[PATCH v7 06/10] iommu/sva: Refactoring iommu_sva_bind/unbind_device()

Lu Baolu
2022-05-19T07:25:27Z

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
set/block_pasid_dev ops and align them with the concept of the SVA
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@linux.intel.com>
---
include/linux/iommu.h | 48 ++++++++------
drivers/iommu/iommu-sva-lib.h | 1 +
drivers/iommu/iommu-sva-lib.c | 113 ++++++++++++++++++++++++++++++++
drivers/iommu/iommu.c | 119 ++++++++--------------------------
4 files changed, 170 insertions(+), 111 deletions(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index e8cf82d46ce1..d9ac5ebe5bbb 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -635,6 +635,7 @@ struct iommu_fwspec {
*/
struct iommu_sva {
struct device *dev;
+ refcount_t users;
};

int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
@@ -677,11 +678,6 @@ 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 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);

@@ -693,6 +689,8 @@ int iommu_set_device_pasid(struct iommu_domain *domain, struct device *dev,
ioasid_t pasid);
void iommu_block_device_pasid(struct iommu_domain *domain, struct device *dev,
ioasid_t pasid);
+struct iommu_domain *
+iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid);
#else /* CONFIG_IOMMU_API */

struct iommu_ops {};
@@ -1023,21 +1021,6 @@ 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)
-{
- 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;
@@ -1077,6 +1060,12 @@ static inline void iommu_block_device_pasid(struct iommu_domain *domain,
struct device *dev, ioasid_t pasid)
{
}
+
+static inline struct iommu_domain *
+iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid)
+{
+ return NULL;
+}
#endif /* CONFIG_IOMMU_API */

/**
@@ -1108,6 +1097,10 @@ iommu_sva_alloc_domain(struct bus_type *bus, struct mm_struct *mm);
void iommu_sva_free_domain(struct iommu_domain *domain);
int iommu_sva_set_domain(struct iommu_domain *domain, struct device *dev,
ioasid_t pasid);
+struct iommu_sva *iommu_sva_bind_device(struct device *dev,
+ struct mm_struct *mm);
+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_domain *
iommu_sva_alloc_domain(struct bus_type *bus, struct mm_struct *mm)
@@ -1124,6 +1117,21 @@ static inline int iommu_sva_set_domain(struct iommu_domain *domain,
{
return -EINVAL;
}
+
+static inline struct iommu_sva *
+iommu_sva_bind_device(struct device *dev, struct mm_struct *mm)
+{
+ 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 */

#endif /* __LINUX_IOMMU_H */
diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
index 1be21e6b93ec..ebab5a8cb126 100644
--- a/drivers/iommu/iommu-sva-lib.h
+++ b/drivers/iommu/iommu-sva-lib.h
@@ -20,6 +20,7 @@ struct iopf_queue;
struct iommu_sva_domain {
struct iommu_domain domain;
struct mm_struct *mm;
+ struct iommu_sva bond;
};

#define to_sva_domain(d) container_of_safe(d, struct iommu_sva_domain, domain)
diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
index 210c376f6043..568e0f64edac 100644
--- a/drivers/iommu/iommu-sva-lib.c
+++ b/drivers/iommu/iommu-sva-lib.c
@@ -4,6 +4,8 @@
*/
#include <linux/mutex.h>
#include <linux/sched/mm.h>
+#include <linux/pci.h>
+#include <linux/pci-ats.h>

#include "iommu-sva-lib.h"

@@ -117,3 +119,114 @@ int iommu_sva_set_domain(struct iommu_domain *domain, struct device *dev,

return iommu_set_device_pasid(domain, dev, pasid);
}
+
+/**
+ * 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 mm_users
+ *
+ * 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)
+{
+ struct iommu_sva_domain *sva_domain;
+ struct iommu_domain *domain;
+ ioasid_t max_pasid = 0;
+ int ret = -EINVAL;
+
+ /* Allocate mm->pasid if necessary. */
+ if (!dev->iommu->iommu_dev->pasids)
+ return ERR_PTR(-EOPNOTSUPP);
+
+ if (dev_is_pci(dev)) {
+ max_pasid = pci_max_pasids(to_pci_dev(dev));
+ if (max_pasid < 0)
+ return ERR_PTR(max_pasid);
+ } else {
+ ret = device_property_read_u32(dev, "pasid-num-bits",
+ &max_pasid);
+ if (ret)
+ return ERR_PTR(ret);
+ max_pasid = (1UL << max_pasid);
+ }
+ max_pasid = min_t(u32, max_pasid, dev->iommu->iommu_dev->pasids);
+ ret = iommu_sva_alloc_pasid(mm, 1, max_pasid - 1);
+ if (ret)
+ return ERR_PTR(ret);
+
+ mutex_lock(&iommu_sva_lock);
+ /* Search for an existing domain. */
+ domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid);
+ if (domain) {
+ sva_domain = to_sva_domain(domain);
+ refcount_inc(&sva_domain->bond.users);
+ goto out_success;
+ }
+
+ /* Allocate a new domain and set it on device pasid. */
+ domain = iommu_sva_alloc_domain(dev->bus, mm);
+ if (IS_ERR(domain)) {
+ ret = PTR_ERR(domain);
+ goto out_unlock;
+ }
+
+ ret = iommu_sva_set_domain(domain, dev, mm->pasid);
+ if (ret)
+ goto out_free_domain;
+ sva_domain = to_sva_domain(domain);
+ sva_domain->bond.dev = dev;
+ refcount_set(&sva_domain->bond.users, 1);
+
+out_success:
+ mutex_unlock(&iommu_sva_lock);
+ return &sva_domain->bond;
+
+out_free_domain:
+ iommu_sva_free_domain(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_sva_domain *sva_domain =
+ container_of(handle, struct iommu_sva_domain, bond);
+ ioasid_t pasid = iommu_sva_get_pasid(handle);
+
+ mutex_lock(&iommu_sva_lock);
+ if (refcount_dec_and_test(&sva_domain->bond.users)) {
+ iommu_block_device_pasid(&sva_domain->domain, dev, pasid);
+ iommu_sva_free_domain(&sva_domain->domain);
+ }
+ mutex_unlock(&iommu_sva_lock);
+}
+EXPORT_SYMBOL_GPL(iommu_sva_unbind_device);
+
+u32 iommu_sva_get_pasid(struct iommu_sva *handle)
+{
+ struct iommu_sva_domain *sva_domain =
+ container_of(handle, struct iommu_sva_domain, bond);
+
+ return sva_domain->mm->pasid;
+}
+EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 789816e4b9d6..e49c5a5b8cc1 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2766,97 +2766,6 @@ 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
- *
- * 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)
-{
- 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);
-
-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
*
@@ -3322,3 +3231,31 @@ void iommu_block_device_pasid(struct iommu_domain *domain, struct device *dev,

iommu_group_put(group);
}
+
+/*
+ * This is a variant of iommu_get_domain_for_dev(). It returns the existing
+ * domain attached to pasid of a device. It's only for internal use of the
+ * IOMMU subsystem. The caller must take care to avoid any possible
+ * use-after-free case.
+ */
+struct iommu_domain *
+iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid)
+{
+ struct iommu_domain *domain;
+ struct iommu_group *group;
+
+ if (!pasid_valid(pasid))
+ return NULL;
+
+ group = iommu_group_get(dev);
+ if (!group)
+ return NULL;
+ /*
+ * The xarray protects its internal state with RCU. Hence the domain
+ * obtained is either NULL or fully formed.
+ */
+ domain = xa_load(&group->pasid_array, pasid);
+ iommu_group_put(group);
+
+ return domain;
+}
--
2.25.1