Re: [PATCH 0/4] Add Split indirect descriptors for SVQ

[Jason Wang <jasowang@redhat.com>]

On Fri, Dec 5, 2025 at 9:30 AM Wafer <wafer@jaguarmicro.com> wrote:
>
>
>
> > -----Original Message-----
> > From: Jason Wang <jasowang@redhat.com>
> > Sent: 2025年12月4日 15:56
> > To: Wafer <wafer@jaguarmicro.com>
> > Cc: mst@redhat.com; eperezma@redhat.com; qemu-devel@nongnu.org;
> > leiyang@redhat.com; sgarzare@redhat.com; Angus Chen
> > <angus.chen@jaguarmicro.com>
> > Subject: Re: [PATCH 0/4] Add Split indirect descriptors for SVQ
> >
> > External Mail: This email originated from OUTSIDE of the organization!
> > Do not click links, open attachments or provide ANY information unless you
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> >
> > On Thu, Dec 4, 2025 at 3:38 PM Wafer Xie <wafer@jaguarmicro.com> wrote:
> > >
> > > This patch series adds support for VIRTIO split indirect descriptors.
> > > The feature is VIRTIO_RING_F_INDIRECT_DESC.
> > >
> > > Eugenio hs submitted a patch: vhost: accept indirect descriptors in
> > > shadow virtqueue
> > > https://lists.nongnu.org/archive/html/qemu-devel/2025-
> > 12/msg00056.html
> > > Therefore, this patch must be applied first.
> >
> > I may miss something but svq can read indirect descriptors even though it
> > doesn't use indirect descriptor, that's sufficient for making it claims to
> > support indirect descriptors. That's what Eugenio said in that series.
> >
> > This series could be an optimization on top?
> >
> > Thanks
> >
>
> Thanks for your reply!
> Right, the current svq implementation can read the indirect descriptors provided by the driver, but it cannot use indirect descriptors when interacting with the backend device.
> However, if a backend device implements indirect descriptors and wants to use QEMU to validate its indirect descriptor support, then QEMU needs to fully support indirect descriptors in this path. This series is intended to provide that full support, so that such backend devices can be properly tested and validated via QEMU.

Great, let's tweak the changelog for the next version like this.

Thanks

>
> > >
> > >
> > > Wafer Xie (4):
> > >   vhost: add data structure of virtio indirect descriptors in SVQ
> > >   vdpa: implement the interfaces alloc/free for indirect desc
> > >   vhost: supported the virtio indirect desc of available ring
> > >   vhost: supported the viriot indriect desc of used ring
> > >
> > >  hw/virtio/vhost-shadow-virtqueue.c | 224
> > > +++++++++++++++++++++++++++--  hw/virtio/vhost-shadow-virtqueue.h
> > |  57 +++++++-
> > >  hw/virtio/vhost-vdpa.c             | 130 ++++++++++++++++-
> > >  3 files changed, 395 insertions(+), 16 deletions(-)
> > >
> > > --
> > > 2.34.1
> > >
>