[dpdk-stable] [PATCH v1 1/2] vdpa/mlx5: workaround FW first completion in start

[Xueming(Steven) Li]

On Fri, 2021-10-15 at 15:57 +0200, Maxime Coquelin wrote:
> 
> On 10/15/21 15:43, Xueming Li wrote:
> > After a vDPA application restart, qemu restores VQ with used and
> > available index, new incoming packet triggers virtio driver to
> > handle buffers. Under heavy traffic, no available buffer for
> > firmware to receive new packets, no Rx interrupts generated,
> > driver is stuck on endless interrupt waiting.
> > 
> > As a firmware workaround, this patch sends a notification after
> > VQ setup to ask driver handling buffers and filling new buffers.
> > 
> 
> As I mentionned on my reply to the v1, I would expect a Fixes tag,
> it would make downstream maintainers life easier.
> 
> Maybe pointing to the commit introducing the function would help.
> this is not ideal, but otherwise the risk is that your patch get
> missed by the stable maintainers.

Yes, my bad, a Fixes tag should be helpful to identify which LTS need
it, thanks!

> 
> Thanks!
> Maxime
> 
> > Cc: stable at dpdk.org
> > 
> > Signed-off-by: Xueming Li <xuemingl at nvidia.com>
> > Reviewed-by: Matan Azrad <matan at nvidia.com>
> > ---
> >   drivers/vdpa/mlx5/mlx5_vdpa_virtq.c | 4 ++++
> >   1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c b/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c
> > index f530646058f..71470d23d9e 100644
> > --- a/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c
> > +++ b/drivers/vdpa/mlx5/mlx5_vdpa_virtq.c
> > @@ -4,6 +4,7 @@
> >   #include <string.h>
> >   #include <unistd.h>
> >   #include <sys/mman.h>
> > +#include <sys/eventfd.h>
> >   
> >   #include <rte_malloc.h>
> >   #include <rte_errno.h>
> > @@ -367,6 +368,9 @@ mlx5_vdpa_virtq_setup(struct mlx5_vdpa_priv *priv, int index)
> >   		goto error;
> >   	}
> >   	virtq->stopped = false;
> > +	/* Initial notification to ask qemu handling completed buffers. */
> > +	if (virtq->eqp.cq.callfd != -1)
> > +		eventfd_write(virtq->eqp.cq.callfd, (eventfd_t)1);
> >   	DRV_LOG(DEBUG, "vid %u virtq %u was created successfully.", priv->vid,
> >   		index);
> >   	return 0;
> > 
>