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From: Jason Wang <jasowang@redhat.com>
To: Eugenio Perez Martin <eperezma@redhat.com>
Cc: Shannon Nelson <shannon.nelson@amd.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	si-wei.liu@oracle.com,  longpeng2@huawei.com,
	Lei Yang <leiyang@redhat.com>,
	 Laurent Vivier <lvivier@redhat.com>,
	alvaro.karsz@solid-run.com,  Gautam Dawar <gdawar@xilinx.com>,
	Cindy Lu <lulu@redhat.com>,
	 Zhu Lingshan <lingshan.zhu@intel.com>,
	Liuxiangdong <liuxiangdong5@huawei.com>,
	 Parav Pandit <parav@mellanox.com>,
	Harpreet Singh Anand <hanand@xilinx.com>,
	 "Gonglei (Arei)" <arei.gonglei@huawei.com>,
	Shannon Nelson <snelson@pensando.io>,
	 Stefano Garzarella <sgarzare@redhat.com>,
	Dragos Tatulea <dtatulea@nvidia.com>,
	 Virtio-Dev <virtio-dev@lists.oasis-open.org>
Subject: [virtio-dev] Re: [RFC 1/4] vdpa: add VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK flag
Date: Wed, 24 May 2023 12:06:47 +0800	[thread overview]
Message-ID: <CACGkMEudc7M5ZqRvhYkW35Sb6pK9yp1LObcFZLkX-sMRYwEj7w@mail.gmail.com> (raw)
In-Reply-To: <CAJaqyWd632RiE9Zhc8OLsQbnaC42VG1FW97UMDHPQRofukYPrg@mail.gmail.com>

On Tue, May 23, 2023 at 1:55 PM Eugenio Perez Martin
<eperezma@redhat.com> wrote:
>
> On Mon, May 22, 2023 at 11:22 PM Shannon Nelson <shannon.nelson@amd.com> wrote:
> >
> > On 5/22/23 1:07 PM, Eugenio Perez Martin wrote:
> > >
> > > On Mon, May 22, 2023 at 9:23 PM Michael S. Tsirkin <mst@redhat.com> wrote:
> > >>
> > >> On Mon, May 22, 2023 at 08:57:27PM +0200, Eugenio Pérez wrote:
> > >>> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > >>> ---
> > >>>   include/uapi/linux/vhost_types.h | 2 ++
> > >>>   1 file changed, 2 insertions(+)
> > >>>
> > >>> diff --git a/include/uapi/linux/vhost_types.h b/include/uapi/linux/vhost_types.h
> > >>> index c5690a8992d8..a1b316f49b38 100644
> > >>> --- a/include/uapi/linux/vhost_types.h
> > >>> +++ b/include/uapi/linux/vhost_types.h
> > >>> @@ -165,5 +165,7 @@ struct vhost_vdpa_iova_range {
> > >>>   #define VHOST_BACKEND_F_SUSPEND  0x4
> > >>>   /* Device can be resumed */
> > >>>   #define VHOST_BACKEND_F_RESUME  0x5
> > >>> +/* Device can enable virtqueues after DRIVER_OK */
> > >>
> > >> A bit more detail on what does this mean?
> > >> It's normally driver that enables VQs not device itself ...
> > >>
> > >
> > > I agree, it is not well explained.
> > >
> > > What about "Device supports the driver to enable virtqueues after DRIVER_OK"?
> > >
> > >>> +#define VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK  0x6
> >
> > Does this mean it is possible only after DRIVER_OK, or does it mean in
> > addition to before DRIVER_OK?  It isn't clear to me.
> >
> > Maybe something like
> > "Device supports virtqueue enable only after DRIVER_OK"
> > or
> > "Device supports virtqueue enable both before and after DRIVER_OK"
> >
>
> I agree too,
>
> With the previous suggestion it would be:
>
> "Device supports the driver to enable virtqueues both before and after
> DRIVER_OK"

Btw, I think it might be worth clarifying whether or not this is
supported by the current virtio spec. Spec seems to be unclear on
this:

1) The driver MUST NOT write a 0 to queue_enable.
2) if reset is support, driver can wrote 1 to re-enable a virtqueue

But it doesn't say if the driver can write 1 after DRIVER_OK without reset.

Thanks


>
> Does it look better?
>
> Thanks!
>
> > sln
> >
> >
> > >>>
> > >>>   #endif
> > >>> --
> > >>> 2.31.1
> > >>
> > >
> >
>


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       reply	other threads:[~2023-05-24  4:07 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20230522185730.3233001-1-eperezma@redhat.com>
     [not found] ` <20230522185730.3233001-2-eperezma@redhat.com>
     [not found]   ` <20230522152226-mutt-send-email-mst@kernel.org>
     [not found]     ` <CAJaqyWfSzqdyPHogzccuYBeThJgcx-A_AfF8tmqLgxKNVczBWA@mail.gmail.com>
     [not found]       ` <1735e461-a858-5bf2-bf9f-d9418e281d0c@amd.com>
     [not found]         ` <CAJaqyWd632RiE9Zhc8OLsQbnaC42VG1FW97UMDHPQRofukYPrg@mail.gmail.com>
2023-05-24  4:06           ` Jason Wang [this message]
2023-05-24 10:10             ` [virtio-dev] Re: [RFC 1/4] vdpa: add VHOST_BACKEND_F_ENABLE_AFTER_DRIVER_OK flag Michael S. Tsirkin
2023-05-26  6:21               ` Jason Wang
2023-05-24 16:25             ` Eugenio Perez Martin
2023-05-26  6:25               ` Jason Wang
2023-05-26  8:08                 ` Eugenio Perez Martin

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