Stefano Garzarella
2022-Mar-22 14:05 UTC
[PATCH net] vsock/virtio: enable VQs early on probe
On Tue, Mar 22, 2022 at 09:36:14AM -0400, Michael S. Tsirkin wrote:>On Tue, Mar 22, 2022 at 11:38:23AM +0100, Stefano Garzarella wrote: >> virtio spec requires drivers to set DRIVER_OK before using VQs. >> This is set automatically after probe returns, but virtio-vsock >> driver uses VQs in the probe function to fill rx and event VQs >> with new buffers. > > >So this is a spec violation. absolutely. > >> Let's fix this, calling virtio_device_ready() before using VQs >> in the probe function. >> >> Fixes: 0ea9e1d3a9e3 ("VSOCK: Introduce virtio_transport.ko") >> Signed-off-by: Stefano Garzarella <sgarzare at redhat.com> >> --- >> net/vmw_vsock/virtio_transport.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c >> index 5afc194a58bb..b1962f8cd502 100644 >> --- a/net/vmw_vsock/virtio_transport.c >> +++ b/net/vmw_vsock/virtio_transport.c >> @@ -622,6 +622,8 @@ static int virtio_vsock_probe(struct virtio_device *vdev) >> INIT_WORK(&vsock->event_work, virtio_transport_event_work); >> INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work); >> >> + virtio_device_ready(vdev); >> + >> mutex_lock(&vsock->tx_lock); >> vsock->tx_run = true; >> mutex_unlock(&vsock->tx_lock); > >Here's the whole code snippet: > > > mutex_lock(&vsock->tx_lock); > vsock->tx_run = true; > mutex_unlock(&vsock->tx_lock); > > mutex_lock(&vsock->rx_lock); > virtio_vsock_rx_fill(vsock); > vsock->rx_run = true; > mutex_unlock(&vsock->rx_lock); > > mutex_lock(&vsock->event_lock); > virtio_vsock_event_fill(vsock); > vsock->event_run = true; > mutex_unlock(&vsock->event_lock); > > if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET)) > vsock->seqpacket_allow = true; > > vdev->priv = vsock; > rcu_assign_pointer(the_virtio_vsock, vsock); > > mutex_unlock(&the_virtio_vsock_mutex); > > >I worry that this is not the only problem here: >seqpacket_allow and setting of vdev->priv at least after >device is active look suspicious.Right, so if you agree I'll move these before virtio_device_ready().>E.g.: > >static void virtio_vsock_event_done(struct virtqueue *vq) >{ > struct virtio_vsock *vsock = vq->vdev->priv; > > if (!vsock) > return; > queue_work(virtio_vsock_workqueue, &vsock->event_work); >} > >looks like it will miss events now they will be reported earlier. >One might say that since vq has been kicked it might send >interrupts earlier too so not a new problem, but >there's a chance device actually waits until DRIVER_OK >to start operating.Yes I see, should I break into 2 patches (one where I move the code already present and this one)? Maybe a single patch is fine since it's the complete solution. Thank you for the detailed explanation, Stefano
Michael S. Tsirkin
2022-Mar-22 14:09 UTC
[PATCH net] vsock/virtio: enable VQs early on probe
On Tue, Mar 22, 2022 at 03:05:00PM +0100, Stefano Garzarella wrote:> On Tue, Mar 22, 2022 at 09:36:14AM -0400, Michael S. Tsirkin wrote: > > On Tue, Mar 22, 2022 at 11:38:23AM +0100, Stefano Garzarella wrote: > > > virtio spec requires drivers to set DRIVER_OK before using VQs. > > > This is set automatically after probe returns, but virtio-vsock > > > driver uses VQs in the probe function to fill rx and event VQs > > > with new buffers. > > > > > > So this is a spec violation. absolutely. > > > > > Let's fix this, calling virtio_device_ready() before using VQs > > > in the probe function. > > > > > > Fixes: 0ea9e1d3a9e3 ("VSOCK: Introduce virtio_transport.ko") > > > Signed-off-by: Stefano Garzarella <sgarzare at redhat.com> > > > --- > > > net/vmw_vsock/virtio_transport.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c > > > index 5afc194a58bb..b1962f8cd502 100644 > > > --- a/net/vmw_vsock/virtio_transport.c > > > +++ b/net/vmw_vsock/virtio_transport.c > > > @@ -622,6 +622,8 @@ static int virtio_vsock_probe(struct virtio_device *vdev) > > > INIT_WORK(&vsock->event_work, virtio_transport_event_work); > > > INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work); > > > > > > + virtio_device_ready(vdev); > > > + > > > mutex_lock(&vsock->tx_lock); > > > vsock->tx_run = true; > > > mutex_unlock(&vsock->tx_lock); > > > > Here's the whole code snippet: > > > > > > mutex_lock(&vsock->tx_lock); > > vsock->tx_run = true; > > mutex_unlock(&vsock->tx_lock); > > > > mutex_lock(&vsock->rx_lock); > > virtio_vsock_rx_fill(vsock); > > vsock->rx_run = true; > > mutex_unlock(&vsock->rx_lock); > > > > mutex_lock(&vsock->event_lock); > > virtio_vsock_event_fill(vsock); > > vsock->event_run = true; > > mutex_unlock(&vsock->event_lock); > > > > if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET)) > > vsock->seqpacket_allow = true; > > > > vdev->priv = vsock; > > rcu_assign_pointer(the_virtio_vsock, vsock); > > > > mutex_unlock(&the_virtio_vsock_mutex); > > > > > > I worry that this is not the only problem here: > > seqpacket_allow and setting of vdev->priv at least after > > device is active look suspicious. > > Right, so if you agree I'll move these before virtio_device_ready(). > > > E.g.: > > > > static void virtio_vsock_event_done(struct virtqueue *vq) > > { > > struct virtio_vsock *vsock = vq->vdev->priv; > > > > if (!vsock) > > return; > > queue_work(virtio_vsock_workqueue, &vsock->event_work); > > } > > > > looks like it will miss events now they will be reported earlier. > > One might say that since vq has been kicked it might send > > interrupts earlier too so not a new problem, but > > there's a chance device actually waits until DRIVER_OK > > to start operating. > > Yes I see, should I break into 2 patches (one where I move the code already > present and this one)? > > Maybe a single patch is fine since it's the complete solution. > > Thank you for the detailed explanation, > StefanoTwo I think since movement can be backported to before the hardening effort. -- MST