This series is to share sva(shared virtual addressing) domains with all
devices bound to one mm.
Problem
-------
In the current iommu core code, sva domain is allocated per IOMMU group,
when device driver is binding a process address space to a device (which is
handled in iommu_sva_bind_device()). If one than more device is bound to
the same process address space, there must be more than one sva domain
instance, with each device having one. In other words, the sva domain
doesn't share between those devices bound to the same process address
space, and that leads to two problems:
1) device driver has to duplicate sva domains with enqcmd, as those sva
domains have the same PASID and are relevant to one virtual address space.
This makes the sva domain handling complex in device drivers.
2) IOMMU driver cannot get sufficient info of the IOMMUs that have
devices behind them bound to the same virtual address space, when handling
mmu_notifier_ops callbacks. As a result, IOMMU IOTLB invalidation is
performed per device instead of per IOMMU, and that may lead to
superfluous IOTLB invalidation issue, especially in a virtualization
environment where all devices may be behind one virtual IOMMU.
Solution
--------
This patch-set tries to fix those two problems by allowing sharing sva
domains with all devices bound to a mm. To achieve this, a new structure
pointer is introduced to mm to replace the old PASID field, which can keep
the info of PASID as well as the corresponding shared sva domains.
Besides, function iommu_sva_bind_device() is updated to ensure a new sva
domain can only be allocated when the old ones cannot work for the IOMMU.
With these changes, a device driver can expect one sva domain could work
for per PASID instance(e.g., enqcmd PASID instance), and therefore may get
rid of handling sva domain duplication. Besides, IOMMU driver (e.g., intel
vt-d driver) can get sufficient info (e.g., the info of the IOMMUs having
their devices bound to one virtual address space) when handling
mmu_notifier_ops callbacks, to remove the redundant IOTLB invalidations.
Arguably there shouldn't be more than one sva_domain with the same PASID,
and in any sane configuration there should be only 1 type of IOMMU driver
that needs only 1 SVA domain. However, in reality, IOMMUs on one platform
may not be identical to each other. Thus, attaching a sva domain that has
been successfully bound to device A behind a IOMMU A, to device B behind
IOMMU B may get failed due to the difference between IOMMU A and IOMMU
B. In this case, a new sva domain with the same PASID needs to be
allocated to work with IOMMU B. That's why we need a list to keep sva
domains of one PASID. For the platform where IOMMUs are compatible to each
other, there should be one sva domain in the list.
v9:
- Add Jason's patch which solves an issue of Kconfig symbol naming used in
mm_struct and update this patch-set on it.
v8: https://lore.kernel.org/linux-iommu/[email protected]/
- CC more people
- CC [email protected] mailing list.
When sending version 7, some issue happened in my CC list and that caused
version 7 wasn't sent to [email protected].
- Rebase to v6.6-rc6 and make a few format changes.
v7: https://lore.kernel.org/lkml/[email protected]/
- Add mm_pasid_init() back and do zeroing mm->iommu_mm pointer in
mm_pasid_init() to avoid the use-after-free/double-free problem.
- Update the commit message of patch "iommu: Add mm_get_enqcmd_pasid()
helper function".
v6: https://lore.kernel.org/linux-iommu/[email protected]/
- Rename iommu_sva_alloc_pasid() to iommu_alloc_mm_data().
- Hold the iommu_sva_lock before invoking iommu_alloc_mm_data().
- Remove "iommu: Introduce mm_get_pasid() helper function" patch, because
SMMUv3 decides to use mm_get_enqcmd_pasid() instead and other users are
using iommu_sva_get_pasid() to get the pasid value. Besides, the iommu
core accesses iommu_mm_data in the critical section protected by
iommu_sva_lock. So no need to add another helper to retrieve PASID
atomically.
v5: https://lore.kernel.org/linux-iommu/[email protected]/
- Order patch "iommu/vt-d: Remove mm->pasid in intel_sva_bind_mm()"
first in this series.
- Update commit message of patch "iommu: Introduce mm_get_pasid()
helper function"
- Use smp_store_release() & READ_ONCE() in storing and loading mm's
pasid value.
v4: https://lore.kernel.org/linux-iommu/[email protected]/
- Rebase to v6.6-rc1.
v3: https://lore.kernel.org/linux-iommu/[email protected]/
- Add a comment describing domain->next.
- Expand explanation of why PASID isn't released in
iommu_sva_unbind_device().
- Add a patch to remove mm->pasid in intel_sva_bind_mm()
v2: https://lore.kernel.org/linux-iommu/[email protected]/
- Add mm_get_enqcmd_pasid().
- Update commit message.
v1: https://lore.kernel.org/linux-iommu/[email protected]/
RFC: https://lore.kernel.org/linux-iommu/[email protected]/
Jason Gunthorpe (1):
iommu: Change kconfig around IOMMU_SVA
Tina Zhang (5):
iommu/vt-d: Remove mm->pasid in intel_sva_bind_mm()
iommu: Add mm_get_enqcmd_pasid() helper function
mm: Add structure to keep sva information
iommu: Support mm PASID 1:n with sva domains
mm: Deprecate pasid field
arch/Kconfig | 5 +
arch/x86/Kconfig | 1 +
arch/x86/kernel/traps.c | 4 +-
drivers/iommu/Kconfig | 1 +
.../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 23 +++--
drivers/iommu/intel/svm.c | 14 +--
drivers/iommu/iommu-sva.c | 94 +++++++++++--------
include/linux/iommu.h | 40 +++++++-
include/linux/mm_types.h | 5 +-
include/linux/sched.h | 2 +-
kernel/fork.c | 2 +-
mm/Kconfig | 3 +
mm/init-mm.c | 3 -
13 files changed, 131 insertions(+), 66 deletions(-)
--
2.39.3
Introduce iommu_mm_data structure to keep sva information (pasid and the
related sva domains). Add iommu_mm pointer, pointing to an instance of
iommu_mm_data structure, to mm.
Reviewed-by: Vasant Hegde <[email protected]>
Reviewed-by: Lu Baolu <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Tested-by: Nicolin Chen <[email protected]>
Signed-off-by: Tina Zhang <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
---
include/linux/iommu.h | 5 +++++
include/linux/mm_types.h | 2 ++
2 files changed, 7 insertions(+)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 95792bf42f96..a807182c3d2e 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -679,6 +679,11 @@ struct iommu_sva {
struct iommu_domain *domain;
};
+struct iommu_mm_data {
+ u32 pasid;
+ struct list_head sva_domains;
+};
+
int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
const struct iommu_ops *ops);
void iommu_fwspec_free(struct device *dev);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 330f3cd8d5ad..2dbf18e26c5a 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -670,6 +670,7 @@ struct mm_cid {
#endif
struct kioctx_table;
+struct iommu_mm_data;
struct mm_struct {
struct {
/*
@@ -883,6 +884,7 @@ struct mm_struct {
#ifdef CONFIG_IOMMU_MM_DATA
u32 pasid;
+ struct iommu_mm_data *iommu_mm;
#endif
#ifdef CONFIG_KSM
/*
--
2.39.3
mm_get_enqcmd_pasid() should be used by architecture code and closely
related to learn the PASID value that the x86 ENQCMD operation should
use for the mm.
For the moment SMMUv3 uses this without any connection to ENQCMD, it
will be cleaned up similar to how the prior patch made VT-d use the
PASID argument of set_dev_pasid().
The motivation is to replace mm->pasid with an iommu private data
structure that is introduced in a later patch.
Reviewed-by: Lu Baolu <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Tested-by: Nicolin Chen <[email protected]>
Signed-off-by: Tina Zhang <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
---
arch/x86/kernel/traps.c | 2 +-
.../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 23 ++++++++++++-------
drivers/iommu/iommu-sva.c | 2 +-
include/linux/iommu.h | 12 ++++++++++
4 files changed, 29 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 2b62dbb3396a..5944d759afe7 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -591,7 +591,7 @@ static bool try_fixup_enqcmd_gp(void)
if (!mm_valid_pasid(current->mm))
return false;
- pasid = current->mm->pasid;
+ pasid = mm_get_enqcmd_pasid(current->mm);
/*
* Did this thread already have its PASID activated?
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
index 353248ab18e7..05722121f00e 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
@@ -246,7 +246,8 @@ static void arm_smmu_mm_arch_invalidate_secondary_tlbs(struct mmu_notifier *mn,
smmu_domain);
}
- arm_smmu_atc_inv_domain(smmu_domain, mm->pasid, start, size);
+ arm_smmu_atc_inv_domain(smmu_domain, mm_get_enqcmd_pasid(mm), start,
+ size);
}
static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
@@ -264,10 +265,11 @@ static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
* DMA may still be running. Keep the cd valid to avoid C_BAD_CD events,
* but disable translation.
*/
- arm_smmu_update_ctx_desc_devices(smmu_domain, mm->pasid, &quiet_cd);
+ arm_smmu_update_ctx_desc_devices(smmu_domain, mm_get_enqcmd_pasid(mm),
+ &quiet_cd);
arm_smmu_tlb_inv_asid(smmu_domain->smmu, smmu_mn->cd->asid);
- arm_smmu_atc_inv_domain(smmu_domain, mm->pasid, 0, 0);
+ arm_smmu_atc_inv_domain(smmu_domain, mm_get_enqcmd_pasid(mm), 0, 0);
smmu_mn->cleared = true;
mutex_unlock(&sva_lock);
@@ -325,10 +327,13 @@ arm_smmu_mmu_notifier_get(struct arm_smmu_domain *smmu_domain,
spin_lock_irqsave(&smmu_domain->devices_lock, flags);
list_for_each_entry(master, &smmu_domain->devices, domain_head) {
- ret = arm_smmu_write_ctx_desc(master, mm->pasid, cd);
+ ret = arm_smmu_write_ctx_desc(master, mm_get_enqcmd_pasid(mm),
+ cd);
if (ret) {
- list_for_each_entry_from_reverse(master, &smmu_domain->devices, domain_head)
- arm_smmu_write_ctx_desc(master, mm->pasid, NULL);
+ list_for_each_entry_from_reverse(
+ master, &smmu_domain->devices, domain_head)
+ arm_smmu_write_ctx_desc(
+ master, mm_get_enqcmd_pasid(mm), NULL);
break;
}
}
@@ -358,7 +363,8 @@ static void arm_smmu_mmu_notifier_put(struct arm_smmu_mmu_notifier *smmu_mn)
list_del(&smmu_mn->list);
- arm_smmu_update_ctx_desc_devices(smmu_domain, mm->pasid, NULL);
+ arm_smmu_update_ctx_desc_devices(smmu_domain, mm_get_enqcmd_pasid(mm),
+ NULL);
/*
* If we went through clear(), we've already invalidated, and no
@@ -366,7 +372,8 @@ static void arm_smmu_mmu_notifier_put(struct arm_smmu_mmu_notifier *smmu_mn)
*/
if (!smmu_mn->cleared) {
arm_smmu_tlb_inv_asid(smmu_domain->smmu, cd->asid);
- arm_smmu_atc_inv_domain(smmu_domain, mm->pasid, 0, 0);
+ arm_smmu_atc_inv_domain(smmu_domain, mm_get_enqcmd_pasid(mm), 0,
+ 0);
}
/* Frees smmu_mn */
diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index b78671a8a914..4a2f5699747f 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -141,7 +141,7 @@ u32 iommu_sva_get_pasid(struct iommu_sva *handle)
{
struct iommu_domain *domain = handle->domain;
- return domain->mm->pasid;
+ return mm_get_enqcmd_pasid(domain->mm);
}
EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index c1f2b6f9a3d0..95792bf42f96 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -1198,6 +1198,12 @@ static inline bool mm_valid_pasid(struct mm_struct *mm)
{
return mm->pasid != IOMMU_PASID_INVALID;
}
+
+static inline u32 mm_get_enqcmd_pasid(struct mm_struct *mm)
+{
+ return mm->pasid;
+}
+
void mm_pasid_drop(struct mm_struct *mm);
struct iommu_sva *iommu_sva_bind_device(struct device *dev,
struct mm_struct *mm);
@@ -1220,6 +1226,12 @@ static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle)
}
static inline void mm_pasid_init(struct mm_struct *mm) {}
static inline bool mm_valid_pasid(struct mm_struct *mm) { return false; }
+
+static inline u32 mm_get_enqcmd_pasid(struct mm_struct *mm)
+{
+ return IOMMU_PASID_INVALID;
+}
+
static inline void mm_pasid_drop(struct mm_struct *mm) {}
#endif /* CONFIG_IOMMU_SVA */
--
2.39.3
Each mm bound to devices gets a PASID and corresponding sva domains
allocated in iommu_sva_bind_device(), which are referenced by iommu_mm
field of the mm. The PASID is released in __mmdrop(), while a sva domain
is released when no one is using it (the reference count is decremented
in iommu_sva_unbind_device()). However, although sva domains and their
PASID are separate objects such that their own life cycles could be
handled independently, an enqcmd use case may require releasing the
PASID in releasing the mm (i.e., once a PASID is allocated for a mm, it
will be permanently used by the mm and won't be released until the end
of mm) and only allows to drop the PASID after the sva domains are
released. To this end, mmgrab() is called in iommu_sva_domain_alloc() to
increment the mm reference count and mmdrop() is invoked in
iommu_domain_free() to decrement the mm reference count.
Since the required info of PASID and sva domains is kept in struct
iommu_mm_data of a mm, use mm->iommu_mm field instead of the old pasid
field in mm struct. The sva domain list is protected by iommu_sva_lock.
Besides, this patch removes mm_pasid_init(), as with the introduced
iommu_mm structure, initializing mm pasid in mm_init() is unnecessary.
Reviewed-by: Lu Baolu <[email protected]>
Reviewed-by: Vasant Hegde <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Tested-by: Nicolin Chen <[email protected]>
Signed-off-by: Tina Zhang <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
---
drivers/iommu/iommu-sva.c | 92 +++++++++++++++++++++++----------------
include/linux/iommu.h | 23 ++++++++--
2 files changed, 74 insertions(+), 41 deletions(-)
diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index 4a2f5699747f..5175e8d85247 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -12,32 +12,42 @@
static DEFINE_MUTEX(iommu_sva_lock);
/* Allocate a PASID for the mm within range (inclusive) */
-static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev)
+static struct iommu_mm_data *iommu_alloc_mm_data(struct mm_struct *mm, struct device *dev)
{
+ struct iommu_mm_data *iommu_mm;
ioasid_t pasid;
- int ret = 0;
+
+ lockdep_assert_held(&iommu_sva_lock);
if (!arch_pgtable_dma_compat(mm))
- return -EBUSY;
+ return ERR_PTR(-EBUSY);
- mutex_lock(&iommu_sva_lock);
+ iommu_mm = mm->iommu_mm;
/* Is a PASID already associated with this mm? */
- if (mm_valid_pasid(mm)) {
- if (mm->pasid >= dev->iommu->max_pasids)
- ret = -EOVERFLOW;
- goto out;
+ if (iommu_mm) {
+ if (iommu_mm->pasid >= dev->iommu->max_pasids)
+ return ERR_PTR(-EOVERFLOW);
+ return iommu_mm;
}
+ iommu_mm = kzalloc(sizeof(struct iommu_mm_data), GFP_KERNEL);
+ if (!iommu_mm)
+ return ERR_PTR(-ENOMEM);
+
pasid = iommu_alloc_global_pasid(dev);
if (pasid == IOMMU_PASID_INVALID) {
- ret = -ENOSPC;
- goto out;
+ kfree(iommu_mm);
+ return ERR_PTR(-ENOSPC);
}
- mm->pasid = pasid;
- ret = 0;
-out:
- mutex_unlock(&iommu_sva_lock);
- return ret;
+ iommu_mm->pasid = pasid;
+ INIT_LIST_HEAD(&iommu_mm->sva_domains);
+ /*
+ * Make sure the write to mm->iommu_mm is not reordered in front of
+ * initialization to iommu_mm fields. If it does, readers may see a
+ * valid iommu_mm with uninitialized values.
+ */
+ smp_store_release(&mm->iommu_mm, iommu_mm);
+ return iommu_mm;
}
/**
@@ -58,31 +68,33 @@ static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev)
*/
struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm)
{
+ struct iommu_mm_data *iommu_mm;
struct iommu_domain *domain;
struct iommu_sva *handle;
int ret;
+ mutex_lock(&iommu_sva_lock);
+
/* Allocate mm->pasid if necessary. */
- ret = iommu_sva_alloc_pasid(mm, dev);
- if (ret)
- return ERR_PTR(ret);
+ iommu_mm = iommu_alloc_mm_data(mm, dev);
+ if (IS_ERR(iommu_mm)) {
+ ret = PTR_ERR(iommu_mm);
+ goto out_unlock;
+ }
handle = kzalloc(sizeof(*handle), GFP_KERNEL);
- if (!handle)
- return ERR_PTR(-ENOMEM);
-
- mutex_lock(&iommu_sva_lock);
- /* Search for an existing domain. */
- domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid,
- IOMMU_DOMAIN_SVA);
- if (IS_ERR(domain)) {
- ret = PTR_ERR(domain);
+ if (!handle) {
+ ret = -ENOMEM;
goto out_unlock;
}
- if (domain) {
- domain->users++;
- goto out;
+ /* Search for an existing domain. */
+ list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next) {
+ ret = iommu_attach_device_pasid(domain, dev, iommu_mm->pasid);
+ if (!ret) {
+ domain->users++;
+ goto out;
+ }
}
/* Allocate a new domain and set it on device pasid. */
@@ -92,23 +104,23 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
goto out_unlock;
}
- ret = iommu_attach_device_pasid(domain, dev, mm->pasid);
+ ret = iommu_attach_device_pasid(domain, dev, iommu_mm->pasid);
if (ret)
goto out_free_domain;
domain->users = 1;
+ list_add(&domain->next, &mm->iommu_mm->sva_domains);
+
out:
mutex_unlock(&iommu_sva_lock);
handle->dev = dev;
handle->domain = domain;
-
return handle;
out_free_domain:
iommu_domain_free(domain);
+ kfree(handle);
out_unlock:
mutex_unlock(&iommu_sva_lock);
- kfree(handle);
-
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(iommu_sva_bind_device);
@@ -124,12 +136,13 @@ EXPORT_SYMBOL_GPL(iommu_sva_bind_device);
void iommu_sva_unbind_device(struct iommu_sva *handle)
{
struct iommu_domain *domain = handle->domain;
- ioasid_t pasid = domain->mm->pasid;
+ struct iommu_mm_data *iommu_mm = domain->mm->iommu_mm;
struct device *dev = handle->dev;
mutex_lock(&iommu_sva_lock);
+ iommu_detach_device_pasid(domain, dev, iommu_mm->pasid);
if (--domain->users == 0) {
- iommu_detach_device_pasid(domain, dev, pasid);
+ list_del(&domain->next);
iommu_domain_free(domain);
}
mutex_unlock(&iommu_sva_lock);
@@ -205,8 +218,11 @@ iommu_sva_handle_iopf(struct iommu_fault *fault, void *data)
void mm_pasid_drop(struct mm_struct *mm)
{
- if (likely(!mm_valid_pasid(mm)))
+ struct iommu_mm_data *iommu_mm = mm->iommu_mm;
+
+ if (!iommu_mm)
return;
- iommu_free_global_pasid(mm->pasid);
+ iommu_free_global_pasid(iommu_mm->pasid);
+ kfree(iommu_mm);
}
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index a807182c3d2e..98b199603588 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -113,6 +113,11 @@ struct iommu_domain {
struct { /* IOMMU_DOMAIN_SVA */
struct mm_struct *mm;
int users;
+ /*
+ * Next iommu_domain in mm->iommu_mm->sva-domains list
+ * protected by iommu_sva_lock.
+ */
+ struct list_head next;
};
};
};
@@ -1197,16 +1202,28 @@ static inline bool tegra_dev_iommu_get_stream_id(struct device *dev, u32 *stream
#ifdef CONFIG_IOMMU_MM_DATA
static inline void mm_pasid_init(struct mm_struct *mm)
{
- mm->pasid = IOMMU_PASID_INVALID;
+ /*
+ * During dup_mm(), a new mm will be memcpy'd from an old one and that makes
+ * the new mm and the old one point to a same iommu_mm instance. When either
+ * one of the two mms gets released, the iommu_mm instance is freed, leaving
+ * the other mm running into a use-after-free/double-free problem. To avoid
+ * the problem, zeroing the iommu_mm pointer of a new mm is needed here.
+ */
+ mm->iommu_mm = NULL;
}
+
static inline bool mm_valid_pasid(struct mm_struct *mm)
{
- return mm->pasid != IOMMU_PASID_INVALID;
+ return READ_ONCE(mm->iommu_mm);
}
static inline u32 mm_get_enqcmd_pasid(struct mm_struct *mm)
{
- return mm->pasid;
+ struct iommu_mm_data *iommu_mm = READ_ONCE(mm->iommu_mm);
+
+ if (!iommu_mm)
+ return IOMMU_PASID_INVALID;
+ return iommu_mm->pasid;
}
void mm_pasid_drop(struct mm_struct *mm);
--
2.39.3
Drop the pasid field, as all the information needed for sva domain
management has been moved to the newly added iommu_mm field.
Reviewed-by: Lu Baolu <[email protected]>
Reviewed-by: Vasant Hegde <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Signed-off-by: Tina Zhang <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
---
include/linux/mm_types.h | 1 -
mm/init-mm.c | 3 ---
2 files changed, 4 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 2dbf18e26c5a..5fb881b4758c 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -883,7 +883,6 @@ struct mm_struct {
struct work_struct async_put_work;
#ifdef CONFIG_IOMMU_MM_DATA
- u32 pasid;
struct iommu_mm_data *iommu_mm;
#endif
#ifdef CONFIG_KSM
diff --git a/mm/init-mm.c b/mm/init-mm.c
index c52dc2740a3d..24c809379274 100644
--- a/mm/init-mm.c
+++ b/mm/init-mm.c
@@ -44,9 +44,6 @@ struct mm_struct init_mm = {
#endif
.user_ns = &init_user_ns,
.cpu_bitmap = CPU_BITS_NONE,
-#ifdef CONFIG_IOMMU_MM_DATA
- .pasid = IOMMU_PASID_INVALID,
-#endif
INIT_MM_CONTEXT(init_mm)
};
--
2.39.3
On Fri, Oct 27, 2023 at 08:05:19AM +0800, Tina Zhang wrote:
> Jason Gunthorpe (1):
> iommu: Change kconfig around IOMMU_SVA
>
> Tina Zhang (5):
> iommu/vt-d: Remove mm->pasid in intel_sva_bind_mm()
> iommu: Add mm_get_enqcmd_pasid() helper function
> mm: Add structure to keep sva information
> iommu: Support mm PASID 1:n with sva domains
> mm: Deprecate pasid field
Applied, thanks.
Hi, Tina
On Fri, 27 Oct 2023 at 08:06, Tina Zhang <[email protected]> wrote:
>
> Each mm bound to devices gets a PASID and corresponding sva domains
> allocated in iommu_sva_bind_device(), which are referenced by iommu_mm
> field of the mm. The PASID is released in __mmdrop(), while a sva domain
> is released when no one is using it (the reference count is decremented
> in iommu_sva_unbind_device()). However, although sva domains and their
> PASID are separate objects such that their own life cycles could be
> handled independently, an enqcmd use case may require releasing the
> PASID in releasing the mm (i.e., once a PASID is allocated for a mm, it
> will be permanently used by the mm and won't be released until the end
> of mm) and only allows to drop the PASID after the sva domains are
> released. To this end, mmgrab() is called in iommu_sva_domain_alloc() to
> increment the mm reference count and mmdrop() is invoked in
> iommu_domain_free() to decrement the mm reference count.
>
> Since the required info of PASID and sva domains is kept in struct
> iommu_mm_data of a mm, use mm->iommu_mm field instead of the old pasid
> field in mm struct. The sva domain list is protected by iommu_sva_lock.
>
> Besides, this patch removes mm_pasid_init(), as with the introduced
> iommu_mm structure, initializing mm pasid in mm_init() is unnecessary.
>
> Reviewed-by: Lu Baolu <[email protected]>
> Reviewed-by: Vasant Hegde <[email protected]>
> Reviewed-by: Jason Gunthorpe <[email protected]>
> Tested-by: Nicolin Chen <[email protected]>
> Signed-off-by: Tina Zhang <[email protected]>
> Signed-off-by: Jason Gunthorpe <[email protected]>
> ---
> drivers/iommu/iommu-sva.c | 92 +++++++++++++++++++++++----------------
> include/linux/iommu.h | 23 ++++++++--
> 2 files changed, 74 insertions(+), 41 deletions(-)
>
> diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
> index 4a2f5699747f..5175e8d85247 100644
> --- a/drivers/iommu/iommu-sva.c
> +++ b/drivers/iommu/iommu-sva.c
> @@ -12,32 +12,42 @@
> static DEFINE_MUTEX(iommu_sva_lock);
>
> /* Allocate a PASID for the mm within range (inclusive) */
> -static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev)
> +static struct iommu_mm_data *iommu_alloc_mm_data(struct mm_struct *mm, struct device *dev)
> {
> + struct iommu_mm_data *iommu_mm;
> ioasid_t pasid;
> - int ret = 0;
> +
> + lockdep_assert_held(&iommu_sva_lock);
>
> if (!arch_pgtable_dma_compat(mm))
> - return -EBUSY;
> + return ERR_PTR(-EBUSY);
>
> - mutex_lock(&iommu_sva_lock);
> + iommu_mm = mm->iommu_mm;
> /* Is a PASID already associated with this mm? */
> - if (mm_valid_pasid(mm)) {
> - if (mm->pasid >= dev->iommu->max_pasids)
> - ret = -EOVERFLOW;
> - goto out;
> + if (iommu_mm) {
> + if (iommu_mm->pasid >= dev->iommu->max_pasids)
> + return ERR_PTR(-EOVERFLOW);
> + return iommu_mm;
> }
>
> + iommu_mm = kzalloc(sizeof(struct iommu_mm_data), GFP_KERNEL);
> + if (!iommu_mm)
> + return ERR_PTR(-ENOMEM);
> +
> pasid = iommu_alloc_global_pasid(dev);
> if (pasid == IOMMU_PASID_INVALID) {
> - ret = -ENOSPC;
> - goto out;
> + kfree(iommu_mm);
> + return ERR_PTR(-ENOSPC);
> }
> - mm->pasid = pasid;
> - ret = 0;
> -out:
> - mutex_unlock(&iommu_sva_lock);
> - return ret;
> + iommu_mm->pasid = pasid;
> + INIT_LIST_HEAD(&iommu_mm->sva_domains);
> + /*
> + * Make sure the write to mm->iommu_mm is not reordered in front of
> + * initialization to iommu_mm fields. If it does, readers may see a
> + * valid iommu_mm with uninitialized values.
> + */
> + smp_store_release(&mm->iommu_mm, iommu_mm);
> + return iommu_mm;
> }
>
> /**
> @@ -58,31 +68,33 @@ static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev)
> */
> struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm)
> {
> + struct iommu_mm_data *iommu_mm;
> struct iommu_domain *domain;
> struct iommu_sva *handle;
> int ret;
>
> + mutex_lock(&iommu_sva_lock);
> +
> /* Allocate mm->pasid if necessary. */
> - ret = iommu_sva_alloc_pasid(mm, dev);
> - if (ret)
> - return ERR_PTR(ret);
> + iommu_mm = iommu_alloc_mm_data(mm, dev);
> + if (IS_ERR(iommu_mm)) {
> + ret = PTR_ERR(iommu_mm);
> + goto out_unlock;
> + }
>
> handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> - if (!handle)
> - return ERR_PTR(-ENOMEM);
> -
> - mutex_lock(&iommu_sva_lock);
> - /* Search for an existing domain. */
> - domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid,
> - IOMMU_DOMAIN_SVA);
> - if (IS_ERR(domain)) {
> - ret = PTR_ERR(domain);
> + if (!handle) {
> + ret = -ENOMEM;
> goto out_unlock;
> }
>
> - if (domain) {
> - domain->users++;
> - goto out;
Our multi bind test case broke since 6.8-rc1.
The test case can use same domain & pasid, return different handle,
6.7 simply domain->users ++ and return.
> + /* Search for an existing domain. */
> + list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next) {
> + ret = iommu_attach_device_pasid(domain, dev, iommu_mm->pasid);
Now iommu_attach_device_pasid return BUSY since the same pasid.
And then iommu_sva_bind_device attach ret=-16
> + if (!ret) {
Simply tried if (!ret || ret == -EBUSY)
The test passes, but report waring
WARNING: CPU: 12 PID: 2992 at drivers/iommu/iommu.c:3591
iommu_detach_device_pasid+0xa4/0xd0
Will check more tomorrow.
> + domain->users++;
> + goto out;
> + }
> }
>
Thanks
Hi Zhangfei,
> -----Original Message-----
> From: Zhangfei Gao <[email protected]>
> Sent: Wednesday, February 21, 2024 12:27 AM
> To: Zhang, Tina <[email protected]>
> Cc: [email protected]; [email protected]; David Woodhouse
> <[email protected]>; Lu Baolu <[email protected]>; Joerg
> Roedel <[email protected]>; Will Deacon <[email protected]>; Robin Murphy
> <[email protected]>; Jason Gunthorpe <[email protected]>; Tian, Kevin
> <[email protected]>; Nicolin Chen <[email protected]>; Michael Shavit
> <[email protected]>; Vasant Hegde <[email protected]>; Jason
> Gunthorpe <[email protected]>
> Subject: Re: [PATCH v10 5/6] iommu: Support mm PASID 1:n with sva
> domains
>
> Hi, Tina
>
> On Fri, 27 Oct 2023 at 08:06, Tina Zhang <[email protected]> wrote:
> >
> > Each mm bound to devices gets a PASID and corresponding sva domains
> > allocated in iommu_sva_bind_device(), which are referenced by
> iommu_mm
> > field of the mm. The PASID is released in __mmdrop(), while a sva
> > domain is released when no one is using it (the reference count is
> > decremented in iommu_sva_unbind_device()). However, although sva
> > domains and their PASID are separate objects such that their own life
> > cycles could be handled independently, an enqcmd use case may require
> > releasing the PASID in releasing the mm (i.e., once a PASID is
> > allocated for a mm, it will be permanently used by the mm and won't be
> > released until the end of mm) and only allows to drop the PASID after
> > the sva domains are released. To this end, mmgrab() is called in
> > iommu_sva_domain_alloc() to increment the mm reference count and
> > mmdrop() is invoked in
> > iommu_domain_free() to decrement the mm reference count.
> >
> > Since the required info of PASID and sva domains is kept in struct
> > iommu_mm_data of a mm, use mm->iommu_mm field instead of the old
> pasid
> > field in mm struct. The sva domain list is protected by iommu_sva_lock.
> >
> > Besides, this patch removes mm_pasid_init(), as with the introduced
> > iommu_mm structure, initializing mm pasid in mm_init() is unnecessary.
> >
> > Reviewed-by: Lu Baolu <[email protected]>
> > Reviewed-by: Vasant Hegde <[email protected]>
> > Reviewed-by: Jason Gunthorpe <[email protected]>
> > Tested-by: Nicolin Chen <[email protected]>
> > Signed-off-by: Tina Zhang <[email protected]>
> > Signed-off-by: Jason Gunthorpe <[email protected]>
> > ---
> > drivers/iommu/iommu-sva.c | 92 +++++++++++++++++++++++----------------
> > include/linux/iommu.h | 23 ++++++++--
> > 2 files changed, 74 insertions(+), 41 deletions(-)
> >
> > diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
> > index 4a2f5699747f..5175e8d85247 100644
> > --- a/drivers/iommu/iommu-sva.c
> > +++ b/drivers/iommu/iommu-sva.c
> > @@ -12,32 +12,42 @@
> > static DEFINE_MUTEX(iommu_sva_lock);
> >
> > /* Allocate a PASID for the mm within range (inclusive) */ -static
> > int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev)
> > +static struct iommu_mm_data *iommu_alloc_mm_data(struct mm_struct
> > +*mm, struct device *dev)
> > {
> > + struct iommu_mm_data *iommu_mm;
> > ioasid_t pasid;
> > - int ret = 0;
> > +
> > + lockdep_assert_held(&iommu_sva_lock);
> >
> > if (!arch_pgtable_dma_compat(mm))
> > - return -EBUSY;
> > + return ERR_PTR(-EBUSY);
> >
> > - mutex_lock(&iommu_sva_lock);
> > + iommu_mm = mm->iommu_mm;
> > /* Is a PASID already associated with this mm? */
> > - if (mm_valid_pasid(mm)) {
> > - if (mm->pasid >= dev->iommu->max_pasids)
> > - ret = -EOVERFLOW;
> > - goto out;
> > + if (iommu_mm) {
> > + if (iommu_mm->pasid >= dev->iommu->max_pasids)
> > + return ERR_PTR(-EOVERFLOW);
> > + return iommu_mm;
> > }
> >
> > + iommu_mm = kzalloc(sizeof(struct iommu_mm_data), GFP_KERNEL);
> > + if (!iommu_mm)
> > + return ERR_PTR(-ENOMEM);
> > +
> > pasid = iommu_alloc_global_pasid(dev);
> > if (pasid == IOMMU_PASID_INVALID) {
> > - ret = -ENOSPC;
> > - goto out;
> > + kfree(iommu_mm);
> > + return ERR_PTR(-ENOSPC);
> > }
> > - mm->pasid = pasid;
> > - ret = 0;
> > -out:
> > - mutex_unlock(&iommu_sva_lock);
> > - return ret;
> > + iommu_mm->pasid = pasid;
> > + INIT_LIST_HEAD(&iommu_mm->sva_domains);
> > + /*
> > + * Make sure the write to mm->iommu_mm is not reordered in front
> of
> > + * initialization to iommu_mm fields. If it does, readers may see a
> > + * valid iommu_mm with uninitialized values.
> > + */
> > + smp_store_release(&mm->iommu_mm, iommu_mm);
> > + return iommu_mm;
> > }
> >
> > /**
> > @@ -58,31 +68,33 @@ static int iommu_sva_alloc_pasid(struct mm_struct
> *mm, struct device *dev)
> > */
> > struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct
> > mm_struct *mm) {
> > + struct iommu_mm_data *iommu_mm;
> > struct iommu_domain *domain;
> > struct iommu_sva *handle;
> > int ret;
> >
> > + mutex_lock(&iommu_sva_lock);
> > +
> > /* Allocate mm->pasid if necessary. */
> > - ret = iommu_sva_alloc_pasid(mm, dev);
> > - if (ret)
> > - return ERR_PTR(ret);
> > + iommu_mm = iommu_alloc_mm_data(mm, dev);
> > + if (IS_ERR(iommu_mm)) {
> > + ret = PTR_ERR(iommu_mm);
> > + goto out_unlock;
> > + }
> >
> > handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> > - if (!handle)
> > - return ERR_PTR(-ENOMEM);
> > -
> > - mutex_lock(&iommu_sva_lock);
> > - /* Search for an existing domain. */
> > - domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid,
> > - IOMMU_DOMAIN_SVA);
> > - if (IS_ERR(domain)) {
> > - ret = PTR_ERR(domain);
> > + if (!handle) {
> > + ret = -ENOMEM;
> > goto out_unlock;
> > }
> >
> > - if (domain) {
> > - domain->users++;
> > - goto out;
>
> Our multi bind test case broke since 6.8-rc1.
> The test case can use same domain & pasid, return different handle,
> 6.7 simply domain->users ++ and return.
>
> > + /* Search for an existing domain. */
> > + list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next)
> {
> > + ret = iommu_attach_device_pasid(domain, dev,
> > + iommu_mm->pasid);
>
> Now iommu_attach_device_pasid return BUSY since the same pasid.
> And then iommu_sva_bind_device attach ret=-16
Sounds like the test case tries to bind a device to a same mm multiple times without unbinding the device and the expectation is that it can always return a valid handle to pass the test. Right?
Regards,
-Tina
>
> > + if (!ret) {
>
> Simply tried if (!ret || ret == -EBUSY)
> The test passes, but report waring
> WARNING: CPU: 12 PID: 2992 at drivers/iommu/iommu.c:3591
> iommu_detach_device_pasid+0xa4/0xd0
>
> Will check more tomorrow.
>
> > + domain->users++;
> > + goto out;
> > + }
> > }
> >
>
> Thanks
Hi, Tina
On Wed, 21 Feb 2024 at 07:58, Zhang, Tina <[email protected]> wrote:
> > > struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct
> > > mm_struct *mm) {
> > > + struct iommu_mm_data *iommu_mm;
> > > struct iommu_domain *domain;
> > > struct iommu_sva *handle;
> > > int ret;
> > >
> > > + mutex_lock(&iommu_sva_lock);
> > > +
> > > /* Allocate mm->pasid if necessary. */
> > > - ret = iommu_sva_alloc_pasid(mm, dev);
> > > - if (ret)
> > > - return ERR_PTR(ret);
> > > + iommu_mm = iommu_alloc_mm_data(mm, dev);
> > > + if (IS_ERR(iommu_mm)) {
> > > + ret = PTR_ERR(iommu_mm);
> > > + goto out_unlock;
> > > + }
> > >
> > > handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> > > - if (!handle)
> > > - return ERR_PTR(-ENOMEM);
> > > -
> > > - mutex_lock(&iommu_sva_lock);
> > > - /* Search for an existing domain. */
> > > - domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid,
> > > - IOMMU_DOMAIN_SVA);
> > > - if (IS_ERR(domain)) {
> > > - ret = PTR_ERR(domain);
> > > + if (!handle) {
> > > + ret = -ENOMEM;
> > > goto out_unlock;
> > > }
> > >
> > > - if (domain) {
> > > - domain->users++;
> > > - goto out;
> >
> > Our multi bind test case broke since 6.8-rc1.
> > The test case can use same domain & pasid, return different handle,
> > 6.7 simply domain->users ++ and return.
> >
> > > + /* Search for an existing domain. */
> > > + list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next)
> > {
> > > + ret = iommu_attach_device_pasid(domain, dev,
> > > + iommu_mm->pasid);
> >
> > Now iommu_attach_device_pasid return BUSY since the same pasid.
> > And then iommu_sva_bind_device attach ret=-16
> Sounds like the test case tries to bind a device to a same mm multiple times without unbinding the device and the expectation is that it can always return a valid handle to pass the test. Right?
Yes
The device can bind to the same mm multi-times and return different handle,
Since the refcount, no need to unbind and bind sequently,
The unbind can happen later with the handle.
Thanks
On Wed, 21 Feb 2024 at 09:28, Zhangfei Gao <[email protected]> wrote:
>
> Hi, Tina
>
> On Wed, 21 Feb 2024 at 07:58, Zhang, Tina <[email protected]> wrote:
>
> > > > struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct
> > > > mm_struct *mm) {
> > > > + struct iommu_mm_data *iommu_mm;
> > > > struct iommu_domain *domain;
> > > > struct iommu_sva *handle;
> > > > int ret;
> > > >
> > > > + mutex_lock(&iommu_sva_lock);
> > > > +
> > > > /* Allocate mm->pasid if necessary. */
> > > > - ret = iommu_sva_alloc_pasid(mm, dev);
> > > > - if (ret)
> > > > - return ERR_PTR(ret);
> > > > + iommu_mm = iommu_alloc_mm_data(mm, dev);
> > > > + if (IS_ERR(iommu_mm)) {
> > > > + ret = PTR_ERR(iommu_mm);
> > > > + goto out_unlock;
> > > > + }
> > > >
> > > > handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> > > > - if (!handle)
> > > > - return ERR_PTR(-ENOMEM);
> > > > -
> > > > - mutex_lock(&iommu_sva_lock);
> > > > - /* Search for an existing domain. */
> > > > - domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid,
> > > > - IOMMU_DOMAIN_SVA);
> > > > - if (IS_ERR(domain)) {
> > > > - ret = PTR_ERR(domain);
> > > > + if (!handle) {
> > > > + ret = -ENOMEM;
> > > > goto out_unlock;
> > > > }
> > > >
> > > > - if (domain) {
> > > > - domain->users++;
> > > > - goto out;
> > >
> > > Our multi bind test case broke since 6.8-rc1.
> > > The test case can use same domain & pasid, return different handle,
> > > 6.7 simply domain->users ++ and return.
> > >
> > > > + /* Search for an existing domain. */
> > > > + list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next)
> > > {
> > > > + ret = iommu_attach_device_pasid(domain, dev,
> > > > + iommu_mm->pasid);
> > >
> > > Now iommu_attach_device_pasid return BUSY since the same pasid.
> > > And then iommu_sva_bind_device attach ret=-16
> > Sounds like the test case tries to bind a device to a same mm multiple times without unbinding the device and the expectation is that it can always return a valid handle to pass the test. Right?
>
> Yes
>
> The device can bind to the same mm multi-times and return different handle,
> Since the refcount, no need to unbind and bind sequently,
> The unbind can happen later with the handle.
With this diff can solve the issue, what's your suggestion?
@@ -88,10 +94,12 @@ struct iommu_sva *iommu_sva_bind_device(struct
device *dev, struct mm_struct *mm
/* Search for an existing domain. */
list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next) {
ret = iommu_attach_device_pasid(domain, dev, iommu_mm->pasid);
- if (!ret) {
+ if (!ret || ret == -EBUSY) {
domain->users++;
goto out;
}
@@ -141,8 +151,8 @@ void iommu_sva_unbind_device(struct iommu_sva *handle)
struct device *dev = handle->dev;
mutex_lock(&iommu_sva_lock);
- iommu_detach_device_pasid(domain, dev, iommu_mm->pasid);
if (--domain->users == 0) {
+ iommu_detach_device_pasid(domain, dev, iommu_mm->pasid);
list_del(&domain->next);
iommu_domain_free(domain);
}
Thanks
On 2024/2/21 9:28, Zhangfei Gao wrote:
> On Wed, 21 Feb 2024 at 07:58, Zhang, Tina<[email protected]> wrote:
>
>>>> struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct
>>>> mm_struct *mm) {
>>>> + struct iommu_mm_data *iommu_mm;
>>>> struct iommu_domain *domain;
>>>> struct iommu_sva *handle;
>>>> int ret;
>>>>
>>>> + mutex_lock(&iommu_sva_lock);
>>>> +
>>>> /* Allocate mm->pasid if necessary. */
>>>> - ret = iommu_sva_alloc_pasid(mm, dev);
>>>> - if (ret)
>>>> - return ERR_PTR(ret);
>>>> + iommu_mm = iommu_alloc_mm_data(mm, dev);
>>>> + if (IS_ERR(iommu_mm)) {
>>>> + ret = PTR_ERR(iommu_mm);
>>>> + goto out_unlock;
>>>> + }
>>>>
>>>> handle = kzalloc(sizeof(*handle), GFP_KERNEL);
>>>> - if (!handle)
>>>> - return ERR_PTR(-ENOMEM);
>>>> -
>>>> - mutex_lock(&iommu_sva_lock);
>>>> - /* Search for an existing domain. */
>>>> - domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid,
>>>> - IOMMU_DOMAIN_SVA);
>>>> - if (IS_ERR(domain)) {
>>>> - ret = PTR_ERR(domain);
>>>> + if (!handle) {
>>>> + ret = -ENOMEM;
>>>> goto out_unlock;
>>>> }
>>>>
>>>> - if (domain) {
>>>> - domain->users++;
>>>> - goto out;
>>> Our multi bind test case broke since 6.8-rc1.
>>> The test case can use same domain & pasid, return different handle,
>>> 6.7 simply domain->users ++ and return.
>>>
>>>> + /* Search for an existing domain. */
>>>> + list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next)
>>> {
>>>> + ret = iommu_attach_device_pasid(domain, dev,
>>>> + iommu_mm->pasid);
>>> Now iommu_attach_device_pasid return BUSY since the same pasid.
>>> And then iommu_sva_bind_device attach ret=-16
>> Sounds like the test case tries to bind a device to a same mm multiple times without unbinding the device and the expectation is that it can always return a valid handle to pass the test. Right?
> Yes
>
> The device can bind to the same mm multi-times and return different handle,
> Since the refcount, no need to unbind and bind sequently,
> The unbind can happen later with the handle.
Is there any real use case to bind an mm to the pasid of a device
multiple times? If there are cases, is it better to handle this in the
uacce driver?
From iommu core's perspective, it doesn't make sense to attach the same
domain to the same device (or pasid) multiple times.
Best regards,
baolu
On Wed, 21 Feb 2024 at 10:06, Baolu Lu <[email protected]> wrote:
>
> On 2024/2/21 9:28, Zhangfei Gao wrote:
> > On Wed, 21 Feb 2024 at 07:58, Zhang, Tina<[email protected]> wrote:
> >
> >>>> struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct
> >>>> mm_struct *mm) {
> >>>> + struct iommu_mm_data *iommu_mm;
> >>>> struct iommu_domain *domain;
> >>>> struct iommu_sva *handle;
> >>>> int ret;
> >>>>
> >>>> + mutex_lock(&iommu_sva_lock);
> >>>> +
> >>>> /* Allocate mm->pasid if necessary. */
> >>>> - ret = iommu_sva_alloc_pasid(mm, dev);
> >>>> - if (ret)
> >>>> - return ERR_PTR(ret);
> >>>> + iommu_mm = iommu_alloc_mm_data(mm, dev);
> >>>> + if (IS_ERR(iommu_mm)) {
> >>>> + ret = PTR_ERR(iommu_mm);
> >>>> + goto out_unlock;
> >>>> + }
> >>>>
> >>>> handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> >>>> - if (!handle)
> >>>> - return ERR_PTR(-ENOMEM);
> >>>> -
> >>>> - mutex_lock(&iommu_sva_lock);
> >>>> - /* Search for an existing domain. */
> >>>> - domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid,
> >>>> - IOMMU_DOMAIN_SVA);
> >>>> - if (IS_ERR(domain)) {
> >>>> - ret = PTR_ERR(domain);
> >>>> + if (!handle) {
> >>>> + ret = -ENOMEM;
> >>>> goto out_unlock;
> >>>> }
> >>>>
> >>>> - if (domain) {
> >>>> - domain->users++;
> >>>> - goto out;
> >>> Our multi bind test case broke since 6.8-rc1.
> >>> The test case can use same domain & pasid, return different handle,
> >>> 6.7 simply domain->users ++ and return.
> >>>
> >>>> + /* Search for an existing domain. */
> >>>> + list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next)
> >>> {
> >>>> + ret = iommu_attach_device_pasid(domain, dev,
> >>>> + iommu_mm->pasid);
> >>> Now iommu_attach_device_pasid return BUSY since the same pasid.
> >>> And then iommu_sva_bind_device attach ret=-16
> >> Sounds like the test case tries to bind a device to a same mm multiple times without unbinding the device and the expectation is that it can always return a valid handle to pass the test. Right?
> > Yes
> >
> > The device can bind to the same mm multi-times and return different handle,
> > Since the refcount, no need to unbind and bind sequently,
> > The unbind can happen later with the handle.
>
> Is there any real use case to bind an mm to the pasid of a device
> multiple times? If there are cases, is it better to handle this in the
> uacce driver?
Yes, it is required for multi-thread, the device can provide
multi-queue to speed up.
>
> From iommu core's perspective, it doesn't make sense to attach the same
> domain to the same device (or pasid) multiple times.
But is it the refcount domain->user++ used for?
Is there any reason not doing this.
Thanks
On 2024/2/21 10:45, Zhangfei Gao wrote:
> On Wed, 21 Feb 2024 at 10:06, Baolu Lu<[email protected]>
> wrote:
>> On 2024/2/21 9:28, Zhangfei Gao wrote:
>>> On Wed, 21 Feb 2024 at 07:58, Zhang, Tina<[email protected]>
>>> wrote:
>>>
>>>>>> struct iommu_sva *iommu_sva_bind_device(struct device
>>>>>> *dev, struct mm_struct *mm) { + struct
>>>>>> iommu_mm_data *iommu_mm; struct iommu_domain *domain;
>>>>>> struct iommu_sva *handle; int ret;
>>>>>>
>>>>>> + mutex_lock(&iommu_sva_lock); + /* Allocate
>>>>>> mm->pasid if necessary. */ - ret =
>>>>>> iommu_sva_alloc_pasid(mm, dev); - if (ret) - return
>>>>>> ERR_PTR(ret); + iommu_mm = iommu_alloc_mm_data(mm,
>>>>>> dev); + if (IS_ERR(iommu_mm)) { + ret =
>>>>>> PTR_ERR(iommu_mm); + goto out_unlock; + }
>>>>>>
>>>>>> handle = kzalloc(sizeof(*handle), GFP_KERNEL); - if
>>>>>> (!handle) - return ERR_PTR(-ENOMEM); - -
>>>>>> mutex_lock(&iommu_sva_lock); - /* Search for an
>>>>>> existing domain. */ - domain =
>>>>>> iommu_get_domain_for_dev_pasid(dev, mm->pasid, -
>>>>>> IOMMU_DOMAIN_SVA); - if (IS_ERR(domain)) { - ret =
>>>>>> PTR_ERR(domain); + if (!handle) { + ret = -ENOMEM;
>>>>>> goto out_unlock; }
>>>>>>
>>>>>> - if (domain) { - domain->users++; -
>>>>>> goto out;
>>>>> Our multi bind test case broke since 6.8-rc1. The test case
>>>>> can use same domain & pasid, return different handle, 6.7
>>>>> simply domain->users ++ and return.
>>>>>
>>>>>> + /* Search for an existing domain. */ +
>>>>>> list_for_each_entry(domain, &mm->iommu_mm->sva_domains,
>>>>>> next)
>>>>> {
>>>>>> + ret = iommu_attach_device_pasid(domain,
>>>>>> dev, + iommu_mm->pasid);
>>>>> Now iommu_attach_device_pasid return BUSY since the same
>>>>> pasid. And then iommu_sva_bind_device attach ret=-16
>>>> Sounds like the test case tries to bind a device to a same mm
>>>> multiple times without unbinding the device and the
>>>> expectation is that it can always return a valid handle to pass
>>>> the test. Right?
>>> Yes
>>>
>>> The device can bind to the same mm multi-times and return
>>> different handle, Since the refcount, no need to unbind and bind
>>> sequently, The unbind can happen later with the handle.
>> Is there any real use case to bind an mm to the pasid of a device
>> multiple times? If there are cases, is it better to handle this in
>> the uacce driver?
> Yes, it is required for multi-thread, the device can provide
> multi-queue to speed up.
>
>> From iommu core's perspective, it doesn't make sense to attach the
>> same domain to the same device (or pasid) multiple times.
> But is it the refcount domain->user++ used for? Is there any reason
> not doing this.
I was just thinking about whether to do this in the iommu core, or in
the upper layers, like uacce or iommufd. It seems that there is no need
to attach a domain to a device or pasid again if it has already been
attached.
Best regards,
baolu
On Wed, 21 Feb 2024 at 11:52, Baolu Lu <[email protected]> wrote:
>
> On 2024/2/21 10:45, Zhangfei Gao wrote:
> > On Wed, 21 Feb 2024 at 10:06, Baolu Lu<[email protected]>
> > wrote:
> >> On 2024/2/21 9:28, Zhangfei Gao wrote:
> >>> On Wed, 21 Feb 2024 at 07:58, Zhang, Tina<[email protected]>
> >>> wrote:
> >>>
> >>>>>> struct iommu_sva *iommu_sva_bind_device(struct device
> >>>>>> *dev, struct mm_struct *mm) { + struct
> >>>>>> iommu_mm_data *iommu_mm; struct iommu_domain *domain;
> >>>>>> struct iommu_sva *handle; int ret;
> >>>>>>
> >>>>>> + mutex_lock(&iommu_sva_lock); + /* Allocate
> >>>>>> mm->pasid if necessary. */ - ret =
> >>>>>> iommu_sva_alloc_pasid(mm, dev); - if (ret) - return
> >>>>>> ERR_PTR(ret); + iommu_mm = iommu_alloc_mm_data(mm,
> >>>>>> dev); + if (IS_ERR(iommu_mm)) { + ret =
> >>>>>> PTR_ERR(iommu_mm); + goto out_unlock; + }
> >>>>>>
> >>>>>> handle = kzalloc(sizeof(*handle), GFP_KERNEL); - if
> >>>>>> (!handle) - return ERR_PTR(-ENOMEM); - -
> >>>>>> mutex_lock(&iommu_sva_lock); - /* Search for an
> >>>>>> existing domain. */ - domain =
> >>>>>> iommu_get_domain_for_dev_pasid(dev, mm->pasid, -
> >>>>>> IOMMU_DOMAIN_SVA); - if (IS_ERR(domain)) { - ret =
> >>>>>> PTR_ERR(domain); + if (!handle) { + ret = -ENOMEM;
> >>>>>> goto out_unlock; }
> >>>>>>
> >>>>>> - if (domain) { - domain->users++; -
> >>>>>> goto out;
> >>>>> Our multi bind test case broke since 6.8-rc1. The test case
> >>>>> can use same domain & pasid, return different handle, 6.7
> >>>>> simply domain->users ++ and return.
> >>>>>
> >>>>>> + /* Search for an existing domain. */ +
> >>>>>> list_for_each_entry(domain, &mm->iommu_mm->sva_domains,
> >>>>>> next)
> >>>>> {
> >>>>>> + ret = iommu_attach_device_pasid(domain,
> >>>>>> dev, + iommu_mm->pasid);
> >>>>> Now iommu_attach_device_pasid return BUSY since the same
> >>>>> pasid. And then iommu_sva_bind_device attach ret=-16
> >>>> Sounds like the test case tries to bind a device to a same mm
> >>>> multiple times without unbinding the device and the
> >>>> expectation is that it can always return a valid handle to pass
> >>>> the test. Right?
> >>> Yes
> >>>
> >>> The device can bind to the same mm multi-times and return
> >>> different handle, Since the refcount, no need to unbind and bind
> >>> sequently, The unbind can happen later with the handle.
> >> Is there any real use case to bind an mm to the pasid of a device
> >> multiple times? If there are cases, is it better to handle this in
> >> the uacce driver?
> > Yes, it is required for multi-thread, the device can provide
> > multi-queue to speed up.
> >
> >> From iommu core's perspective, it doesn't make sense to attach the
> >> same domain to the same device (or pasid) multiple times.
> > But is it the refcount domain->user++ used for? Is there any reason
> > not doing this.
>
> I was just thinking about whether to do this in the iommu core, or in
> the upper layers, like uacce or iommufd. It seems that there is no need
> to attach a domain to a device or pasid again if it has already been
> attached.
It would be more complicated since the return handle can be used to
distinguish different queues of the device.
I think domain->user should handle this case as before.
Anyway, I have sent a patch to get more feedback.
Thanks
Hi,
> -----Original Message-----
> From: Zhangfei Gao <[email protected]>
> Sent: Wednesday, February 21, 2024 10:45 AM
> To: Baolu Lu <[email protected]>
> Cc: Zhang, Tina <[email protected]>; [email protected]; linux-
> [email protected]; David Woodhouse <[email protected]>; Joerg
> Roedel <[email protected]>; Will Deacon <[email protected]>; Robin Murphy
> <[email protected]>; Jason Gunthorpe <[email protected]>; Tian, Kevin
> <[email protected]>; Nicolin Chen <[email protected]>; Michael Shavit
> <[email protected]>; Vasant Hegde <[email protected]>; Jason
> Gunthorpe <[email protected]>; Jean-Philippe Brucker <jean-
> [email protected]>; Hao Fang <[email protected]>
> Subject: Re: [PATCH v10 5/6] iommu: Support mm PASID 1:n with sva
> domains
>
> On Wed, 21 Feb 2024 at 10:06, Baolu Lu <[email protected]> wrote:
> >
> > On 2024/2/21 9:28, Zhangfei Gao wrote:
> > > On Wed, 21 Feb 2024 at 07:58, Zhang, Tina<[email protected]>
> wrote:
> > >
> > >>>> struct iommu_sva *iommu_sva_bind_device(struct device *dev,
> > >>>> struct mm_struct *mm) {
> > >>>> + struct iommu_mm_data *iommu_mm;
> > >>>> struct iommu_domain *domain;
> > >>>> struct iommu_sva *handle;
> > >>>> int ret;
> > >>>>
> > >>>> + mutex_lock(&iommu_sva_lock);
> > >>>> +
> > >>>> /* Allocate mm->pasid if necessary. */
> > >>>> - ret = iommu_sva_alloc_pasid(mm, dev);
> > >>>> - if (ret)
> > >>>> - return ERR_PTR(ret);
> > >>>> + iommu_mm = iommu_alloc_mm_data(mm, dev);
> > >>>> + if (IS_ERR(iommu_mm)) {
> > >>>> + ret = PTR_ERR(iommu_mm);
> > >>>> + goto out_unlock;
> > >>>> + }
> > >>>>
> > >>>> handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> > >>>> - if (!handle)
> > >>>> - return ERR_PTR(-ENOMEM);
> > >>>> -
> > >>>> - mutex_lock(&iommu_sva_lock);
> > >>>> - /* Search for an existing domain. */
> > >>>> - domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid,
> > >>>> - IOMMU_DOMAIN_SVA);
> > >>>> - if (IS_ERR(domain)) {
> > >>>> - ret = PTR_ERR(domain);
> > >>>> + if (!handle) {
> > >>>> + ret = -ENOMEM;
> > >>>> goto out_unlock;
> > >>>> }
> > >>>>
> > >>>> - if (domain) {
> > >>>> - domain->users++;
> > >>>> - goto out;
> > >>> Our multi bind test case broke since 6.8-rc1.
> > >>> The test case can use same domain & pasid, return different
> > >>> handle,
> > >>> 6.7 simply domain->users ++ and return.
> > >>>
> > >>>> + /* Search for an existing domain. */
> > >>>> + list_for_each_entry(domain, &mm->iommu_mm->sva_domains,
> > >>>> + next)
> > >>> {
> > >>>> + ret = iommu_attach_device_pasid(domain, dev,
> > >>>> + iommu_mm->pasid);
> > >>> Now iommu_attach_device_pasid return BUSY since the same pasid.
> > >>> And then iommu_sva_bind_device attach ret=-16
> > >> Sounds like the test case tries to bind a device to a same mm multiple
> times without unbinding the device and the expectation is that it can always
> return a valid handle to pass the test. Right?
> > > Yes
> > >
> > > The device can bind to the same mm multi-times and return different
> > > handle, Since the refcount, no need to unbind and bind sequently,
> > > The unbind can happen later with the handle.
> >
> > Is there any real use case to bind an mm to the pasid of a device
> > multiple times? If there are cases, is it better to handle this in the
> > uacce driver?
>
> Yes, it is required for multi-thread, the device can provide multi-queue to
> speed up.
>
> >
> > From iommu core's perspective, it doesn't make sense to attach the
> > same domain to the same device (or pasid) multiple times.
>
> But is it the refcount domain->user++ used for?
> Is there any reason not doing this.
The domain->user is a refcount of the devices (or iommu group) attached to the domain. IOMMU core needs to keep this refcount to ensure that a sva domain will be released when no device uses it.
Regards,
-Tina
>
> Thanks
On Wed, 21 Feb 2024 at 15:41, Zhang, Tina <[email protected]> wrote:
>
> Hi,
>
> > -----Original Message-----
> > From: Zhangfei Gao <[email protected]>
> > Sent: Wednesday, February 21, 2024 10:45 AM
> > To: Baolu Lu <[email protected]>
> > Cc: Zhang, Tina <[email protected]>; [email protected]; linux-
> > [email protected]; David Woodhouse <[email protected]>; Joerg
> > Roedel <[email protected]>; Will Deacon <[email protected]>; Robin Murphy
> > <[email protected]>; Jason Gunthorpe <[email protected]>; Tian, Kevin
> > <[email protected]>; Nicolin Chen <[email protected]>; Michael Shavit
> > <[email protected]>; Vasant Hegde <[email protected]>; Jason
> > Gunthorpe <[email protected]>; Jean-Philippe Brucker <jean-
> > [email protected]>; Hao Fang <[email protected]>
> > Subject: Re: [PATCH v10 5/6] iommu: Support mm PASID 1:n with sva
> > domains
> >
> > On Wed, 21 Feb 2024 at 10:06, Baolu Lu <[email protected]> wrote:
> > >
> > > On 2024/2/21 9:28, Zhangfei Gao wrote:
> > > > On Wed, 21 Feb 2024 at 07:58, Zhang, Tina<[email protected]>
> > wrote:
> > > >
> > > >>>> struct iommu_sva *iommu_sva_bind_device(struct device *dev,
> > > >>>> struct mm_struct *mm) {
> > > >>>> + struct iommu_mm_data *iommu_mm;
> > > >>>> struct iommu_domain *domain;
> > > >>>> struct iommu_sva *handle;
> > > >>>> int ret;
> > > >>>>
> > > >>>> + mutex_lock(&iommu_sva_lock);
> > > >>>> +
> > > >>>> /* Allocate mm->pasid if necessary. */
> > > >>>> - ret = iommu_sva_alloc_pasid(mm, dev);
> > > >>>> - if (ret)
> > > >>>> - return ERR_PTR(ret);
> > > >>>> + iommu_mm = iommu_alloc_mm_data(mm, dev);
> > > >>>> + if (IS_ERR(iommu_mm)) {
> > > >>>> + ret = PTR_ERR(iommu_mm);
> > > >>>> + goto out_unlock;
> > > >>>> + }
> > > >>>>
> > > >>>> handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> > > >>>> - if (!handle)
> > > >>>> - return ERR_PTR(-ENOMEM);
> > > >>>> -
> > > >>>> - mutex_lock(&iommu_sva_lock);
> > > >>>> - /* Search for an existing domain. */
> > > >>>> - domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid,
> > > >>>> - IOMMU_DOMAIN_SVA);
> > > >>>> - if (IS_ERR(domain)) {
> > > >>>> - ret = PTR_ERR(domain);
> > > >>>> + if (!handle) {
> > > >>>> + ret = -ENOMEM;
> > > >>>> goto out_unlock;
> > > >>>> }
> > > >>>>
> > > >>>> - if (domain) {
> > > >>>> - domain->users++;
> > > >>>> - goto out;
> > > >>> Our multi bind test case broke since 6.8-rc1.
> > > >>> The test case can use same domain & pasid, return different
> > > >>> handle,
> > > >>> 6.7 simply domain->users ++ and return.
> > > >>>
> > > >>>> + /* Search for an existing domain. */
> > > >>>> + list_for_each_entry(domain, &mm->iommu_mm->sva_domains,
> > > >>>> + next)
> > > >>> {
> > > >>>> + ret = iommu_attach_device_pasid(domain, dev,
> > > >>>> + iommu_mm->pasid);
> > > >>> Now iommu_attach_device_pasid return BUSY since the same pasid.
> > > >>> And then iommu_sva_bind_device attach ret=-16
> > > >> Sounds like the test case tries to bind a device to a same mm multiple
> > times without unbinding the device and the expectation is that it can always
> > return a valid handle to pass the test. Right?
> > > > Yes
> > > >
> > > > The device can bind to the same mm multi-times and return different
> > > > handle, Since the refcount, no need to unbind and bind sequently,
> > > > The unbind can happen later with the handle.
> > >
> > > Is there any real use case to bind an mm to the pasid of a device
> > > multiple times? If there are cases, is it better to handle this in the
> > > uacce driver?
> >
> > Yes, it is required for multi-thread, the device can provide multi-queue to
> > speed up.
> >
> > >
> > > From iommu core's perspective, it doesn't make sense to attach the
> > > same domain to the same device (or pasid) multiple times.
> >
> > But is it the refcount domain->user++ used for?
> > Is there any reason not doing this.
> The domain->user is a refcount of the devices (or iommu group) attached to the domain. IOMMU core needs to keep this refcount to ensure that a sva domain will be released when no device uses it.
I think the limitation of one user only attach one domain one time
does not make sense.
Just like one file can only be opened one time by a user, then
refcount is meanless.
Thanks
>
> Regards,
> -Tina
>
> >
> > Thanks