[RFC PATCH 28/33] vfio: selftests: Add iommufd mode

23 May 2025

Add a new IOMMU mode for using iommufd directly. In this mode userspace
opens /dev/iommu and binds it to a device FD acquired through
/dev/vfio/devices/vfioX.
Signed-off-by: David Matlack dmatlack@google.com
---
 .../selftests/vfio/lib/include/vfio_util.h    |   3 +
 .../selftests/vfio/lib/vfio_pci_device.c      | 175 ++++++++++++++----
 2 files changed, 144 insertions(+), 34 deletions(-)

diff --git a/tools/testing/selftests/vfio/lib/include/vfio_util.h b/tools/testing/selftests/vfio/lib/include/vfio_util.h
index 9989528c21b9..b03b3d8f5a52 100644
--- a/tools/testing/selftests/vfio/lib/include/vfio_util.h
+++ b/tools/testing/selftests/vfio/lib/include/vfio_util.h
@@ -155,6 +155,9 @@ struct vfio_pci_device {
    int group_fd;
    int container_fd;
+	int iommufd;
+	u32 ioas_id;
+
    struct vfio_device_info info;
    struct vfio_region_info config_space;
    struct vfio_pci_bar bars[PCI_STD_NUM_BARS];
diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
index 205bbfb3d54e..d996e012a646 100644
--- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
+++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
@@ -10,10 +10,12 @@
 #include <sys/ioctl.h>
 #include <sys/mman.h>
+#include <uapi/linux/types.h>
 #include <linux/limits.h>
 #include <linux/mman.h>
 #include <linux/types.h>
 #include <linux/vfio.h>
+#include <linux/iommufd.h>
#include "../../../kselftest.h"
 #include <vfio_util.h>
@@ -140,32 +142,80 @@ static void vfio_pci_irq_get(struct vfio_pci_device *device, u32 index,
    ioctl_assert(device->fd, VFIO_DEVICE_GET_IRQ_INFO, irq_info);
 }
-void vfio_pci_dma_map(struct vfio_pci_device *device,
-		      struct vfio_dma_region *region)
+static void vfio_iommu_dma_map(struct vfio_pci_device *device,
+			       struct vfio_dma_region *region)
 {
-	struct vfio_iommu_type1_dma_map map = {
-		.argsz = sizeof(map),
+	struct vfio_iommu_type1_dma_map args = {
+		.argsz = sizeof(args),
    	.flags = VFIO_DMA_MAP_FLAG_READ | VFIO_DMA_MAP_FLAG_WRITE,
    	.vaddr = (u64)region->vaddr,
    	.iova = region->iova,
    	.size = region->size,
    };
-	ioctl_assert(device->container_fd, VFIO_IOMMU_MAP_DMA, &map);
+	ioctl_assert(device->container_fd, VFIO_IOMMU_MAP_DMA, &args);
+}
+
+static void iommufd_dma_map(struct vfio_pci_device *device,
+			    struct vfio_dma_region *region)
+{
+	struct iommu_ioas_map args = {
+		.size = sizeof(args),
+		.flags = IOMMU_IOAS_MAP_READABLE |
+			 IOMMU_IOAS_MAP_WRITEABLE |
+			 IOMMU_IOAS_MAP_FIXED_IOVA,
+		.user_va = (u64)region->vaddr,
+		.iova = region->iova,
+		.length = region->size,
+		.ioas_id = device->ioas_id,
+	};
+
+	ioctl_assert(device->iommufd, IOMMU_IOAS_MAP, &args);
+}
+
+void vfio_pci_dma_map(struct vfio_pci_device *device,
+		      struct vfio_dma_region *region)
+{
+	if (device->iommufd)
+		iommufd_dma_map(device, region);
+	else
+		vfio_iommu_dma_map(device, region);
list_add(&region->link, &device->dma_regions);
 }
-void vfio_pci_dma_unmap(struct vfio_pci_device *device,
-			struct vfio_dma_region *region)
+static void vfio_iommu_dma_unmap(struct vfio_pci_device *device,
+				 struct vfio_dma_region *region)
 {
-	struct vfio_iommu_type1_dma_unmap unmap = {
-		.argsz = sizeof(unmap),
+	struct vfio_iommu_type1_dma_unmap args = {
+		.argsz = sizeof(args),
    	.iova = region->iova,
    	.size = region->size,
    };
-	ioctl_assert(device->container_fd, VFIO_IOMMU_UNMAP_DMA, &unmap);
+	ioctl_assert(device->container_fd, VFIO_IOMMU_UNMAP_DMA, &args);
+}
+
+static void iommufd_dma_unmap(struct vfio_pci_device *device,
+			      struct vfio_dma_region *region)
+{
+	struct iommu_ioas_unmap args = {
+		.size = sizeof(args),
+		.iova = region->iova,
+		.length = region->size,
+		.ioas_id = device->ioas_id,
+	};
+
+	ioctl_assert(device->iommufd, IOMMU_IOAS_UNMAP, &args);
+}
+
+void vfio_pci_dma_unmap(struct vfio_pci_device *device,
+			struct vfio_dma_region *region)
+{
+	if (device->iommufd)
+		iommufd_dma_unmap(device, region);
+	else
+		vfio_iommu_dma_unmap(device, region);
list_del(&region->link);
 }
@@ -254,18 +304,6 @@ static unsigned int vfio_pci_get_group_from_dev(const char *bdf)
    return group;
 }
-static void vfio_pci_container_setup(struct vfio_pci_device *device)
-{
-	const char *path = device->iommu_mode->container_path;
-	int version;
-
-	device->container_fd = open(path, O_RDWR);
-	VFIO_ASSERT_GE(device->container_fd, 0, "open(%s) failed\n", path);
-
-	version = ioctl(device->container_fd, VFIO_GET_API_VERSION);
-	VFIO_ASSERT_EQ(version, VFIO_API_VERSION);
-}
-
 static void vfio_pci_group_setup(struct vfio_pci_device *device, const char *bdf)
 {
    struct vfio_group_status group_status = {
@@ -286,26 +324,34 @@ static void vfio_pci_group_setup(struct vfio_pci_device *device, const char *bdf
    ioctl_assert(device->group_fd, VFIO_GROUP_SET_CONTAINER, &device->container_fd);
 }
-static void vfio_pci_iommu_setup(struct vfio_pci_device *device)
+static void vfio_pci_container_setup(struct vfio_pci_device *device, const char *bdf)
 {
    unsigned long iommu_type = device->iommu_mode->group_iommu_type;
+	const char *path = device->iommu_mode->container_path;
+	int version;
    int ret;
-	INIT_LIST_HEAD(&device->dma_regions);
+	device->container_fd = open(path, O_RDWR);
+	VFIO_ASSERT_GE(device->container_fd, 0, "open(%s) failed\n", path);
+
+	version = ioctl(device->container_fd, VFIO_GET_API_VERSION);
+	VFIO_ASSERT_EQ(version, VFIO_API_VERSION, "Unsupported version: %d\n", version);
+
+	vfio_pci_group_setup(device, bdf);
ret = ioctl(device->container_fd, VFIO_CHECK_EXTENSION, iommu_type);
    VFIO_ASSERT_GT(ret, 0, "VFIO IOMMU type %lu not supported\n", iommu_type);
ioctl_assert(device->container_fd, VFIO_SET_IOMMU, (void *)iommu_type);
+
+	device->fd = ioctl(device->group_fd, VFIO_GROUP_GET_DEVICE_FD, bdf);
+	VFIO_ASSERT_GE(device->fd, 0);
 }
-static void vfio_pci_device_setup(struct vfio_pci_device *device, const char *bdf)
+static void vfio_pci_device_setup(struct vfio_pci_device *device)
 {
    int i;
-	device->fd = ioctl(device->group_fd, VFIO_GROUP_GET_DEVICE_FD, bdf);
-	VFIO_ASSERT_GE(device->fd, 0);
-
    device->info.argsz = sizeof(device->info);
    ioctl_assert(device->fd, VFIO_DEVICE_GET_INFO, &device->info);
@@ -381,6 +427,9 @@ static const struct vfio_iommu_mode iommu_modes[] = {
    	.container_path = "/dev/iommu",
    	.group_iommu_type = VFIO_TYPE1v2_IOMMU,
    },
+	{
+		.name = "iommufd",
+	},
 };
const char *default_iommu_mode = "vfio_type1_iommu";
@@ -417,6 +466,57 @@ static const struct vfio_iommu_mode *lookup_iommu_mode(const char *iommu_mode)
    VFIO_FAIL("Unrecognized IOMMU mode: %s\n", iommu_mode);
 }
+static void vfio_device_bind_iommufd(int device_fd, int iommufd)
+{
+	struct vfio_device_bind_iommufd args = {
+		.argsz = sizeof(args),
+		.iommufd = iommufd,
+	};
+
+	ioctl_assert(device_fd, VFIO_DEVICE_BIND_IOMMUFD, &args);
+}
+
+static u32 iommufd_ioas_alloc(int iommufd)
+{
+	struct iommu_ioas_alloc args = {
+		.size = sizeof(args),
+	};
+
+	ioctl_assert(iommufd, IOMMU_IOAS_ALLOC, &args);
+	return args.out_ioas_id;
+}
+
+static void vfio_device_attach_iommufd_pt(int device_fd, u32 pt_id)
+{
+	struct vfio_device_attach_iommufd_pt args = {
+		.argsz = sizeof(args),
+		.pt_id = pt_id,
+	};
+
+	ioctl_assert(device_fd, VFIO_DEVICE_ATTACH_IOMMUFD_PT, &args);
+}
+
+static void vfio_pci_iommufd_setup(struct vfio_pci_device *device, const char *bdf)
+{
+	const char *cdev_path = vfio_pci_get_cdev_path(bdf);
+
+	device->fd = open(cdev_path, O_RDWR);
+	VFIO_ASSERT_GE(device->fd, 0);
+	free((void *)cdev_path);
+
+	/*
+	 * Require device->iommufd to be >0 so that a simple non-0 check can be
+	 * used to check if iommufd is enabled. In practice open() will never
+	 * return 0 unless stdin is closed.
+	 */
+	device->iommufd = open("/dev/iommu", O_RDWR);
+	VFIO_ASSERT_GT(device->iommufd, 0);
+
+	vfio_device_bind_iommufd(device->fd, device->iommufd);
+	device->ioas_id = iommufd_ioas_alloc(device->iommufd);
+	vfio_device_attach_iommufd_pt(device->fd, device->ioas_id);
+}
+
 struct vfio_pci_device *vfio_pci_device_init(const char *bdf, const char *iommu_mode)
 {
    struct vfio_pci_device *device;
@@ -424,13 +524,16 @@ struct vfio_pci_device *vfio_pci_device_init(const char *bdf, const char *iommu_
    device = calloc(1, sizeof(*device));
    VFIO_ASSERT_NOT_NULL(device);
+	INIT_LIST_HEAD(&device->dma_regions);
+
    device->iommu_mode = lookup_iommu_mode(iommu_mode);
-	vfio_pci_container_setup(device);
-	vfio_pci_group_setup(device, bdf);
-	vfio_pci_iommu_setup(device);
-	vfio_pci_device_setup(device, bdf);
+	if (device->iommu_mode->container_path)
+		vfio_pci_container_setup(device, bdf);
+	else
+		vfio_pci_iommufd_setup(device, bdf);
+	vfio_pci_device_setup(device);
    vfio_pci_driver_probe(device);
return device;
@@ -454,8 +557,12 @@ void vfio_pci_device_cleanup(struct vfio_pci_device *device)
    	VFIO_ASSERT_EQ(close(device->msi_eventfds[i]), 0);
    }
-	VFIO_ASSERT_EQ(close(device->group_fd), 0);
-	VFIO_ASSERT_EQ(close(device->container_fd), 0);
+	if (device->iommufd) {
+		VFIO_ASSERT_EQ(close(device->iommufd), 0);
+	} else {
+		VFIO_ASSERT_EQ(close(device->group_fd), 0);
+		VFIO_ASSERT_EQ(close(device->container_fd), 0);
+	}
free(device);
 }
-- 
2.49.0.1151.ga128411c76-goog



    

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[RFC PATCH 28/33] vfio: selftests: Add iommufd mode