It's desirable to query or modify virgl_renderer state for various values.

We've done it for resources (virgl_renderer_get_fd_for_texture /
virgl_renderer_get_fd_for_texture2 / virgl_renderer_resource_get_info) a
few times, but more parameters are often desired.

Let's define a protocol instead.  That way, more queries/operations (is "ctx
{num} lost?", "is x host feature supported?") can be formulated.

It's also possible to put the protocol in virgl_hw.h, so in theory
the guest can recieve a response directly from virglrenderer. Any
opinions on this?

v2: virgl_renderer_query --> virgl_renderer_execute

Reviewed-by: David Riley <davidriley@chromium.org>
Signed-off-by: Gurchetan Singh <gurchetansingh@chromium.org>