Messages in this thread | | | From | Eugenio Perez Martin <> | Date | Thu, 2 Mar 2023 19:19:55 +0100 | Subject | Re: [PATCH v2] vdpa_sim: set last_used_idx as last_avail_idx in vdpasim_queue_ready |
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On Tue, Feb 28, 2023 at 1:13 PM Michael S. Tsirkin <mst@redhat.com> wrote: > > On Fri, Feb 03, 2023 at 03:25:01PM +0100, Eugenio Pérez wrote: > > Starting from an used_idx different than 0 is needed in use cases like > > virtual machine migration. Not doing so and letting the caller set an > > avail idx different than 0 causes destination device to try to use old > > buffers that source driver already recover and are not available > > anymore. > > > > Since vdpa_sim does not support receive inflight descriptors as a > > destination of a migration, let's set both avail_idx and used_idx the > > same at vq start. This is how vhost-user works in a > > VHOST_SET_VRING_BASE call. > > > > Although the simple fix is to set last_used_idx at vdpasim_set_vq_state, > > it would be reset at vdpasim_queue_ready. The last_avail_idx case is > > fixed with commit a09f493c ("vdpa_sim: not reset state in > > vdpasim_queue_ready"). Since the only option is to make it equal to > > last_avail_idx, adding the only change needed here. > > > > This was discovered and tested live migrating the vdpa_sim_net device. > > > > Fixes: 2c53d0f64c06 ("vdpasim: vDPA device simulator") > > Signed-off-by: Eugenio Pérez <eperezma@redhat.com> > > --- > > Cherry-picked from patch 2/2 of the series [1]. Differences are: > > * Set the value of used_idx at vdpasim_queue_ready instead of fetching > > from the guest vring like vhost-kernel. > > > > v2: Actually update last_used_idx only at vdpasim_queue_ready. > > > > Note that commit id present in the patch text is not in master but in > > git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git. > > > > [1] https://lkml.org/lkml/2023/1/18/1041 > > > Can you post with a fixed hash please? >
Sent v3, please let me know if I need to do further modifications.
Thanks!
> > --- > > drivers/vdpa/vdpa_sim/vdpa_sim.c | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c > > index 6a0a65814626..79ac585e40b9 100644 > > --- a/drivers/vdpa/vdpa_sim/vdpa_sim.c > > +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c > > @@ -68,6 +68,7 @@ static void vdpasim_queue_ready(struct vdpasim *vdpasim, unsigned int idx) > > (uintptr_t)vq->device_addr); > > > > vq->vring.last_avail_idx = last_avail_idx; > > + vq->vring.last_used_idx = last_avail_idx; > > vq->vring.notify = vdpasim_vq_notify; > > } > > > > -- > > 2.31.1 >
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