On Mon, Jun 5, 2023 at 10:58?PM Stefano Garzarella <sgarzare at redhat.com> wrote:> > On Mon, Jun 05, 2023 at 09:54:57AM -0400, Michael S. Tsirkin wrote: > >On Mon, Jun 05, 2023 at 03:30:35PM +0200, Stefano Garzarella wrote: > >> 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 at vger.kernel.org > >> > > > > Signed-off-by: Stefano Garzarella <sgarzare at redhat.com> > >> > > > > --- > >> > > > > > >> > > > > 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 at amd.com/ > >> > > > > >> > > > 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 > > > >Well this is in my tree already. Just reply with > >Fixes: <> > >to each and I will add these tags. > > I tried, but it is not easy since we added the support for packed > virtqueue in vdpa and vhost incrementally. > > Initially I was thinking of adding the same tag used here: > > Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend") > > Then I discovered that vq_state wasn't there, so I was thinking of > > Fixes: 530a5678bc00 ("vdpa: support packed virtqueue for set/get_vq_state()") > > So we would have to backport quite a few patches into the stable branches. > I don't know if it's worth it... > > I still think it is better to disable packed in the stable branches, > otherwise I have to make a list of all the patches we need. > > Any other ideas?AFAIK, except for vp_vdpa, pds seems to be the first parent that supports packed virtqueue. Users should not notice anything wrong if they don't use packed virtqueue. And the problem of vp_vdpa + packed virtqueue came since the day0 of vp_vdpa. It seems fine to do nothing I guess. Thanks> > Thanks, > Stefano > >
Stefano Garzarella
2023-Jun-06 10:18 UTC
[PATCH] vhost-vdpa: filter VIRTIO_F_RING_PACKED feature
On Tue, Jun 06, 2023 at 09:29:22AM +0800, Jason Wang wrote:>On Mon, Jun 5, 2023 at 10:58?PM Stefano Garzarella <sgarzare at redhat.com> wrote: >> >> On Mon, Jun 05, 2023 at 09:54:57AM -0400, Michael S. Tsirkin wrote: >> >On Mon, Jun 05, 2023 at 03:30:35PM +0200, Stefano Garzarella wrote: >> >> 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 at vger.kernel.org >> >> > > > > Signed-off-by: Stefano Garzarella <sgarzare at redhat.com> >> >> > > > > --- >> >> > > > > >> >> > > > > 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 at amd.com/ >> >> > > > >> >> > > > 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 >> > >> >Well this is in my tree already. Just reply with >> >Fixes: <> >> >to each and I will add these tags. >> >> I tried, but it is not easy since we added the support for packed >> virtqueue in vdpa and vhost incrementally. >> >> Initially I was thinking of adding the same tag used here: >> >> Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend") >> >> Then I discovered that vq_state wasn't there, so I was thinking of >> >> Fixes: 530a5678bc00 ("vdpa: support packed virtqueue for set/get_vq_state()") >> >> So we would have to backport quite a few patches into the stable branches. >> I don't know if it's worth it... >> >> I still think it is better to disable packed in the stable branches, >> otherwise I have to make a list of all the patches we need. >> >> Any other ideas? > >AFAIK, except for vp_vdpa, pds seems to be the first parent thatIIUC also vduse and snet supports packed virtqueue.>supports packed virtqueue. Users should not notice anything wrong if >they don't use packed virtqueue. And the problem of vp_vdpa + packed >virtqueue came since the day0 of vp_vdpa. It seems fine to do nothing >I guess.Okay, maybe I'm overthinking it, not having a specific problem I don't object, it was just a concern about uAPI. Thanks, Stefano
Michael S. Tsirkin
2023-Jun-06 12:58 UTC
[PATCH] vhost-vdpa: filter VIRTIO_F_RING_PACKED feature
On Tue, Jun 06, 2023 at 09:29:22AM +0800, Jason Wang wrote:> On Mon, Jun 5, 2023 at 10:58?PM Stefano Garzarella <sgarzare at redhat.com> wrote: > > > > On Mon, Jun 05, 2023 at 09:54:57AM -0400, Michael S. Tsirkin wrote: > > >On Mon, Jun 05, 2023 at 03:30:35PM +0200, Stefano Garzarella wrote: > > >> 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 at vger.kernel.org > > >> > > > > Signed-off-by: Stefano Garzarella <sgarzare at redhat.com> > > >> > > > > --- > > >> > > > > > > >> > > > > 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 at amd.com/ > > >> > > > > > >> > > > 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 > > > > > >Well this is in my tree already. Just reply with > > >Fixes: <> > > >to each and I will add these tags. > > > > I tried, but it is not easy since we added the support for packed > > virtqueue in vdpa and vhost incrementally. > > > > Initially I was thinking of adding the same tag used here: > > > > Fixes: 4c8cf31885f6 ("vhost: introduce vDPA-based backend") > > > > Then I discovered that vq_state wasn't there, so I was thinking of > > > > Fixes: 530a5678bc00 ("vdpa: support packed virtqueue for set/get_vq_state()") > > > > So we would have to backport quite a few patches into the stable branches. > > I don't know if it's worth it... > > > > I still think it is better to disable packed in the stable branches, > > otherwise I have to make a list of all the patches we need. > > > > Any other ideas? > > AFAIK, except for vp_vdpa, pds seems to be the first parent that > supports packed virtqueue. Users should not notice anything wrong if > they don't use packed virtqueue. And the problem of vp_vdpa + packed > virtqueue came since the day0 of vp_vdpa. It seems fine to do nothing > I guess. > > ThanksI have a question though, what if down the road there is a new feature that needs more changes? It will be broken too just like PACKED no? Shouldn't vdpa have an allowlist of features it knows how to support?> > > > Thanks, > > Stefano > > > >