From: Eugenio Perez Martin <eperezma@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: leiyang@redhat.com, Laurent Vivier <lvivier@redhat.com>,
sgarzare@redhat.com, jasowang@redhat.com,
Zhu Lingshan <lingshan.zhu@intel.com>,
virtualization@lists.linux-foundation.org, si-wei.liu@oracle.com,
linux-kernel@vger.kernel.org, lulu@redhat.com,
Gautam Dawar <gdawar@xilinx.com>,
alvaro.karsz@solid-run.com
Subject: Re: [PATCH 2/2] vringh: fetch used_idx from vring at vringh_init_iotlb
Date: Wed, 1 Feb 2023 18:24:06 +0100 [thread overview]
Message-ID: <CAJaqyWdaTY=fHpKxOhWw1Ap-FT4taZB3FogVuMa-Ackjdfz0vw@mail.gmail.com> (raw)
In-Reply-To: <20230201111108-mutt-send-email-mst@kernel.org>
On Wed, Feb 1, 2023 at 5:11 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Wed, Jan 18, 2023 at 05:43:59PM +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.
> >
> > While callers like vdpa_sim set avail_idx directly it does not set
> > used_idx. Instead of let the caller do the assignment, fetch it from
> > the guest at initialization like vhost-kernel do.
> >
> > To perform the same at vring_kernel_init and vring_user_init is left for
> > the future.
> >
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
>
>
> So I applied 1/2 and dropped 2/2 for now, right?
>
Yes, please. 2/2 needs tweaking, I'll address them ASAP.
Thanks!
> > ---
> > drivers/vhost/vringh.c | 25 +++++++++++++++++++++++--
> > 1 file changed, 23 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
> > index 33eb941fcf15..0eed825197f2 100644
> > --- a/drivers/vhost/vringh.c
> > +++ b/drivers/vhost/vringh.c
> > @@ -1301,6 +1301,17 @@ static inline int putused_iotlb(const struct vringh *vrh,
> > return 0;
> > }
> >
> > +/**
> > + * vringh_update_used_idx - fetch used idx from driver's used split vring
> > + * @vrh: The vring.
> > + *
> > + * Returns -errno or 0.
> > + */
> > +static inline int vringh_update_used_idx(struct vringh *vrh)
> > +{
> > + return getu16_iotlb(vrh, &vrh->last_used_idx, &vrh->vring.used->idx);
> > +}
> > +
> > /**
> > * vringh_init_iotlb - initialize a vringh for a ring with IOTLB.
> > * @vrh: the vringh to initialize.
> > @@ -1319,8 +1330,18 @@ int vringh_init_iotlb(struct vringh *vrh, u64 features,
> > struct vring_avail *avail,
> > struct vring_used *used)
> > {
> > - return vringh_init_kern(vrh, features, num, weak_barriers,
> > - desc, avail, used);
> > + int r = vringh_init_kern(vrh, features, num, weak_barriers, desc,
> > + avail, used);
> > +
> > + if (r != 0)
> > + return r;
> > +
> > + /* Consider the ring not initialized */
> > + if ((void *)desc == used)
> > + return 0;
> > +
> > + return vringh_update_used_idx(vrh);
> > +
> > }
> > EXPORT_SYMBOL(vringh_init_iotlb);
> >
> > --
> > 2.31.1
>
next prev parent reply other threads:[~2023-02-01 17:26 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-18 16:43 [PATCH 0/2] Fix expected set_vq_state behavior on vdpa_sim Eugenio Pérez
2023-01-18 16:43 ` [PATCH 1/2] vdpa_sim: not reset state in vdpasim_queue_ready Eugenio Pérez
2023-01-19 3:16 ` Jason Wang
2023-01-19 9:14 ` Eugenio Perez Martin
2023-01-29 5:56 ` Jason Wang
2023-01-31 15:44 ` Lei Yang
2023-01-18 16:43 ` [PATCH 2/2] vringh: fetch used_idx from vring at vringh_init_iotlb Eugenio Pérez
2023-01-19 3:20 ` Jason Wang
2023-01-19 8:10 ` Eugenio Perez Martin
2023-01-29 6:00 ` Jason Wang
2023-01-30 16:38 ` Eugenio Perez Martin
2023-01-31 3:16 ` Jason Wang
2023-01-31 7:58 ` Eugenio Perez Martin
2023-02-13 12:03 ` Michael S. Tsirkin
2023-02-01 16:11 ` Michael S. Tsirkin
2023-02-01 17:24 ` Eugenio Perez Martin [this message]
2023-01-27 10:53 ` [PATCH 0/2] Fix expected set_vq_state behavior on vdpa_sim Michael S. Tsirkin
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