From: Jason Wang <jasowang@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Si-Wei Liu <si-wei.liu@oracle.com>,
elic@nvidia.com, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org
Subject: Re: [PATCH] vdpa/mlx5: set_features should allow reset to zero
Date: Tue, 2 Mar 2021 18:53:50 +0800 [thread overview]
Message-ID: <178f8ea7-cebd-0e81-3dc7-10a058d22c07@redhat.com> (raw)
In-Reply-To: <20210302043419-mutt-send-email-mst@kernel.org>
On 2021/3/2 5:47 下午, Michael S. Tsirkin wrote:
> On Mon, Mar 01, 2021 at 11:56:50AM +0800, Jason Wang wrote:
>> On 2021/3/1 5:34 上午, Michael S. Tsirkin wrote:
>>> On Wed, Feb 24, 2021 at 10:24:41AM -0800, Si-Wei Liu wrote:
>>>>> Detecting it isn't enough though, we will need a new ioctl to notify
>>>>> the kernel that it's a legacy guest. Ugh :(
>>>> Well, although I think adding an ioctl is doable, may I know what the use
>>>> case there will be for kernel to leverage such info directly? Is there a
>>>> case QEMU can't do with dedicate ioctls later if there's indeed
>>>> differentiation (legacy v.s. modern) needed?
>>> BTW a good API could be
>>>
>>> #define VHOST_SET_ENDIAN _IOW(VHOST_VIRTIO, ?, int)
>>> #define VHOST_GET_ENDIAN _IOW(VHOST_VIRTIO, ?, int)
>>>
>>> we did it per vring but maybe that was a mistake ...
>>
>> Actually, I wonder whether it's good time to just not support legacy driver
>> for vDPA. Consider:
>>
>> 1) It's definition is no-normative
>> 2) A lot of budren of codes
>>
>> So qemu can still present the legacy device since the config space or other
>> stuffs that is presented by vhost-vDPA is not expected to be accessed by
>> guest directly. Qemu can do the endian conversion when necessary in this
>> case?
>>
>> Thanks
>>
> Overall I would be fine with this approach but we need to avoid breaking
> working userspace, qemu releases with vdpa support are out there and
> seem to work for people. Any changes need to take that into account
> and document compatibility concerns.
Agree, let me check.
> I note that any hardware
> implementation is already broken for legacy except on platforms with
> strong ordering which might be helpful in reducing the scope.
Yes.
Thanks
>
>
next prev parent reply other threads:[~2021-03-03 4:10 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-19 11:54 [PATCH] vdpa/mlx5: set_features should allow reset to zero Si-Wei Liu
2021-02-21 14:44 ` Eli Cohen
2021-02-21 21:52 ` Michael S. Tsirkin
2021-02-22 6:05 ` Eli Cohen
2021-02-23 9:26 ` Michael S. Tsirkin
2021-02-23 9:48 ` Jason Wang
2021-02-23 9:55 ` Michael S. Tsirkin
2021-02-22 4:14 ` Jason Wang
2021-02-22 7:34 ` Michael S. Tsirkin
2021-02-23 1:12 ` Si-Wei Liu
2021-02-23 2:03 ` Jason Wang
2021-02-23 13:26 ` Michael S. Tsirkin
2021-02-23 19:35 ` Si-Wei Liu
2021-02-24 3:20 ` Jason Wang
2021-02-24 5:17 ` Michael S. Tsirkin
2021-02-24 6:02 ` Jason Wang
2021-02-24 6:45 ` Eli Cohen
2021-02-24 6:47 ` Michael S. Tsirkin
2021-02-24 6:55 ` Jason Wang
2021-02-24 7:12 ` Michael S. Tsirkin
2021-02-24 12:40 ` Eli Cohen
2021-02-24 7:17 ` Eli Cohen
2021-02-24 5:04 ` Michael S. Tsirkin
2021-02-24 6:04 ` Jason Wang
2021-02-24 6:46 ` Michael S. Tsirkin
2021-02-24 6:53 ` Jason Wang
2021-02-24 7:17 ` Michael S. Tsirkin
[not found] ` <babc654d-8dcd-d8a2-c3b6-d20cc4fc554c@redhat.com>
2021-02-24 8:43 ` Michael S. Tsirkin
2021-02-24 9:30 ` Jason Wang
2021-02-28 21:30 ` Michael S. Tsirkin
2021-03-01 3:53 ` Jason Wang
2021-02-24 18:24 ` Si-Wei Liu
2021-02-26 0:56 ` Si-Wei Liu
2021-02-28 21:27 ` Michael S. Tsirkin
2021-03-01 18:08 ` Si-Wei Liu
2021-02-28 21:28 ` Michael S. Tsirkin
2021-02-28 21:34 ` Michael S. Tsirkin
2021-03-01 3:56 ` Jason Wang
2021-03-02 9:47 ` Michael S. Tsirkin
2021-03-02 10:53 ` Jason Wang [this message]
2021-12-11 1:44 ` vdpa legacy guest support (was Re: [PATCH] vdpa/mlx5: set_features should allow reset to zero) Si-Wei Liu
2021-12-12 9:26 ` Michael S. Tsirkin
2021-12-13 3:02 ` Jason Wang
2021-12-13 8:06 ` Michael S. Tsirkin
2021-12-13 8:57 ` Jason Wang
2021-12-13 10:42 ` Michael S. Tsirkin
2021-12-14 1:13 ` Si-Wei Liu
2021-12-14 1:59 ` Si-Wei Liu
2021-12-14 3:01 ` Jason Wang
2021-12-14 5:06 ` Michael S. Tsirkin
2021-12-15 1:05 ` Si-Wei Liu
2021-12-15 2:06 ` Jason Wang
2021-12-15 20:52 ` Si-Wei Liu
2021-12-15 21:33 ` Michael S. Tsirkin
2021-12-16 2:01 ` Si-Wei Liu
2021-12-16 2:53 ` Jason Wang
2021-12-16 22:32 ` Si-Wei Liu
2021-12-17 1:57 ` Jason Wang
2021-12-17 2:00 ` Michael S. Tsirkin
2021-12-17 2:15 ` Jason Wang
2021-12-16 6:35 ` Michael S. Tsirkin
2021-12-16 3:43 ` Jason Wang
2021-12-17 1:08 ` Si-Wei Liu
2021-12-17 2:01 ` Jason Wang
2021-02-22 17:09 ` [PATCH] vdpa/mlx5: set_features should allow reset to zero Si-Wei Liu
2021-02-23 2:03 ` Jason Wang
2021-02-23 9:25 ` Michael S. Tsirkin
2021-02-23 9:46 ` Jason Wang
2021-02-23 10:01 ` Michael S. Tsirkin
2021-02-23 10:17 ` Jason Wang
2021-02-24 9:40 ` Jason Wang
2021-02-23 10:04 ` [virtio-dev] " Cornelia Huck
2021-02-23 10:31 ` Jason Wang
2021-02-23 10:58 ` Cornelia Huck
2021-02-24 9:29 ` Jason Wang
2021-02-24 11:12 ` Cornelia Huck
2021-02-25 4:36 ` Jason Wang
2021-02-25 13:26 ` Cornelia Huck
2021-02-25 18:53 ` Michael S. Tsirkin
2021-02-26 8:19 ` Jason Wang
2021-02-28 21:25 ` Michael S. Tsirkin
2021-03-01 3:51 ` Jason Wang
2021-03-02 12:08 ` Cornelia Huck
[not found] ` <5f6972fe-7246-b622-958d-9cab8dd98e21@redhat.com>
2021-03-03 8:29 ` Cornelia Huck
2021-03-04 8:24 ` Jason Wang
2021-03-04 13:50 ` Cornelia Huck
2021-03-05 3:01 ` Jason Wang
2021-02-23 12:26 ` Michael S. Tsirkin
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