On Fri, Mar 15, 2024 at 11:59 PM Kevin Wolf <kw...@redhat.com> wrote: > > VDUSE requires that virtqueues are first enabled before the DRIVER_OK > status flag is set; with the current API of the kernel module, it is > impossible to enable the opposite order in our block export code because > userspace is not notified when a virtqueue is enabled. > > This requirement also mathces the normal initialisation order as done by > the generic vhost code in QEMU. However, commit 6c482547 accidentally > changed the order for vdpa-dev and broke access to VDUSE devices with > this. > > This changes vdpa-dev to use the normal order again and use the standard > vhost callback .vhost_set_vring_enable for this. VDUSE devices can be > used with vdpa-dev again after this fix. > > vhost_net intentionally avoided enabling the vrings for vdpa and does > this manually later while it does enable them for other vhost backends. > Reflect this in the vhost_net code and return early for vdpa, so that > the behaviour doesn't change for this device. > > Cc: qemu-sta...@nongnu.org > Fixes: 6c4825476a4351530bcac17abab72295b75ffe98 > Signed-off-by: Kevin Wolf <kw...@redhat.com> > --- > v2: > - Actually make use of the @enable parameter > - Change vhost_net to preserve the current behaviour > > v3: > - Updated trace point [Stefano] > - Fixed typo in comment [Stefano] > > hw/net/vhost_net.c | 10 ++++++++++ > hw/virtio/vdpa-dev.c | 5 +---- > hw/virtio/vhost-vdpa.c | 29 ++++++++++++++++++++++++++--- > hw/virtio/vhost.c | 8 +++++++- > hw/virtio/trace-events | 2 +- > 5 files changed, 45 insertions(+), 9 deletions(-) > > diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c > index e8e1661646..fd1a93701a 100644 > --- a/hw/net/vhost_net.c > +++ b/hw/net/vhost_net.c > @@ -541,6 +541,16 @@ int vhost_set_vring_enable(NetClientState *nc, int > enable) > VHostNetState *net = get_vhost_net(nc); > const VhostOps *vhost_ops = net->dev.vhost_ops; > > + /* > + * vhost-vdpa network devices need to enable dataplane virtqueues after > + * DRIVER_OK, so they can recover device state before starting dataplane. > + * Because of that, we don't enable virtqueues here and leave it to > + * net/vhost-vdpa.c. > + */ > + if (nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) { > + return 0; > + }
I think we need some inputs from Eugenio, this is only needed for shadow virtqueue during live migration but not other cases. Thanks