From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>,
virtualization <virtualization@lists.linux-foundation.org>,
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Subject: Re: [PATCH v10 25/41] virtio_pci: struct virtio_pci_common_cfg add queue_notify_data
Date: Tue, 28 Jun 2022 02:10:30 -0400 [thread overview]
Message-ID: <20220628020832-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <CACGkMEuzrmVsM5Xa3N_9n0-XOqyMAz65AON8oxkgmjnXb_bAFg@mail.gmail.com>
On Tue, Jun 28, 2022 at 02:07:28PM +0800, Jason Wang wrote:
> On Tue, Jun 28, 2022 at 1:46 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> >
> > On Tue, Jun 28, 2022 at 11:50:37AM +0800, Jason Wang wrote:
> > > On Mon, Jun 27, 2022 at 7:53 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > > >
> > > > On Mon, Jun 27, 2022 at 04:14:20PM +0800, Jason Wang wrote:
> > > > > On Mon, Jun 27, 2022 at 3:58 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > > > > >
> > > > > > On Mon, Jun 27, 2022 at 03:45:30PM +0800, Jason Wang wrote:
> > > > > > > On Mon, Jun 27, 2022 at 2:39 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > > > > > > >
> > > > > > > > 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@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.
> > > > > > >
> > > > > > > Yes, but that's the device/driver interface. What's done here is the
> > > > > > > userspace/kernel.
> > > > > > >
> > > > > > > Userspace may break if it uses e.g sizeof(struct virtio_pci_common_cfg)?
> > > > > > >
> > > > > > > Thanks
> > > > > >
> > > > > > Hmm I guess there's risk... but then how are we going to maintain this
> > > > > > going forward? Add a new struct on any change?
> > > > >
> > > > > This is the way we have used it for the past 5 or more years. I don't
> > > > > see why this must be handled in the vq reset feature.
> > > > >
> > > > > >Can we at least
> > > > > > prevent this going forward somehow?
> > > > >
> > > > > Like have some padding?
> > > > >
> > > > > Thanks
> > > >
> > > > Maybe - this is what QEMU does ...
> > >
> > > Do you want this to be addressed in this series (it's already very huge anyhow)?
> > >
> > > Thanks
> >
> > Let's come up with a solution at least. QEMU does not seem to need the struct.
>
> If we want to implement it in Qemu we need that:
>
> https://github.com/fengidri/qemu/commit/39b79335cb55144d11a3b01f93d46cc73342c6bb
>
> > Let's just put
> > it in virtio_pci_modern.h for now then?
>
> Does this mean userspace needs to define the struct by their own
> instead of depending on the uapi in the future?
>
> Thanks
$ git grep 'struct virtio_pci_common_cfg'
include/standard-headers/linux/virtio_pci.h:struct virtio_pci_common_cfg {
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, device_feature));
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, device_feature));
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, guest_feature));
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, guest_feature));
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, queue_select),
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, queue_size));
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, queue_desc_lo),
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, queue_desc_hi),
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, queue_avail_lo),
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, queue_avail_hi),
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, queue_used_lo),
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, queue_used_hi),
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, queue_enable), 1);
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, msix_config), entry);
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg, queue_msix_vector),
tests/qtest/libqos/virtio-pci-modern.c: offsetof(struct virtio_pci_common_cfg,
The only user of the struct is libqos and it just wants
the offsets so can use macros just as well.
> >
> > > >
> > > > > >
> > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > >
> > > > > > > > >
> > > > > > > > > >
> > > > > > > > > >
> > > > > > > > > > > Since I want to add queue_reset after queue_notify_data, I submitted
> > > > > > > > > > > this patch first.
> > > > > > > > > > >
> > > > > > > > > > > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > > > > > > > > > > Acked-by: Jason Wang <jasowang@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
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > > >
> >
next prev parent reply other threads:[~2022-06-28 6:10 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-24 2:55 [PATCH v10 00/41] virtio pci support VIRTIO_F_RING_RESET Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 01/41] remoteproc: rename len of rpoc_vring to num Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 02/41] virtio: add helper virtqueue_get_vring_max_size() Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 03/41] virtio: struct virtio_config_ops add callbacks for queue_reset Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 04/41] virtio_ring: update the document of the virtqueue_detach_unused_buf for queue reset Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 05/41] virtio_ring: remove the arg vq of vring_alloc_desc_extra() Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 06/41] virtio_ring: extract the logic of freeing vring Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 07/41] virtio_ring: split vring_virtqueue Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 08/41] virtio_ring: introduce virtqueue_init() Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 09/41] virtio_ring: split: introduce vring_free_split() Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 10/41] virtio_ring: split: extract the logic of alloc queue Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 11/41] virtio_ring: split: extract the logic of alloc state and extra Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 12/41] virtio_ring: split: extract the logic of attach vring Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 13/41] virtio_ring: split: extract the logic of vring init Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 14/41] virtio_ring: split: introduce virtqueue_reinit_split() Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 15/41] virtio_ring: split: reserve vring_align, may_reduce_num Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 16/41] virtio_ring: split: introduce virtqueue_resize_split() Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 17/41] virtio_ring: packed: introduce vring_free_packed Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 18/41] virtio_ring: packed: extract the logic of alloc queue Xuan Zhuo
2022-06-24 2:55 ` [PATCH v10 19/41] virtio_ring: packed: extract the logic of alloc state and extra Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 20/41] virtio_ring: packed: extract the logic of attach vring Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 21/41] virtio_ring: packed: extract the logic of vring init Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 22/41] virtio_ring: packed: introduce virtqueue_reinit_packed() Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 23/41] virtio_ring: packed: introduce virtqueue_resize_packed() Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 24/41] virtio_ring: introduce virtqueue_resize() Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 25/41] virtio_pci: struct virtio_pci_common_cfg add queue_notify_data Xuan Zhuo
2022-06-24 6:59 ` Michael S. Tsirkin
2022-06-24 7:22 ` Xuan Zhuo
2022-06-27 2:30 ` Jason Wang
2022-06-27 6:39 ` Michael S. Tsirkin
2022-06-27 7:45 ` Jason Wang
2022-06-27 7:57 ` Michael S. Tsirkin
2022-06-27 8:14 ` Jason Wang
2022-06-27 11:53 ` Michael S. Tsirkin
2022-06-28 3:50 ` Jason Wang
2022-06-28 5:45 ` Michael S. Tsirkin
2022-06-28 6:07 ` Jason Wang
2022-06-28 6:10 ` Michael S. Tsirkin [this message]
2022-06-28 6:12 ` Jason Wang
2022-06-28 6:54 ` Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 26/41] virtio: queue_reset: add VIRTIO_F_RING_RESET Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 27/41] virtio: allow to unbreak/break virtqueue individually Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 28/41] virtio_pci: update struct virtio_pci_common_cfg Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 29/41] virtio_pci: introduce helper to get/set queue reset Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 30/41] virtio_pci: extract the logic of active vq for modern pci Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 31/41] virtio_pci: support VIRTIO_F_RING_RESET Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 32/41] virtio: find_vqs() add arg sizes Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 33/41] virtio_pci: support the arg sizes of find_vqs() Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 34/41] virtio_mmio: " Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 35/41] virtio: add helper virtio_find_vqs_ctx_size() Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 36/41] virtio_net: set the default max ring size by find_vqs() Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 37/41] virtio_net: get ringparam by virtqueue_get_vring_max_size() Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 38/41] virtio_net: split free_unused_bufs() Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 39/41] virtio_net: support rx queue resize Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 40/41] virtio_net: support tx " Xuan Zhuo
2022-06-24 2:56 ` [PATCH v10 41/41] virtio_net: support set_ringparam Xuan Zhuo
2022-06-24 7:00 ` [PATCH v10 00/41] virtio pci support VIRTIO_F_RING_RESET Michael S. Tsirkin
2022-06-24 7:23 ` Xuan Zhuo
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