[dpdk-dev] [PATCH 2/2] vhost: only drop vqs with built-in virtio_net.c driver
Maxime Coquelin
maxime.coquelin at redhat.com
Wed Jan 31 19:07:50 CET 2018
Hi Stefan,
On 01/31/2018 06:46 PM, Stefan Hajnoczi wrote:
> Commit e29109323595beb3884da58126ebb3b878cb66f5 ("vhost: destroy unused
> virtqueues when multiqueue not negotiated") broke vhost-scsi by removing
> virtqueues when the virtio-net-specific VIRTIO_NET_F_MQ feature bit is
> missing.
>
> The vhost_user.c code shouldn't assume all devices are vhost net device
> backends. Use the new VIRTIO_DEV_BUILTIN_VIRTIO_NET flag to check
> whether virtio_net.c is being used.
>
> This fixes examples/vhost_scsi.
>
> Cc: Maxime Coquelin <maxime.coquelin at redhat.com>
> Signed-off-by: Stefan Hajnoczi <stefanha at redhat.com>
> ---
> lib/librte_vhost/vhost_user.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 1dd1a61b6..65ee33919 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -187,7 +187,8 @@ vhost_user_set_features(struct virtio_net *dev, uint64_t features)
> (dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ? "on" : "off",
> (dev->features & (1ULL << VIRTIO_F_VERSION_1)) ? "on" : "off");
>
> - if (!(dev->features & (1ULL << VIRTIO_NET_F_MQ))) {
> + if ((dev->flags & VIRTIO_DEV_BUILTIN_VIRTIO_NET) &&
> + !(dev->features & (1ULL << VIRTIO_NET_F_MQ))) {
If we had an external net backend using the library, we would also need
to remove extra queues if it advertised VIRTIO_NET_F_MQ, but the feature
isn't negotiated.
In this case, the fix I suggested yesterday would work:
if ((vhost_features & (1ULL << VIRTIO_NET_F_MQ)) &&
!(dev->features & (1ULL << VIRTIO_NET_F_MQ)) {
...
}
For any backend that does not advertise the feature, no queues will be
destroyed.
Thanks,
Maxime
> /*
> * Remove all but first queue pair if MQ hasn't been
> * negotiated. This is safe because the device is not
>
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