CHROMIUM: virtwl: add dmabuf sync ioctl

This can be used to synchronize access to dmabuf backed virtio
buffers. The virtio wayland device will use this to issue
matching DMA_BUF_SYNC ioctls. The dmabuf driver on the host side
can then handle this correctly (e.g. flush memory before it is
potentially scanned out by display hardware).

TEST=cache-line artifacts no longer noticeable
BUG=chromium:837209

Change-Id: I0e797123fc0cfbc179a44e98ffd2ce7def53e2f5
Signed-off-by: David Reveman <reveman@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1076927
Reviewed-by: Dmitry Torokhov <dtor@chromium.org>
Reviewed-by: Zach Reizner <zachr@chromium.org>
3 files changed