RE: Multiple vIOMMU instance support in QEMU?

[Tian, Kevin]

> From: Jason Gunthorpe <jgg@nvidia.com>
> Sent: Friday, May 19, 2023 4:19 AM
> 
> On Thu, May 18, 2023 at 03:45:24PM -0400, Peter Xu wrote:
> 
> > I see that Intel is already copied here (at least Yi and Kevin) so I assume
> > there're already some kind of synchronizations on multi-vIOMMU vs recent
> > works on Intel side, which is definitely nice and can avoid work conflicts.
> 
> I actually don't know that.. Intel sees multiple DMAR blocks in SW and
> they have kernel level replication of invalidation.. Intel doesn't
> have a HW fast path yet so they can rely on mediation to fix it. Thus
> I expect there is no HW replication of invalidations here. Kevin?
> 

No HW fast path so single vIOMMU instance is sufficient on Intel now.