Michael S. Tsirkin
2021-Dec-14 23:26 UTC
[RFC PATCH] virtio: do not reset stateful devices on resume
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?> --- > 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 > > > --