[PATCH RFC v2 03/11] iommu/sva: Add iommu_domain type for SVA

[Lu Baolu <baolu.lu@linux.intel.com>]

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