Virtualization - Jun 2022 - [PATCH v10 25/41] virtio_pci: struct virtio_pci_common_cfg add queue_notify_data

On Fri, Jun 24, 2022 at 2:59 PM Michael S. Tsirkin <mst at redhat.com>
wrote:
>
> On Fri, Jun 24, 2022 at 10:56:05AM +0800, Xuan Zhuo wrote:
> > Add queue_notify_data in struct virtio_pci_common_cfg, which comes
from
> > here https://github.com/oasis-tcs/virtio-spec/issues/89
> >
> > For not breaks uABI, add a new struct virtio_pci_common_cfg_notify.
>
> What exactly is meant by not breaking uABI?
> Users are supposed to be prepared for struct size to change ... no?
Not sure, any doc for this?

Thanks

>
>
> > Since I want to add queue_reset after queue_notify_data, I submitted
> > this patch first.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> > Acked-by: Jason Wang <jasowang at redhat.com>
> > ---
> >  include/uapi/linux/virtio_pci.h | 7 +++++++
> >  1 file changed, 7 insertions(+)
> >
> > diff --git a/include/uapi/linux/virtio_pci.h
b/include/uapi/linux/virtio_pci.h
> > index 3a86f36d7e3d..22bec9bd0dfc 100644
> > --- a/include/uapi/linux/virtio_pci.h
> > +++ b/include/uapi/linux/virtio_pci.h
> > @@ -166,6 +166,13 @@ struct virtio_pci_common_cfg {
> >       __le32 queue_used_hi;           /* read-write */
> >  };
> >
> > +struct virtio_pci_common_cfg_notify {
> > +     struct virtio_pci_common_cfg cfg;
> > +
> > +     __le16 queue_notify_data;       /* read-write */
> > +     __le16 padding;
> > +};
> > +
> >  /* Fields in VIRTIO_PCI_CAP_PCI_CFG: */
> >  struct virtio_pci_cfg_cap {
> >       struct virtio_pci_cap cap;
> > --
> > 2.31.0
>

On Mon, Jun 27, 2022 at 10:30:42AM +0800, Jason Wang
wrote:
> On Fri, Jun 24, 2022 at 2:59 PM Michael S. Tsirkin <mst at
redhat.com> wrote:
> >
> > On Fri, Jun 24, 2022 at 10:56:05AM +0800, Xuan Zhuo wrote:
> > > Add queue_notify_data in struct virtio_pci_common_cfg, which
comes from
> > > here https://github.com/oasis-tcs/virtio-spec/issues/89
> > >
> > > For not breaks uABI, add a new struct
virtio_pci_common_cfg_notify.
> >
> > What exactly is meant by not breaking uABI?
> > Users are supposed to be prepared for struct size to change ... no?
> 
> Not sure, any doc for this?
> 
> Thanks

Well we have this:

        The drivers SHOULD only map part of configuration structure
        large enough for device operation.  The drivers MUST handle
        an unexpectedly large \field{length}, but MAY check that \field{length}
        is large enough for device operation.


> 
> >
> >
> > > Since I want to add queue_reset after queue_notify_data, I
submitted
> > > this patch first.
> > >
> > > Signed-off-by: Xuan Zhuo <xuanzhuo at linux.alibaba.com>
> > > Acked-by: Jason Wang <jasowang at redhat.com>
> > > ---
> > >  include/uapi/linux/virtio_pci.h | 7 +++++++
> > >  1 file changed, 7 insertions(+)
> > >
> > > diff --git a/include/uapi/linux/virtio_pci.h
b/include/uapi/linux/virtio_pci.h
> > > index 3a86f36d7e3d..22bec9bd0dfc 100644
> > > --- a/include/uapi/linux/virtio_pci.h
> > > +++ b/include/uapi/linux/virtio_pci.h
> > > @@ -166,6 +166,13 @@ struct virtio_pci_common_cfg {
> > >       __le32 queue_used_hi;           /* read-write */
> > >  };
> > >
> > > +struct virtio_pci_common_cfg_notify {
> > > +     struct virtio_pci_common_cfg cfg;
> > > +
> > > +     __le16 queue_notify_data;       /* read-write */
> > > +     __le16 padding;
> > > +};
> > > +
> > >  /* Fields in VIRTIO_PCI_CAP_PCI_CFG: */
> > >  struct virtio_pci_cfg_cap {
> > >       struct virtio_pci_cap cap;
> > > --
> > > 2.31.0
> >