On Tue, Feb 8, 2022 at 11:29 AM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote: > > On Tue, 8 Feb 2022 11:24:13 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote: > > On Tue, Feb 8, 2022 at 11:20 AM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote: > > > > > > On Tue, 8 Feb 2022 11:03:17 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > > On Tue, Feb 8, 2022 at 10:17 AM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote: > > > > > > > > > > On Mon, 7 Feb 2022 16:06:15 +0800, Jason Wang <jasowang@xxxxxxxxxx> wrote: > > > > > > On Mon, Feb 7, 2022 at 2:07 PM Xuan Zhuo <xuanzhuo@xxxxxxxxxxxxxxxxx> wrote: > > > > > > > > > > > > > > On Mon, 7 Feb 2022 11:41:06 +0800, Jason Wang <jasowang@xxxxxxxxxx> 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 <xuanzhuo@xxxxxxxxxxxxxxxxx> > > > > > > > > > --- > > > > > > > > > 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 */ > } Right, this is sub-optimal, and we need padding in cfg_notify probably. But I couldn't think of a better idea currently, maybe we can listen from others opinion But we use something like this for vnet_header extension struct virtio_net_hdr_v1{ }; struct virtio_net_hdr_v1_hash{ struct virtio_net_hdr_v1; __le32 XXX; ... __le16 padding; }; And it's not hard to imagine there would be another container for struct virtio_net_hdr_v1_hash in the future if we want to extend vnet header. Thanks > > > Thanks. > > > > > Thanks > > > > > > > > Thanks. > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > Thanks > > > > > > > > > > > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > > > > > > > > > THanks > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > /* Fields in VIRTIO_PCI_CAP_PCI_CFG: */ > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
