In addition to memfd, a blob resource can also have its backing storage in a VFIO device region. Since, there is no effective way to determine where the backing storage is located, we first try to create a dmabuf assuming it is in memfd. If that fails, we try to create a dmabuf assuming it is in VFIO device region.
So, we first call virtio_gpu_create_udmabuf() to check if the blob's backing storage is located in a memfd or not. If it is not, we invoke the vfio_device_create_dmabuf_fd() API which identifies the right VFIO device and eventually creates a dmabuf fd. Note that, for mmapping the dmabuf, we directly call mmap() if the dmabuf fd was created via virtio_gpu_create_udmabuf() since we know that the udmabuf driver supports mmap(). However, if the dmabuf was created via vfio_device_create_dmabuf_fd(), we use the vfio_device_mmap_dmabuf() API to get a mapping for the dmabuf. Cc: Marc-André Lureau <[email protected]> Cc: Alex Bennée <[email protected]> Cc: Akihiko Odaki <[email protected]> Cc: Dmitry Osipenko <[email protected]> Cc: Alex Williamson <[email protected]> Cc: Cédric Le Goater <[email protected]> Reviewed-by: Akihiko Odaki <[email protected]> Signed-off-by: Vivek Kasireddy <[email protected]> --- hw/display/virtio-gpu-dmabuf.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) diff --git a/hw/display/virtio-gpu-dmabuf.c b/hw/display/virtio-gpu-dmabuf.c index 89aa487654..f953db0fbe 100644 --- a/hw/display/virtio-gpu-dmabuf.c +++ b/hw/display/virtio-gpu-dmabuf.c @@ -147,9 +147,26 @@ void virtio_gpu_init_dmabuf(struct virtio_gpu_simple_resource *res) if (res->dmabuf_fd == VFIO_DMABUF_CREATE_ERR_INVALID_IOV) { error_free_or_abort(&local_err); - qemu_log_mask(LOG_GUEST_ERROR, - "Cannot create dmabuf: incompatible memory\n"); - return; + res->dmabuf_fd = vfio_device_create_dmabuf_fd(res->iov, + res->iov_cnt, + res->blob_size, + &local_err); + if (res->dmabuf_fd == VFIO_DMABUF_CREATE_ERR_INVALID_IOV) { + error_free_or_abort(&local_err); + qemu_log_mask(LOG_GUEST_ERROR, + "Cannot create dmabuf: incompatible memory\n"); + return; + } + + if (res->dmabuf_fd >= 0) { + pdata = vfio_device_mmap_dmabuf(res->iov, res->iov_cnt, + res->blob_size, &local_err); + if (!pdata) { + virtio_gpu_destroy_dmabuf(res); + } + } else { + res->dmabuf_fd = -1; + } } else if (res->dmabuf_fd >= 0) { pdata = virtio_gpu_remap_dmabuf(res, &local_err); if (!pdata) { -- 2.53.0
