Re: [PATCH] intel_iommu: support snoop control

[Peter Xu]

On Mon, Feb 14, 2022 at 02:35:18PM +0800, Jason Wang wrote:
> On Mon, Feb 14, 2022 at 2:31 PM Peter Xu <peterx@redhat.com> wrote:
> >
> > On Mon, Feb 14, 2022 at 02:03:46PM +0800, Jason Wang wrote:
> > > SC is required for some kernel features like vhost-vDPA. So this patch
> > > implements basic SC feature. The idea is pretty simple, for software
> > > emulated DMA it would be always coherent. In this case we can simple
> > > advertise ECAP_SC bit. For VFIO and vhost, thing will be more much
> > > complicated, so this patch simply fail the IOMMU notifier
> > > registration.
> >
> > Could we spell out which vhost branch won't work?
> 
> For vhost, it should work but the problem is that we need to introduce
> more logics to demonstrate the notifier ability (e.g a dedicated
> notifier flag for cc).
> 
> > How about also mention what
> > this patch is used for (perhaps for some pure vdpa tests on fully emulated)?
> 
> That's fine, the main use case so far is to test vDPA in L1 guest.

Yeah, that looks okay.  Leave it be or add some commit message would work too,
either way:

Reviewed-by: Peter Xu <peterx@redhat.com>

Thanks,

-- 
Peter Xu