[PATCH v4 13/14] iommu: Add ops->domain_alloc_sva()

[Vasant Hegde <vasant.hegde@amd.com>]

From: Jason Gunthorpe <jgg@nvidia.com>

Make a new op that receives the device and the mm_struct that the SVA
domain should be created for. Unlike domain_alloc_paging() the dev
argument is never NULL here.

This allows drivers to fully initialize the SVA domain and allocate the
mmu_notifier during allocation. It allows the notifier lifetime to follow
the lifetime of the iommu_domain.

Since we have only one call site, upgrade the new op to return ERR_PTR
instead of NULL.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
[Updated domain owner and removed smmu3 related changes - Vasant]
Signed-off-by: Vasant Hegde <vasant.hegde@amd.com>
---
 drivers/iommu/iommu-sva.c | 17 ++++++++++++-----
 include/linux/iommu.h     |  3 +++
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/iommu-sva.c b/drivers/iommu/iommu-sva.c
index b0e069562bb8..0d78d7c92d79 100644
--- a/drivers/iommu/iommu-sva.c
+++ b/drivers/iommu/iommu-sva.c
@@ -99,8 +99,8 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm
 
 	/* Allocate a new domain and set it on device pasid. */
 	domain = iommu_sva_domain_alloc(dev, mm);
-	if (!domain) {
-		ret = -ENOMEM;
+	if (IS_ERR(domain)) {
+		ret = PTR_ERR(domain);
 		goto out_free_handle;
 	}
 
@@ -270,11 +270,18 @@ struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
 	const struct iommu_ops *ops = dev_iommu_ops(dev);
 	struct iommu_domain *domain;
 
-	domain = ops->domain_alloc(IOMMU_DOMAIN_SVA);
-	if (!domain)
-		return NULL;
+	if (ops->domain_alloc_sva) {
+		domain = ops->domain_alloc_sva(dev, mm);
+		if (IS_ERR(domain))
+			return domain;
+	} else {
+		domain = ops->domain_alloc(IOMMU_DOMAIN_SVA);
+		if (!domain)
+			return ERR_PTR(-ENOMEM);
+	}
 
 	domain->type = IOMMU_DOMAIN_SVA;
+	domain->owner = ops;
 	mmgrab(mm);
 	domain->mm = mm;
 	domain->iopf_handler = iommu_sva_iopf_handler;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index b3b48e347c3d..0b18f1bd8b8a 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -450,6 +450,7 @@ static inline int __iommu_copy_struct_from_user(
  *                     Upon failure, ERR_PTR must be returned.
  * @domain_alloc_paging: Allocate an iommu_domain that can be used for
  *                       UNMANAGED, DMA, and DMA_FQ domain types.
+ * @domain_alloc_sva: Allocate an iommu_domain for Shared Virtual Addressing.
  * @probe_device: Add device to iommu driver handling
  * @release_device: Remove device from iommu driver handling
  * @probe_finalize: Do final setup work after the device is added to an IOMMU
@@ -490,6 +491,8 @@ struct iommu_ops {
 		struct device *dev, u32 flags, struct iommu_domain *parent,
 		const struct iommu_user_data *user_data);
 	struct iommu_domain *(*domain_alloc_paging)(struct device *dev);
+	struct iommu_domain *(*domain_alloc_sva)(struct device *dev,
+						 struct mm_struct *mm);
 
 	struct iommu_device *(*probe_device)(struct device *dev);
 	void (*release_device)(struct device *dev);
-- 
2.31.1