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Re: [Xen-devel] [PATCH v3 11/16] x86/VPMU: Add support for PMU register handling on PV guests
On 01/13/2014 10:58 AM, Jan Beulich wrote:
On 13.01.14 at 16:44, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
On 01/13/2014 09:12 AM, Jan Beulich wrote:
On 06.01.14 at 20:24, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> wrote:
@@ -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.
Did you look at the other call site? Iirc it calls the function for all
input values (and hence the need for the current first parameter
of the function). I take it that the expectation was that further
perfctr related leaves might be added later and/or perfctr code
may need to override more than just leaf 0xa values.
Oh, you meant the problem is that I don't cover leaves *other* than 0xa.
I can move vpmu_do_cpuid() down to the exit path ("out" label) so that
all cpuid calls are checked. This will add latency to every cpuid
invocation in the guest but I guess it should be negligible (and this is
what HVM does already).
Incidentally, this will also solve my non-dom0 CPUID bug that I mentioned.
-boris
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