On Mon, Jun 05, 2023 at 09:00:25AM -0400, Michael S. Tsirkin wrote:
On Mon, Jun 05, 2023 at 02:54:20PM +0200, Stefano Garzarella wrote:
On Mon, Jun 05, 2023 at 08:41:54AM -0400, Michael S. Tsirkin wrote:
> On Mon, Jun 05, 2023 at 01:06:44PM +0200, Stefano Garzarella wrote:
> > vhost-vdpa IOCTLs (eg. VHOST_GET_VRING_BASE, VHOST_SET_VRING_BASE)
> > don't support packed virtqueue well yet, so let's filter the
> > VIRTIO_F_RING_PACKED feature for now in vhost_vdpa_get_features().
> >
> > This way, even if the device supports it, we don't risk it being
> > negotiated, then the VMM is unable to set the vring state properly.
> >
> > Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> > ---
> >
> > Notes:
> > This patch should be applied before the "[PATCH v2 0/3] vhost_vdpa:
> > better PACKED support" series [1] and backported in stable branches.
> >
> > We can revert it when we are sure that everything is working with
> > packed virtqueues.
> >
> > Thanks,
> > Stefano
> >
> > [1] https://lore.kernel.org/virtualization/20230424225031.18947-1-shannon.nelson@xxxxxxx/
>
> I'm a bit lost here. So why am I merging "better PACKED support" then?
To really support packed virtqueue with vhost-vdpa, at that point we would
also have to revert this patch.
I wasn't sure if you wanted to queue the series for this merge window.
In that case do you think it is better to send this patch only for stable
branches?
> Does this patch make them a NOP?
Yep, after applying the "better PACKED support" series and being sure
that
the IOCTLs of vhost-vdpa support packed virtqueue, we should revert this
patch.
Let me know if you prefer a different approach.
I'm concerned that QEMU uses vhost-vdpa IOCTLs thinking that the kernel
interprets them the right way, when it does not.
Thanks,
Stefano
If this fixes a bug can you add Fixes tags to each of them? Then it's ok
to merge in this window. Probably easier than the elaborate
mask/unmask dance.
CCing Shannon (the original author of the "better PACKED support"
series).
IIUC Shannon is going to send a v3 of that series to fix the
documentation, so Shannon can you also add the Fixes tags?
Thanks,
Stefano
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