[PATCH 0/4] iommu/vt-d: SVM implementation cleanup

[PATCH 0/4] iommu/vt-d: SVM implementation cleanup

[Lu Baolu]

This is a cleanup series after the merge of commit be51b1d6bbff
("iommu/sva: Refactoring iommu_sva_bind/unbind_device()"). It removes
the unused/duplicate data and code.

Lu Baolu (4):
  iommu/vt-d: Remove include/linux/intel-svm.h
  iommu/vt-d: Remove unused fields in svm structures
  iommu/vt-d: Remove users from intel_svm_dev
  iommu/vt-d: Remove sva from intel_svm_dev

 include/linux/intel-svm.h   | 16 -------
 drivers/iommu/intel/iommu.h | 11 +++--
 drivers/iommu/intel/iommu.c |  1 -
 drivers/iommu/intel/svm.c   | 88 +++++++++++++++----------------------
 MAINTAINERS                 |  1 -
 5 files changed, 41 insertions(+), 76 deletions(-)
 delete mode 100644 include/linux/intel-svm.h

-- 
2.34.1

[PATCH 1/4] iommu/vt-d: Remove include/linux/intel-svm.h

[Lu Baolu]

There's no need to have a public header for Intel SVA implementation.
The device driver should interact with Intel SVA implementation via
the IOMMU generic APIs.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 include/linux/intel-svm.h   | 16 ----------------
 drivers/iommu/intel/iommu.h |  5 +++++
 drivers/iommu/intel/iommu.c |  1 -
 drivers/iommu/intel/svm.c   |  1 -
 MAINTAINERS                 |  1 -
 5 files changed, 5 insertions(+), 19 deletions(-)
 delete mode 100644 include/linux/intel-svm.h

diff --git a/include/linux/intel-svm.h b/include/linux/intel-svm.h
deleted file mode 100644
index f9a0d44f6fdb..000000000000
--- a/include/linux/intel-svm.h
+++ /dev/null
@@ -1,16 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0-only */
-/*
- * Copyright © 2015 Intel Corporation.
- *
- * Authors: David Woodhouse <David.Woodhouse@intel.com>
- */
-
-#ifndef __INTEL_SVM_H__
-#define __INTEL_SVM_H__
-
-/* Page Request Queue depth */
-#define PRQ_ORDER	4
-#define PRQ_RING_MASK	((0x1000 << PRQ_ORDER) - 0x20)
-#define PRQ_DEPTH	((0x1000 << PRQ_ORDER) >> 5)
-
-#endif /* __INTEL_SVM_H__ */
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 06e61e474856..f89f63d7a72a 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -438,6 +438,11 @@ struct q_inval {
 	int             free_cnt;
 };
 
+/* Page Request Queue depth */
+#define PRQ_ORDER	4
+#define PRQ_RING_MASK	((0x1000 << PRQ_ORDER) - 0x20)
+#define PRQ_DEPTH	((0x1000 << PRQ_ORDER) >> 5)
+
 struct dmar_pci_notify_info;
 
 #ifdef CONFIG_IRQ_REMAP
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 59df7e42fd53..317af67b6098 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -16,7 +16,6 @@
 #include <linux/crash_dump.h>
 #include <linux/dma-direct.h>
 #include <linux/dmi.h>
-#include <linux/intel-svm.h>
 #include <linux/memory.h>
 #include <linux/pci.h>
 #include <linux/pci-ats.h>
diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index c76b66263467..d38a54396c23 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -9,7 +9,6 @@
 #include <linux/sched.h>
 #include <linux/sched/mm.h>
 #include <linux/slab.h>
-#include <linux/intel-svm.h>
 #include <linux/rculist.h>
 #include <linux/pci.h>
 #include <linux/pci-ats.h>
diff --git a/MAINTAINERS b/MAINTAINERS
index a36df9ed283d..43fd97f0e1df 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10459,7 +10459,6 @@ L:	iommu@lists.linux.dev
 S:	Supported
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git
 F:	drivers/iommu/intel/
-F:	include/linux/intel-svm.h
 
 INTEL IPU3 CSI-2 CIO2 DRIVER
 M:	Yong Zhi <yong.zhi@intel.com>
-- 
2.34.1

[PATCH 2/4] iommu/vt-d: Remove unused fields in svm structures

[Lu Baolu]

They aren't used anywhere. Remove them to avoid dead code.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.h | 4 ----
 drivers/iommu/intel/svm.c   | 2 --
 2 files changed, 6 deletions(-)

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index f89f63d7a72a..e7c732979364 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -762,18 +762,14 @@ struct intel_svm_dev {
 	struct device *dev;
 	struct intel_iommu *iommu;
 	struct iommu_sva sva;
-	u32 pasid;
 	int users;
 	u16 did;
-	u16 dev_iotlb:1;
 	u16 sid, qdep;
 };
 
 struct intel_svm {
 	struct mmu_notifier notifier;
 	struct mm_struct *mm;
-
-	unsigned int flags;
 	u32 pasid;
 	struct list_head devs;
 };
diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index d38a54396c23..d1e445f03aa6 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -351,11 +351,9 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
 	sdev->did = FLPT_DEFAULT_DID;
 	sdev->sid = PCI_DEVID(info->bus, info->devfn);
 	sdev->users = 1;
-	sdev->pasid = svm->pasid;
 	sdev->sva.dev = dev;
 	init_rcu_head(&sdev->rcu);
 	if (info->ats_enabled) {
-		sdev->dev_iotlb = 1;
 		sdev->qdep = info->ats_qdep;
 		if (sdev->qdep >= QI_DEV_EIOTLB_MAX_INVS)
 			sdev->qdep = 0;
-- 
2.34.1

[PATCH 3/4] iommu/vt-d: Remove users from intel_svm_dev

[Lu Baolu]

It was used as a reference counter of an existing bond between device
and user application memory address. Commit be51b1d6bbff ("iommu/sva:
Refactoring iommu_sva_bind/unbind_device()") has added this in iommu
core. Remove it to avoid duplicate code.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.h |  1 -
 drivers/iommu/intel/svm.c   | 62 ++++++++++++++++---------------------
 2 files changed, 27 insertions(+), 36 deletions(-)

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index e7c732979364..2a1619ff0d79 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -762,7 +762,6 @@ struct intel_svm_dev {
 	struct device *dev;
 	struct intel_iommu *iommu;
 	struct iommu_sva sva;
-	int users;
 	u16 did;
 	u16 sid, qdep;
 };
diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index d1e445f03aa6..c7dc53e40c26 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -333,13 +333,6 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
 		}
 	}
 
-	/* Find the matching device in svm list */
-	sdev = svm_lookup_device_by_dev(svm, dev);
-	if (sdev) {
-		sdev->users++;
-		goto success;
-	}
-
 	sdev = kzalloc(sizeof(*sdev), GFP_KERNEL);
 	if (!sdev) {
 		ret = -ENOMEM;
@@ -350,7 +343,6 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
 	sdev->iommu = iommu;
 	sdev->did = FLPT_DEFAULT_DID;
 	sdev->sid = PCI_DEVID(info->bus, info->devfn);
-	sdev->users = 1;
 	sdev->sva.dev = dev;
 	init_rcu_head(&sdev->rcu);
 	if (info->ats_enabled) {
@@ -367,7 +359,7 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
 		goto free_sdev;
 
 	list_add_rcu(&sdev->list, &svm->devs);
-success:
+
 	return &sdev->sva;
 
 free_sdev:
@@ -401,32 +393,32 @@ static int intel_svm_unbind_mm(struct device *dev, u32 pasid)
 	mm = svm->mm;
 
 	if (sdev) {
-		sdev->users--;
-		if (!sdev->users) {
-			list_del_rcu(&sdev->list);
-			/* Flush the PASID cache and IOTLB for this device.
-			 * Note that we do depend on the hardware *not* using
-			 * the PASID any more. Just as we depend on other
-			 * devices never using PASIDs that they have no right
-			 * to use. We have a *shared* PASID table, because it's
-			 * large and has to be physically contiguous. So it's
-			 * hard to be as defensive as we might like. */
-			intel_pasid_tear_down_entry(iommu, dev,
-						    svm->pasid, false);
-			intel_svm_drain_prq(dev, svm->pasid);
-			kfree_rcu(sdev, rcu);
-
-			if (list_empty(&svm->devs)) {
-				if (svm->notifier.ops)
-					mmu_notifier_unregister(&svm->notifier, mm);
-				pasid_private_remove(svm->pasid);
-				/* We mandate that no page faults may be outstanding
-				 * for the PASID when intel_svm_unbind_mm() is called.
-				 * If that is not obeyed, subtle errors will happen.
-				 * Let's make them less subtle... */
-				memset(svm, 0x6b, sizeof(*svm));
-				kfree(svm);
-			}
+		list_del_rcu(&sdev->list);
+		/*
+		 * Flush the PASID cache and IOTLB for this device.
+		 * Note that we do depend on the hardware *not* using
+		 * the PASID any more. Just as we depend on other
+		 * devices never using PASIDs that they have no right
+		 * to use. We have a *shared* PASID table, because it's
+		 * large and has to be physically contiguous. So it's
+		 * hard to be as defensive as we might like.
+		 */
+		intel_pasid_tear_down_entry(iommu, dev, svm->pasid, false);
+		intel_svm_drain_prq(dev, svm->pasid);
+		kfree_rcu(sdev, rcu);
+
+		if (list_empty(&svm->devs)) {
+			if (svm->notifier.ops)
+				mmu_notifier_unregister(&svm->notifier, mm);
+			pasid_private_remove(svm->pasid);
+			/*
+			 * We mandate that no page faults may be outstanding
+			 * for the PASID when intel_svm_unbind_mm() is called.
+			 * If that is not obeyed, subtle errors will happen.
+			 * Let's make them less subtle...
+			 */
+			memset(svm, 0x6b, sizeof(*svm));
+			kfree(svm);
 		}
 	}
 out:
-- 
2.34.1

[PATCH 4/4] iommu/vt-d: Remove sva from intel_svm_dev

[Lu Baolu]

After commit be51b1d6bbff ("iommu/sva: Refactoring
iommu_sva_bind/unbind_device()"), the iommu driver doesn't need to
return an iommu_sva pointer anymore. This removes the sva field
from intel_svm_dev and cleanups the code accordingly.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel/iommu.h |  1 -
 drivers/iommu/intel/svm.c   | 23 +++++++++--------------
 2 files changed, 9 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 2a1619ff0d79..f0222ad38757 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -761,7 +761,6 @@ struct intel_svm_dev {
 	struct rcu_head rcu;
 	struct device *dev;
 	struct intel_iommu *iommu;
-	struct iommu_sva sva;
 	u16 did;
 	u16 sid, qdep;
 };
diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index c7dc53e40c26..e7b9bedebcc0 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -298,9 +298,8 @@ static int pasid_to_svm_sdev(struct device *dev, unsigned int pasid,
 	return 0;
 }
 
-static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
-					   struct device *dev,
-					   struct mm_struct *mm)
+static int intel_svm_bind_mm(struct intel_iommu *iommu, struct device *dev,
+			     struct mm_struct *mm)
 {
 	struct device_domain_info *info = dev_iommu_priv_get(dev);
 	struct intel_svm_dev *sdev;
@@ -312,7 +311,7 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
 	if (!svm) {
 		svm = kzalloc(sizeof(*svm), GFP_KERNEL);
 		if (!svm)
-			return ERR_PTR(-ENOMEM);
+			return -ENOMEM;
 
 		svm->pasid = mm->pasid;
 		svm->mm = mm;
@@ -322,14 +321,14 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
 		ret = mmu_notifier_register(&svm->notifier, mm);
 		if (ret) {
 			kfree(svm);
-			return ERR_PTR(ret);
+			return ret;
 		}
 
 		ret = pasid_private_add(svm->pasid, svm);
 		if (ret) {
 			mmu_notifier_unregister(&svm->notifier, mm);
 			kfree(svm);
-			return ERR_PTR(ret);
+			return ret;
 		}
 	}
 
@@ -343,7 +342,6 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
 	sdev->iommu = iommu;
 	sdev->did = FLPT_DEFAULT_DID;
 	sdev->sid = PCI_DEVID(info->bus, info->devfn);
-	sdev->sva.dev = dev;
 	init_rcu_head(&sdev->rcu);
 	if (info->ats_enabled) {
 		sdev->qdep = info->ats_qdep;
@@ -360,7 +358,7 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
 
 	list_add_rcu(&sdev->list, &svm->devs);
 
-	return &sdev->sva;
+	return 0;
 
 free_sdev:
 	kfree(sdev);
@@ -371,7 +369,7 @@ static struct iommu_sva *intel_svm_bind_mm(struct intel_iommu *iommu,
 		kfree(svm);
 	}
 
-	return ERR_PTR(ret);
+	return ret;
 }
 
 /* Caller must hold pasid_mutex */
@@ -843,13 +841,10 @@ 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;
-	struct iommu_sva *sva;
-	int ret = 0;
+	int ret;
 
 	mutex_lock(&pasid_mutex);
-	sva = intel_svm_bind_mm(iommu, dev, mm);
-	if (IS_ERR(sva))
-		ret = PTR_ERR(sva);
+	ret = intel_svm_bind_mm(iommu, dev, mm);
 	mutex_unlock(&pasid_mutex);
 
 	return ret;
-- 
2.34.1

RE: [PATCH 0/4] iommu/vt-d: SVM implementation cleanup

[Tian, Kevin]

> From: Lu Baolu <baolu.lu@linux.intel.com>
> Sent: Monday, January 9, 2023 9:50 AM
> 
> This is a cleanup series after the merge of commit be51b1d6bbff
> ("iommu/sva: Refactoring iommu_sva_bind/unbind_device()"). It removes
> the unused/duplicate data and code.
> 
> Lu Baolu (4):
>   iommu/vt-d: Remove include/linux/intel-svm.h
>   iommu/vt-d: Remove unused fields in svm structures
>   iommu/vt-d: Remove users from intel_svm_dev
>   iommu/vt-d: Remove sva from intel_svm_dev
> 

For the series:

Reviewed-by: Kevin Tian <kevin.tian@intel.com>

Re: [PATCH 0/4] iommu/vt-d: SVM implementation cleanup

[Baolu Lu]

On 2023/1/9 9:49, Lu Baolu wrote:
> This is a cleanup series after the merge of commit be51b1d6bbff
> ("iommu/sva: Refactoring iommu_sva_bind/unbind_device()"). It removes
> the unused/duplicate data and code.
> 
> Lu Baolu (4):
>    iommu/vt-d: Remove include/linux/intel-svm.h
>    iommu/vt-d: Remove unused fields in svm structures
>    iommu/vt-d: Remove users from intel_svm_dev
>    iommu/vt-d: Remove sva from intel_svm_dev

Patches queued for v6.3.

https://lore.kernel.org/linux-iommu/20230131073740.378984-1-baolu.lu@linux.intel.com/

Best regards,
baolu