[PATCH v5 04/12] iommu/sva: Basic data structures for SVA

Lu Baolu
2022-05-02T01:52:12Z

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
grabs 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 grabs 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@linux.intel.com>
---
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 ab36244d4e94..f582f434c513 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)
@@ -628,7 +635,12 @@ 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