Re: [Xen-devel] [PATCH 09/17] [V3]PVH xen: create PVH vmcs, and initialization

[Tim Deegan <tim@xxxxxxx>]

At 07:56 +0100 on 16 Apr (1366098967), Jan Beulich wrote:
> >>> On 16.04.13 at 03:08, Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:
> > On Mon, 15 Apr 2013 16:47:49 +0100 "Jan Beulich" <JBeulich@xxxxxxxx> wrote:
> >> > @@ -4514,6 +4591,8 @@ static int hvm_memory_event_traps(long p,
> >> > uint32_t reason, 
> >> >  void hvm_memory_event_cr0(unsigned long value, unsigned long old) 
> >> >  {
> >> > +    if ( is_pvh_vcpu(current) )
> >> > +        return;
> >> 
> >> This is temporary only, isn't it? If so, it should be clearly marked
> >> as such.
> > 
> > I am not sure what these event calls are about, I guessed it was for
> > some external debugger? 
> 
> No, these are for paging and/or page sharing afaik.

They're a separate thing from those, but along those lines.  They're
used for monitoring guest behaviour in an external tool (say, a virus
scanner).

> And this is
> functionality you definitely want for PVH guests (since it's only
> the PV MMU interface that prevents PV guests from having this
> enabled without a _lot_ of work).

Yes, if at all possible they should Just Work.  And if not, the control
hypercalls that turn them on must have appropriate gates to stop them
being enabled on PV guests.

Tim.

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