Krowiak <[email protected]>
---
drivers/s390/crypto/vfio_ap_drv.c | 1 +
drivers/s390/crypto/vfio_ap_ops.c | 81 ++++++++++++++++++++++++++-
drivers/s390/crypto/vfio_ap_private.h | 2 +
3 files changed, 82 insertions(+), 2 deletions(-)
diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index e8f3540ebfda..c4f0e28b1e91 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -103,6 +103,7 @@ static const struct attribute_group vfio_queue_attr_group = {
static struct ap_driver vfio_ap_drv = {
.probe = vfio_ap_mdev_probe_queue,
.remove = vfio_ap_mdev_remove_queue,
+ .in_use = vfio_ap_mdev_resource_in_use,
.ids = ap_queue_ids,
};
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index e9f7ec6fc6a5..63dfb9b89581 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -617,10 +617,32 @@ static int vfio_ap_mdev_verify_no_sharing(unsigned long *mdev_apm,
return 0;
}
+/**
+ * vfio_ap_mdev_validate_masks - verify that the APQNs assigned to the mdev are
+ * not reserved for the default zcrypt driver and
+ * are not assigned to another mdev.
+ *
+ * @matrix_mdev: the mdev to which the APQNs being validated are assigned.
+ *
+ * Return: One of the following values:
+ * o the error returned from the ap_apqn_in_matrix_owned_by_def_drv() function,
+ * most likely -EBUSY indicating the ap_perms_mutex lock is already held.
+ * o EADDRNOTAVAIL if an APQN assigned to @matrix_mdev is reserved for the
+ * zcrypt default driver.
+ * o EADDRINUSE if an APQN assigned to @matrix_mdev is assigned to another mdev
+ * o A zero indicating validation succeeded.
+ */
static int vfio_ap_mdev_validate_masks(struct ap_matrix_mdev *matrix_mdev)
{
- if (ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev->matrix.apm,
- matrix_mdev->matrix.aqm))
+ int ret;
+
+ ret = ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev->matrix.apm,
+ matrix_mdev->matrix.aqm);
+
+ if (ret < 0)
+ return ret;
+
+ if (ret == 1)
return -EADDRNOTAVAIL;
return vfio_ap_mdev_verify_no_sharing(matrix_mdev->matrix.apm,
@@ -711,6 +733,10 @@ static void vfio_ap_mdev_put_locks(struct ap_matrix_mdev *matrix_mdev)
* An APQN derived from the cross product of the APID being assigned
* and the APQIs previously assigned is being used by another mediated
* matrix device
+ *
+ * 5. -EAGAIN
+ * A lock required to validate the mdev's AP configuration could not
+ * be obtained.
*/
static ssize_t assign_adapter_store(struct device *dev,
struct device_attribute *attr,
@@ -897,6 +923,10 @@ static void vfio_ap_mdev_link_domain(struct ap_matrix_mdev *matrix_mdev,
* An APQN derived from the cross product of the APQI being assigned
* and the APIDs previously assigned is being used by another mediated
* matrix device
+ *
+ * 5. -EAGAIN
+ * The lock required to validate the mdev's AP configuration could not
+ * be obtained.
*/
static ssize_t assign_domain_store(struct device *dev,
struct device_attribute *attr,
@@ -1741,3 +1771,50 @@ void vfio_ap_mdev_remove_queue(struct ap_device *apdev)
kfree(q);
vfio_ap_mdev_put_qlocks(matrix_mdev);
}
+
+/**
+ * vfio_ap_mdev_resource_in_use: check whether any of a set of APQNs is
+ * assigned to a mediated device under the control
+ * of the vfio_ap device driver.
+ *
+ * @apm: a bitmap specifying a set of APIDs comprising the APQNs to check.
+ * @aqm: a bitmap specifying a set of APQIs comprising the APQNs to check.
+ *
+ * This function is invoked by the AP bus when changes to the apmask/aqmask
+ * attributes will result in giving control of the queue devices specified via
+ * @apm and @aqm to the default zcrypt device driver. Prior to calling this
+ * function, the AP bus locks the ap_perms_mutex. If this function is called
+ * while an adapter or domain is being assigned to a mediated device, the
+ * assignment operations will take the matrix_dev->guests_lock and
+ * matrix_dev->mdevs_lock then call the ap_apqn_in_matrix_owned_by_def_drv
+ * function, which also locks the ap_perms_mutex. This could result in a
+ * deadlock.
+ *
+ * To avoid a deadlock, this function will verify that the
+ * matrix_dev->guests_lock and matrix_dev->mdevs_lock are not currently held and
+ * will return -EBUSY if the locks can not be obtained.
+ *
+ * Return:
+ * * -EBUSY if the locks required by this function are already locked.
+ * * -EADDRINUSE if one or more of the APQNs specified via @apm/@aqm are
+ * assigned to a mediated device under the control of the vfio_ap
+ * device driver.
+ */
+int vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm)
+{
+ int ret;
+
+ if (!mutex_trylock(&matrix_dev->guests_lock))
+ return -EBUSY;
+
+ if (!mutex_trylock(&matrix_dev->mdevs_lock)) {
+ mutex_unlock(&matrix_dev->guests_lock);
+ return -EBUSY;
+ }
+
+ ret = vfio_ap_mdev_verify_no_sharing(apm, aqm);
+ mutex_unlock(&matrix_dev->mdevs_lock);
+ mutex_unlock(&matrix_dev->guests_lock);
+
+ return ret;
+}
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index a3811cd9852d..e30f171f89ec 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -146,4 +146,6 @@ void vfio_ap_mdev_unregister(void);
int vfio_ap_mdev_probe_queue(struct ap_device *queue);
void vfio_ap_mdev_remove_queue(struct ap_device *queue);
+int vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm);
+
#endif /* _VFIO_AP_PRIVATE_H_ */
--
2.31.1
PING!!
On 2/14/22 19:50, Tony Krowiak wrote:
> The current design for AP pass-through does not support making dynamic
> changes to the AP matrix of a running guest resulting in a few
> deficiencies this patch series is intended to mitigate:
>
> 1. Adapters, domains and control domains can not be added to or removed
> from a running guest. In order to modify a guest's AP configuration,
> the guest must be terminated; only then can AP resources be assigned
> to or unassigned from the guest's matrix mdev. The new AP
> configuration becomes available to the guest when it is subsequently
> restarted.
>
> 2. The AP bus's /sys/bus/ap/apmask and /sys/bus/ap/aqmask interfaces can
> be modified by a root user without any restrictions. A change to
> either mask can result in AP queue devices being unbound from the
> vfio_ap device driver and bound to a zcrypt device driver even if a
> guest is using the queues, thus giving the host access to the guest's
> private crypto data and vice versa.
>
> 3. The APQNs derived from the Cartesian product of the APIDs of the
> adapters and APQIs of the domains assigned to a matrix mdev must
> reference an AP queue device bound to the vfio_ap device driver. The
> AP architecture allows assignment of AP resources that are not
> available to the system, so this artificial restriction is not
> compliant with the architecture.
>
> 4. The AP configuration profile can be dynamically changed for the linux
> host after a KVM guest is started. For example, a new domain can be
> dynamically added to the configuration profile via the SE or an HMC
> connected to a DPM enabled lpar. Likewise, AP adapters can be
> dynamically configured (online state) and deconfigured (standby state)
> using the SE, an SCLP command or an HMC connected to a DPM enabled
> lpar. This can result in inadvertent sharing of AP queues between the
> guest and host.
>
> 5. A root user can manually unbind an AP queue device representing a
> queue in use by a KVM guest via the vfio_ap device driver's sysfs
> unbind attribute. In this case, the guest will be using a queue that
> is not bound to the driver which violates the device model.
>
> This patch series introduces the following changes to the current design
> to alleviate the shortcomings described above as well as to implement
> more of the AP architecture:
>
> 1. A root user will be prevented from making edits to the AP bus's
> /sys/bus/ap/apmask or /sys/bus/ap/aqmask if the change would transfer
> ownership of an APQN from the vfio_ap device driver to a zcrypt driver
> while the APQN is assigned to a matrix mdev.
>
> 2. Allow a root user to hot plug/unplug AP adapters, domains and control
> domains for a KVM guest using the matrix mdev via its sysfs
> assign/unassign attributes.
>
> 4. Allow assignment of an AP adapter or domain to a matrix mdev even if
> it results in assignment of an APQN that does not reference an AP
> queue device bound to the vfio_ap device driver, as long as the APQN
> is not reserved for use by the default zcrypt drivers (also known as
> over-provisioning of AP resources). Allowing over-provisioning of AP
> resources better models the architecture which does not preclude
> assigning AP resources that are not yet available in the system. Such
> APQNs, however, will not be assigned to the guest using the matrix
> mdev; only APQNs referencing AP queue devices bound to the vfio_ap
> device driver will actually get assigned to the guest.
>
> 5. Handle dynamic changes to the AP device model.
>
> 1. Rationale for changes to AP bus's apmask/aqmask interfaces:
> ----------------------------------------------------------
> Due to the extremely sensitive nature of cryptographic data, it is
> imperative that great care be taken to ensure that such data is secured.
> Allowing a root user, either inadvertently or maliciously, to configure
> these masks such that a queue is shared between the host and a guest is
> not only avoidable, it is advisable. It was suggested that this scenario
> is better handled in user space with management software, but that does
> not preclude a malicious administrator from using the sysfs interfaces
> to gain access to a guest's crypto data. It was also suggested that this
> scenario could be avoided by taking access to the adapter away from the
> guest and zeroing out the queues prior to the vfio_ap driver releasing the
> device; however, stealing an adapter in use from a guest as a by-product
> of an operation is bad and will likely cause problems for the guest
> unnecessarily. It was decided that the most effective solution with the
> least number of negative side effects is to prevent the situation at the
> source.
>
> 2. Rationale for hot plug/unplug using matrix mdev sysfs interfaces:
> ----------------------------------------------------------------
> Allowing a user to hot plug/unplug AP resources using the matrix mdev
> sysfs interfaces circumvents the need to terminate the guest in order to
> modify its AP configuration. Allowing dynamic configuration makes
> reconfiguring a guest's AP matrix much less disruptive.
>
> 3. Rationale for allowing over-provisioning of AP resources:
> -----------------------------------------------------------
> Allowing assignment of AP resources to a matrix mdev and ultimately to a
> guest better models the AP architecture. The architecture does not
> preclude assignment of unavailable AP resources. If a queue subsequently
> becomes available while a guest using the matrix mdev to which its APQN
> is assigned, the guest will be given access to it. If an APQN
> is dynamically unassigned from the underlying host system, it will
> automatically become unavailable to the guest.
>
> Change log v17-v18:
> ------------------
> * Added a new document, Documentation/s390/vfio-ap-locking.rst to describe
> the locking design for this series. This included a patch for adding the
> new doc to the MAITAINERS file for the VFIO AP maintainers.
>
>
> * Added Reviewed-by for Halil in patch 6
>
> * Restore filtering in the queue remove callback. (Halil)
>
> * Added patch s390/vfio-ap: hot unplug of AP devices when mdev removed to
> unplug all AP devices from the guest when the mdev is removed.
>
> * Split patch 9 (s390/vfio-ap: allow hot plug/unplug of AP resources using
> mdev device) into xx patches:
> - allow hot plug/unplug of AP devices when assigned/unassigned
>
> * Replaced v17 patch 08/15, s390/vfio-ap: keep track of active guests with
> s390/vfio-ap: introduce new mutex to control access to the KVM pointer.
> No longer tracking guests with a list of struct ap_guest objects. Added a
> global mutex called kvm_lock which must be held whenever the kvm->lock is
> taken. (Halil)
>
> * Changed signature of the filtering function to limit the APQNs
> examined. This change resulted in a cascade of changes to patches 5, 8
> and 12. (Halil)
>
> * Removed v17 patch 01/15 (s390/vfio-ap: Set pqap hook when vfio_ap module
> is loaded). (Halil, Jason).
>
> * Split patch 14 (notify drivers on config changed and scan complete
> callbacks) into two patches: One to make the AP bus changes and the other
> to implement the callbacks in the vfio_ap device driver. This was done
> to facilitate merging the AP bus changes separately from the vfio_ap
> driver changes. (Harald)
>
> * Removed check of driver flags in the __verify_card_reservations and
> __verify_queue_reservations functions in ap_bus.c to balance the
> weighting between the default and vfio_ap drivers. (Harald)
>
>
> Tony Krowiak (17):
> s390/ap: driver callback to indicate resource in use
> s390/ap: notify drivers on config changed and scan complete callbacks
> s390/vfio-ap: use new AP bus interface to search for queue devices
> s390/vfio-ap: move probe and remove callbacks to vfio_ap_ops.c
> s390/vfio-ap: manage link between queue struct and matrix mdev
> s390/vfio-ap: introduce shadow APCB
> s390/vfio-ap: refresh guest's APCB by filtering APQNs assigned to mdev
> s390/vfio-ap: allow assignment of unavailable AP queues to mdev device
> s390/vfio-ap: introduce new mutex to control access to the KVM pointer
> s390/vfio-ap: allow hot plug/unplug of AP devices when
> assigned/unassigned
> s390/vfio-ap: hot plug/unplug of AP devices when probed/removed
> s390/vfio-ap: reset queues after adapter/domain unassignment
> s390/vfio-ap: implement in-use callback for vfio_ap driver
> s390/vfio-ap: sysfs attribute to display the guest's matrix
> s390/vfio-ap: handle config changed and scan complete notification
> s390/vfio-ap: update docs to include dynamic config support
> s390/Docs: new doc describing lock usage by the vfio_ap device driver
> MAINTAINERS: pick up all vfio_ap docs for VFIO AP maintainers
>
> Documentation/s390/vfio-ap-locking.rst | 389 +++++++
> Documentation/s390/vfio-ap.rst | 492 ++++++---
> MAINTAINERS | 2 +-
> drivers/s390/crypto/ap_bus.c | 226 +++-
> drivers/s390/crypto/ap_bus.h | 16 +
> drivers/s390/crypto/vfio_ap_drv.c | 71 +-
> drivers/s390/crypto/vfio_ap_ops.c | 1347 ++++++++++++++++++------
> drivers/s390/crypto/vfio_ap_private.h | 57 +-
> 8 files changed, 2058 insertions(+), 542 deletions(-)
> create mode 100644 Documentation/s390/vfio-ap-locking.rst
>
PING!! Any takers?
On 2/14/22 19:50, Tony Krowiak wrote:
> The current design for AP pass-through does not support making dynamic
> changes to the AP matrix of a running guest resulting in a few
> deficiencies this patch series is intended to mitigate:
>
> 1. Adapters, domains and control domains can not be added to or removed
> from a running guest. In order to modify a guest's AP configuration,
> the guest must be terminated; only then can AP resources be assigned
> to or unassigned from the guest's matrix mdev. The new AP
> configuration becomes available to the guest when it is subsequently
> restarted.
>
> 2. The AP bus's /sys/bus/ap/apmask and /sys/bus/ap/aqmask interfaces can
> be modified by a root user without any restrictions. A change to
> either mask can result in AP queue devices being unbound from the
> vfio_ap device driver and bound to a zcrypt device driver even if a
> guest is using the queues, thus giving the host access to the guest's
> private crypto data and vice versa.
>
> 3. The APQNs derived from the Cartesian product of the APIDs of the
> adapters and APQIs of the domains assigned to a matrix mdev must
> reference an AP queue device bound to the vfio_ap device driver. The
> AP architecture allows assignment of AP resources that are not
> available to the system, so this artificial restriction is not
> compliant with the architecture.
>
> 4. The AP configuration profile can be dynamically changed for the linux
> host after a KVM guest is started. For example, a new domain can be
> dynamically added to the configuration profile via the SE or an HMC
> connected to a DPM enabled lpar. Likewise, AP adapters can be
> dynamically configured (online state) and deconfigured (standby state)
> using the SE, an SCLP command or an HMC connected to a DPM enabled
> lpar. This can result in inadvertent sharing of AP queues between the
> guest and host.
>
> 5. A root user can manually unbind an AP queue device representing a
> queue in use by a KVM guest via the vfio_ap device driver's sysfs
> unbind attribute. In this case, the guest will be using a queue that
> is not bound to the driver which violates the device model.
>
> This patch series introduces the following changes to the current design
> to alleviate the shortcomings described above as well as to implement
> more of the AP architecture:
>
> 1. A root user will be prevented from making edits to the AP bus's
> /sys/bus/ap/apmask or /sys/bus/ap/aqmask if the change would transfer
> ownership of an APQN from the vfio_ap device driver to a zcrypt driver
> while the APQN is assigned to a matrix mdev.
>
> 2. Allow a root user to hot plug/unplug AP adapters, domains and control
> domains for a KVM guest using the matrix mdev via its sysfs
> assign/unassign attributes.
>
> 4. Allow assignment of an AP adapter or domain to a matrix mdev even if
> it results in assignment of an APQN that does not reference an AP
> queue device bound to the vfio_ap device driver, as long as the APQN
> is not reserved for use by the default zcrypt drivers (also known as
> over-provisioning of AP resources). Allowing over-provisioning of AP
> resources better models the architecture which does not preclude
> assigning AP resources that are not yet available in the system. Such
> APQNs, however, will not be assigned to the guest using the matrix
> mdev; only APQNs referencing AP queue devices bound to the vfio_ap
> device driver will actually get assigned to the guest.
>
> 5. Handle dynamic changes to the AP device model.
>
> 1. Rationale for changes to AP bus's apmask/aqmask interfaces:
> ----------------------------------------------------------
> Due to the extremely sensitive nature of cryptographic data, it is
> imperative that great care be taken to ensure that such data is secured.
> Allowing a root user, either inadvertently or maliciously, to configure
> these masks such that a queue is shared between the host and a guest is
> not only avoidable, it is advisable. It was suggested that this scenario
> is better handled in user space with management software, but that does
> not preclude a malicious administrator from using the sysfs interfaces
> to gain access to a guest's crypto data. It was also suggested that this
> scenario could be avoided by taking access to the adapter away from the
> guest and zeroing out the queues prior to the vfio_ap driver releasing the
> device; however, stealing an adapter in use from a guest as a by-product
> of an operation is bad and will likely cause problems for the guest
> unnecessarily. It was decided that the most effective solution with the
> least number of negative side effects is to prevent the situation at the
> source.
>
> 2. Rationale for hot plug/unplug using matrix mdev sysfs interfaces:
> ----------------------------------------------------------------
> Allowing a user to hot plug/unplug AP resources using the matrix mdev
> sysfs interfaces circumvents the need to terminate the guest in order to
> modify its AP configuration. Allowing dynamic configuration makes
> reconfiguring a guest's AP matrix much less disruptive.
>
> 3. Rationale for allowing over-provisioning of AP resources:
> -----------------------------------------------------------
> Allowing assignment of AP resources to a matrix mdev and ultimately to a
> guest better models the AP architecture. The architecture does not
> preclude assignment of unavailable AP resources. If a queue subsequently
> becomes available while a guest using the matrix mdev to which its APQN
> is assigned, the guest will be given access to it. If an APQN
> is dynamically unassigned from the underlying host system, it will
> automatically become unavailable to the guest.
>
> Change log v17-v18:
> ------------------
> * Added a new document, Documentation/s390/vfio-ap-locking.rst to describe
> the locking design for this series. This included a patch for adding the
> new doc to the MAITAINERS file for the VFIO AP maintainers.
>
>
> * Added Reviewed-by for Halil in patch 6
>
> * Restore filtering in the queue remove callback. (Halil)
>
> * Added patch s390/vfio-ap: hot unplug of AP devices when mdev removed to
> unplug all AP devices from the guest when the mdev is removed.
>
> * Split patch 9 (s390/vfio-ap: allow hot plug/unplug of AP resources using
> mdev device) into xx patches:
> - allow hot plug/unplug of AP devices when assigned/unassigned
>
> * Replaced v17 patch 08/15, s390/vfio-ap: keep track of active guests with
> s390/vfio-ap: introduce new mutex to control access to the KVM pointer.
> No longer tracking guests with a list of struct ap_guest objects. Added a
> global mutex called kvm_lock which must be held whenever the kvm->lock is
> taken. (Halil)
>
> * Changed signature of the filtering function to limit the APQNs
> examined. This change resulted in a cascade of changes to patches 5, 8
> and 12. (Halil)
>
> * Removed v17 patch 01/15 (s390/vfio-ap: Set pqap hook when vfio_ap module
> is loaded). (Halil, Jason).
>
> * Split patch 14 (notify drivers on config changed and scan complete
> callbacks) into two patches: One to make the AP bus changes and the other
> to implement the callbacks in the vfio_ap device driver. This was done
> to facilitate merging the AP bus changes separately from the vfio_ap
> driver changes. (Harald)
>
> * Removed check of driver flags in the __verify_card_reservations and
> __verify_queue_reservations functions in ap_bus.c to balance the
> weighting between the default and vfio_ap drivers. (Harald)
>
>
> Tony Krowiak (17):
> s390/ap: driver callback to indicate resource in use
> s390/ap: notify drivers on config changed and scan complete callbacks
> s390/vfio-ap: use new AP bus interface to search for queue devices
> s390/vfio-ap: move probe and remove callbacks to vfio_ap_ops.c
> s390/vfio-ap: manage link between queue struct and matrix mdev
> s390/vfio-ap: introduce shadow APCB
> s390/vfio-ap: refresh guest's APCB by filtering APQNs assigned to mdev
> s390/vfio-ap: allow assignment of unavailable AP queues to mdev device
> s390/vfio-ap: introduce new mutex to control access to the KVM pointer
> s390/vfio-ap: allow hot plug/unplug of AP devices when
> assigned/unassigned
> s390/vfio-ap: hot plug/unplug of AP devices when probed/removed
> s390/vfio-ap: reset queues after adapter/domain unassignment
> s390/vfio-ap: implement in-use callback for vfio_ap driver
> s390/vfio-ap: sysfs attribute to display the guest's matrix
> s390/vfio-ap: handle config changed and scan complete notification
> s390/vfio-ap: update docs to include dynamic config support
> s390/Docs: new doc describing lock usage by the vfio_ap device driver
> MAINTAINERS: pick up all vfio_ap docs for VFIO AP maintainers
>
> Documentation/s390/vfio-ap-locking.rst | 389 +++++++
> Documentation/s390/vfio-ap.rst | 492 ++++++---
> MAINTAINERS | 2 +-
> drivers/s390/crypto/ap_bus.c | 226 +++-
> drivers/s390/crypto/ap_bus.h | 16 +
> drivers/s390/crypto/vfio_ap_drv.c | 71 +-
> drivers/s390/crypto/vfio_ap_ops.c | 1347 ++++++++++++++++++------
> drivers/s390/crypto/vfio_ap_private.h | 57 +-
> 8 files changed, 2058 insertions(+), 542 deletions(-)
> create mode 100644 Documentation/s390/vfio-ap-locking.rst
>
On 2/14/22 19:50, Tony Krowiak wrote:
> Refresh the guest's APCB by filtering the APQNs assigned to the matrix mdev
> that do not reference an AP queue device bound to the vfio_ap device
> driver. The mdev's APQNs will be filtered according to the following rules:
>
> * The APID of each adapter and the APQI of each domain that is not in the
> host's AP configuration is filtered out.
>
> * The APID of each adapter comprising an APQN that does not reference a
> queue device bound to the vfio_ap device driver is filtered. The APQNs
> are derived from the Cartesian product of the APID of each adapter and
> APQI of each domain assigned to the mdev.
>
> The control domains that are not assigned to the host's AP configuration
> will also be filtered before assigning them to the guest's APCB.
>
> Signed-off-by: Tony Krowiak <[email protected]>
> ---
> drivers/s390/crypto/vfio_ap_ops.c | 96 ++++++++++++++++++++++++++++++-
> 1 file changed, 93 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 4b676a55f203..b67b2f0faeea 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -317,6 +317,63 @@ static void vfio_ap_matrix_init(struct ap_config_info *info,
> matrix->adm_max = info->apxa ? info->Nd : 15;
> }
>
> +static void vfio_ap_mdev_filter_cdoms(struct ap_matrix_mdev *matrix_mdev)
> +{
> + bitmap_and(matrix_mdev->shadow_apcb.adm, matrix_mdev->matrix.adm,
> + (unsigned long *)matrix_dev->info.adm, AP_DOMAINS);
> +}
> +
> +/*
> + * vfio_ap_mdev_filter_matrix - copy the mdev's AP configuration to the KVM
> + * guest's APCB then filter the APIDs that do not
> + * comprise at least one APQN that references a
> + * queue device bound to the vfio_ap device driver.
> + *
> + * @matrix_mdev: the mdev whose AP configuration is to be filtered.
> + */
> +static void vfio_ap_mdev_filter_matrix(unsigned long *apm, unsigned long *aqm,
> + struct ap_matrix_mdev *matrix_mdev)
> +{
> + int ret;
> + unsigned long apid, apqi, apqn;
> +
> + ret = ap_qci(&matrix_dev->info);
> + if (ret)
> + return;
> +
> + vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb);
Do you need to call vfio_ap_matrix_init here? It seems to me like this would
only be necesarry if apxa could be dynamically added or removed. Here is a
copy of vfio_ap_matrix_init, for reference:
static void vfio_ap_matrix_init(struct ap_config_info *info,
struct ap_matrix *matrix)
{
matrix->apm_max = info->apxa ? info->Na : 63;
matrix->aqm_max = info->apxa ? info->Nd : 15;
matrix->adm_max = info->apxa ? info->Nd : 15;
}
It seems like this should be figured out once and stored when the
ap_matrix_mdev struct is first created. Unless I'm wrong, and the status of
apxa can change dynamically, in which case the maximums would need to be
updated somewhere.
--
-- Jason J. Herne ([email protected])
On 2/28/22 10:53, Tony Krowiak wrote:
> PING!! Any takers?
I'm taking a look, starting where I left off on v17, patch #7.
--
-- Jason J. Herne ([email protected])
On 3/2/22 14:35, Jason J. Herne wrote:
> On 2/14/22 19:50, Tony Krowiak wrote:
>> Refresh the guest's APCB by filtering the APQNs assigned to the
>> matrix mdev
>> that do not reference an AP queue device bound to the vfio_ap device
>> driver. The mdev's APQNs will be filtered according to the following
>> rules:
>>
>> * The APID of each adapter and the APQI of each domain that is not in
>> the
>> host's AP configuration is filtered out.
>>
>> * The APID of each adapter comprising an APQN that does not reference a
>> queue device bound to the vfio_ap device driver is filtered. The APQNs
>> are derived from the Cartesian product of the APID of each adapter and
>> APQI of each domain assigned to the mdev.
>>
>> The control domains that are not assigned to the host's AP configuration
>> will also be filtered before assigning them to the guest's APCB.
>>
>> Signed-off-by: Tony Krowiak <[email protected]>
>> ---
>> drivers/s390/crypto/vfio_ap_ops.c | 96 ++++++++++++++++++++++++++++++-
>> 1 file changed, 93 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
>> b/drivers/s390/crypto/vfio_ap_ops.c
>> index 4b676a55f203..b67b2f0faeea 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -317,6 +317,63 @@ static void vfio_ap_matrix_init(struct
>> ap_config_info *info,
>> matrix->adm_max = info->apxa ? info->Nd : 15;
>> }
>> +static void vfio_ap_mdev_filter_cdoms(struct ap_matrix_mdev
>> *matrix_mdev)
>> +{
>> + bitmap_and(matrix_mdev->shadow_apcb.adm, matrix_mdev->matrix.adm,
>> + (unsigned long *)matrix_dev->info.adm, AP_DOMAINS);
>> +}
>> +
>> +/*
>> + * vfio_ap_mdev_filter_matrix - copy the mdev's AP configuration to
>> the KVM
>> + * guest's APCB then filter the APIDs that do not
>> + * comprise at least one APQN that references a
>> + * queue device bound to the vfio_ap device driver.
>> + *
>> + * @matrix_mdev: the mdev whose AP configuration is to be filtered.
>> + */
>> +static void vfio_ap_mdev_filter_matrix(unsigned long *apm, unsigned
>> long *aqm,
>> + struct ap_matrix_mdev *matrix_mdev)
>> +{
>> + int ret;
>> + unsigned long apid, apqi, apqn;
>> +
>> + ret = ap_qci(&matrix_dev->info);
>> + if (ret)
>> + return;
>> +
>> + vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb);
>
> Do you need to call vfio_ap_matrix_init here? It seems to me like this
> would
> only be necesarry if apxa could be dynamically added or removed. Here
> is a
> copy of vfio_ap_matrix_init, for reference:
>
> static void vfio_ap_matrix_init(struct ap_config_info *info,
> struct ap_matrix *matrix)
> {
> matrix->apm_max = info->apxa ? info->Na : 63;
> matrix->aqm_max = info->apxa ? info->Nd : 15;
> matrix->adm_max = info->apxa ? info->Nd : 15;
> }
>
> It seems like this should be figured out once and stored when the
> ap_matrix_mdev struct is first created. Unless I'm wrong, and the
> status of
> apxa can change dynamically, in which case the maximums would need to be
> updated somewhere.
It's an interesting question to which I don't have a definitive answer.
I'll run it
by our architects. On the other hand, making this call here is not entirely
unreasonable and merely superfluous at worst, but I'll look into it.
Tony K
>
>
On 3/22/22 09:13, Jason J. Herne wrote:
> On 2/14/22 19:50, Tony Krowiak wrote:
> ...
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c
>> b/drivers/s390/crypto/vfio_ap_ops.c
>> index e9f7ec6fc6a5..63dfb9b89581 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -617,10 +617,32 @@ static int
>> vfio_ap_mdev_verify_no_sharing(unsigned long *mdev_apm,
>> return 0;
>> }
>> +/**
>> + * vfio_ap_mdev_validate_masks - verify that the APQNs assigned to
>> the mdev are
>> + * not reserved for the default zcrypt driver and
>> + * are not assigned to another mdev.
>> + *
>> + * @matrix_mdev: the mdev to which the APQNs being validated are
>> assigned.
>> + *
>> + * Return: One of the following values:
>> + * o the error returned from the
>> ap_apqn_in_matrix_owned_by_def_drv() function,
>> + * most likely -EBUSY indicating the ap_perms_mutex lock is
>> already held.
>> + * o EADDRNOTAVAIL if an APQN assigned to @matrix_mdev is reserved
>> for the
>> + * zcrypt default driver.
>> + * o EADDRINUSE if an APQN assigned to @matrix_mdev is assigned to
>> another mdev
>> + * o A zero indicating validation succeeded.
>> + */
>> static int vfio_ap_mdev_validate_masks(struct ap_matrix_mdev
>> *matrix_mdev)
>> {
>> - if (ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev->matrix.apm,
>> - matrix_mdev->matrix.aqm))
>> + int ret;
>> +
>> + ret = ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev->matrix.apm,
>> + matrix_mdev->matrix.aqm);
>> +
>> + if (ret < 0)
>> + return ret;
>> +
>> + if (ret == 1)
>> return -EADDRNOTAVAIL;
>
> I took a look at ap_apqn_in_matrix_owned_by_def_drv(). It appears that
> this function
> can only ever return 0 or 1. This patch is changed to watch for a
> negative return
> value from ap_apqn_in_matrix_owned_by_def_drv(). Am I missing something?
That's odd, careless error, I'll fix it.
>
>
On 2/14/22 19:50, Tony Krowiak wrote:
...
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index e9f7ec6fc6a5..63dfb9b89581 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -617,10 +617,32 @@ static int vfio_ap_mdev_verify_no_sharing(unsigned long *mdev_apm,
> return 0;
> }
>
> +/**
> + * vfio_ap_mdev_validate_masks - verify that the APQNs assigned to the mdev are
> + * not reserved for the default zcrypt driver and
> + * are not assigned to another mdev.
> + *
> + * @matrix_mdev: the mdev to which the APQNs being validated are assigned.
> + *
> + * Return: One of the following values:
> + * o the error returned from the ap_apqn_in_matrix_owned_by_def_drv() function,
> + * most likely -EBUSY indicating the ap_perms_mutex lock is already held.
> + * o EADDRNOTAVAIL if an APQN assigned to @matrix_mdev is reserved for the
> + * zcrypt default driver.
> + * o EADDRINUSE if an APQN assigned to @matrix_mdev is assigned to another mdev
> + * o A zero indicating validation succeeded.
> + */
> static int vfio_ap_mdev_validate_masks(struct ap_matrix_mdev *matrix_mdev)
> {
> - if (ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev->matrix.apm,
> - matrix_mdev->matrix.aqm))
> + int ret;
> +
> + ret = ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev->matrix.apm,
> + matrix_mdev->matrix.aqm);
> +
> + if (ret < 0)
> + return ret;
> +
> + if (ret == 1)
> return -EADDRNOTAVAIL;
I took a look at ap_apqn_in_matrix_owned_by_def_drv(). It appears that this function
can only ever return 0 or 1. This patch is changed to watch for a negative return
value from ap_apqn_in_matrix_owned_by_def_drv(). Am I missing something?
--
-- Jason J. Herne ([email protected])