Date:   Thu, 21 Apr 2022 13:21:17 +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 v4 08/12] 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         |  44 ++++----
 drivers/iommu/iommu-sva-lib.h |   5 +
 drivers/iommu/iommu-sva-lib.c | 196 ++++++++++++++++++++++++++++++++++
 drivers/iommu/iommu.c         |  95 +---------------
 4 files changed, 227 insertions(+), 113 deletions(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 14c3b2197b35..2a2d17431826 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -677,12 +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);
 
@@ -1019,21 +1013,6 @@ 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;
@@ -1075,6 +1054,29 @@ static inline void iommu_detach_device_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.h b/drivers/iommu/iommu-sva-lib.h
index 9c5e108e2c8a..724af2226581 100644
--- a/drivers/iommu/iommu-sva-lib.h
+++ b/drivers/iommu/iommu-sva-lib.h
@@ -27,6 +27,7 @@ int iopf_queue_flush_dev(struct device *dev);
 struct iopf_queue *iopf_queue_alloc(const char *name);
 void iopf_queue_free(struct iopf_queue *queue);
 int iopf_queue_discard_partial(struct iopf_queue *queue);
+void iommu_sva_ioas_put(struct iommu_sva_ioas *ioas);
 
 #else /* CONFIG_IOMMU_SVA */
 static inline int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
@@ -64,5 +65,9 @@ static inline int iopf_queue_discard_partial(struct iopf_queue *queue)
 {
 	return -ENODEV;
 }
+
+static inline void iommu_sva_ioas_put(struct iommu_sva_ioas *ioas)
+{
+}
 #endif /* CONFIG_IOMMU_SVA */
 #endif /* _IOMMU_SVA_LIB_H */
diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
index d524a402be3b..7439f046d2ab 100644
--- a/drivers/iommu/iommu-sva-lib.c
+++ b/drivers/iommu/iommu-sva-lib.c
@@ -11,6 +11,7 @@
 
 static DEFINE_MUTEX(iommu_sva_lock);
 static DECLARE_IOASID_SET(iommu_sva_pasid);
+static DEFINE_XARRAY_ALLOC(iommu_sva_ioas_array);
 
 struct iommu_sva_ioas {
 	struct mm_struct *mm;
@@ -87,3 +88,198 @@ struct mm_struct *iommu_sva_find(ioasid_t pasid)
 	return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero);
 }
 EXPORT_SYMBOL_GPL(iommu_sva_find);
+
+/*
+ * Get or put an ioas for a shared memory.
+ */
+static struct iommu_sva_ioas *iommu_sva_ioas_get(struct mm_struct *mm,
+						 ioasid_t pasid)
+{
+	struct iommu_sva_ioas *ioas;
+	int ret;
+
+	ioas = xa_load(&iommu_sva_ioas_array, pasid);
+	if (ioas) {
+		if (WARN_ON(ioas->mm != mm))
+			return ERR_PTR(-EINVAL);
+		refcount_inc(&ioas->users);
+		return ioas;
+	}
+
+	ioas = kzalloc(sizeof(*ioas), GFP_KERNEL);
+	if (!ioas)
+		return ERR_PTR(-ENOMEM);
+
+	ioas->mm = mm;
+	ioas->pasid = pasid;
+	refcount_set(&ioas->users, 1);
+	INIT_LIST_HEAD(&ioas->bonds);
+	ret = xa_err(xa_store(&iommu_sva_ioas_array, pasid, ioas, GFP_KERNEL));
+	if (ret) {
+		kfree(ioas);
+		return ERR_PTR(ret);
+	}
+
+	mmgrab(mm);
+
+	return ioas;
+}
+
+void iommu_sva_ioas_put(struct iommu_sva_ioas *ioas)
+{
+	if (!ioas)
+		return;
+
+	if (refcount_dec_and_test(&ioas->users)) {
+		WARN_ON(!list_empty(&ioas->bonds));
+		xa_erase(&iommu_sva_ioas_array, ioas->pasid);
+		mmdrop(ioas->mm);
+		kfree(ioas);
+	}
+}
+
+/*
+ * IOMMU SVA driver-oriented interfaces
+ */
+static struct iommu_domain *
+iommu_sva_alloc_domain(struct device *dev, struct iommu_sva_ioas *ioas)
+{
+	struct bus_type *bus = dev->bus;
+	struct iommu_domain *domain;
+
+	if (!bus || !bus->iommu_ops)
+		return NULL;
+
+	domain = bus->iommu_ops->domain_alloc(IOMMU_DOMAIN_SVA);
+	if (!domain)
+		return NULL;
+
+	/* The caller must hold a reference to ioas. */
+	domain->sva_ioas = ioas;
+	domain->type = IOMMU_DOMAIN_SVA;
+
+	return domain;
+}
+
+/**
+ * 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;
+	struct iommu_sva_ioas *ioas;
+
+	/*
+	 * TODO: Remove the drvdata parameter after kernel PASID support is
+	 * enabled for the idxd driver.
+	 */
+	if (drvdata)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	/* Allocate mm->pasid if necessary. */
+	ret = iommu_sva_alloc_pasid(mm, 1, (1U << dev->iommu->pasid_bits) - 1);
+	if (ret)
+		return ERR_PTR(ret);
+
+	mutex_lock(&iommu_sva_lock);
+	ioas = iommu_sva_ioas_get(mm, mm->pasid);
+	if (IS_ERR(ioas)) {
+		ret = PTR_ERR(ioas);
+		goto out_unlock;
+	}
+
+	/* Search for an existing bond. */
+	list_for_each_entry(handle, &ioas->bonds, node) {
+		if (handle->dev == dev) {
+			refcount_inc(&handle->users);
+			/* No new bond, drop the counter. */
+			iommu_sva_ioas_put(ioas);
+			goto out_success;
+		}
+	}
+
+	handle = kzalloc(sizeof(*handle), GFP_KERNEL);
+	if (!handle) {
+		ret = -ENOMEM;
+		goto out_put_ioas;
+	}
+
+	/* The reference to ioas will be kept until domain free. */
+	domain = iommu_sva_alloc_domain(dev, ioas);
+	if (!domain) {
+		ret = -ENODEV;
+		goto out_free_handle;
+	}
+
+	ret = iommu_attach_device_pasid(domain, dev, mm->pasid);
+	if (ret)
+		goto out_free_domain;
+
+	handle->dev = dev;
+	handle->domain = domain;
+	handle->sva_ioas = ioas;
+	refcount_set(&handle->users, 1);
+	list_add_tail(&handle->node, &ioas->bonds);
+
+out_success:
+	mutex_unlock(&iommu_sva_lock);
+	return handle;
+
+out_free_domain:
+	domain->ops->free(domain);
+out_free_handle:
+	kfree(handle);
+out_put_ioas:
+	iommu_sva_ioas_put(ioas);
+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 iommu_sva_ioas *ioas = handle->sva_ioas;
+
+	mutex_lock(&iommu_sva_lock);
+	if (refcount_dec_and_test(&handle->users)) {
+		list_del(&handle->node);
+		iommu_detach_device_pasid(domain, dev, ioas->pasid);
+		iommu_domain_free(domain);
+		kfree(handle);
+	}
+	mutex_unlock(&iommu_sva_lock);
+}
+EXPORT_SYMBOL_GPL(iommu_sva_unbind_device);
+
+u32 iommu_sva_get_pasid(struct iommu_sva *handle)
+{
+	return handle->sva_ioas->pasid;
+}
+EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index c6fdc0067d76..7ed0a61351a5 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -27,6 +27,8 @@
 #include <linux/cc_platform.h>
 #include <trace/events/iommu.h>
 
+#include "iommu-sva-lib.h"
+
 static struct kset *iommu_group_kset;
 static DEFINE_IDA(iommu_group_ida);
 
@@ -1905,6 +1907,7 @@ EXPORT_SYMBOL_GPL(iommu_domain_alloc);
 void iommu_domain_free(struct iommu_domain *domain)
 {
 	iommu_put_dma_cookie(domain);
+	iommu_sva_ioas_put(domain->sva_ioas);
 	domain->ops->free(domain);
 }
 EXPORT_SYMBOL_GPL(iommu_domain_free);
@@ -2708,98 +2711,6 @@ 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_device_count(group) != 1)
-		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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