[PATCH RFC v3 04/12] iommu/sva: Basic data structures for SVA

[Lu Baolu]

Use below data structures for SVA implementation in the IOMMU core:

- struct iommu_sva_ioas
  Represent the I/O address space shared with an application CPU address
  space. This structure has a 1:1 relationship with an mm_struct. It
  graps a "mm->mm_count" refcount during creation and drop it on release.

- struct iommu_domain (IOMMU_DOMAIN_SVA type)
  Represent a hardware pagetable that the IOMMU hardware could use for
  SVA translation. Multiple iommu domains could be bound with an SVA ioas
  and each graps a refcount from ioas in order to make sure ioas could
  only be freed after all domains have been unbound.

- struct iommu_sva
  Represent a bond relationship between an SVA ioas and an iommu domain.
  If a bond already exists, it's reused and a reference is taken.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 include/linux/iommu.h         | 14 +++++++++++++-
 drivers/iommu/iommu-sva-lib.h |  1 +
 drivers/iommu/iommu-sva-lib.c | 18 ++++++++++++++++++
 3 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index fe7d9ee2bc2b..14c3b2197b35 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -42,6 +42,7 @@ struct notifier_block;
 struct iommu_sva;
 struct iommu_fault_event;
 struct iommu_dma_cookie;
+struct iommu_sva_ioas;
 
 /* iommu fault flags */
 #define IOMMU_FAULT_READ	0x0
@@ -64,6 +65,9 @@ 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_SHARED	(1U << 4)  /* Page table shared from CPU  */
+#define __IOMMU_DOMAIN_HOST_VA	(1U << 5)  /* Host CPU virtual address */
+
 /*
  * This are the possible domain-types
  *
@@ -86,6 +90,8 @@ 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_SHARED |	\
+				 __IOMMU_DOMAIN_HOST_VA)
 
 struct iommu_domain {
 	unsigned type;
@@ -95,6 +101,7 @@ struct iommu_domain {
 	void *handler_token;
 	struct iommu_domain_geometry geometry;
 	struct iommu_dma_cookie *iova_cookie;
+	struct iommu_sva_ioas *sva_ioas;
 };
 
 static inline bool iommu_is_dma_domain(struct iommu_domain *domain)
@@ -622,7 +629,12 @@ struct iommu_fwspec {
  * struct iommu_sva - handle to a device-mm bond
  */
 struct iommu_sva {
-	struct device			*dev;
+	struct device		*dev;
+	struct iommu_sva_ioas	*sva_ioas;
+	struct iommu_domain	*domain;
+	/* Link to sva ioas's bonds list */
+	struct list_head	node;
+	refcount_t		users;
 };
 
 int iommu_fwspec_init(struct device *dev, struct fwnode_handle *iommu_fwnode,
diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
index 8909ea1094e3..9c5e108e2c8a 100644
--- a/drivers/iommu/iommu-sva-lib.h
+++ b/drivers/iommu/iommu-sva-lib.h
@@ -10,6 +10,7 @@
 
 int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max);
 struct mm_struct *iommu_sva_find(ioasid_t pasid);
+struct mm_struct *iommu_sva_domain_mm(struct iommu_domain *domain);
 
 /* I/O Page fault */
 struct device;
diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
index 106506143896..d524a402be3b 100644
--- a/drivers/iommu/iommu-sva-lib.c
+++ b/drivers/iommu/iommu-sva-lib.c
@@ -3,6 +3,8 @@
  * Helpers for IOMMU drivers implementing SVA
  */
 #include <linux/mutex.h>
+#include <linux/iommu.h>
+#include <linux/slab.h>
 #include <linux/sched/mm.h>
 
 #include "iommu-sva-lib.h"
@@ -10,6 +12,22 @@
 static DEFINE_MUTEX(iommu_sva_lock);
 static DECLARE_IOASID_SET(iommu_sva_pasid);
 
+struct iommu_sva_ioas {
+	struct mm_struct *mm;
+	ioasid_t pasid;
+
+	/* Counter of domains attached to this ioas. */
+	refcount_t users;
+
+	/* All bindings are linked here. */
+	struct list_head bonds;
+};
+
+struct mm_struct *iommu_sva_domain_mm(struct iommu_domain *domain)
+{
+	return domain->sva_ioas->mm;
+}
+
 /**
  * iommu_sva_alloc_pasid - Allocate a PASID for the mm
  * @mm: the mm
-- 
2.25.1