virtio-gpu-udmabuf: create udmabuf for blob even when iov_cnt == 1

[PATCH] virtio-gpu-udmabuf: create udmabuf for blob even when iov_cnt == 1

Posted by Dongwon Kim 1 year, 9 months ago

There were often cases where a scanout blob sometimes has just 1 entry
that is linked to many pages in it. So just checking whether iov_cnt is 1
is not enough for screening small, non-scanout blobs. Therefore adding
iov_len check as well to make sure it creates an udmabuf only for a scanout
blob, which is at least bigger than one page size.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
---
 hw/display/virtio-gpu-udmabuf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/display/virtio-gpu-udmabuf.c b/hw/display/virtio-gpu-udmabuf.c
index 69e2cf0bd6..ef1a740de5 100644
--- a/hw/display/virtio-gpu-udmabuf.c
+++ b/hw/display/virtio-gpu-udmabuf.c
@@ -132,7 +132,8 @@ void virtio_gpu_init_udmabuf(struct virtio_gpu_simple_resource *res)
     void *pdata = NULL;
 
     res->dmabuf_fd = -1;
-    if (res->iov_cnt == 1) {
+    if (res->iov_cnt == 1 &&
+        res->iov[0].iov_len < 4096) {
         pdata = res->iov[0].iov_base;
     } else {
         virtio_gpu_create_udmabuf(res);
-- 
2.34.1

Re: [PATCH] virtio-gpu-udmabuf: create udmabuf for blob even when iov_cnt == 1

Posted by Marc-André Lureau 1 year, 9 months ago

On Thu, Jun 22, 2023 at 12:47 AM Dongwon Kim <dongwon.kim@intel.com> wrote:

> There were often cases where a scanout blob sometimes has just 1 entry
> that is linked to many pages in it. So just checking whether iov_cnt is 1
> is not enough for screening small, non-scanout blobs. Therefore adding
> iov_len check as well to make sure it creates an udmabuf only for a scanout
> blob, which is at least bigger than one page size.
>
> Cc: Gerd Hoffmann <kraxel@redhat.com>
> Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
> Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
> Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


> ---
>  hw/display/virtio-gpu-udmabuf.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/hw/display/virtio-gpu-udmabuf.c
> b/hw/display/virtio-gpu-udmabuf.c
> index 69e2cf0bd6..ef1a740de5 100644
> --- a/hw/display/virtio-gpu-udmabuf.c
> +++ b/hw/display/virtio-gpu-udmabuf.c
> @@ -132,7 +132,8 @@ void virtio_gpu_init_udmabuf(struct
> virtio_gpu_simple_resource *res)
>      void *pdata = NULL;
>
>      res->dmabuf_fd = -1;
> -    if (res->iov_cnt == 1) {
> +    if (res->iov_cnt == 1 &&
> +        res->iov[0].iov_len < 4096) {
>          pdata = res->iov[0].iov_base;
>      } else {
>          virtio_gpu_create_udmabuf(res);
> --
> 2.34.1
>
>
>

-- 
Marc-André Lureau