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Date:   Mon, 9 May 2022 21:01:33 +0800
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Subject: Re: [PATCH v4 3/7] perf/x86/amd/core: Detect PerfMonV2 support
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To:     Sandipan Das <sandipan.das@amd.com>
Cc:     peterz@infradead.org, bp@alien8.de, dave.hansen@linux.intel.com,
        acme@kernel.org, mark.rutland@arm.com,
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        puwen@hygon.cn, ananth.narayan@amd.com, ravi.bangoria@amd.com,
        santosh.shukla@amd.com,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-perf-users@vger.kernel.org, x86@kernel.org
References: <cover.1651058600.git.sandipan.das@amd.com>
 <8d3e23760726cf6647a98999e1fcd12a37f36a42.1651058600.git.sandipan.das@amd.com>
From:   Like Xu <like.xu.linux@gmail.com>
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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 ?