Re: [V8 PATCH 7/8] pvh dom0: add check for pvh in vioapic_range

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

On Tue, 01 Apr 2014 16:09:15 +0100
"Jan Beulich" <JBeulich@suse.com> wrote:

> >>> On 01.04.14 at 16:40, <george.dunlap@eu.citrix.com> wrote:
> > On 03/24/2014 09:34 AM, Jan Beulich wrote:
> >>>>> On 22.03.14 at 02:39, <mukesh.rathor@oracle.com> wrote:
> >>> --- a/xen/arch/x86/hvm/vioapic.c
> >>> +++ b/xen/arch/x86/hvm/vioapic.c
> >>> @@ -238,8 +238,13 @@ static int vioapic_write(
> >>>
> >>>   static int vioapic_range(struct vcpu *v, unsigned long addr)
> >>>   {
> >>> -    struct hvm_hw_vioapic *vioapic = domain_vioapic(v->domain);
> >>> +    struct hvm_hw_vioapic *vioapic;
> >>> +
> >>> +    /* pvh uses event channel callback */
> >>> +    if ( is_pvh_vcpu(v) )
> >>> +        return 0;
> >>>
> >>> +    vioapic = domain_vioapic(v->domain);
> >>
> >> I can see why the extra check is needed, but I can't see why you
> >> convert the initializer to an assignment: Afaict domain_vioapic()
> >> is safe even if d->arch.hvm_domain.vioapic == NULL.
> > 
> > Or better yet, just make it something like:
> > 
> > return vioapic && ((addr >= [...original range check]))
> > 
> > That way we don't have to have a PVH-specific hook at all.  If a
> > domain doesn't have a vioapic for any reason, return 0.
> 
> No, vioapic isn't going to be NULL for PVH:
> 
> #define domain_vioapic(d)
> (&(d)->arch.hvm_domain.vioapic->hvm_hw_vioapic)

No, viopaic is NULL for PVH, hence the patch. So, can prob just check
for the ptr like George suggests and remove the pvh check.

thanks
mukesh