Re: [PATCH v10 08/12] iommu/sva: Refactoring iommu_sva_bind/unbind_device()
From: Baolu Lu
Date: Sun Jul 31 2022 - 09:51:48 EST
On 2022/7/31 20:55, Yi Liu wrote:
On 2022/7/5 13:07, Lu Baolu wrote:
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@xxxxxxxxxxxxxxx>
Tested-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
Tested-by: Tony Zhu <tony.zhu@xxxxxxxxx>
---
include/linux/iommu.h | 67 +++++++++++--------
drivers/iommu/iommu-sva-lib.c | 98 ++++++++++++++++++++++++++++
drivers/iommu/iommu.c | 119 ++++++++--------------------------
3 files changed, 165 insertions(+), 119 deletions(-)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 42f0418dc22c..f59b0ecd3995 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -39,7 +39,6 @@ struct device;
struct iommu_domain;
struct iommu_domain_ops;
struct notifier_block;
-struct iommu_sva;
struct iommu_fault_event;
struct iommu_dma_cookie;
@@ -57,6 +56,14 @@ struct iommu_domain_geometry {
bool force_aperture; /* DMA only allowed in mappable
range? */
};
+/**
+ * struct iommu_sva - handle to a device-mm bond
+ */
+struct iommu_sva {
+ struct device *dev;
+ refcount_t users;
+};
+
/* Domain feature flags */
#define __IOMMU_DOMAIN_PAGING (1U << 0) /* Support for
iommu_map/unmap */
#define __IOMMU_DOMAIN_DMA_API (1U << 1) /* Domain for use in
DMA-API
@@ -105,6 +112,7 @@ struct iommu_domain {
};
struct { /* IOMMU_DOMAIN_SVA */
struct mm_struct *mm;
+ struct iommu_sva bond;
};
};
};
@@ -638,13 +646,6 @@ struct iommu_fwspec {
/* ATS is supported */
#define IOMMU_FWSPEC_PCI_RC_ATS (1 << 0)
-/**
- * struct iommu_sva - handle to a device-mm bond
- */
-struct iommu_sva {
- struct device *dev;
-};
-
int iommu_fwspec_init(struct device *dev, struct fwnode_handle
*iommu_fwnode,
const struct iommu_ops *ops);
void iommu_fwspec_free(struct device *dev);
@@ -685,11 +686,6 @@ 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);
@@ -703,6 +699,8 @@ int iommu_attach_device_pasid(struct iommu_domain
*domain, struct device *dev,
ioasid_t pasid);
void iommu_detach_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 {};
@@ -1033,21 +1031,6 @@ 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;
@@ -1093,6 +1076,12 @@ static inline void
iommu_detach_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 */
/**
@@ -1118,4 +1107,26 @@ void iommu_debugfs_setup(void);
static inline void iommu_debugfs_setup(void) {}
#endif
+#ifdef CONFIG_IOMMU_SVA
+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
+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.c
b/drivers/iommu/iommu-sva-lib.c
index 106506143896..751366980232 100644
--- a/drivers/iommu/iommu-sva-lib.c
+++ b/drivers/iommu/iommu-sva-lib.c
@@ -4,6 +4,7 @@
*/
#include <linux/mutex.h>
#include <linux/sched/mm.h>
+#include <linux/iommu.h>
#include "iommu-sva-lib.h"
@@ -69,3 +70,100 @@ 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);
+
+/**
+ * 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_domain *domain;
+ ioasid_t max_pasids;
+ int ret = -EINVAL;
+
+ max_pasids = dev->iommu->max_pasids;
+ if (!max_pasids)
+ return ERR_PTR(-EOPNOTSUPP);
+
+ /* Allocate mm->pasid if necessary. */
+ ret = iommu_sva_alloc_pasid(mm, 1, max_pasids - 1);
do we want to call mmgrab() before iomu_sva_alloc_pasid() to
avoid using mm without any reference? In your current code,
mmgrab() is called in iommu_sva_domain_alloc().
As the comment of this API states "caller must hold a reference to
mm_users".
Best regards,
baolu