iommu/virtio: Return size mapped for a detached domain

When map() is called on a detached domain, the domain does not exist in
the device so we do not send a MAP request, but we do update the
internal mapping tree, to be replayed on the next attach. Since this
constitutes a successful iommu_map() call, return *mapped in this case
too.

Fixes: 7e62edd7 ("iommu/virtio: Add map/unmap_pages() callbacks implementation")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20230515113946.1017624-3-jean-philippe@linaro.orgSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/virtio-iommu.c

@@ -833,25 +833,26 @@ static int viommu_map_pages(struct iommu_domain *domain, unsigned long iova,
 	if (ret)
 		return ret;
 
-	map = (struct virtio_iommu_req_map) {
-		.head.type	= VIRTIO_IOMMU_T_MAP,
-		.domain		= cpu_to_le32(vdomain->id),
-		.virt_start	= cpu_to_le64(iova),
-		.phys_start	= cpu_to_le64(paddr),
-		.virt_end	= cpu_to_le64(end),
-		.flags		= cpu_to_le32(flags),
-	};
-
-	if (!vdomain->nr_endpoints)
-		return 0;
+	if (vdomain->nr_endpoints) {
+		map = (struct virtio_iommu_req_map) {
+			.head.type	= VIRTIO_IOMMU_T_MAP,
+			.domain		= cpu_to_le32(vdomain->id),
+			.virt_start	= cpu_to_le64(iova),
+			.phys_start	= cpu_to_le64(paddr),
+			.virt_end	= cpu_to_le64(end),
+			.flags		= cpu_to_le32(flags),
+		};
 
-	ret = viommu_send_req_sync(vdomain->viommu, &map, sizeof(map));
-	if (ret)
-		viommu_del_mappings(vdomain, iova, end);
-	else if (mapped)
+		ret = viommu_send_req_sync(vdomain->viommu, &map, sizeof(map));
+		if (ret) {
+			viommu_del_mappings(vdomain, iova, end);
+			return ret;
+		}
+	}
+	if (mapped)
 		*mapped = size;
 
-	return ret;
+	return 0;
 }
 
 static size_t viommu_unmap_pages(struct iommu_domain *domain, unsigned long iova,