Re: [Xen-devel] [PATCH v3 11/16] x86/VPMU: Add support for PMU register handling on PV guests

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 01/13/2014 09:12 AM, Jan Beulich wrote:
> > > > On 06.01.14 at 20:24, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
> > @@ -866,7 +867,6 @@ void pv_cpuid(struct cpu_user_regs *regs)
> >           break;
> >   
> >       case 0x00000005: /* MONITOR/MWAIT */
> > -    case 0x0000000a: /* Architectural Performance Monitor Features */
> >       case 0x0000000b: /* Extended Topology Enumeration */
> >       case 0x8000000a: /* SVM revision and features */
> >       case 0x8000001b: /* Instruction Based Sampling */
> > @@ -875,7 +875,9 @@ void pv_cpuid(struct cpu_user_regs *regs)
> >       unsupported:
> >           a = b = c = d = 0;
> >           break;
> > -
> > +    case 0x0000000a: /* Architectural Performance Monitor Features (Intel) */
> > +        vpmu_do_cpuid(0xa, &a, &b, &c, &d);
> > +        break;
> >       default:
> Rather than removing a blank line here, you ought to insert a
> second one so that there's one before _and_ after the added
> code block.
>
> Furthermore the need to pass 0xa as the first argument suggests
> that you're not in line with the intentions of vpmu_do_cpuid():
> Either you drop the first parameter from the function, or you get
> your code in line with the existing caller.
Not sure I understand the problem. We fill a, b, c and d with HW values 
for dom0 and then call vpmu_do_cpuid() to adjust them if needed. And 
whether or not this is needed is based on the first argument.
(There is a bug in this routine in that it looks like I am not calling 
vpmu_do_cpuid() for non-dom0 PV guest but that's a different issue).
-boris


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