[PATCH v3 0/6] Share sva domains with all devices bound to a mm

[PATCH v3 0/6] Share sva domains with all devices bound to a mm

[Tina Zhang]

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.

v3:
 - 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:
 - Add mm_get_enqcmd_pasid().
 - Update commit message.

v1: https://lore.kernel.org/linux-iommu/20230808074944.7825-1-tina.zhang@intel.com/

Tina Zhang (6):
  iommu: Add mm_get_enqcmd_pasid() helper function
  iommu/vt-d: Remove mm->pasid in intel_sva_bind_mm()
  iommu: Introduce mm_get_pasid() helper function
  mm: Add structure to keep sva information
  iommu: Support mm PASID 1:n with sva domains
  mm: Deprecate pasid field

 arch/x86/kernel/traps.c                       |  2 +-
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   | 12 ++---
 drivers/iommu/intel/svm.c                     | 14 +++---
 drivers/iommu/iommu-sva.c                     | 50 ++++++++++++-------
 include/linux/iommu.h                         | 31 ++++++++++--
 include/linux/mm_types.h                      |  3 +-
 kernel/fork.c                                 |  1 -
 mm/init-mm.c                                  |  3 --
 8 files changed, 73 insertions(+), 43 deletions(-)

-- 
2.17.1

[PATCH v3 1/6] iommu: Add mm_get_enqcmd_pasid() helper function

[Tina Zhang]

mm_get_enqcmd_pasid() is for getting enqcmd pasid value.

The motivation is to replace mm->pasid with an iommu private data
structure that is introduced in a later patch.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Tina Zhang <tina.zhang@intel.com>
---

Changes in v2:
- Change mm_get_pasid() to mm_get_enqcmd_pasid()

 arch/x86/kernel/traps.c | 2 +-
 include/linux/iommu.h   | 8 ++++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 4a817d20ce3b..d9034b1bbfdd 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -678,7 +678,7 @@ 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/include/linux/iommu.h b/include/linux/iommu.h
index d31642596675..ab9919746fd3 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -1180,6 +1180,10 @@ 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);
@@ -1202,6 +1206,10 @@ 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 */
 
-- 
2.17.1

[PATCH v3 2/6] iommu/vt-d: Remove mm->pasid in intel_sva_bind_mm()

[Tina Zhang]

The pasid is passed in as a parameter through .set_dev_pasid() callback.
Thus, intel_sva_bind_mm() can directly use it instead of retrieving the
pasid value from mm->pasid.

Suggested-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Tina Zhang <tina.zhang@intel.com>
---
 drivers/iommu/intel/svm.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index e95b339e9cdc..3527f8833d84 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -298,21 +298,22 @@ static int pasid_to_svm_sdev(struct device *dev, unsigned int pasid,
 }
 
 static int intel_svm_bind_mm(struct intel_iommu *iommu, struct device *dev,
-			     struct mm_struct *mm)
+			     struct iommu_domain *domain, ioasid_t pasid)
 {
 	struct device_domain_info *info = dev_iommu_priv_get(dev);
+	struct mm_struct *mm = domain->mm;
 	struct intel_svm_dev *sdev;
 	struct intel_svm *svm;
 	unsigned long sflags;
 	int ret = 0;
 
-	svm = pasid_private_find(mm->pasid);
+	svm = pasid_private_find(pasid);
 	if (!svm) {
 		svm = kzalloc(sizeof(*svm), GFP_KERNEL);
 		if (!svm)
 			return -ENOMEM;
 
-		svm->pasid = mm->pasid;
+		svm->pasid = pasid;
 		svm->mm = mm;
 		INIT_LIST_HEAD_RCU(&svm->devs);
 
@@ -350,7 +351,7 @@ static int intel_svm_bind_mm(struct intel_iommu *iommu, struct device *dev,
 
 	/* Setup the pasid table: */
 	sflags = cpu_feature_enabled(X86_FEATURE_LA57) ? PASID_FLAG_FL5LP : 0;
-	ret = intel_pasid_setup_first_level(iommu, dev, mm->pgd, mm->pasid,
+	ret = intel_pasid_setup_first_level(iommu, dev, mm->pgd, pasid,
 					    FLPT_DEFAULT_DID, sflags);
 	if (ret)
 		goto free_sdev;
@@ -364,7 +365,7 @@ static int intel_svm_bind_mm(struct intel_iommu *iommu, struct device *dev,
 free_svm:
 	if (list_empty(&svm->devs)) {
 		mmu_notifier_unregister(&svm->notifier, mm);
-		pasid_private_remove(mm->pasid);
+		pasid_private_remove(pasid);
 		kfree(svm);
 	}
 
@@ -839,11 +840,10 @@ static int intel_svm_set_dev_pasid(struct iommu_domain *domain,
 {
 	struct device_domain_info *info = dev_iommu_priv_get(dev);
 	struct intel_iommu *iommu = info->iommu;
-	struct mm_struct *mm = domain->mm;
 	int ret;
 
 	mutex_lock(&pasid_mutex);
-	ret = intel_svm_bind_mm(iommu, dev, mm);
+	ret = intel_svm_bind_mm(iommu, dev, domain, pasid);
 	mutex_unlock(&pasid_mutex);
 
 	return ret;
-- 
2.17.1

[PATCH v3 3/6] iommu: Introduce mm_get_pasid() helper function

[Tina Zhang]

Use the helper function mm_get_pasid() to get a mm assigned pasid
value. The motivation is to replace mm->pasid with an iommu private
data structure that is introduced in a later patch.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Tina Zhang <tina.zhang@intel.com>
---

Changes in v2:
- Update commit message
- Let mm_get_enqcmd_pasid() call mm_get_pasid() to get pasid

 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c | 12 ++++++------
 drivers/iommu/iommu-sva.c                       | 14 +++++++-------
 include/linux/iommu.h                           | 10 +++++++++-
 3 files changed, 22 insertions(+), 14 deletions(-)

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 a5a63b1c947e..0b455654d365 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
@@ -204,7 +204,7 @@ static void arm_smmu_mm_invalidate_range(struct mmu_notifier *mn,
 	if (!(smmu_domain->smmu->features & ARM_SMMU_FEAT_BTM))
 		arm_smmu_tlb_inv_range_asid(start, size, smmu_mn->cd->asid,
 					    PAGE_SIZE, false, smmu_domain);
-	arm_smmu_atc_inv_domain(smmu_domain, mm->pasid, start, size);
+	arm_smmu_atc_inv_domain(smmu_domain, mm_get_pasid(mm), start, size);
 }
 
 static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
@@ -222,10 +222,10 @@ 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_write_ctx_desc(smmu_domain, mm->pasid, &quiet_cd);
+	arm_smmu_write_ctx_desc(smmu_domain, mm_get_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_pasid(mm), 0, 0);
 
 	smmu_mn->cleared = true;
 	mutex_unlock(&sva_lock);
@@ -279,7 +279,7 @@ arm_smmu_mmu_notifier_get(struct arm_smmu_domain *smmu_domain,
 		goto err_free_cd;
 	}
 
-	ret = arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, cd);
+	ret = arm_smmu_write_ctx_desc(smmu_domain, mm_get_pasid(mm), cd);
 	if (ret)
 		goto err_put_notifier;
 
@@ -304,7 +304,7 @@ static void arm_smmu_mmu_notifier_put(struct arm_smmu_mmu_notifier *smmu_mn)
 		return;
 
 	list_del(&smmu_mn->list);
-	arm_smmu_write_ctx_desc(smmu_domain, mm->pasid, NULL);
+	arm_smmu_write_ctx_desc(smmu_domain, mm_get_pasid(mm), NULL);
 
 	/*
 	 * If we went through clear(), we've already invalidated, and no
@@ -312,7 +312,7 @@ 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_pasid(mm), 0, 0);
 	}
 
 	/* Frees smmu_mn */
diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index 05c0fb2acbc4..0a4a1ed40814 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -28,7 +28,7 @@ static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t ma
 	mutex_lock(&iommu_sva_lock);
 	/* Is a PASID already associated with this mm? */
 	if (mm_valid_pasid(mm)) {
-		if (mm->pasid < min || mm->pasid > max)
+		if (mm_get_pasid(mm) < min || mm_get_pasid(mm) > max)
 			ret = -EOVERFLOW;
 		goto out;
 	}
@@ -71,7 +71,7 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
 	if (!max_pasids)
 		return ERR_PTR(-EOPNOTSUPP);
 
-	/* Allocate mm->pasid if necessary. */
+	/* Allocate pasid if necessary. */
 	ret = iommu_sva_alloc_pasid(mm, 1, max_pasids - 1);
 	if (ret)
 		return ERR_PTR(ret);
@@ -82,7 +82,7 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
 
 	mutex_lock(&iommu_sva_lock);
 	/* Search for an existing domain. */
-	domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid,
+	domain = iommu_get_domain_for_dev_pasid(dev, mm_get_pasid(mm),
 						IOMMU_DOMAIN_SVA);
 	if (IS_ERR(domain)) {
 		ret = PTR_ERR(domain);
@@ -101,7 +101,7 @@ 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, mm_get_pasid(mm));
 	if (ret)
 		goto out_free_domain;
 	domain->users = 1;
@@ -133,7 +133,7 @@ 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;
+	ioasid_t pasid = mm_get_pasid(domain->mm);
 	struct device *dev = handle->dev;
 
 	mutex_lock(&iommu_sva_lock);
@@ -150,7 +150,7 @@ u32 iommu_sva_get_pasid(struct iommu_sva *handle)
 {
 	struct iommu_domain *domain = handle->domain;
 
-	return domain->mm->pasid;
+	return mm_get_pasid(domain->mm);
 }
 EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
 
@@ -217,5 +217,5 @@ void mm_pasid_drop(struct mm_struct *mm)
 	if (likely(!mm_valid_pasid(mm)))
 		return;
 
-	ida_free(&iommu_global_pasid_ida, mm->pasid);
+	ida_free(&iommu_global_pasid_ida, mm_get_pasid(mm));
 }
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index ab9919746fd3..ab8784dfdbd9 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -1180,10 +1180,14 @@ 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)
+static inline u32 mm_get_pasid(struct mm_struct *mm)
 {
 	return mm->pasid;
 }
+static inline u32 mm_get_enqcmd_pasid(struct mm_struct *mm)
+{
+	return mm_get_pasid(mm);
+}
 void mm_pasid_drop(struct mm_struct *mm);
 struct iommu_sva *iommu_sva_bind_device(struct device *dev,
 					struct mm_struct *mm);
@@ -1206,6 +1210,10 @@ 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_pasid(struct mm_struct *mm)
+{
+	return IOMMU_PASID_INVALID;
+}
 static inline u32 mm_get_enqcmd_pasid(struct mm_struct *mm)
 {
 	return IOMMU_PASID_INVALID;
-- 
2.17.1

[PATCH v3 4/6] mm: Add structure to keep sva information

[Tina Zhang]

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.

Signed-off-by: Tina Zhang <tina.zhang@intel.com>
---
 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 ab8784dfdbd9..937f3abc26f2 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -670,6 +670,11 @@ 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 7d30dc4ff0ff..b486f521afee 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -595,6 +595,7 @@ struct mm_cid {
 #endif
 
 struct kioctx_table;
+struct iommu_mm_data;
 struct mm_struct {
 	struct {
 		/*
@@ -808,6 +809,7 @@ struct mm_struct {
 
 #ifdef CONFIG_IOMMU_SVA
 		u32 pasid;
+		struct iommu_mm_data *iommu_mm;
 #endif
 #ifdef CONFIG_KSM
 		/*
-- 
2.17.1

[PATCH v3 5/6] iommu: Support mm PASID 1:n with sva domains

[Tina Zhang]

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 <baolu.lu@linux.intel.com>
Signed-off-by: Tina Zhang <tina.zhang@intel.com>
---

Changes in v3:
- Add a comment describing domain->next.
- Update the commit message.

 drivers/iommu/iommu-sva.c | 38 +++++++++++++++++++++++++-------------
 include/linux/iommu.h     | 14 +++++++-------
 kernel/fork.c             |  1 -
 3 files changed, 32 insertions(+), 21 deletions(-)

diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index 0a4a1ed40814..e7e3aeaa7055 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -15,6 +15,7 @@ static DEFINE_IDA(iommu_global_pasid_ida);
 /* Allocate a PASID for the mm within range (inclusive) */
 static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
 {
+	struct iommu_mm_data *iommu_mm;
 	int ret = 0;
 
 	if (min == IOMMU_PASID_INVALID ||
@@ -33,11 +34,22 @@ static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t ma
 		goto out;
 	}
 
+	iommu_mm = kzalloc(sizeof(struct iommu_mm_data), GFP_KERNEL);
+	if (!iommu_mm) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
 	ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, GFP_KERNEL);
-	if (ret < 0)
+	if (ret < 0) {
+		kfree(iommu_mm);
 		goto out;
+	}
+
+	iommu_mm->pasid = ret;
+	INIT_LIST_HEAD(&iommu_mm->sva_domains);
+	mm->iommu_mm = iommu_mm;
 
-	mm->pasid = ret;
 	ret = 0;
 out:
 	mutex_unlock(&iommu_sva_lock);
@@ -82,16 +94,12 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
 
 	mutex_lock(&iommu_sva_lock);
 	/* Search for an existing domain. */
-	domain = iommu_get_domain_for_dev_pasid(dev, mm_get_pasid(mm),
-						IOMMU_DOMAIN_SVA);
-	if (IS_ERR(domain)) {
-		ret = PTR_ERR(domain);
-		goto out_unlock;
-	}
-
-	if (domain) {
-		domain->users++;
-		goto out;
+	list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next) {
+		ret = iommu_attach_device_pasid(domain, dev, mm_get_pasid(mm));
+		if (!ret) {
+			domain->users++;
+			goto out;
+		}
 	}
 
 	/* Allocate a new domain and set it on device pasid. */
@@ -105,6 +113,8 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
 	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;
@@ -137,8 +147,9 @@ 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, 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);
@@ -218,4 +229,5 @@ void mm_pasid_drop(struct mm_struct *mm)
 		return;
 
 	ida_free(&iommu_global_pasid_ida, mm_get_pasid(mm));
+	kfree(mm->iommu_mm);
 }
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 937f3abc26f2..95ada53f24ec 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -109,6 +109,11 @@ 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;
 		};
 	};
 };
@@ -1177,17 +1182,13 @@ static inline bool tegra_dev_iommu_get_stream_id(struct device *dev, u32 *stream
 }
 
 #ifdef CONFIG_IOMMU_SVA
-static inline void mm_pasid_init(struct mm_struct *mm)
-{
-	mm->pasid = IOMMU_PASID_INVALID;
-}
 static inline bool mm_valid_pasid(struct mm_struct *mm)
 {
-	return mm->pasid != IOMMU_PASID_INVALID;
+	return mm->iommu_mm ? true : false;
 }
 static inline u32 mm_get_pasid(struct mm_struct *mm)
 {
-	return mm->pasid;
+	return mm->iommu_mm ? mm->iommu_mm->pasid : IOMMU_PASID_INVALID;
 }
 static inline u32 mm_get_enqcmd_pasid(struct mm_struct *mm)
 {
@@ -1213,7 +1214,6 @@ static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle)
 {
 	return IOMMU_PASID_INVALID;
 }
-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_pasid(struct mm_struct *mm)
 {
diff --git a/kernel/fork.c b/kernel/fork.c
index d2e12b6d2b18..f06392dd1ca8 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1274,7 +1274,6 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
 	mm_init_cpumask(mm);
 	mm_init_aio(mm);
 	mm_init_owner(mm, p);
-	mm_pasid_init(mm);
 	RCU_INIT_POINTER(mm->exe_file, NULL);
 	mmu_notifier_subscriptions_init(mm);
 	init_tlb_flush_pending(mm);
-- 
2.17.1

[PATCH v3 6/6] mm: Deprecate pasid field

[Tina Zhang]

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 <baolu.lu@linux.intel.com>
Signed-off-by: Tina Zhang <tina.zhang@intel.com>
---
 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 b486f521afee..fb0e4416d9d7 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -808,7 +808,6 @@ struct mm_struct {
 		struct work_struct async_put_work;
 
 #ifdef CONFIG_IOMMU_SVA
-		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 efa97b57acfd..69719291463e 100644
--- a/mm/init-mm.c
+++ b/mm/init-mm.c
@@ -42,9 +42,6 @@ struct mm_struct init_mm = {
 #endif
 	.user_ns	= &init_user_ns,
 	.cpu_bitmap	= CPU_BITS_NONE,
-#ifdef CONFIG_IOMMU_SVA
-	.pasid		= IOMMU_PASID_INVALID,
-#endif
 	INIT_MM_CONTEXT(init_mm)
 };
 
-- 
2.17.1

Re: [PATCH v3 5/6] iommu: Support mm PASID 1:n with sva domains

[Vasant Hegde]

On 9/5/2023 5:39 AM, Tina Zhang 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 <baolu.lu@linux.intel.com>
> Signed-off-by: Tina Zhang <tina.zhang@intel.com>

Looks good to me.

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>

-Vasant

> ---
> 
> Changes in v3:
> - Add a comment describing domain->next.
> - Update the commit message.
> 
>  drivers/iommu/iommu-sva.c | 38 +++++++++++++++++++++++++-------------
>  include/linux/iommu.h     | 14 +++++++-------
>  kernel/fork.c             |  1 -
>  3 files changed, 32 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
> index 0a4a1ed40814..e7e3aeaa7055 100644
> --- a/drivers/iommu/iommu-sva.c
> +++ b/drivers/iommu/iommu-sva.c
> @@ -15,6 +15,7 @@ static DEFINE_IDA(iommu_global_pasid_ida);
>  /* Allocate a PASID for the mm within range (inclusive) */
>  static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
>  {
> +	struct iommu_mm_data *iommu_mm;
>  	int ret = 0;
>  
>  	if (min == IOMMU_PASID_INVALID ||
> @@ -33,11 +34,22 @@ static int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t ma
>  		goto out;
>  	}
>  
> +	iommu_mm = kzalloc(sizeof(struct iommu_mm_data), GFP_KERNEL);
> +	if (!iommu_mm) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}
> +
>  	ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, GFP_KERNEL);
> -	if (ret < 0)
> +	if (ret < 0) {
> +		kfree(iommu_mm);
>  		goto out;
> +	}
> +
> +	iommu_mm->pasid = ret;
> +	INIT_LIST_HEAD(&iommu_mm->sva_domains);
> +	mm->iommu_mm = iommu_mm;
>  
> -	mm->pasid = ret;
>  	ret = 0;
>  out:
>  	mutex_unlock(&iommu_sva_lock);
> @@ -82,16 +94,12 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
>  
>  	mutex_lock(&iommu_sva_lock);
>  	/* Search for an existing domain. */
> -	domain = iommu_get_domain_for_dev_pasid(dev, mm_get_pasid(mm),
> -						IOMMU_DOMAIN_SVA);
> -	if (IS_ERR(domain)) {
> -		ret = PTR_ERR(domain);
> -		goto out_unlock;
> -	}
> -
> -	if (domain) {
> -		domain->users++;
> -		goto out;
> +	list_for_each_entry(domain, &mm->iommu_mm->sva_domains, next) {
> +		ret = iommu_attach_device_pasid(domain, dev, mm_get_pasid(mm));
> +		if (!ret) {
> +			domain->users++;
> +			goto out;
> +		}
>  	}
>  
>  	/* Allocate a new domain and set it on device pasid. */
> @@ -105,6 +113,8 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
>  	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;
> @@ -137,8 +147,9 @@ 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, 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);
> @@ -218,4 +229,5 @@ void mm_pasid_drop(struct mm_struct *mm)
>  		return;
>  
>  	ida_free(&iommu_global_pasid_ida, mm_get_pasid(mm));
> +	kfree(mm->iommu_mm);
>  }
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 937f3abc26f2..95ada53f24ec 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -109,6 +109,11 @@ 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;
>  		};
>  	};
>  };
> @@ -1177,17 +1182,13 @@ static inline bool tegra_dev_iommu_get_stream_id(struct device *dev, u32 *stream
>  }
>  
>  #ifdef CONFIG_IOMMU_SVA
> -static inline void mm_pasid_init(struct mm_struct *mm)
> -{
> -	mm->pasid = IOMMU_PASID_INVALID;
> -}
>  static inline bool mm_valid_pasid(struct mm_struct *mm)
>  {
> -	return mm->pasid != IOMMU_PASID_INVALID;
> +	return mm->iommu_mm ? true : false;
>  }
>  static inline u32 mm_get_pasid(struct mm_struct *mm)
>  {
> -	return mm->pasid;
> +	return mm->iommu_mm ? mm->iommu_mm->pasid : IOMMU_PASID_INVALID;
>  }
>  static inline u32 mm_get_enqcmd_pasid(struct mm_struct *mm)
>  {
> @@ -1213,7 +1214,6 @@ static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle)
>  {
>  	return IOMMU_PASID_INVALID;
>  }
> -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_pasid(struct mm_struct *mm)
>  {
> diff --git a/kernel/fork.c b/kernel/fork.c
> index d2e12b6d2b18..f06392dd1ca8 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1274,7 +1274,6 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
>  	mm_init_cpumask(mm);
>  	mm_init_aio(mm);
>  	mm_init_owner(mm, p);
> -	mm_pasid_init(mm);
>  	RCU_INIT_POINTER(mm->exe_file, NULL);
>  	mmu_notifier_subscriptions_init(mm);
>  	init_tlb_flush_pending(mm);

Re: [PATCH v3 4/6] mm: Add structure to keep sva information

[Vasant Hegde]

On 9/5/2023 5:39 AM, Tina Zhang wrote:
> 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.
> 
> Signed-off-by: Tina Zhang <tina.zhang@intel.com>

Looks good to me.

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>

-Vasant


> ---
>  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 ab8784dfdbd9..937f3abc26f2 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -670,6 +670,11 @@ 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 7d30dc4ff0ff..b486f521afee 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -595,6 +595,7 @@ struct mm_cid {
>  #endif
>  
>  struct kioctx_table;
> +struct iommu_mm_data;
>  struct mm_struct {
>  	struct {
>  		/*
> @@ -808,6 +809,7 @@ struct mm_struct {
>  
>  #ifdef CONFIG_IOMMU_SVA
>  		u32 pasid;
> +		struct iommu_mm_data *iommu_mm;
>  #endif
>  #ifdef CONFIG_KSM
>  		/*

Re: [PATCH v3 6/6] mm: Deprecate pasid field

[Vasant Hegde]

On 9/5/2023 5:39 AM, Tina Zhang wrote:
> 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 <baolu.lu@linux.intel.com>
> Signed-off-by: Tina Zhang <tina.zhang@intel.com>

Looks good to me.

Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>

-Vasant



> ---
>  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 b486f521afee..fb0e4416d9d7 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -808,7 +808,6 @@ struct mm_struct {
>  		struct work_struct async_put_work;
>  
>  #ifdef CONFIG_IOMMU_SVA
> -		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 efa97b57acfd..69719291463e 100644
> --- a/mm/init-mm.c
> +++ b/mm/init-mm.c
> @@ -42,9 +42,6 @@ struct mm_struct init_mm = {
>  #endif
>  	.user_ns	= &init_user_ns,
>  	.cpu_bitmap	= CPU_BITS_NONE,
> -#ifdef CONFIG_IOMMU_SVA
> -	.pasid		= IOMMU_PASID_INVALID,
> -#endif
>  	INIT_MM_CONTEXT(init_mm)
>  };
>