Re: [PATCH RFC v13 08/20] pvh: PVH access to hypercalls

[Mukesh Rathor <mukesh.rathor@oracle.com>]

On Thu, 26 Sep 2013 16:33:07 +0100
"Jan Beulich" <JBeulich@suse.com> wrote:

> >>> On 23.09.13 at 18:49, George Dunlap <george.dunlap@eu.citrix.com>
> >>> wrote:
> > --- a/xen/arch/x86/hvm/mtrr.c
> > +++ b/xen/arch/x86/hvm/mtrr.c
> > @@ -578,6 +578,7 @@ int32_t hvm_set_mem_pinned_cacheattr(
> >  {
> >      struct hvm_mem_pinned_cacheattr_range *range;
> >  
> > +    /* Side note: A PVH guest writes to MSR_IA32_CR_PAT natively.
> > */ if ( !((type == PAT_TYPE_UNCACHABLE) ||
> >             (type == PAT_TYPE_WRCOMB) ||
> >             (type == PAT_TYPE_WRTHROUGH) ||
> 
> I always wondered what this comment is trying to tell the
> reader.

Original code:

    /* Side note: A PVH guest writes to MSR_IA32_CR_PAT natively. */
    if ( is_pvh_domain(d) )
        return -EOPNOTSUPP;

We don't support this because the guest writes PAT natively, was 
my intention. Either it was your comment to return EOPNOTSUPP
or just my thought - it will return EINVAL now, I guess ok too.

thanks
mukesh