Re: [PATCH 1/2] Virtio: Add CONFIG_VIRTIO_MMIO_POLL_RESET

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Sep 26, 2024 at 11:50:32AM +0800, Jason Wang wrote:
> On Thu, Sep 26, 2024 at 11:31 AM Jianguo Sun (QUIC)
> <quic_jianguos@quicinc.com> wrote:
> >
> > Hi @Jason
> >
> > Both hypervisor and backend device may need to support virtio-mmio device reset
> 
> Then you need to patch the virtio spec first. Or it is already
> supported by the spec?
> 
> > Adding CONFIG_VIRTIO_MMIO_POLL_RESET is for the system that has such support.
> 
> And we will probably have a feature or transport bit/flag for this.
> 
> Thanks

feature bits can't affect reset.
I don't know what a transport bit/flag is, in the context of MMIO.

We can just make it a recommendation.


> >
> > A config option (feature bit) is a better approach.
> > Thanks for the review.
> >
> > BR
> > Jianguo
> >
> > -----Original Message-----
> > From: Jason Wang <jasowang@redhat.com>
> > Sent: Tuesday, September 24, 2024 3:39 PM
> > To: Jianguo Sun (QUIC) <quic_jianguos@quicinc.com>
> > Cc: mst@redhat.com; xuanzhuo@linux.alibaba.com; eperezma@redhat.com; virtualization@lists.linux.dev; Anant Goel (QUIC) <quic_anantg@quicinc.com>
> > Subject: Re: [PATCH 1/2] Virtio: Add CONFIG_VIRTIO_MMIO_POLL_RESET
> >
> > On Sun, Sep 22, 2024 at 8:35 PM Jianguo Sun <quic_jianguos@quicinc.com> wrote:
> > >
> > > Add CONFIG_VIRTIO_MMIO_POLL_RESET to as an option to enable
> > > synchronous reset for the MMIO based transport for virtio.
> > >
> > > Change-Id: Ifa7e29b4c0cfa26922535f921c6ab69eacdc4cfc
> > > Signed-off-by: Jianguo Sun <quic_jianguos@quicinc.com>
> > > Signed-off-by: Anant Goel <quic_anantg@quicinc.com>
> >
> > Any reason this is not a feature but a config option?
> >
> > > ---
> > >  drivers/virtio/Kconfig | 8 ++++++++
> > >  1 file changed, 8 insertions(+)
> > >
> > > diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig index
> > > 42a48ac763ee..fb17b1078d53 100644
> > > --- a/drivers/virtio/Kconfig
> > > +++ b/drivers/virtio/Kconfig
> > > @@ -188,4 +188,12 @@ config VIRTIO_DEBUG
> > >
> > >           If unsure, say N.
> > >
> > > +config VIRTIO_MMIO_POLL_RESET
> > > +       bool "Virti-mmio device synchronous reset support"
> > > +       depends on VIRTIO_MMIO
> > > +       help
> > > +         Say y here to enable synchronous reset for the MMIO transport based
> > > +         virtio device. After writing 0 to device_status, the driver must
> > > +         wait for a read of device_status to return 0 before reinitializing
> > > +         the device.
> > >  endif # VIRTIO_MENU
> > > --
> > > 2.17.1
> > >
> >
> > Thanks
> >