Hi Mark
On Sat, Jul 3, 2021 at 9:15 AM Mark Cave-Ayland <
mark.cave-ayl...@ilande.co.uk> wrote:
> On 01/07/2021 08:18, marcandre.lur...@redhat.com wrote:
>
> > From: Marc-André Lureau <marcandre.lur...@redhat.com>
> >
> > This avoids failing to initialize virgl and crashing later on, and clear
> > the user expectations.
> >
> > Signed-off-by: Marc-André Lureau <marcandre.lur...@redhat.com>
> > ---
> > hw/display/virtio-gpu-gl.c | 12 ++++++++++++
> > 1 file changed, 12 insertions(+)
> >
> > diff --git a/hw/display/virtio-gpu-gl.c b/hw/display/virtio-gpu-gl.c
> > index d971b48080..c973d4824b 100644
> > --- a/hw/display/virtio-gpu-gl.c
> > +++ b/hw/display/virtio-gpu-gl.c
> > @@ -25,6 +25,8 @@
> >
> > #include <virglrenderer.h>
> >
> > +static int virgl_count = 0;
> > +
> > static void virtio_gpu_gl_update_cursor_data(VirtIOGPU *g,
> > struct virtio_gpu_scanout
> *s,
> > uint32_t resource_id)
> > @@ -113,6 +115,11 @@ static void
> virtio_gpu_gl_device_realize(DeviceState *qdev, Error **errp)
> > return;
> > #endif
> >
> > + if (virgl_count++ > 0) {
> > + error_setg(errp, "multiple virgl devices aren't supported yet");
> > + return;
> > + }
> > +
> > if (!display_opengl) {
> > error_setg(errp, "opengl is not available");
> > return;
> > @@ -124,6 +131,10 @@ static void
> virtio_gpu_gl_device_realize(DeviceState *qdev, Error **errp)
> >
> > virtio_gpu_device_realize(qdev, errp);
> > }
> > +static void virtio_gpu_gl_device_unrealize(DeviceState *dev)
> > +{
> > + virgl_count--;
> > +}
> >
> > static Property virtio_gpu_gl_properties[] = {
> > DEFINE_PROP_BIT("stats", VirtIOGPU, parent_obj.conf.flags,
> > @@ -144,6 +155,7 @@ static void virtio_gpu_gl_class_init(ObjectClass
> *klass, void *data)
> > vgc->update_cursor_data = virtio_gpu_gl_update_cursor_data;
> >
> > vdc->realize = virtio_gpu_gl_device_realize;
> > + vdc->unrealize = virtio_gpu_gl_device_unrealize;
> > vdc->reset = virtio_gpu_gl_reset;
> > device_class_set_props(dc, virtio_gpu_gl_properties);
> > }
>
> FWIW I think the best way to prevent instantiation of multiple devices is
> to use the
> QOM API to detect if more than one instance of a class exists within the
> QOM tree.
>
> Have a look at fw_cfg_find() and its usage from fw_cfg_common_realize() in
> hw/nvram/fw_cfg.c for an example of this.
>
Good idea, I forgot about that trick. Sent "[PATCH v2] hw/display: fail
early when multiple virgl devices are requested".
thanks
--
Marc-André Lureau
