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

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

On 2014/7/24 17:41, Jan Beulich wrote:
> > > > On 24.07.14 at 10:28, <tiejun.chen@xxxxxxxxx> wrote:
> > 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.
> Then tell me the scenario where iommu_use_hap_pt(d) is true and
> both iommu_passthrough and is_hardware_domain(d) are true too.
Then HVM?

Anyway I did a test like this,

        if (iommu_use_hap_pt(d))
        {
                ASSERT (iommu_passthrough && is_hardware_domain(d));

Then Xen really reboot.

Thanks
Tiejun

> Remember that for Dom0 iommu_use_hap_pt() can be true only for
> PVH, and PVH implies !iommu_passthrough.
>
> Jan
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