Messages in this thread | | | Date | Mon, 9 May 2022 15:11:49 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v4 3/7] perf/x86/amd/core: Detect PerfMonV2 support |
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On Mon, May 09, 2022 at 06:38:19PM +0530, Sandipan Das wrote: > > On 5/9/2022 6:31 PM, Like Xu wrote: > > On 27/4/2022 7:31 pm, Sandipan Das wrote: > > > >> x86_pmu.num_counters = AMD64_NUM_COUNTERS_CORE; > > > > Thus boot_cpu_has(X86_FEATURE_PERFCTR_CORE) is true. > > > >> + > >> + /* Check for Performance Monitoring v2 support */ > >> + if (boot_cpu_has(X86_FEATURE_PERFMON_V2)) { > >> + /* Update PMU version for later usage */ > >> + x86_pmu.version = 2; > > > > Is it safe to assume that once AMD CPU has the PERFMON_V2 (or further) bit, > > > > it must also have the PERFCTR_CORE bit set ? > > > > Yes, always. There won't be a case where PERFCTR_CORE is absent > but PERFMON_V2 is present.
Let me introduce you to this dodgy virt stuff :-) Best put a sanity check on it.
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