Jason Wang
2021-Dec-16 02:55 UTC
[RFC PATCH] virtio: do not reset stateful devices on resume
On Thu, Dec 16, 2021 at 1:27 AM Mikhail Golubev <mgo at opensynergy.com> wrote:> > The 12/14/2021 18:26, Michael S. Tsirkin wrote: > > On Tue, Dec 14, 2021 at 05:33:05PM +0100, Mikhail Golubev wrote: > > > From: Anton Yakovlev <Anton.Yakovlev at opensynergy.com> > > > > > > We assume that stateful devices can maintain their state while > > > suspended. And for this reason they don't have a freeze callback. If > > > such a device is reset during resume, the device state/context will be > > > lost on the device side. And the virtual device will stop working. > > > > > > Signed-off-by: Anton Yakovlev <Anton.Yakovlev at opensynergy.com> > > > Signed-off-by: Mikhail Golubev <mikhail.golubev at opensynergy.com> > > > > A bit more specific? Which configs does this patch fix? > > We had encountered an issue related to 'stateful' GPU 3d (virglrenderer) and > video (gstreamer) devices.Adding Gerd and Stefan. I wonder if we suffer from a similar issue with virtio-fs. Thanks> > BR, > Mikhail > > > > > > --- > > > drivers/virtio/virtio.c | 8 ++++++++ > > > 1 file changed, 8 insertions(+) > > > > > > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > > > index 236081afe9a2..defa15b56eb8 100644 > > > --- a/drivers/virtio/virtio.c > > > +++ b/drivers/virtio/virtio.c > > > @@ -472,6 +472,13 @@ int virtio_device_restore(struct virtio_device *dev) > > > struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); > > > int ret; > > > > > > + /* Short path for stateful devices. Here we assume that if the device > > > + * does not have a freeze callback, its state was not changed when > > > + * suspended. > > > + */ > > > + if (drv && !drv->freeze) > > > + goto on_config_enable; > > > + > > > /* We always start by resetting the device, in case a previous > > > * driver messed it up. */ > > > dev->config->reset(dev); > > > @@ -503,6 +510,7 @@ int virtio_device_restore(struct virtio_device *dev) > > > /* Finally, tell the device we're all set */ > > > virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK); > > > > > > +on_config_enable: > > > virtio_config_enable(dev); > > > > > > return 0; > > > -- > > > 2.34.1 > > > > > > > > > -- > > > > -- >