Re: [Xen-devel] [PATCH v3.1 08/15] x86/vtd: fix mapping of RMRR regions

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

On Fri, Nov 04, 2016 at 10:13:08AM -0600, Jan Beulich wrote:
> >>> On 04.11.16 at 16:33, <roger.pau@xxxxxxxxxx> wrote:
> > --- a/xen/include/asm-x86/p2m.h
> > +++ b/xen/include/asm-x86/p2m.h
> > @@ -834,6 +834,7 @@ static inline unsigned int 
> > p2m_get_iommu_flags(p2m_type_t p2mt)
> >      case p2m_grant_map_rw:
> >      case p2m_ram_logdirty:
> >      case p2m_map_foreign:
> > +    case p2m_mmio_direct:
> >          flags =  IOMMUF_readable | IOMMUF_writable;
> >          break;
> >      case p2m_ram_ro:
> 
> Generally this may be the route to go. But if we want to do so, we
> need to throughly understand why this type wasn't included here
> before (and I don't know myself).

It was me that introduced p2m_get_iommu_flags, and I just didn't think it 
would be useful at that point, that's why it wasn't included.

The patch that introduced p2m_get_iommu_flags was focused on fixing DMA'ing 
from grant-pages on HVM guests with passed-through hardware, this was needed 
for driver domains and later on by classic PVH Dom0

Roger.

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