Re: [Xen-devel] [PATCH 1/1] xen:vtd: missing RMRR mapping while share EPT

["Chen, Tiejun" <tiejun.chen@xxxxxxxxx>]

On 2014/7/24 15:45, Jan Beulich wrote:
> > > > On 24.07.14 at 09:00, <tiejun.chen@xxxxxxxxx> wrote:
> > On 2014/7/24 14:14, Jan Beulich wrote:
> > > > > > On 24.07.14 at 03:23, <tiejun.chen@xxxxxxxxx> wrote:
> > > > @@ -1867,7 +1869,21 @@ static int rmrr_identity_mapping(struct domain *d,
> > > >
> > > >         while ( base_pfn < end_pfn )
> > > >         {
> > > > -        if ( intel_iommu_map_page(d, base_pfn, base_pfn,
> > > > +        if ( iommu_use_hap_pt(d) )
> > > Don't you, btw, need to extend this condition by
> > > && (!iommu_passthrough || !is_hardware_domain(d))?
> > Why do we need these checks here?
> At least for documentation purposes: It would be wrong to try to
> establish these mappings. I reckon iommu_use_hap_pt() implies the
> combined other condition, so an ASSERT() would presumably be fine
> as well (and get even closer to the intended documentation purpose).
I think if() should be reasonable here. Because

intel_iommu_map_page()
{
        ...
    /* do nothing if dom0 and iommu supports pass thru */
    if ( iommu_passthrough && is_hardware_domain(d) )
        return 0;

We just do nothing to return simply. But if ASSERT will cause abort.

Thanks
Tiejun

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