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Subject[PATCH RFC v2 03/11] iommu/sva: Add iommu_domain type for SVA
Date
Add a new iommu domain type IOMMU_DOMAIN_SVA to represent an I/O page
table which is shared from CPU host VA. Add some helpers to get and
put an SVA domain and implement SVA domain life cycle management.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
include/linux/iommu.h | 7 +++
drivers/iommu/iommu-sva-lib.h | 10 ++++
drivers/iommu/iommu-sva-lib.c | 89 +++++++++++++++++++++++++++++++++++
3 files changed, 106 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 36f43af0af53..29c4c2edd706 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_cookie;

/* 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_cookie *sva_cookie;
};

static inline bool iommu_is_dma_domain(struct iommu_domain *domain)
diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
index 8909ea1094e3..1a71218b07f5 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;
@@ -26,6 +27,8 @@ int iopf_queue_flush_dev(struct device *dev);
struct iopf_queue *iopf_queue_alloc(const char *name);
void iopf_queue_free(struct iopf_queue *queue);
int iopf_queue_discard_partial(struct iopf_queue *queue);
+bool iommu_sva_domain_get_user(struct iommu_domain *domain);
+void iommu_sva_domain_put_user(struct iommu_domain *domain);

#else /* CONFIG_IOMMU_SVA */
static inline int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
@@ -63,5 +66,12 @@ static inline int iopf_queue_discard_partial(struct iopf_queue *queue)
{
return -ENODEV;
}
+
+static inline bool iommu_sva_domain_get_user(struct iommu_domain *domain)
+{
+ return false;
+}
+
+static inline void iommu_sva_domain_put_user(struct iommu_domain *domain) { }
#endif /* CONFIG_IOMMU_SVA */
#endif /* _IOMMU_SVA_LIB_H */
diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
index 106506143896..78820be23f15 100644
--- a/drivers/iommu/iommu-sva-lib.c
+++ b/drivers/iommu/iommu-sva-lib.c
@@ -3,12 +3,21 @@
* 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"

static DEFINE_MUTEX(iommu_sva_lock);
static DECLARE_IOASID_SET(iommu_sva_pasid);
+static DEFINE_XARRAY_ALLOC(sva_domain_array);
+
+struct iommu_sva_cookie {
+ struct mm_struct *mm;
+ ioasid_t pasid;
+ refcount_t users;
+};

/**
* iommu_sva_alloc_pasid - Allocate a PASID for the mm
@@ -69,3 +78,83 @@ 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);
+
+static struct iommu_domain *
+iommu_sva_alloc_domain(struct device *dev, struct mm_struct *mm)
+{
+ struct bus_type *bus = dev->bus;
+ struct iommu_sva_cookie *cookie;
+ struct iommu_domain *domain;
+ void *curr;
+
+ if (!bus || !bus->iommu_ops)
+ return NULL;
+
+ cookie = kzalloc(sizeof(*cookie), GFP_KERNEL);
+ if (!cookie)
+ return NULL;
+
+ domain = bus->iommu_ops->domain_alloc(IOMMU_DOMAIN_SVA);
+ if (!domain)
+ goto err_domain_alloc;
+
+ cookie->mm = mm;
+ cookie->pasid = mm->pasid;
+ refcount_set(&cookie->users, 1);
+ domain->type = IOMMU_DOMAIN_SVA;
+ domain->sva_cookie = cookie;
+ curr = xa_store(&sva_domain_array, mm->pasid, domain, GFP_KERNEL);
+ if (xa_err(curr))
+ goto err_xa_store;
+
+ return domain;
+err_xa_store:
+ domain->ops->free(domain);
+err_domain_alloc:
+ kfree(cookie);
+ return NULL;
+}
+
+static void iommu_sva_free_domain(struct iommu_domain *domain)
+{
+ xa_erase(&sva_domain_array, domain->sva_cookie->pasid);
+ kfree(domain->sva_cookie);
+ domain->ops->free(domain);
+}
+
+bool iommu_sva_domain_get_user(struct iommu_domain *domain)
+{
+ struct iommu_sva_cookie *cookie = domain->sva_cookie;
+
+ return refcount_inc_not_zero(&cookie->users);
+}
+
+void iommu_sva_domain_put_user(struct iommu_domain *domain)
+{
+ struct iommu_sva_cookie *cookie = domain->sva_cookie;
+
+ if (refcount_dec_and_test(&cookie->users))
+ iommu_sva_free_domain(domain);
+}
+
+static __maybe_unused struct iommu_domain *
+iommu_sva_get_domain(struct device *dev, struct mm_struct *mm)
+{
+ struct iommu_domain *domain;
+ ioasid_t pasid = mm->pasid;
+
+ if (pasid == INVALID_IOASID)
+ return NULL;
+
+ domain = xa_load(&sva_domain_array, pasid);
+ if (!domain)
+ return iommu_sva_alloc_domain(dev, mm);
+ iommu_sva_domain_get_user(domain);
+
+ return domain;
+}
+
+struct mm_struct *iommu_sva_domain_mm(struct iommu_domain *domain)
+{
+ return domain->sva_cookie->mm;
+}
--
2.25.1
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