[RFC PATCH v1 3/8] iommufd: Split software MSI map lookup and allocation

[Andrew Jones]

Separate lookup of an existing software MSI mapping from allocation of a
new mapping. This prepares the code for allocating multiple mappings for
an MSI physical address list.

Signed-off-by: Andrew Jones <andrew.jones@xxxxxxxxxxxxxxxx>
---
 drivers/iommu/iommufd/driver.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/iommufd/driver.c b/drivers/iommu/iommufd/driver.c
index d0b05b1fda42..3856989f5c4b 100644
--- a/drivers/iommu/iommufd/driver.c
+++ b/drivers/iommu/iommufd/driver.c
@@ -189,6 +189,23 @@ iommufd_sw_msi_get_map(struct iommufd_ctx *ictx, phys_addr_t msi_addr,
 		       phys_addr_t sw_msi_start)
 {
 	struct iommufd_sw_msi_map *cur;
+
+	lockdep_assert_held(&ictx->sw_msi_lock);
+
+	list_for_each_entry(cur, &ictx->sw_msi_list, sw_msi_item) {
+		if (cur->sw_msi_start != sw_msi_start)
+			continue;
+		if (cur->msi_addr == msi_addr)
+			return cur;
+	}
+	return NULL;
+}
+
+static struct iommufd_sw_msi_map *
+iommufd_sw_msi_alloc_map(struct iommufd_ctx *ictx, phys_addr_t msi_addr,
+			 phys_addr_t sw_msi_start)
+{
+	struct iommufd_sw_msi_map *cur;
 	unsigned int max_pgoff = 0;
 
 	lockdep_assert_held(&ictx->sw_msi_lock);
@@ -199,8 +216,6 @@ iommufd_sw_msi_get_map(struct iommufd_ctx *ictx, phys_addr_t msi_addr,
 		if (cur->pgoff == UINT_MAX)
 			return ERR_PTR(-EOVERFLOW);
 		max_pgoff = max(max_pgoff, cur->pgoff + 1);
-		if (cur->msi_addr == msi_addr)
-			return cur;
 	}
 
 	if (ictx->sw_msi_id > IOMMUFD_SW_MSI_MAX_ID ||
@@ -293,6 +308,10 @@ int iommufd_sw_msi(struct iommu_domain *domain, struct msi_desc *desc,
 	msi_map = iommufd_sw_msi_get_map(handle->idev->ictx,
 					 msi_addr & PAGE_MASK,
 					 handle->idev->igroup->sw_msi_start);
+	if (!msi_map)
+		msi_map = iommufd_sw_msi_alloc_map(handle->idev->ictx,
+						   msi_addr & PAGE_MASK,
+						   handle->idev->igroup->sw_msi_start);
 	if (IS_ERR(msi_map))
 		return PTR_ERR(msi_map);
 
-- 
2.43.0