On Tue, May 16, 2023 at 11:37 AM Jason Wang <[email protected]> wrote: > > > 在 2023/5/16 02:01, Michael S. Tsirkin 写道: > > On Mon, May 15, 2023 at 06:00:02PM +0000, Parav Pandit wrote: > >>> From: Michael S. Tsirkin <[email protected]> > >>> Sent: Monday, May 15, 2023 1:56 PM > >>> > >>> On Mon, May 15, 2023 at 05:51:05PM +0000, Parav Pandit wrote: > >>>>> From: Michael S. Tsirkin <[email protected]> > >>>>> Sent: Monday, May 15, 2023 1:45 PM > >>>>> > >>>>> On Mon, May 15, 2023 at 03:49:44PM +0000, Parav Pandit wrote: > >>>>>> All legacy interface via AQ. > >>>>>> All modern interface access via PCI or its own transport between > >>>>>> driver and > >>>>> device. > >>>>> > >>>>> I am wondering however about the hypervisor notifications. > >>>>> Generally these are the most problematic aspect here I feel. For > >>>>> example, how does it interact with VIRTIO_F_NOTIF_CONFIG_DATA? And > >>>>> generally, having both guest and host be allowed to access device's BAR > >>> seems problematic. > >>>>> Can we reserve a PF BAR region for these things or is that too > >>>>> expensive? > >>>> VIRTIO_F_NOTIF_CONFIG_DATA is not present for the legacy. > >>> it is not but it just might be required, or it won't be there. > >>> > >> How can it be required if it not part of it? > >> I likely didn't follow your question/comment, can you please explain. > > VIRTIO_F_NOTIF_CONFIG_DATA is there presumably for a reason. > > > >>>> For modern device, guest driver will access the device own BAR directly > >>>> with > >>> its own config_data anyway. > >>>> Should we reserve a region in the PF BAR for SF/SIOV device?, should > >>>> device > >>> report which BAR/area to use for the given SF/SIOV device? > >>>> May be yes, those are different discussions with tradeoff to consider > >>>> during > >>> SIOV discussions. It is not related to VFs. > >>> > >>> For SIOV it's a given. But we can do this for SRIOV: reserve a PF region > >>> per VF. > >> Each VF has its own BAR area for driver notifications. > > But it is passed through to guest presumably. > > > Probably not in the case of VIRTIO_F_NOTIF_CONFIG_DATA. Did you see any > problem if we do mediation here except for some performance penalty?
Ok, rethink of this, when using legacy, VIRTIO_F_NOTIF_CONFIG_DATA should be assumed to be not negotiated. So I think I agree with Parav, it should not be a problem. Or do you mean for the devices that have some mandated features? Thanks > > Thanks > > > > --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
