On Tue, 8 Feb 2022 11:24:13 +0800, Jason Wang <[email protected]> wrote:
> On Tue, Feb 8, 2022 at 11:20 AM Xuan Zhuo <[email protected]> wrote:
> >
> > On Tue, 8 Feb 2022 11:03:17 +0800, Jason Wang <[email protected]> wrote:
> > > On Tue, Feb 8, 2022 at 10:17 AM Xuan Zhuo <[email protected]>
> > > wrote:
> > > >
> > > > On Mon, 7 Feb 2022 16:06:15 +0800, Jason Wang <[email protected]>
> > > > wrote:
> > > > > On Mon, Feb 7, 2022 at 2:07 PM Xuan Zhuo <[email protected]>
> > > > > wrote:
> > > > > >
> > > > > > On Mon, 7 Feb 2022 11:41:06 +0800, Jason Wang <[email protected]>
> > > > > > wrote:
> > > > > > >
> > > > > > > 在 2022/1/26 下午3:35, Xuan Zhuo 写道:
> > > > > > > > Add queue_notify_data in struct virtio_pci_common_cfg, which
> > > > > > > > comes from
> > > > > > > > here https://github.com/oasis-tcs/virtio-spec/issues/89
> > > > > > > >
> > > > > > > > Since I want to add queue_reset after it, I submitted this
> > > > > > > > patch first.
> > > > > > > >
> > > > > > > > Signed-off-by: Xuan Zhuo <[email protected]>
> > > > > > > > ---
> > > > > > > > include/uapi/linux/virtio_pci.h | 1 +
> > > > > > > > 1 file changed, 1 insertion(+)
> > > > > > > >
> > > > > > > > diff --git a/include/uapi/linux/virtio_pci.h
> > > > > > > > b/include/uapi/linux/virtio_pci.h
> > > > > > > > index 3a86f36d7e3d..492c89f56c6a 100644
> > > > > > > > --- a/include/uapi/linux/virtio_pci.h
> > > > > > > > +++ b/include/uapi/linux/virtio_pci.h
> > > > > > > > @@ -164,6 +164,7 @@ struct virtio_pci_common_cfg {
> > > > > > > > __le32 queue_avail_hi; /* read-write */
> > > > > > > > __le32 queue_used_lo; /* read-write */
> > > > > > > > __le32 queue_used_hi; /* read-write */
> > > > > > > > + __le16 queue_notify_data; /* read-write */
> > > > > > > > };
> > > > > > >
> > > > > > >
> > > > > > > So I had the same concern as previous version.
> > > > > > >
> > > > > > > This breaks uABI where program may try to use sizeof(struct
> > > > > > > virtio_pci_common_cfg).
> > > > > > >
> > > > > > > We probably need a container structure here.
> > > > > >
> > > > > > I see, I plan to add a struct like this, do you think it's
> > > > > > appropriate?
> > > > > >
> > > > > > struct virtio_pci_common_cfg_v1 {
> > > > > > struct virtio_pci_common_cfg cfg;
> > > > > > __le16 queue_notify_data; /* read-write */
> > > > > > }
> > > > >
> > > > > Something like this but we probably need a better name.
> > > >
> > > >
> > > > how about this?
> > > >
> > > > /* Ext Fields in VIRTIO_PCI_CAP_COMMON_CFG: */
> > > > struct virtio_pci_common_cfg_ext {
> > > > struct virtio_pci_common_cfg cfg;
> > > >
> > > > __le16 queue_notify_data; /* read-write */
> > > >
> > > > __le16 reserved0;
> > > > __le16 reserved1;
> > > > __le16 reserved2;
> > > > __le16 reserved3;
> > > > __le16 reserved4;
> > > > __le16 reserved5;
> > > > __le16 reserved6;
> > > > __le16 reserved7;
> > > > __le16 reserved8;
> > > > __le16 reserved9;
> > > > __le16 reserved10;
> > > > __le16 reserved11;
> > > > __le16 reserved12;
> > > > __le16 reserved13;
> > > > __le16 reserved14;
> > > > };
> > >
> > > I still think the container without padding is better. Otherwise
> > > userspace needs to use offset_of() trick instead of sizeof().
> >
> > In this case, as virtio_pci_common_cfg_ext adds new members in the future,
> > we
> > will add more container structures.
> >
> > In that case, I think virtio_pci_common_cfg_v1 is a good name instead.
>
> Something like "virtio_pci_common_cfg_notify" might be a little bit better.
Although there is only one notify_data in this patch, I plan to look like this
after my patch set:
struct virtio_pci_common_cfg_v1 {
struct virtio_pci_common_cfg cfg;
__le16 queue_notify_data; /* read-write */
__le16 queue_reset; /* read-write */
}
If we use virtio_pci_common_cfg_notify, then we will get two structures after
this patch set:
struct virtio_pci_common_cfg_notify {
struct virtio_pci_common_cfg cfg;
__le16 queue_notify_data; /* read-write */
}
struct virtio_pci_common_cfg_reset {
struct virtio_pci_common_cfg_notify cfg;
__le16 queue_reset; /* read-write */
}
Thanks.
>
> Thanks
>
> >
> > Thanks.
> >
> >
> > >
> > > Thanks
> > >
> > > >
> > > > Thanks
> > > >
> > > > >
> > > > > Thanks
> > > > >
> > > > > >
> > > > > > Thanks.
> > > > > >
> > > > > > >
> > > > > > > THanks
> > > > > > >
> > > > > > >
> > > > > > > >
> > > > > > > > /* Fields in VIRTIO_PCI_CAP_PCI_CFG: */
> > > > > > >
> > > > > >
> > > > >
> > > >
> > >
> >
>
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