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]> Signed-off-by: Vivek Kasireddy <[email protected]> --- hw/display/virtio-gpu-dmabuf.c | 24 +++++++++++++++++++----- 1 file changed, 19 insertions(+), 5 deletions(-) diff --git a/hw/display/virtio-gpu-dmabuf.c b/hw/display/virtio-gpu-dmabuf.c index dd64fbbc2d..7f4c399416 100644 --- a/hw/display/virtio-gpu-dmabuf.c +++ b/hw/display/virtio-gpu-dmabuf.c @@ -136,7 +136,7 @@ bool virtio_gpu_have_udmabuf(void) void virtio_gpu_init_dmabuf(struct virtio_gpu_simple_resource *res) { - Error *local_err = NULL; + Error *local_err = NULL, *vfio_err = NULL; void *pdata = NULL; int ret; @@ -155,10 +155,24 @@ void virtio_gpu_init_dmabuf(struct virtio_gpu_simple_resource *res) } if (ret == VFIO_DMABUF_CREATE_ERR_INVALID_IOV) { - qemu_log_mask(LOG_GUEST_ERROR, - "Cannot create dmabuf: incompatible memory\n"); - error_free(local_err); - return; + ret = vfio_device_create_dmabuf_fd(res->iov, res->iov_cnt, + &vfio_err); + if (ret > 0) { + if (vfio_device_mmap_dmabuf(res->iov, res->iov_cnt, &pdata, + res->blob_size, &vfio_err)) { + error_free(local_err); + goto out; + } + } + + if (ret == VFIO_DMABUF_CREATE_ERR_INVALID_IOV) { + qemu_log_mask(LOG_GUEST_ERROR, + "Cannot create dmabuf: incompatible memory\n"); + error_free(vfio_err); + error_free(local_err); + return; + } + error_report_err(vfio_err); } error_report_err(local_err); return; -- 2.53.0
