Hi all,
The series provides:
1- interception of the STSI instruction forwarding the CPU topology
2- interpretation of the PTF instruction
3- a KVM capability for the userland hypervisor to ask KVM to
setup PTF interpretation.
4- KVM ioctl to get and set the MTCR bit of the SCA in order to
migrate this bit during a migration.
0- Foreword
The S390 CPU topology is reported using two instructions:
- PTF, to get information if the CPU topology did change since last
PTF instruction or a subsystem reset.
- STSI, to get the topology information, consisting of the topology
of the CPU inside the sockets, of the sockets inside the books etc.
The PTF(2) instruction report a change if the STSI(15.1.2) instruction
will report a difference with the last STSI(15.1.2) instruction*.
With the SIE interpretation, the PTF(2) instruction will report a
change to the guest if the host sets the SCA.MTCR bit.
*The STSI(15.1.2) instruction reports:
- The cores address within a socket
- The polarization of the cores
- The CPU type of the cores
- If the cores are dedicated or not
We decided to implement the CPU topology for S390 in several steps:
- first we report CPU hotplug
In future development we will provide:
- modification of the CPU mask inside sockets
- handling of shared CPUs
- reporting of the CPU Type
- reporting of the polarization
1- Interception of STSI
To provide Topology information to the guest through the STSI
instruction, we forward STSI with Function Code 15 to the
userland hypervisor which will take care to provide the right
information to the guest.
To let the guest use both the PTF instruction to check if a topology
change occurred and sthe STSI_15.x.x instruction we add a new KVM
capability to enable the topology facility.
2- Interpretation of PTF with FC(2)
The PTF instruction reports a topology change if there is any change
with a previous STSI(15.1.2) SYSIB.
Changes inside a STSI(15.1.2) SYSIB occur if CPU bits are set or clear
inside the CPU Topology List Entry CPU mask field, which happens with
changes in CPU polarization, dedication, CPU types and adding or
removing CPUs in a socket.
Considering that the KVM guests currently only supports:
- horizontal polarization
- type 3 (Linux) CPU
And that we decide to support only:
- dedicated CPUs on the host
- pinned vCPUs on the guest
the creation of vCPU will is the only trigger to set the MTCR bit for
a guest.
The reporting to the guest is done using the Multiprocessor
Topology-Change-Report (MTCR) bit of the utility entry of the guest's
SCA which will be cleared during the interpretation of PTF.
Regards,
Pierre
Pierre Morel (2):
KVM: s390: guest support for topology function
KVM: s390: resetting the Topology-Change-Report
Documentation/virt/kvm/api.rst | 25 ++++++++++
arch/s390/include/asm/kvm_host.h | 18 +++++--
arch/s390/include/uapi/asm/kvm.h | 1 +
arch/s390/kvm/kvm-s390.c | 82 ++++++++++++++++++++++++++++++++
arch/s390/kvm/priv.c | 20 ++++++--
arch/s390/kvm/vsie.c | 8 ++++
include/uapi/linux/kvm.h | 1 +
7 files changed, 148 insertions(+), 7 deletions(-)
--
2.31.1
Changelog:
from v12 to v13
- remove check for protected virtualization
(Janosch)
- move stting of sca out of the loop
(Janis)
- Change some function names and typos
(Janis, Janosch)
from v11 to v12
- protect sca pointer
(Janis)
- check for user_stsi before returning information
to userland
(Janis)
- check for protected virtualization
(Pierre)
from v10 to v11
- access mctr with interlocked access instead of ipte_lock
(Janis)
- set mctr in kvm_arch_vcpu_destroy
(Nico)
- better function documentation
(Claudio)
- use a single function to set and clear
(Janosch)
- Use u8 as API data
(David, Janis)
- Check KVM_CAP_S390_USER_STSI before returning
data to userspace
(Nico)
from v9 to v10
- Suppression of the check on real CPU migration
(Christian)
- Changed the check on fc in handle_stsi
(David)
from v8 to v9
- bug correction in kvm_s390_topology_changed
(Heiko)
- simplification for ipte_lock/unlock to use kvm
as arg instead of vcpu and test on sclp.has_siif
instead of the SIE ECA_SII.
(David)
- use of a single value for reporting if the
topology changed instead of a structure
(David)
from v7 to v8
- implement reset handling
(Janosch)
- change the way to check if the topology changed
(Nico, Heiko)
from v6 to v7
- rebase
from v5 to v6
- make the subject more accurate
(Claudio)
- Change the kvm_s390_set_mtcr() function to have vcpu in the name
(Janosch)
- Replace the checks on ECB_PTF wit the check of facility 11
(Janosch)
- modify kvm_arch_vcpu_load, move the check in a function in
the header file
(Janosh)
- No magical number replace the "new cpu value" of -1 with a define
(Janosch)
- Make the checks for STSI validity clearer
(Janosch)
from v4 tp v5
- modify the way KVM_CAP is tested to be OK with vsie
(David)
from v3 to v4
- squatch both patches
(David)
- Added Documentation
(David)
- Modified the detection for new vCPUs
(Pierre)
from v2 to v3
- use PTF interpretation
(Christian)
- optimize arch_update_cpu_topology using PTF
(Pierre)
from v1 to v2:
- Add a KVM capability to let QEMU know we support PTF and STSI 15
(David)
- check KVM facility 11 before accepting STSI fc 15
(David)
- handle all we can in userland
(David)
- add tracing to STSI fc 15
(Connie)
During a subsystem reset the Topology-Change-Report is cleared.
Let's give userland the possibility to clear the MTCR in the case
of a subsystem reset.
To migrate the MTCR, we give userland the possibility to
query the MTCR state.
We indicate KVM support for the CPU topology facility with a new
KVM capability: KVM_CAP_S390_CPU_TOPOLOGY.
Signed-off-by: Pierre Morel <[email protected]>
Reviewed-by: Janis Schoetterl-Glausch <[email protected]>
---
Documentation/virt/kvm/api.rst | 25 ++++++++++++++++
arch/s390/include/uapi/asm/kvm.h | 1 +
arch/s390/kvm/kvm-s390.c | 51 ++++++++++++++++++++++++++++++++
include/uapi/linux/kvm.h | 1 +
4 files changed, 78 insertions(+)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 82baa7682829..892fc2e470d7 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -8159,6 +8159,31 @@ PV guests. The `KVM_PV_DUMP` command is available for the
dump related UV data. Also the vcpu ioctl `KVM_S390_PV_CPU_COMMAND` is
available and supports the `KVM_PV_DUMP_CPU` subcommand.
+8.38 KVM_CAP_S390_CPU_TOPOLOGY
+------------------------------
+
+:Capability: KVM_CAP_S390_CPU_TOPOLOGY
+:Architectures: s390
+:Type: vm
+
+This capability indicates that KVM will provide the S390 CPU Topology
+facility which consist of the interpretation of the PTF instruction for
+the function code 2 along with interception and forwarding of both the
+PTF instruction with function codes 0 or 1 and the STSI(15,1,x)
+instruction to the userland hypervisor.
+
+The stfle facility 11, CPU Topology facility, should not be indicated
+to the guest without this capability.
+
+When this capability is present, KVM provides a new attribute group
+on vm fd, KVM_S390_VM_CPU_TOPOLOGY.
+This new attribute allows to get, set or clear the Modified Change
+Topology Report (MTCR) bit of the SCA through the kvm_device_attr
+structure.
+
+When getting the Modified Change Topology Report value, the attr->addr
+must point to a byte where the value will be stored or retrieved from.
+
9. Known KVM API problems
=========================
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 7a6b14874d65..a73cf01a1606 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -74,6 +74,7 @@ struct kvm_s390_io_adapter_req {
#define KVM_S390_VM_CRYPTO 2
#define KVM_S390_VM_CPU_MODEL 3
#define KVM_S390_VM_MIGRATION 4
+#define KVM_S390_VM_CPU_TOPOLOGY 5
/* kvm attributes for mem_ctrl */
#define KVM_S390_VM_MEM_ENABLE_CMMA 0
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 330a0cd4b8c8..b2cb13d1c0cd 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -647,6 +647,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_S390_ZPCI_OP:
r = kvm_s390_pci_interp_allowed();
break;
+ case KVM_CAP_S390_CPU_TOPOLOGY:
+ r = test_facility(11);
+ break;
default:
r = 0;
}
@@ -858,6 +861,20 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
icpt_operexc_on_all_vcpus(kvm);
r = 0;
break;
+ case KVM_CAP_S390_CPU_TOPOLOGY:
+ r = -EINVAL;
+ mutex_lock(&kvm->lock);
+ if (kvm->created_vcpus) {
+ r = -EBUSY;
+ } else if (test_facility(11)) {
+ set_kvm_facility(kvm->arch.model.fac_mask, 11);
+ set_kvm_facility(kvm->arch.model.fac_list, 11);
+ r = 0;
+ }
+ mutex_unlock(&kvm->lock);
+ VM_EVENT(kvm, 3, "ENABLE: CAP_S390_CPU_TOPOLOGY %s",
+ r ? "(not available)" : "(success)");
+ break;
default:
r = -EINVAL;
break;
@@ -1794,6 +1811,31 @@ static void kvm_s390_update_topology_change_report(struct kvm *kvm, bool val)
read_unlock(&kvm->arch.sca_lock);
}
+static int kvm_s390_set_topo_change_indication(struct kvm *kvm,
+ struct kvm_device_attr *attr)
+{
+ if (!test_kvm_facility(kvm, 11))
+ return -ENXIO;
+
+ kvm_s390_update_topology_change_report(kvm, !!attr->attr);
+ return 0;
+}
+
+static int kvm_s390_get_topo_change_indication(struct kvm *kvm,
+ struct kvm_device_attr *attr)
+{
+ u8 topo;
+
+ if (!test_kvm_facility(kvm, 11))
+ return -ENXIO;
+
+ read_lock(&kvm->arch.sca_lock);
+ topo = ((struct bsca_block *)kvm->arch.sca)->utility.mtcr;
+ read_unlock(&kvm->arch.sca_lock);
+
+ return put_user(topo, (u8 __user *)attr->addr);
+}
+
static int kvm_s390_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
{
int ret;
@@ -1814,6 +1856,9 @@ static int kvm_s390_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
case KVM_S390_VM_MIGRATION:
ret = kvm_s390_vm_set_migration(kvm, attr);
break;
+ case KVM_S390_VM_CPU_TOPOLOGY:
+ ret = kvm_s390_set_topo_change_indication(kvm, attr);
+ break;
default:
ret = -ENXIO;
break;
@@ -1839,6 +1884,9 @@ static int kvm_s390_vm_get_attr(struct kvm *kvm, struct kvm_device_attr *attr)
case KVM_S390_VM_MIGRATION:
ret = kvm_s390_vm_get_migration(kvm, attr);
break;
+ case KVM_S390_VM_CPU_TOPOLOGY:
+ ret = kvm_s390_get_topo_change_indication(kvm, attr);
+ break;
default:
ret = -ENXIO;
break;
@@ -1912,6 +1960,9 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
case KVM_S390_VM_MIGRATION:
ret = 0;
break;
+ case KVM_S390_VM_CPU_TOPOLOGY:
+ ret = test_kvm_facility(kvm, 11) ? 0 : -ENXIO;
+ break;
default:
ret = -ENXIO;
break;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 80216c6cece1..16ce54d6a868 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1158,6 +1158,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_SYSTEM_EVENT_DATA 215
#define KVM_CAP_ARM_SYSTEM_SUSPEND 216
#define KVM_CAP_S390_PROTECTED_DUMP 217
+#define KVM_CAP_S390_CPU_TOPOLOGY 218
#define KVM_CAP_S390_ZPCI_OP 221
#ifdef KVM_CAP_IRQ_ROUTING
--
2.31.1
On 7/14/22 12:18, Pierre Morel wrote:
> During a subsystem reset the Topology-Change-Report is cleared.
>
> Let's give userland the possibility to clear the MTCR in the case
> of a subsystem reset.
>
> To migrate the MTCR, we give userland the possibility to
> query the MTCR state.
>
> We indicate KVM support for the CPU topology facility with a new
> KVM capability: KVM_CAP_S390_CPU_TOPOLOGY.
>
> Signed-off-by: Pierre Morel <[email protected]>
> Reviewed-by: Janis Schoetterl-Glausch <[email protected]>
Nit below, but:
Reviewed-by: Janosch Frank <[email protected]>
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1158,6 +1158,7 @@ struct kvm_ppc_resize_hpt {
> #define KVM_CAP_SYSTEM_EVENT_DATA 215
> #define KVM_CAP_ARM_SYSTEM_SUSPEND 216
> #define KVM_CAP_S390_PROTECTED_DUMP 217
> +#define KVM_CAP_S390_CPU_TOPOLOGY 218
> #define KVM_CAP_S390_ZPCI_OP 221
Using 222 and moving it a line down might make more sense as 218 is
KVM_CAP_X86_TRIPLE_FAULT_EVENT.
Can you fix this and push both patches to devel?
Also send the fixed patch as a reply to this message so I can pick it
from the list.
next and devel have diverted a bit so I will need to fix this up for
next, same for the Documentation entry which will be 6.39 instead of 6.38.
>
> #ifdef KVM_CAP_IRQ_ROUTING
During a subsystem reset the Topology-Change-Report is cleared.
Let's give userland the possibility to clear the MTCR in the case
of a subsystem reset.
To migrate the MTCR, we give userland the possibility to
query the MTCR state.
We indicate KVM support for the CPU topology facility with a new
KVM capability: KVM_CAP_S390_CPU_TOPOLOGY.
Signed-off-by: Pierre Morel <[email protected]>
Reviewed-by: Janis Schoetterl-Glausch <[email protected]>
Reviewed-by: Janosch Frank <[email protected]>
---
Documentation/virt/kvm/api.rst | 25 ++++++++++++++++
arch/s390/include/uapi/asm/kvm.h | 1 +
arch/s390/kvm/kvm-s390.c | 51 ++++++++++++++++++++++++++++++++
include/uapi/linux/kvm.h | 1 +
4 files changed, 78 insertions(+)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 82baa7682829..892fc2e470d7 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -8159,6 +8159,31 @@ PV guests. The `KVM_PV_DUMP` command is available for the
dump related UV data. Also the vcpu ioctl `KVM_S390_PV_CPU_COMMAND` is
available and supports the `KVM_PV_DUMP_CPU` subcommand.
+8.38 KVM_CAP_S390_CPU_TOPOLOGY
+------------------------------
+
+:Capability: KVM_CAP_S390_CPU_TOPOLOGY
+:Architectures: s390
+:Type: vm
+
+This capability indicates that KVM will provide the S390 CPU Topology
+facility which consist of the interpretation of the PTF instruction for
+the function code 2 along with interception and forwarding of both the
+PTF instruction with function codes 0 or 1 and the STSI(15,1,x)
+instruction to the userland hypervisor.
+
+The stfle facility 11, CPU Topology facility, should not be indicated
+to the guest without this capability.
+
+When this capability is present, KVM provides a new attribute group
+on vm fd, KVM_S390_VM_CPU_TOPOLOGY.
+This new attribute allows to get, set or clear the Modified Change
+Topology Report (MTCR) bit of the SCA through the kvm_device_attr
+structure.
+
+When getting the Modified Change Topology Report value, the attr->addr
+must point to a byte where the value will be stored or retrieved from.
+
9. Known KVM API problems
=========================
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 7a6b14874d65..a73cf01a1606 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -74,6 +74,7 @@ struct kvm_s390_io_adapter_req {
#define KVM_S390_VM_CRYPTO 2
#define KVM_S390_VM_CPU_MODEL 3
#define KVM_S390_VM_MIGRATION 4
+#define KVM_S390_VM_CPU_TOPOLOGY 5
/* kvm attributes for mem_ctrl */
#define KVM_S390_VM_MEM_ENABLE_CMMA 0
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 330a0cd4b8c8..b2cb13d1c0cd 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -647,6 +647,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_S390_ZPCI_OP:
r = kvm_s390_pci_interp_allowed();
break;
+ case KVM_CAP_S390_CPU_TOPOLOGY:
+ r = test_facility(11);
+ break;
default:
r = 0;
}
@@ -858,6 +861,20 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
icpt_operexc_on_all_vcpus(kvm);
r = 0;
break;
+ case KVM_CAP_S390_CPU_TOPOLOGY:
+ r = -EINVAL;
+ mutex_lock(&kvm->lock);
+ if (kvm->created_vcpus) {
+ r = -EBUSY;
+ } else if (test_facility(11)) {
+ set_kvm_facility(kvm->arch.model.fac_mask, 11);
+ set_kvm_facility(kvm->arch.model.fac_list, 11);
+ r = 0;
+ }
+ mutex_unlock(&kvm->lock);
+ VM_EVENT(kvm, 3, "ENABLE: CAP_S390_CPU_TOPOLOGY %s",
+ r ? "(not available)" : "(success)");
+ break;
default:
r = -EINVAL;
break;
@@ -1794,6 +1811,31 @@ static void kvm_s390_update_topology_change_report(struct kvm *kvm, bool val)
read_unlock(&kvm->arch.sca_lock);
}
+static int kvm_s390_set_topo_change_indication(struct kvm *kvm,
+ struct kvm_device_attr *attr)
+{
+ if (!test_kvm_facility(kvm, 11))
+ return -ENXIO;
+
+ kvm_s390_update_topology_change_report(kvm, !!attr->attr);
+ return 0;
+}
+
+static int kvm_s390_get_topo_change_indication(struct kvm *kvm,
+ struct kvm_device_attr *attr)
+{
+ u8 topo;
+
+ if (!test_kvm_facility(kvm, 11))
+ return -ENXIO;
+
+ read_lock(&kvm->arch.sca_lock);
+ topo = ((struct bsca_block *)kvm->arch.sca)->utility.mtcr;
+ read_unlock(&kvm->arch.sca_lock);
+
+ return put_user(topo, (u8 __user *)attr->addr);
+}
+
static int kvm_s390_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
{
int ret;
@@ -1814,6 +1856,9 @@ static int kvm_s390_vm_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
case KVM_S390_VM_MIGRATION:
ret = kvm_s390_vm_set_migration(kvm, attr);
break;
+ case KVM_S390_VM_CPU_TOPOLOGY:
+ ret = kvm_s390_set_topo_change_indication(kvm, attr);
+ break;
default:
ret = -ENXIO;
break;
@@ -1839,6 +1884,9 @@ static int kvm_s390_vm_get_attr(struct kvm *kvm, struct kvm_device_attr *attr)
case KVM_S390_VM_MIGRATION:
ret = kvm_s390_vm_get_migration(kvm, attr);
break;
+ case KVM_S390_VM_CPU_TOPOLOGY:
+ ret = kvm_s390_get_topo_change_indication(kvm, attr);
+ break;
default:
ret = -ENXIO;
break;
@@ -1912,6 +1960,9 @@ static int kvm_s390_vm_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
case KVM_S390_VM_MIGRATION:
ret = 0;
break;
+ case KVM_S390_VM_CPU_TOPOLOGY:
+ ret = test_kvm_facility(kvm, 11) ? 0 : -ENXIO;
+ break;
default:
ret = -ENXIO;
break;
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 80216c6cece1..08206212fd36 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1159,6 +1159,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_ARM_SYSTEM_SUSPEND 216
#define KVM_CAP_S390_PROTECTED_DUMP 217
#define KVM_CAP_S390_ZPCI_OP 221
+#define KVM_CAP_S390_CPU_TOPOLOGY 222
#ifdef KVM_CAP_IRQ_ROUTING
--
2.31.1
On 7/14/22 12:18, Pierre Morel wrote:
> Hi all,
>
> The series provides:
> 1- interception of the STSI instruction forwarding the CPU topology
> 2- interpretation of the PTF instruction
> 3- a KVM capability for the userland hypervisor to ask KVM to
> setup PTF interpretation.
> 4- KVM ioctl to get and set the MTCR bit of the SCA in order to
> migrate this bit during a migration.
>
Thanks, picked