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

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?

> 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 Fri, 24 Jun 2022 02:59:39 -0400, "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?
This was a previous discussion with Jason Wang, who was concerned about
affecting some existing programs.

https://lore.kernel.org/all/CACGkMEshTp8vSP9=pKj82y8+DDQFu9tFAk1EGhMZLvXUE-OSEA
at mail.gmail.com/

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 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
>