From: "Michael S. Tsirkin" <mst@redhat.com>
To: Jason Wang <jasowang@redhat.com>
Cc: Parav Pandit <parav@nvidia.com>,
"virtio-dev@lists.oasis-open.org"
<virtio-dev@lists.oasis-open.org>,
"cohuck@redhat.com" <cohuck@redhat.com>,
"virtio-comment@lists.oasis-open.org"
<virtio-comment@lists.oasis-open.org>,
Shahaf Shuler <shahafs@nvidia.com>,
Satananda Burla <sburla@marvell.com>
Subject: Re: [virtio-dev] [PATCH 08/11] transport-pci: Introduce virtio extended capability
Date: Wed, 12 Apr 2023 00:20:10 -0400 [thread overview]
Message-ID: <20230412001803-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <CACGkMEsSxnn0+T6ng99HV-PwA3kEe6J050GNDKJjcjBQfQxbfA@mail.gmail.com>
On Wed, Apr 12, 2023 at 12:07:26PM +0800, Jason Wang wrote:
> On Wed, Apr 12, 2023 at 5:25 AM Michael S. Tsirkin <mst@redhat.com> wrote:
> >
> > On Tue, Apr 11, 2023 at 07:01:16PM +0000, Parav Pandit wrote:
> > >
> > > > From: virtio-dev@lists.oasis-open.org <virtio-dev@lists.oasis-open.org> On
> > > > Behalf Of Jason Wang
> > > > Sent: Monday, April 10, 2023 11:29 PM
> > >
> > > > > However, it is not backward compatible, if the device place them in
> > > > > extended capability, it will not work.
> > > > >
> > > >
> > > > It is kind of intended since it is only used for new PCI-E features:
> > > >
> > > New fields in new extended pci cap area is fine.
> > > Migrating old fields to be present in the new extended pci cap, is not your intention. Right?
> > >
> > > > "
> > > > +The location of the virtio structures that depend on the PCI Express
> > > > +capability are specified using a vendor-specific extended capabilities
> > > > +on the extended capabilities list in PCI Express extended configuration
> > > > +space of the device.
> > > > "
> > > >
> > > > > To make it backward compatible, a device needs to expose existing
> > > > > structure in legacy area. And extended structure for same capability
> > > > > in extended pci capability region.
> > > > >
> > > > > In other words, it will have to be a both places.
> > > >
> > > > Then we will run out of config space again?
> > > No.
> > > Only currently defined caps to be placed in two places.
> > > New fields don’t need to be placed in PCI cap, because no driver is looking there.
> > >
> > > We probably already discussed this in previous email by now.
> > >
> > > > Otherwise we need to deal with the
> > > > case when existing structures were only placed at extended capability. Michael
> > > > suggest to add a new feature, but the driver may not negotiate the feature
> > > > which requires more thought.
> > > >
> > > Not sure I understand feature bit.
> >
> > This is because we have a concept of dependency between
> > features but not a concept of dependency of feature on
> > capability.
> >
> > > PCI transport fields existence is usually not dependent on upper layer protocol.
> > >
> > > > > We may need it even sooner than this because the AQ patch is expanding
> > > > > the structure located in legacy area.
> > > >
> > > > Just to make sure I understand this, assuming we have adminq, any reason a
> > > > dedicated pcie ext cap is required?
> > > >
> > > No. it was my short sight. I responded right after above text that AQ doesn’t need cap extension.
> >
> >
> >
> > You know, thinking about this, I begin to feel that we should
> > require that if at least one extended config exists then
> > all caps present in the regular config are *also*
> > mirrored in the extended config. IOW extended >= regular.
> > The reason is that extended config can be emulated more efficiently
> > (2x less exits).
>
> Any reason for it to get less exits?
For a variety of reasons having to do with buggy hardware e.g. linux
likes to use cf8/cfc for legacy ranges. 2 accesses are required for each
read/write. extended space is just 1.
> At least it has not been done in
> current Qemu's emulation. (And do we really care about the performance
> of config space access?)
>
> Thanks
For boot speed, yes. Not minor 5% things but 2x, sure.
> > WDYT?
> >
> >
> > --
> > MST
> >
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next prev parent reply other threads:[~2023-04-12 4:20 UTC|newest]
Thread overview: 200+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-30 22:58 [virtio-dev] [PATCH 00/11] Introduce transitional mmr pci device Parav Pandit
2023-03-30 22:58 ` [virtio-dev] [PATCH 01/11] transport-pci: Use lowecase alphabets Parav Pandit
2023-03-30 22:58 ` [virtio-dev] [PATCH 02/11] transport-pci: Move transitional device id to legacy section Parav Pandit
2023-03-31 6:43 ` [virtio-dev] " Michael S. Tsirkin
2023-03-31 21:24 ` [virtio-dev] " Parav Pandit
2023-04-02 7:54 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 14:42 ` [virtio-dev] " Parav Pandit
2023-04-03 14:50 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 14:58 ` [virtio-dev] " Parav Pandit
2023-04-03 15:14 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 03/11] transport-pci: Split notes of PCI Device Layout Parav Pandit
2023-03-30 22:58 ` [virtio-dev] [PATCH 04/11] transport-pci: Rename and move legacy PCI Device layout section Parav Pandit
2023-03-30 22:58 ` [virtio-dev] [PATCH 05/11] introduction: Add missing helping verb Parav Pandit
2023-03-30 22:58 ` [virtio-dev] [PATCH 06/11] introduction: Introduce transitional MMR interface Parav Pandit
2023-04-07 9:17 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 07/11] transport-pci: Introduce transitional MMR device id Parav Pandit
2023-04-04 7:28 ` [virtio-dev] " Michael S. Tsirkin
2023-04-04 16:08 ` Parav Pandit
2023-04-07 12:03 ` [virtio-dev] Re: [virtio-comment] " Michael S. Tsirkin
2023-04-07 15:18 ` [virtio-dev] " Parav Pandit
2023-04-07 15:51 ` [virtio-dev] " Michael S. Tsirkin
2023-04-09 3:15 ` [virtio-dev] " Parav Pandit
2023-04-10 10:18 ` [virtio-dev] " Michael S. Tsirkin
2023-04-10 14:34 ` Parav Pandit
2023-04-10 19:58 ` Michael S. Tsirkin
2023-04-10 20:16 ` Parav Pandit
2023-04-07 8:37 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 08/11] transport-pci: Introduce virtio extended capability Parav Pandit
2023-04-04 7:35 ` [virtio-dev] " Michael S. Tsirkin
2023-04-04 7:54 ` Cornelia Huck
2023-04-04 12:43 ` Michael S. Tsirkin
2023-04-04 13:19 ` Cornelia Huck
2023-04-04 14:37 ` Michael S. Tsirkin
2023-04-10 16:21 ` Parav Pandit
2023-04-10 19:49 ` Michael S. Tsirkin
2023-04-10 19:57 ` [virtio-dev] " Parav Pandit
2023-04-10 20:02 ` [virtio-dev] " Michael S. Tsirkin
2023-04-11 8:39 ` Cornelia Huck
2023-04-04 21:18 ` [virtio-dev] " Parav Pandit
2023-04-05 5:10 ` [virtio-dev] " Michael S. Tsirkin
2023-04-05 13:16 ` [virtio-dev] " Parav Pandit
2023-04-07 8:15 ` [virtio-dev] " Michael S. Tsirkin
2023-04-10 1:36 ` [virtio-dev] " Jason Wang
2023-04-10 6:24 ` Michael S. Tsirkin
2023-04-10 7:16 ` Jason Wang
2023-04-10 10:04 ` Michael S. Tsirkin
2023-04-11 2:19 ` Jason Wang
2023-04-11 7:00 ` Michael S. Tsirkin
2023-04-11 9:07 ` Jason Wang
2023-04-11 10:43 ` Michael S. Tsirkin
2023-04-11 13:59 ` Parav Pandit
2023-04-11 14:11 ` Michael S. Tsirkin
2023-04-11 13:47 ` Parav Pandit
2023-04-11 14:02 ` Michael S. Tsirkin
2023-04-11 14:07 ` [virtio-dev] RE: [virtio-comment] " Parav Pandit
2023-04-11 14:10 ` [virtio-dev] " Michael S. Tsirkin
2023-04-11 14:30 ` [virtio-dev] " Parav Pandit
2023-04-10 17:54 ` Parav Pandit
2023-04-10 17:58 ` [virtio-dev] RE: [virtio-comment] " Parav Pandit
2023-04-11 3:28 ` Jason Wang
2023-04-11 19:01 ` Parav Pandit
2023-04-11 21:25 ` Michael S. Tsirkin
2023-04-12 0:40 ` Parav Pandit
2023-04-12 2:56 ` Michael S. Tsirkin
2023-04-12 4:07 ` Jason Wang
2023-04-12 4:20 ` Michael S. Tsirkin [this message]
2023-04-12 4:53 ` [virtio-dev] Re: [virtio-comment] " Jason Wang
2023-04-12 5:25 ` Michael S. Tsirkin
2023-04-12 5:37 ` Jason Wang
2023-04-13 17:03 ` Michael S. Tsirkin
2023-04-12 4:04 ` Jason Wang
2023-04-12 4:13 ` Parav Pandit
2023-04-12 4:20 ` Michael S. Tsirkin
2023-04-12 4:55 ` Jason Wang
2023-05-19 6:10 ` [virtio-dev] " Michael S. Tsirkin
2023-05-19 21:02 ` [virtio-dev] " Parav Pandit
2023-05-21 5:57 ` [virtio-dev] " Michael S. Tsirkin
2023-05-21 13:24 ` [virtio-dev] " Parav Pandit
2023-05-21 14:34 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 09/11] transport-pci: Describe PCI MMR dev config registers Parav Pandit
2023-04-07 8:55 ` [virtio-dev] " Michael S. Tsirkin
2023-04-10 1:33 ` [virtio-dev] Re: [virtio-comment] " Jason Wang
2023-04-10 6:14 ` Michael S. Tsirkin
2023-04-10 6:20 ` Jason Wang
2023-04-10 6:39 ` Michael S. Tsirkin
2023-04-10 7:20 ` Jason Wang
2023-04-10 10:06 ` Michael S. Tsirkin
2023-04-11 2:13 ` Jason Wang
2023-04-11 7:04 ` Michael S. Tsirkin
2023-04-11 9:01 ` Jason Wang
[not found] ` <CALBs2cXURMEzCGnULicXbsBfwnKE5cZOz=M-_hhFCXZ=Lqb9Nw@mail.gmail.com>
2023-04-11 10:39 ` Michael S. Tsirkin
2023-04-11 11:03 ` Yan Vugenfirer
2023-04-11 10:42 ` Michael S. Tsirkin
2023-04-12 3:58 ` Jason Wang
2023-04-12 4:15 ` Michael S. Tsirkin
2023-04-12 4:51 ` Jason Wang
2023-04-12 5:01 ` [virtio-dev] " Parav Pandit
2023-04-12 5:14 ` [virtio-dev] " Jason Wang
2023-04-12 5:30 ` [virtio-dev] " Parav Pandit
2023-04-12 5:38 ` [virtio-dev] " Jason Wang
2023-04-12 5:55 ` [virtio-dev] " Parav Pandit
2023-04-12 6:15 ` [virtio-dev] " Jason Wang
2023-04-12 14:23 ` [virtio-dev] " Parav Pandit
2023-04-13 1:48 ` [virtio-dev] " Jason Wang
2023-04-13 3:31 ` Parav Pandit
2023-04-13 5:14 ` Jason Wang
2023-04-13 17:19 ` Michael S. Tsirkin
2023-04-13 19:39 ` [virtio-dev] " Parav Pandit
2023-04-14 3:09 ` [virtio-dev] " Jason Wang
2023-04-14 3:18 ` [virtio-dev] " Parav Pandit
2023-04-14 3:37 ` [virtio-dev] " Jason Wang
2023-04-14 3:51 ` [virtio-dev] " Parav Pandit
2023-04-14 7:05 ` [virtio-dev] " Michael S. Tsirkin
2023-04-17 3:22 ` Jason Wang
2023-04-17 17:23 ` [virtio-dev] " Parav Pandit
2023-04-17 20:26 ` [virtio-dev] " Michael S. Tsirkin
2023-04-17 20:28 ` [virtio-dev] " Parav Pandit
2023-04-18 0:36 ` [virtio-dev] " Jason Wang
2023-04-18 1:30 ` [virtio-dev] " Parav Pandit
2023-04-18 11:58 ` [virtio-dev] " Michael S. Tsirkin
2023-04-18 12:09 ` [virtio-dev] " Parav Pandit
2023-04-18 12:30 ` [virtio-dev] " Michael S. Tsirkin
2023-04-18 12:36 ` [virtio-dev] " Parav Pandit
2023-04-18 1:01 ` [virtio-dev] " Jason Wang
2023-04-18 1:48 ` [virtio-dev] " Parav Pandit
2023-04-13 17:24 ` [virtio-dev] " Parav Pandit
2023-04-13 21:02 ` Michael S. Tsirkin
2023-04-13 21:08 ` [virtio-dev] " Parav Pandit
2023-04-14 2:36 ` [virtio-dev] " Jason Wang
2023-04-14 2:43 ` [virtio-dev] " Parav Pandit
2023-04-14 6:57 ` [virtio-dev] " Michael S. Tsirkin
2023-04-16 13:41 ` [virtio-dev] " Parav Pandit
2023-04-16 20:44 ` [virtio-dev] " Michael S. Tsirkin
2023-04-17 16:59 ` [virtio-dev] " Parav Pandit
2023-04-18 1:09 ` [virtio-dev] " Jason Wang
2023-04-18 1:37 ` [virtio-dev] " Parav Pandit
2023-04-14 6:58 ` [virtio-dev] " Michael S. Tsirkin
2023-04-14 3:08 ` Jason Wang
2023-04-14 3:13 ` [virtio-dev] " Parav Pandit
2023-04-14 3:18 ` [virtio-dev] " Jason Wang
2023-04-14 3:22 ` [virtio-dev] " Parav Pandit
2023-04-14 3:29 ` [virtio-dev] " Jason Wang
2023-04-11 13:57 ` [virtio-dev] " Parav Pandit
2023-04-12 4:33 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 10/11] transport-pci: Use driver notification PCI capability Parav Pandit
2023-04-12 4:31 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 4:37 ` [virtio-dev] " Parav Pandit
2023-04-12 4:43 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 4:48 ` [virtio-dev] " Parav Pandit
2023-04-12 5:02 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 5:06 ` [virtio-dev] RE: [virtio-comment] " Parav Pandit
2023-04-12 5:17 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 5:24 ` [virtio-dev] " Parav Pandit
2023-04-12 5:27 ` [virtio-dev] " Michael S. Tsirkin
2023-03-30 22:58 ` [virtio-dev] [PATCH 11/11] conformance: Add transitional MMR interface conformance Parav Pandit
2023-03-31 7:03 ` [virtio-dev] Re: [PATCH 00/11] Introduce transitional mmr pci device Michael S. Tsirkin
2023-03-31 21:43 ` Parav Pandit
2023-04-03 14:53 ` Michael S. Tsirkin
2023-04-03 14:57 ` [virtio-dev] " Parav Pandit
2023-04-03 15:06 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 15:16 ` [virtio-dev] " Parav Pandit
2023-04-03 15:23 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 15:34 ` Michael S. Tsirkin
2023-04-03 15:47 ` [virtio-dev] " Parav Pandit
2023-04-03 17:28 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 17:35 ` Parav Pandit
2023-04-03 17:39 ` Michael S. Tsirkin
2023-04-03 15:36 ` [virtio-dev] RE: [virtio-comment] " Parav Pandit
2023-04-03 17:16 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 17:29 ` Parav Pandit
2023-04-03 18:02 ` Michael S. Tsirkin
2023-04-03 20:25 ` [virtio-dev] " Parav Pandit
2023-04-03 21:04 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 22:00 ` Parav Pandit
2023-04-07 9:35 ` Michael S. Tsirkin
2023-04-10 1:52 ` Jason Wang
2023-04-03 14:45 ` [virtio-dev] Re: [virtio-comment] " Stefan Hajnoczi
2023-04-03 14:53 ` Parav Pandit
2023-04-03 17:48 ` Michael S. Tsirkin
2023-04-03 19:11 ` Stefan Hajnoczi
2023-04-03 20:03 ` Michael S. Tsirkin
2023-04-03 19:48 ` [virtio-dev] " Parav Pandit
2023-04-03 20:02 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 20:42 ` [virtio-dev] " Parav Pandit
2023-04-03 21:14 ` [virtio-dev] " Michael S. Tsirkin
2023-04-03 22:08 ` Parav Pandit
2023-04-03 19:10 ` Stefan Hajnoczi
2023-04-03 20:27 ` [virtio-dev] " Parav Pandit
2023-04-04 14:30 ` [virtio-dev] " Stefan Hajnoczi
2023-04-12 4:48 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 4:52 ` [virtio-dev] " Parav Pandit
2023-04-12 5:12 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 5:15 ` [virtio-dev] RE: [virtio-comment] " Parav Pandit
2023-04-12 5:23 ` [virtio-dev] " Michael S. Tsirkin
2023-04-12 5:39 ` [virtio-dev] " Parav Pandit
2023-04-12 6:02 ` Parav Pandit
2023-04-12 5:10 ` [virtio-dev] " Halil Pasic
2023-04-25 2:42 ` [virtio-dev] " Parav Pandit
2023-05-02 7:17 ` [virtio-dev] Re: [virtio-comment] " David Edmondson
2023-05-02 13:54 ` [virtio-dev] " Parav Pandit
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