On 7/28/20 3:33 AM, Xuan Ding wrote:
> This patch added known issue for vhost multi-queue reconnection
> with virtio-net/virtio-pmd.
>
> Signed-off-by: Xuan Ding <xuan.d...@intel.com>
> ---
> doc/guides/rel_notes/known_issues.rst | 21 +++++++++++++++++++++
> 1 file changed, 21 insertions(+)
>
> diff --git a/doc/guides/rel_notes/known_issues.rst
> b/doc/guides/rel_notes/known_issues.rst
> index de0782136..3359cf063 100644
> --- a/doc/guides/rel_notes/known_issues.rst
> +++ b/doc/guides/rel_notes/known_issues.rst
> @@ -888,3 +888,24 @@ Unsuitable IOVA mode may be picked as the default
>
> **Driver/Module**:
> ALL.
> +
> +Vhost multi-queue reconnection failed with QEMU version >= 4.2.0
> +-------------------------------------------------
> +
> +**Description**
> + It's a QEMU regression bug (bad commit: c6beefd674ff). QEMU only saves
> + acked features for one vhost-net when vhost quits. When vhost reconnects
> + to virtio-net/virtio-pmd in multi-queue situations, the features been
> + set multiple times are not consistent.
> +
> +**Implication**
> + Vhost cannot reconnect back to virtio-net/virtio-pmd normally.
> +
> +**Resolution/Workaround**:
> + It is possible to filter the incorrect acked features at vhost-user side.
> +
> +**Affected Environment/Platform**:
> + ALL.
> +
> +**Driver/Module**:
> + Virtual Device Poll Mode Driver (PMD).
>
Thanks for documenting this Qemu issue.
Reviewed-by: Maxime Coquelin <maxime.coque...@redhat.com>
Maxime
