linux-kernel - [PATCH v2] perf/x86/intel: make anythread filter support conditional

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Message-Id: <20201028194247.3160610-1-eranian@google.com>
Date:   Wed, 28 Oct 2020 12:42:47 -0700
From:   Stephane Eranian <eranian@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     ak@...ux.intel.com, kan.liang@...el.com, jolsa@...hat.com,
        peterz@...radead.org, mingo@...e.hu, irogers@...gle.com,
        namhyung@...nel.org
Subject: [PATCH v2] perf/x86/intel: make anythread filter support conditional

Starting with Arch Perfmon v5, the anythread filter on generic counters may be
deprecated. The current kernel was exporting the any filter without checking.
On Icelake, it means you could do cpu/event=0x3c,any/ even though the filter
does not exist. This patch corrects the problem by relying on the CPUID 0xa leaf
function to determine if anythread is supported or not as described in the
Intel SDM Vol3b 18.2.5.1 AnyThread Deprecation section.

In V2, we remove intel_arch_v4_format_attrs because it is a duplicate
of intel_arch_format_attrs.

Signed-off-by: Stephane Eranian <eranian@...gle.com>
---
 arch/x86/events/intel/core.c      | 10 ++++++++++
 arch/x86/events/perf_event.h      |  1 +
 arch/x86/include/asm/perf_event.h |  4 +++-
 arch/x86/kvm/cpuid.c              |  4 +++-
 4 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index f1926e9f2143..7daab613052b 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4987,6 +4987,12 @@ __init int intel_pmu_init(void)
 
 	x86_add_quirk(intel_arch_events_quirk); /* Install first, so it runs last */
 
+	if (version >= 5) {
+		x86_pmu.intel_cap.anythread_deprecated = edx.split.anythread_deprecated;
+		if (x86_pmu.intel_cap.anythread_deprecated)
+			pr_cont(" AnyThread deprecated, ");
+	}
+
 	/*
 	 * Install the hw-cache-events table:
 	 */
@@ -5512,6 +5518,10 @@ __init int intel_pmu_init(void)
 	x86_pmu.intel_ctrl |=
 		((1LL << x86_pmu.num_counters_fixed)-1) << INTEL_PMC_IDX_FIXED;
 
+	/* AnyThread may be deprecated on arch perfmon v5 or later */
+	if (x86_pmu.intel_cap.anythread_deprecated)
+		x86_pmu.format_attrs = intel_arch_formats_attr;
+
 	if (x86_pmu.event_constraints) {
 		/*
 		 * event on fixed counter2 (REF_CYCLES) only works on this
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index ee2b9b9fc2a5..906b494083a8 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -585,6 +585,7 @@ union perf_capabilities {
 		u64     pebs_baseline:1;
 		u64	perf_metrics:1;
 		u64	pebs_output_pt_available:1;
+		u64	anythread_deprecated:1;
 	};
 	u64	capabilities;
 };
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 6960cd6d1f23..b9a7fd0a27e2 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -137,7 +137,9 @@ union cpuid10_edx {
 	struct {
 		unsigned int num_counters_fixed:5;
 		unsigned int bit_width_fixed:8;
-		unsigned int reserved:19;
+		unsigned int reserved1:2;
+		unsigned int anythread_deprecated:1;
+		unsigned int reserved2:16;
 	} split;
 	unsigned int full;
 };
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 7456f9ad424b..09097d430961 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -636,7 +636,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 
 		edx.split.num_counters_fixed = min(cap.num_counters_fixed, MAX_FIXED_COUNTERS);
 		edx.split.bit_width_fixed = cap.bit_width_fixed;
-		edx.split.reserved = 0;
+		edx.split.anythread_deprecated = 1;
+		edx.split.reserved1 = 0;
+		edx.split.reserved2 = 0;
 
 		entry->eax = eax.full;
 		entry->ebx = cap.events_mask;
-- 
2.29.1.341.ge80a0c044ae-goog