Date:   Tue, 29 Mar 2022 13:37:57 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>, Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>
Cc:     Eric Auger <eric.auger@...hat.com>, Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH RFC v2 08/11] iommu/sva: Use attach/detach_pasid_dev in SVA interfaces

The existing iommu SVA interfaces are implemented by calling the SVA
specific iommu ops provided by the IOMMU drivers. There's no need for
any SVA specific ops in iommu_ops vector anymore as we can achieve
this through the generic attach/detach_dev_pasid domain ops.

This refactors the IOMMU SVA interfaces implementation by using the
attach/detach_pasid_dev ops and align them with the concept of the
iommu domain. Put the new SVA code in the sva related file in order
to make it self-contained.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 include/linux/iommu.h         |  51 +++++++++-------
 drivers/iommu/iommu-sva-lib.c | 110 +++++++++++++++++++++++++++++++++-
 drivers/iommu/iommu.c         |  92 ----------------------------
 3 files changed, 138 insertions(+), 115 deletions(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index a46285488a57..11c4d99e122d 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -629,7 +629,12 @@ struct iommu_fwspec {
  * struct iommu_sva - handle to a device-mm bond
  */
 struct iommu_sva {
-	struct device			*dev;
+	struct device		*dev;
+	ioasid_t		pasid;
+	struct iommu_domain	*domain;
+	/* Link to sva domain's bonds list */
+	struct list_head	node;
+	refcount_t		users;
 };
 
 int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
@@ -672,12 +677,6 @@ int iommu_dev_enable_feature(struct device *dev, enum iommu_dev_features f);
 int iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features f);
 bool iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features f);
 
-struct iommu_sva *iommu_sva_bind_device(struct device *dev,
-					struct mm_struct *mm,
-					void *drvdata);
-void iommu_sva_unbind_device(struct iommu_sva *handle);
-u32 iommu_sva_get_pasid(struct iommu_sva *handle);
-
 int iommu_device_use_default_domain(struct device *dev);
 void iommu_device_unuse_default_domain(struct device *dev);
 
@@ -1018,21 +1017,6 @@ iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features feat)
 	return -ENODEV;
 }
 
-static inline struct iommu_sva *
-iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
-{
-	return NULL;
-}
-
-static inline void iommu_sva_unbind_device(struct iommu_sva *handle)
-{
-}
-
-static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle)
-{
-	return IOMMU_PASID_INVALID;
-}
-
 static inline struct iommu_fwspec *dev_iommu_fwspec_get(struct device *dev)
 {
 	return NULL;
@@ -1085,6 +1069,29 @@ iommu_put_domain_for_dev_pasid(struct iommu_domain *domain)
 }
 #endif /* CONFIG_IOMMU_API */
 
+#ifdef CONFIG_IOMMU_SVA
+struct iommu_sva *iommu_sva_bind_device(struct device *dev,
+					struct mm_struct *mm,
+					void *drvdata);
+void iommu_sva_unbind_device(struct iommu_sva *handle);
+u32 iommu_sva_get_pasid(struct iommu_sva *handle);
+#else /* CONFIG_IOMMU_SVA */
+static inline struct iommu_sva *
+iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
+{
+	return NULL;
+}
+
+static inline void iommu_sva_unbind_device(struct iommu_sva *handle)
+{
+}
+
+static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle)
+{
+	return IOMMU_PASID_INVALID;
+}
+#endif /* CONFIG_IOMMU_SVA */
+
 /**
  * iommu_map_sgtable - Map the given buffer to the IOMMU domain
  * @domain:	The IOMMU domain to perform the mapping
diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
index 78820be23f15..1b45b7d01836 100644
--- a/drivers/iommu/iommu-sva-lib.c
+++ b/drivers/iommu/iommu-sva-lib.c
@@ -17,6 +17,7 @@ struct iommu_sva_cookie {
 	struct mm_struct *mm;
 	ioasid_t pasid;
 	refcount_t users;
+	struct list_head bonds;
 };
 
 /**
@@ -101,6 +102,7 @@ iommu_sva_alloc_domain(struct device *dev, struct mm_struct *mm)
 	cookie->mm = mm;
 	cookie->pasid = mm->pasid;
 	refcount_set(&cookie->users, 1);
+	INIT_LIST_HEAD(&cookie->bonds);
 	domain->type = IOMMU_DOMAIN_SVA;
 	domain->sva_cookie = cookie;
 	curr = xa_store(&sva_domain_array, mm->pasid, domain, GFP_KERNEL);
@@ -118,6 +120,7 @@ iommu_sva_alloc_domain(struct device *dev, struct mm_struct *mm)
 static void iommu_sva_free_domain(struct iommu_domain *domain)
 {
 	xa_erase(&sva_domain_array, domain->sva_cookie->pasid);
+	WARN_ON(!list_empty(&domain->sva_cookie->bonds));
 	kfree(domain->sva_cookie);
 	domain->ops->free(domain);
 }
@@ -137,7 +140,7 @@ void iommu_sva_domain_put_user(struct iommu_domain *domain)
 		iommu_sva_free_domain(domain);
 }
 
-static __maybe_unused struct iommu_domain *
+static struct iommu_domain *
 iommu_sva_get_domain(struct device *dev, struct mm_struct *mm)
 {
 	struct iommu_domain *domain;
@@ -158,3 +161,108 @@ struct mm_struct *iommu_sva_domain_mm(struct iommu_domain *domain)
 {
 	return domain->sva_cookie->mm;
 }
+
+/**
+ * iommu_sva_bind_device() - Bind a process address space to a device
+ * @dev: the device
+ * @mm: the mm to bind, caller must hold a reference to it
+ * @drvdata: opaque data pointer to pass to bind callback
+ *
+ * Create a bond between device and address space, allowing the device to access
+ * the mm using the returned PASID. If a bond already exists between @device and
+ * @mm, it is returned and an additional reference is taken. Caller must call
+ * iommu_sva_unbind_device() to release each reference.
+ *
+ * iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called first, to
+ * initialize the required SVA features.
+ *
+ * On error, returns an ERR_PTR value.
+ */
+struct iommu_sva *
+iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
+{
+	int ret = -EINVAL;
+	struct iommu_sva *handle;
+	struct iommu_domain *domain;
+
+	ret = iommu_sva_alloc_pasid(mm, 1, (1U << dev->iommu->pasid_bits) - 1);
+	if (ret)
+		return ERR_PTR(ret);
+
+	mutex_lock(&iommu_sva_lock);
+	domain = iommu_sva_get_domain(dev, mm);
+	if (!domain) {
+		ret = -ENOMEM;
+		goto out_unlock;
+	}
+
+	/* Search for an existing bond. */
+	list_for_each_entry(handle, &domain->sva_cookie->bonds, node) {
+		if (handle->dev == dev && handle->pasid == mm->pasid) {
+			refcount_inc(&handle->users);
+			mutex_lock(&iommu_sva_lock);
+
+			return handle;
+		}
+	}
+
+	handle = kzalloc(sizeof(*handle), GFP_KERNEL);
+	if (!handle) {
+		ret = -ENOMEM;
+		goto out_put_domain;
+	}
+
+	ret = iommu_attach_device_pasid(domain, dev, mm->pasid);
+	if (ret)
+		goto out_free_handle;
+
+	handle->dev = dev;
+	handle->domain = domain;
+	handle->pasid = mm->pasid;
+	refcount_set(&handle->users, 1);
+	list_add_tail(&handle->node, &domain->sva_cookie->bonds);
+
+	mutex_unlock(&iommu_sva_lock);
+	return handle;
+
+out_free_handle:
+	kfree(handle);
+out_put_domain:
+	iommu_sva_domain_put_user(domain);
+out_unlock:
+	mutex_unlock(&iommu_sva_lock);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(iommu_sva_bind_device);
+
+/**
+ * iommu_sva_unbind_device() - Remove a bond created with iommu_sva_bind_device
+ * @handle: the handle returned by iommu_sva_bind_device()
+ *
+ * Put reference to a bond between device and address space. The device should
+ * not be issuing any more transaction for this PASID. All outstanding page
+ * requests for this PASID must have been flushed to the IOMMU.
+ */
+void iommu_sva_unbind_device(struct iommu_sva *handle)
+{
+	struct device *dev = handle->dev;
+	struct iommu_domain *domain = handle->domain;
+	struct mm_struct *mm = iommu_sva_domain_mm(domain);
+
+	mutex_lock(&iommu_sva_lock);
+	if (refcount_dec_and_test(&handle->users)) {
+		list_del(&handle->node);
+		iommu_detach_device_pasid(domain, dev, mm->pasid);
+		kfree(handle);
+	}
+
+	iommu_sva_domain_put_user(domain);
+	mutex_unlock(&iommu_sva_lock);
+}
+EXPORT_SYMBOL_GPL(iommu_sva_unbind_device);
+
+u32 iommu_sva_get_pasid(struct iommu_sva *handle)
+{
+	return handle->pasid;
+}
+EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 8163ad7f6902..6b51ead9d63b 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2712,98 +2712,6 @@ bool iommu_dev_feature_enabled(struct device *dev, enum iommu_dev_features feat)
 }
 EXPORT_SYMBOL_GPL(iommu_dev_feature_enabled);
 
-/**
- * iommu_sva_bind_device() - Bind a process address space to a device
- * @dev: the device
- * @mm: the mm to bind, caller must hold a reference to it
- * @drvdata: opaque data pointer to pass to bind callback
- *
- * Create a bond between device and address space, allowing the device to access
- * the mm using the returned PASID. If a bond already exists between @device and
- * @mm, it is returned and an additional reference is taken. Caller must call
- * iommu_sva_unbind_device() to release each reference.
- *
- * iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called first, to
- * initialize the required SVA features.
- *
- * On error, returns an ERR_PTR value.
- */
-struct iommu_sva *
-iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
-{
-	struct iommu_group *group;
-	struct iommu_sva *handle = ERR_PTR(-EINVAL);
-	const struct iommu_ops *ops = dev_iommu_ops(dev);
-
-	if (!ops->sva_bind)
-		return ERR_PTR(-ENODEV);
-
-	group = iommu_group_get(dev);
-	if (!group)
-		return ERR_PTR(-ENODEV);
-
-	/* Ensure device count and domain don't change while we're binding */
-	mutex_lock(&group->mutex);
-
-	/*
-	 * To keep things simple, SVA currently doesn't support IOMMU groups
-	 * with more than one device. Existing SVA-capable systems are not
-	 * affected by the problems that required IOMMU groups (lack of ACS
-	 * isolation, device ID aliasing and other hardware issues).
-	 */
-	if (!iommu_group_singleton_lockdown(group))
-		goto out_unlock;
-
-	handle = ops->sva_bind(dev, mm, drvdata);
-
-out_unlock:
-	mutex_unlock(&group->mutex);
-	iommu_group_put(group);
-
-	return handle;
-}
-EXPORT_SYMBOL_GPL(iommu_sva_bind_device);
-
-/**
- * iommu_sva_unbind_device() - Remove a bond created with iommu_sva_bind_device
- * @handle: the handle returned by iommu_sva_bind_device()
- *
- * Put reference to a bond between device and address space. The device should
- * not be issuing any more transaction for this PASID. All outstanding page
- * requests for this PASID must have been flushed to the IOMMU.
- */
-void iommu_sva_unbind_device(struct iommu_sva *handle)
-{
-	struct iommu_group *group;
-	struct device *dev = handle->dev;
-	const struct iommu_ops *ops = dev_iommu_ops(dev);
-
-	if (!ops->sva_unbind)
-		return;
-
-	group = iommu_group_get(dev);
-	if (!group)
-		return;
-
-	mutex_lock(&group->mutex);
-	ops->sva_unbind(handle);
-	mutex_unlock(&group->mutex);
-
-	iommu_group_put(group);
-}
-EXPORT_SYMBOL_GPL(iommu_sva_unbind_device);
-
-u32 iommu_sva_get_pasid(struct iommu_sva *handle)
-{
-	const struct iommu_ops *ops = dev_iommu_ops(handle->dev);
-
-	if (!ops->sva_get_pasid)
-		return IOMMU_PASID_INVALID;
-
-	return ops->sva_get_pasid(handle);
-}
-EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
-
 /*
  * Changes the default domain of an iommu group that has *only* one device
  *
-- 
2.25.1

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