Add iommu_map_file() and __iommu_map_file() to map a file descriptor
(such as a memfd or VFIO PCI dma-buf) into an iommufd IOAS via
IOMMU_IOAS_MAP_FILE. Also skip regions without a host virtual address in
__iommu_hva2iova(), since file-backed DMA mappings do not require one.

Signed-off-by: David Matlack <dmatlack@google.com>
---
 .../vfio/lib/include/libvfio/iommu.h          |  9 ++++++
 tools/testing/selftests/vfio/lib/iommu.c      | 29 +++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h b/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h
index e9a3386a4719..2b39c49e66da 100644
--- a/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h
+++ b/tools/testing/selftests/vfio/lib/include/libvfio/iommu.h
@@ -42,6 +42,15 @@ static inline void iommu_map(struct iommu *iommu, struct dma_region *region)
 	VFIO_ASSERT_EQ(__iommu_map(iommu, region), 0);
 }
 
+int __iommu_map_file(struct iommu *iommu, int fd, u64 file_offset,
+		     struct dma_region *region);
+
+static inline void iommu_map_file(struct iommu *iommu, int fd, u64 file_offset,
+				  struct dma_region *region)
+{
+	VFIO_ASSERT_EQ(__iommu_map_file(iommu, fd, file_offset, region), 0);
+}
+
 int __iommu_unmap(struct iommu *iommu, struct dma_region *region, u64 *unmapped);
 
 static inline void iommu_unmap(struct iommu *iommu, struct dma_region *region)
diff --git a/tools/testing/selftests/vfio/lib/iommu.c b/tools/testing/selftests/vfio/lib/iommu.c
index b6f3c5c84e01..ba602685f892 100644
--- a/tools/testing/selftests/vfio/lib/iommu.c
+++ b/tools/testing/selftests/vfio/lib/iommu.c
@@ -71,6 +71,9 @@ int __iommu_hva2iova(struct iommu *iommu, void *vaddr, iova_t *iova)
 	struct dma_region *region;
 
 	list_for_each_entry(region, &iommu->dma_regions, link) {
+		if (!region->vaddr)
+			continue;
+
 		if (vaddr < region->vaddr)
 			continue;
 
@@ -149,6 +152,32 @@ int __iommu_map(struct iommu *iommu, struct dma_region *region)
 	return 0;
 }
 
+int __iommu_map_file(struct iommu *iommu, int fd, u64 file_offset,
+		     struct dma_region *region)
+{
+	struct iommu_ioas_map_file args = {
+		.size = sizeof(args),
+		.flags = IOMMU_IOAS_MAP_READABLE |
+			 IOMMU_IOAS_MAP_WRITEABLE |
+			 IOMMU_IOAS_MAP_FIXED_IOVA,
+		.ioas_id = iommu->ioas_id,
+		.fd = fd,
+		.start = file_offset,
+		.length = region->size,
+		.iova = region->iova,
+	};
+
+	if (!iommu->iommufd)
+		return -EOPNOTSUPP;
+
+	if (ioctl(iommu->iommufd, IOMMU_IOAS_MAP_FILE, &args))
+		return -errno;
+
+	list_add(&region->link, &iommu->dma_regions);
+
+	return 0;
+}
+
 static int __vfio_iommu_unmap(int fd, u64 iova, u64 size, u32 flags, u64 *unmapped)
 {
 	struct vfio_iommu_type1_dma_unmap args = {
-- 
2.56.0.567.gdb80ae8cd5-goog