Messages in this thread | | | Date | Tue, 8 Jul 2014 11:25:13 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH V3 1/2] perf ignore LBR and offcore_rsp. |
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On Mon, Jul 07, 2014 at 06:34:25AM -0700, kan.liang@intel.com wrote: > + /* > + * Access LBR MSR may cause #GP under certain circumstances. > + * E.g. KVM doesn't support LBR MSR > + * Check all LBT MSR here. > + * Disable LBR access if any LBR MSRs can not be accessed. > + */ > + if (x86_pmu.lbr_nr) { > + x86_pmu.lbr_msr_access = check_msr(x86_pmu.lbr_tos); > + for (i = 0; i < x86_pmu.lbr_nr; i++) { > + x86_pmu.lbr_msr_access &= > + check_msr(x86_pmu.lbr_from + i); > + x86_pmu.lbr_msr_access &= > + check_msr(x86_pmu.lbr_to + i); > + } > + }
So I was going to refer you to an email I send earlier telling you that this was wrong, but then found it got stuck in a mailqueue on my laptop :-(
In any case its wrong; just clear lbr_nr and kill lbr_msr_access. We already check lbr_nr in all the right places and you added lbr_msr_access to far too few of them (also the fact that every place you check lbr_msr_access already had an lbr_nr test should've been a clue).
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