Re: [Xen-devel] [PATCH v15 07/19] pvh: Disable unneeded features of HVM containers

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

On 11/12/2013 03:03 PM, Jan Beulich wrote:
> > > > On 12.11.13 at 15:56, George Dunlap <george.dunlap@xxxxxxxxxxxxx> wrote:
> > On 11/12/2013 01:51 PM, Jan Beulich wrote:
> > > > > > On 11.11.13 at 15:57, George Dunlap <george.dunlap@xxxxxxxxxxxxx> wrote:
> > > > @@ -1414,6 +1442,7 @@ int hvm_hap_nested_page_fault(paddr_t gpa,
> > > >        /* For the benefit of 32-bit WinXP (& older Windows) on AMD CPUs,
> > > >         * a fast path for LAPIC accesses, skipping the p2m lookup. */
> > > >        if ( !nestedhvm_vcpu_in_guestmode(v)
> > > > +         && is_hvm_vcpu(v)
> > > This change looks unnecessary - nestedhvm_vcpu_enter_guestmode()
> > > (the only way by which nestedhvm_vcpu_in_guestmode() could return
> > > other than zero) must obviously never be used on a PVH guest.
> > You've got the polarity of that check wrong -- PVH guests are never in
> > guest mode, therefore !nestedhvm_vcpu_in_guestmode() is always true.
> Oh, indeed. In which case I'd slightly prefer !is_pvh_vcpu() here,
> but I guess it's not really significant anyway.
The plan I think is for is_pvh to go away, and instead to have a flag 
indicating whether the guest has / is using a LAPIC.
 -George

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