Re: [Qemu-devel] [RFC PATCH 12/13] intel_iommu: do replay when context invalidate

[Peter Xu]

On Thu, Dec 29, 2016 at 07:38:38AM +0000, Liu, Yi L wrote:
> > Before this one we only invalidate context cache when we receive context
> > entry invalidations. However it's possible that the invalidation also
> > contains a domain switch (only if cache-mode is enabled for vIOMMU). In
> > that case we need to notify all the registered components about the new
> > mapping.
> > 
> > Signed-off-by: Peter Xu <address@hidden>
> > ---
> >  hw/i386/intel_iommu.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c
> > index 2fcd7af..0220e63 100644
> > --- a/hw/i386/intel_iommu.c
> > +++ b/hw/i386/intel_iommu.c
> > @@ -1188,6 +1188,7 @@ static void 
> > vtd_context_device_invalidate(IntelIOMMUState 
> > *s,
> >                  trace_vtd_inv_desc_cc_device(bus_n, (devfn_it >> 3) & 0x1f,
> >                                               devfn_it & 3);
> >                  vtd_as->context_cache_entry.context_cache_gen = 0;
> > +                memory_region_iommu_replay_all(&vtd_as->iommu);
> 
> Hi Peter,
> 
> It looks like all the device context invalidation would result in replay even 
> the
> device is not an assigned device. Is it necessary to do replay for a virtual 
> device?

Normal emulated devices won't register for IOMMU notifier. For these
devices, MemoryRegion.iommu_notify will be empty. So replay on those
memory regions should not affect them at all.

Thanks,

-- peterx