On Thu, Sep 10, 2015 at 12:22:54PM +0200, Cornelia Huck wrote: > On Thu, 10 Sep 2015 12:02:44 +0300 > "Michael S. Tsirkin" <m...@redhat.com> wrote: > > > On Fri, Sep 04, 2015 at 10:54:26AM +0200, Cornelia Huck wrote: > > > We allow guests to change the size of the virtqueue rings by supplying > > > a number of buffers that is different from the number of buffers the > > > device was initialized with. Current code has some problems, however, > > > since reset does not reset the ringsizes to the default values (as this > > > is not saved anywhere). > > > > > > Let's extend the core code to keep track of the default ringsizes and > > > migrate them once the guest changed them for any of the virtqueues > > > for a device. > > > > > > Signed-off-by: Cornelia Huck <cornelia.h...@de.ibm.com> > > > --- > > > hw/virtio/virtio.c | 63 > > > ++++++++++++++++++++++++++++++++++++++++++++++ > > > include/hw/virtio/virtio.h | 1 + > > > 2 files changed, 64 insertions(+) > > > > > > > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > > > index cccae89..29870c8 100644 > > > --- a/include/hw/virtio/virtio.h > > > +++ b/include/hw/virtio/virtio.h > > > @@ -90,6 +90,7 @@ struct VirtIODevice > > > VMChangeStateEntry *vmstate; > > > char *bus_name; > > > uint8_t device_endian; > > > + bool non_default_ringsizes; > > > > > > Let's not try to track this separately. Just go over > > rings before migration, and check whether guest changed > > anything. > > I dunno. If we try to figure this out while doing migration, we'll need > to go over the rings and check whether any of them has changed, then go > over the rings again to save the values - while here, we just set this > bool once when the driver changes the value, check once to find out > whether we need to migrate the values and reset once.
Then restore it on load ... State is worse than stateless, without a state you are never out of sync. > > > > > QLIST_HEAD(, VirtQueue) *vector_queues; > > > }; > > > > > > -- > > > 2.3.8 > >
