RE: [RFC] /dev/ioasid uAPI proposal

Tian, Kevin
2021-06-04T09:19:57Z

> From: Alex Williamson <alex.williamson@redhat.com>
> Sent: Friday, June 4, 2021 4:42 AM
>
> > 'qemu --allow-no-snoop' makes more sense to me
>
> I'd be tempted to attach it to the -device vfio-pci option, it's
> specific drivers for specific devices that are going to want this and
> those devices may not be permanently attached to the VM. But I see in
> the other thread you're trying to optimize IOMMU page table sharing.
>
> There's a usability question in either case though and I'm not sure how
> to get around it other than QEMU or the kernel knowing a list of
> devices (explicit IDs or vendor+class) to select per device defaults.
>

"-device vfio-pci" is a per-device option, which implies that the
no-snoop choice is given to the admin then no need to maintain
a fixed device list in Qemu?

Thanks
Kevin