Re: [Xen-devel] [PATCH v2 7/7] npt/shadow: allow getting foreign page table entries

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

On Thu, Feb 14, 2019 at 04:38:54AM -0700, Jan Beulich wrote:
> >>> On 11.02.19 at 18:46, <roger.pau@xxxxxxxxxx> wrote:
> > --- a/xen/arch/x86/mm/p2m-pt.c
> > +++ b/xen/arch/x86/mm/p2m-pt.c
> > @@ -865,7 +865,8 @@ pod_retry_l1:
> >      unmap_domain_page(l1e);
> >  
> >      ASSERT(mfn_valid(mfn) || !p2m_is_ram(*t) || p2m_is_paging(*t));
> > -    return (p2m_is_valid(*t) || p2m_is_grant(*t)) ? mfn : INVALID_MFN;
> > +    return (p2m_is_valid(*t) || p2m_is_grant(*t) || p2m_is_foreign(*t))
> > +           ? mfn : INVALID_MFN;
> >  }
> 
> Wouldn't you better alter the ASSERT() as well, using p2m_is_any_ram()
> instead of p2m_is_ram() now? Grants should have been included there
> before, but omitting foreign ones there before was benign.

Yes, I could use p2m_is_any_ram both in the assert and in the return
condition:

ASSERT(mfn_valid(mfn) || !p2m_is_any_ram(*t) || p2m_is_paging(*t));
return (p2m_is_valid(*t) || p2m_is_any_ram(*t)) ? mfn : INVALID_MFN;

Thanks, Roger.

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