[PATCH v13 06/13] iommu: Add IOMMU SVA domain support

[Lu Baolu]

The SVA iommu_domain represents a hardware pagetable that the IOMMU
hardware could use for SVA translation. This adds some infrastructures
to support SVA domain in the iommu core. It includes:

- Extend the iommu_domain to support a new IOMMU_DOMAIN_SVA domain
  type. The IOMMU drivers that support allocation of the SVA domain
  should provide its own SVA domain specific iommu_domain_ops.
- Add a helper to allocate an SVA domain. The iommu_domain_free()
  is still used to free an SVA domain.

The report_iommu_fault() should be replaced by the new
iommu_report_device_fault(). Leave the existing fault handler with the
existing users and the newly added SVA members excludes it.

Suggested-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reviewed-by: Yi Liu <yi.l.liu@xxxxxxxxx>
Tested-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
Tested-by: Tony Zhu <tony.zhu@xxxxxxxxx>
---
 include/linux/iommu.h | 25 +++++++++++++++++++++++--
 drivers/iommu/iommu.c | 20 ++++++++++++++++++++
 2 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 7332caeea43b..c45236d95355 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -64,6 +64,8 @@ struct iommu_domain_geometry {
 #define __IOMMU_DOMAIN_PT	(1U << 2)  /* Domain is identity mapped   */
 #define __IOMMU_DOMAIN_DMA_FQ	(1U << 3)  /* DMA-API uses flush queue    */
 
+#define __IOMMU_DOMAIN_SVA	(1U << 4)  /* Shared process address space */
+
 /*
  * This are the possible domain-types
  *
@@ -77,6 +79,8 @@ struct iommu_domain_geometry {
  *				  certain optimizations for these domains
  *	IOMMU_DOMAIN_DMA_FQ	- As above, but definitely using batched TLB
  *				  invalidation.
+ *	IOMMU_DOMAIN_SVA	- DMA addresses are shared process addresses
+ *				  represented by mm_struct's.
  */
 #define IOMMU_DOMAIN_BLOCKED	(0U)
 #define IOMMU_DOMAIN_IDENTITY	(__IOMMU_DOMAIN_PT)
@@ -86,15 +90,24 @@ struct iommu_domain_geometry {
 #define IOMMU_DOMAIN_DMA_FQ	(__IOMMU_DOMAIN_PAGING |	\
 				 __IOMMU_DOMAIN_DMA_API |	\
 				 __IOMMU_DOMAIN_DMA_FQ)
+#define IOMMU_DOMAIN_SVA	(__IOMMU_DOMAIN_SVA)
 
 struct iommu_domain {
 	unsigned type;
 	const struct iommu_domain_ops *ops;
 	unsigned long pgsize_bitmap;	/* Bitmap of page sizes in use */
-	iommu_fault_handler_t handler;
-	void *handler_token;
 	struct iommu_domain_geometry geometry;
 	struct iommu_dma_cookie *iova_cookie;
+	union {
+		struct {
+			iommu_fault_handler_t handler;
+			void *handler_token;
+		};
+		struct {	/* IOMMU_DOMAIN_SVA */
+			struct mm_struct *mm;
+			int users;
+		};
+	};
 };
 
 static inline bool iommu_is_dma_domain(struct iommu_domain *domain)
@@ -687,6 +700,8 @@ int iommu_group_claim_dma_owner(struct iommu_group *group, void *owner);
 void iommu_group_release_dma_owner(struct iommu_group *group);
 bool iommu_group_dma_owner_claimed(struct iommu_group *group);
 
+struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
+					    struct mm_struct *mm);
 int iommu_attach_device_pasid(struct iommu_domain *domain,
 			      struct device *dev, ioasid_t pasid);
 void iommu_detach_device_pasid(struct iommu_domain *domain,
@@ -1062,6 +1077,12 @@ static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group)
 	return false;
 }
 
+static inline struct iommu_domain *
+iommu_sva_domain_alloc(struct device *dev, struct mm_struct *mm)
+{
+	return NULL;
+}
+
 static inline int iommu_attach_device_pasid(struct iommu_domain *domain,
 					    struct device *dev, ioasid_t pasid)
 {
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 4ac4fd7d94f6..2d0a1688725a 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -27,6 +27,7 @@
 #include <linux/module.h>
 #include <linux/cc_platform.h>
 #include <trace/events/iommu.h>
+#include <linux/sched/mm.h>
 
 static struct kset *iommu_group_kset;
 static DEFINE_IDA(iommu_group_ida);
@@ -1960,6 +1961,8 @@ EXPORT_SYMBOL_GPL(iommu_domain_alloc);
 
 void iommu_domain_free(struct iommu_domain *domain)
 {
+	if (domain->type == IOMMU_DOMAIN_SVA)
+		mmdrop(domain->mm);
 	iommu_put_dma_cookie(domain);
 	domain->ops->free(domain);
 }
@@ -3388,3 +3391,20 @@ struct iommu_domain *iommu_get_domain_for_dev_pasid(struct device *dev,
 	return domain;
 }
 EXPORT_SYMBOL_GPL(iommu_get_domain_for_dev_pasid);
+
+struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
+					    struct mm_struct *mm)
+{
+	const struct iommu_ops *ops = dev_iommu_ops(dev);
+	struct iommu_domain *domain;
+
+	domain = ops->domain_alloc(IOMMU_DOMAIN_SVA);
+	if (!domain)
+		return NULL;
+
+	domain->type = IOMMU_DOMAIN_SVA;
+	mmgrab(mm);
+	domain->mm = mm;
+
+	return domain;
+}
-- 
2.25.1