Re: [Qemu-devel] [PATCH V3] vhost_net: start/stop guest notifiers properly

[William Dauchy <william@gandi.net>]

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On Aug19 12:56, Jason Wang wrote:
> commit a9f98bb5ebe6fb1869321dcc58e72041ae626ad8 vhost: multiqueue
> support changed the order of stopping the device. Previously
> vhost_dev_stop would disable backend and only afterwards, unset guest
> notifiers. We now unset guest notifiers while vhost is still
> active. This can lose interrupts causing guest networking to fail. In
> particular, this has been observed during migration.
> 
> To adapt this, several other changes are needed:
> - remove the hdev->started assertion in vhost.c since we may want to
> start the guest notifiers before vhost starts and stop the guest
> notifiers after vhost is stopped.
> - introduce the vhost_net_set_vq_index() and call it before setting
> guest notifiers. This is used to guarantee vhost_net has the correct
> virtqueue index when setting guest notifiers.
> 
> Reported-by: "Zhangjie (HZ)" <zhangjie14@huawei.com>
> Cc: William Dauchy <wdauchy@gmail.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> 
> --
> Changes from Michael's patch:
> - Remove the assertion
> Changes from V1:
> - Rebase to latest
> Changes from V2:
> - Introduce vhost_net_set_vq_index() to unbreak multiqueue

indeed I had with v2:
qemu-system-x86_64: hw/virtio/vhost.c:990: vhost_virtqueue_mask: Assertion `n >= hdev->vq_index && n < hdev->vq_index + hdev->nvqs' failed.

v3 seems ok to me
-- 
William

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