linux-kernel - [PATCH 5/5] perf/x86/amd/uncore: Add PerfMonV2 RDPMC assignments

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Date:   Thu, 19 May 2022 15:33:34 +0530
From:   Sandipan Das <sandipan.das@....com>
To:     <linux-kernel@...r.kernel.org>, <linux-perf-users@...r.kernel.org>,
        <x86@...nel.org>
CC:     <peterz@...radead.org>, <bp@...en8.de>, <acme@...nel.org>,
        <namhyung@...nel.org>, <jolsa@...nel.org>, <tglx@...utronix.de>,
        <mingo@...hat.com>, <pbonzini@...hat.com>, <jmattson@...gle.com>,
        <like.xu.linux@...il.com>, <eranian@...gle.com>,
        <ananth.narayan@....com>, <ravi.bangoria@....com>,
        <santosh.shukla@....com>, <sandipan.das@....com>
Subject: [PATCH 5/5] perf/x86/amd/uncore: Add PerfMonV2 RDPMC assignments

The current RDPMC assignment scheme maps four DF PMCs and
six L3 PMCs from index 6 to 15.

If AMD Performance Monitoring Version 2 (PerfMonV2) is
supported, there may be additional DF counters available
which are mapped starting from index 16 i.e. just after
the L3 counters. Update the RDPMC assignments accordingly.

Signed-off-by: Sandipan Das <sandipan.das@....com>
---
 arch/x86/events/amd/uncore.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/x86/events/amd/uncore.c b/arch/x86/events/amd/uncore.c
index ff4238eff087..d568afc705d2 100644
--- a/arch/x86/events/amd/uncore.c
+++ b/arch/x86/events/amd/uncore.c
@@ -158,6 +158,16 @@ static int amd_uncore_add(struct perf_event *event, int flags)
 	hwc->event_base_rdpmc = uncore->rdpmc_base + hwc->idx;
 	hwc->state = PERF_HES_UPTODATE | PERF_HES_STOPPED;
 
+	/*
+	 * The first four DF counters are accessible via RDPMC index 6 to 9
+	 * followed by the L3 counters from index 10 to 15. For processors
+	 * with more than four DF counters, the DF RDPMC assignments become
+	 * discontiguous as the additional counters are accessible starting
+	 * from index 16.
+	 */
+	if (is_nb_event(event) && hwc->idx >= NUM_COUNTERS_NB)
+		hwc->event_base_rdpmc += NUM_COUNTERS_L3;
+
 	if (flags & PERF_EF_START)
 		amd_uncore_start(event, PERF_EF_RELOAD);
 
-- 
2.34.1