Re: [PATCH 1/4] vfio: selftests: add iova range query helpers

On Mon, 10 Nov 2025 13:10:41 -0800 Alex Mastro amastro@fb.com wrote:

VFIO selftests need to map IOVAs from legally accessible ranges, which could vary between hardware. Tests in vfio_dma_mapping_test.c are making excessively strong assumptions about which IOVAs can be mapped.

Add vfio_iommu_iova_ranges(), which queries IOVA ranges from the IOMMUFD or VFIO container associated with the device. The queried ranges are normalized to IOMMUFD's iommu_iova_range representation so that handling of IOVA ranges up the stack can be implementation-agnostic. iommu_iova_range and vfio_iova_range are equivalent, so bias to using the new interface's struct.

Query IOMMUFD's ranges with IOMMU_IOAS_IOVA_RANGES. Query VFIO container's ranges with VFIO_IOMMU_GET_INFO and VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE.

The underlying vfio_iommu_type1_info buffer-related functionality has been kept generic so the same helpers can be used to query other capability chain information, if needed.

Signed-off-by: Alex Mastro amastro@fb.com

.../testing/selftests/vfio/lib/include/vfio_util.h | 8 +- tools/testing/selftests/vfio/lib/vfio_pci_device.c | 161 +++++++++++++++++++++ 2 files changed, 168 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/vfio/lib/include/vfio_util.h b/tools/testing/selftests/vfio/lib/include/vfio_util.h index 240409bf5f8a..fb5efec52316 100644 --- a/tools/testing/selftests/vfio/lib/include/vfio_util.h +++ b/tools/testing/selftests/vfio/lib/include/vfio_util.h @@ -4,9 +4,12 @@ #include <fcntl.h> #include <string.h> -#include <linux/vfio.h>

+#include <uapi/linux/types.h> +#include <linux/iommufd.h> #include <linux/list.h> #include <linux/pci_regs.h> +#include <linux/vfio.h> #include "../../../kselftest.h" @@ -206,6 +209,9 @@ struct vfio_pci_device *vfio_pci_device_init(const char *bdf, const char *iommu_ void vfio_pci_device_cleanup(struct vfio_pci_device *device); void vfio_pci_device_reset(struct vfio_pci_device *device); +struct iommu_iova_range *vfio_pci_iova_ranges(struct vfio_pci_device *device,

• 			      size_t *nranges);
  

int __vfio_pci_dma_map(struct vfio_pci_device *device, struct vfio_dma_region *region); int __vfio_pci_dma_unmap(struct vfio_pci_device *device, diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/testing/selftests/vfio/lib/vfio_pci_device.c index a381fd253aa7..6bedbe65f0a1 100644 --- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c +++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c @@ -29,6 +29,167 @@ VFIO_ASSERT_EQ(__ret, 0, "ioctl(%s, %s, %s) returned %d\n", #_fd, #_op, #_arg, __ret); \ } while (0) +static struct vfio_info_cap_header *next_cap_hdr(void *buf, size_t bufsz,

• 				 size_t *cap_offset)
  

+{

• struct vfio_info_cap_header *hdr;
• if (!*cap_offset)

• return NULL;
  

• /* Cap offset must be in bounds */
• VFIO_ASSERT_LT(*cap_offset, bufsz);
• /* There must be enough remaining space to contain the header */
• VFIO_ASSERT_GE(bufsz - *cap_offset, sizeof(*hdr));
• hdr = (struct vfio_info_cap_header *)((u8 *)buf + *cap_offset);
• /* If there is a next, offset must increase by at least the header size */
• if (hdr->next) {

• VFIO_ASSERT_GT(hdr->next, *cap_offset);
  

• VFIO_ASSERT_GE(hdr->next - *cap_offset, sizeof(*hdr));
  

• }
• *cap_offset = hdr->next;
• return hdr;

+}

+static struct vfio_info_cap_header *vfio_iommu_info_cap_hdr(struct vfio_iommu_type1_info *buf,

• 					    u16 cap_id)
  

+{

• struct vfio_info_cap_header *hdr;
• size_t cap_offset = buf->cap_offset;
• if (!(buf->flags & VFIO_IOMMU_INFO_CAPS))

• return NULL;
  

• if (cap_offset)

• VFIO_ASSERT_GE(cap_offset, sizeof(struct vfio_iommu_type1_info));
  

• while ((hdr = next_cap_hdr(buf, buf->argsz, &cap_offset))) {

• if (hdr->id == cap_id)
  

• 	return hdr;
  

• }
• return NULL;

+}

+/* Return buffer including capability chain, if present. Free with free() */ +static struct vfio_iommu_type1_info *vfio_iommu_info_buf(struct vfio_pci_device *device) +{

• struct vfio_iommu_type1_info *buf;
• buf = malloc(sizeof(*buf));
• VFIO_ASSERT_NOT_NULL(buf);
• *buf = (struct vfio_iommu_type1_info) {

• .argsz = sizeof(*buf),
  

• };
• ioctl_assert(device->container_fd, VFIO_IOMMU_GET_INFO, buf);
• buf = realloc(buf, buf->argsz);
• VFIO_ASSERT_NOT_NULL(buf);
• ioctl_assert(device->container_fd, VFIO_IOMMU_GET_INFO, buf);
• return buf;

+}

+/*

• • Return iova ranges for the device's container. Normalize vfio_iommu_type1 to
• • report iommufd's iommu_iova_range. Free with free().
• */

+static struct iommu_iova_range *vfio_iommu_iova_ranges(struct vfio_pci_device *device,

• 				       size_t *nranges)
  

+{

• struct vfio_iommu_type1_info_cap_iova_range *cap_range;
• struct vfio_iommu_type1_info *buf;
• struct vfio_info_cap_header *hdr;
• struct iommu_iova_range *ranges = NULL;
• buf = vfio_iommu_info_buf(device);
• VFIO_ASSERT_NOT_NULL(buf);
• hdr = vfio_iommu_info_cap_hdr(buf, VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE);
• if (!hdr)

• goto free_buf;
  

• cap_range = container_of(hdr, struct vfio_iommu_type1_info_cap_iova_range, header);
• if (!cap_range->nr_iovas)

• goto free_buf;
  

• ranges = malloc(cap_range->nr_iovas * sizeof(*ranges));

Natural calloc() use case.

• VFIO_ASSERT_NOT_NULL(ranges);
• for (u32 i = 0; i < cap_range->nr_iovas; i++) {

• ranges[i] = (struct iommu_iova_range){
  

• 	.start = cap_range->iova_ranges[i].start,
  

• 	.last = cap_range->iova_ranges[i].end,
  

• };
  

• }
• *nranges = cap_range->nr_iovas;

+free_buf:

• free(buf);
• return ranges;

+}

+/* Return iova ranges of the device's IOAS. Free with free() */ +struct iommu_iova_range *iommufd_iova_ranges(struct vfio_pci_device *device,

• 			     size_t *nranges)
  

+{

• struct iommu_iova_range *ranges;
• int ret;
• struct iommu_ioas_iova_ranges query = {

• .size = sizeof(query),
  

• .ioas_id = device->ioas_id,
  

• };
• ret = ioctl(device->iommufd, IOMMU_IOAS_IOVA_RANGES, &query);
• VFIO_ASSERT_EQ(ret, -1);
• VFIO_ASSERT_EQ(errno, EMSGSIZE);
• VFIO_ASSERT_GT(query.num_iovas, 0);
• ranges = malloc(query.num_iovas * sizeof(*ranges));

Same.

• VFIO_ASSERT_NOT_NULL(ranges);
• query.allowed_iovas = (uintptr_t)ranges;
• ioctl_assert(device->iommufd, IOMMU_IOAS_IOVA_RANGES, &query);
• *nranges = query.num_iovas;
• return ranges;

+}

+struct iommu_iova_range *vfio_pci_iova_ranges(struct vfio_pci_device *device,

• 			      size_t *nranges)
  

+{

• struct iommu_iova_range *ranges;
• if (device->iommufd)

• ranges = iommufd_iova_ranges(device, nranges);
  

• else

• ranges = vfio_iommu_iova_ranges(device, nranges);
  

• if (!ranges)

• return NULL;
  

• /* ranges should be valid, ascending, and non-overlapping */

I don't recall that ranges are required to be in any particular order. Thanks,

Alex

• VFIO_ASSERT_GT(*nranges, 0);
• VFIO_ASSERT_LT(ranges[0].start, ranges[0].last);
• for (size_t i = 1; i < *nranges; i++) {

• VFIO_ASSERT_LT(ranges[i].start, ranges[i].last);
  

• VFIO_ASSERT_LT(ranges[i - 1].last, ranges[i].start);
  

• }
• return ranges;

+}

iova_t __to_iova(struct vfio_pci_device *device, void *vaddr) { struct vfio_dma_region *region;