linux-kernel - [PATCH RESEND v3 09/11] perf: x86/core: Add interface to query perfmon_event

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Message-Id: <20220518132512.37864-10-likexu@tencent.com>
Date:   Wed, 18 May 2022 21:25:10 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Joerg Roedel <joro@...tes.org>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Subject: [PATCH RESEND v3 09/11] perf: x86/core: Add interface to query perfmon_event_map[] directly

From: Like Xu <likexu@...cent.com>

Currently, we have [intel|knc|p4|p6]_perfmon_event_map on the Intel
platforms and amd_[f17h]_perfmon_event_map on the AMD platforms.

Early clumsy KVM code or other potential perf_event users may have
hard-coded these perfmon_maps (e.g., arch/x86/kvm/svm/pmu.c), so
it would not make sense to program a common hardware event based
on the generic "enum perf_hw_id" once the two tables do not match.

Let's provide an interface for callers outside the perf subsystem to get
the counter config based on the perfmon_event_map currently in use,
and it also helps to save bytes.

Cc: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Like Xu <likexu@...cent.com>
Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/x86/events/core.c            | 11 +++++++++++
 arch/x86/include/asm/perf_event.h |  6 ++++++
 2 files changed, 17 insertions(+)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 7f1d10dbabc0..99cf67d63cf3 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2997,3 +2997,14 @@ void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap)
 	cap->pebs_ept		= x86_pmu.pebs_ept;
 }
 EXPORT_SYMBOL_GPL(perf_get_x86_pmu_capability);
+
+u64 perf_get_hw_event_config(int hw_event)
+{
+	int max = x86_pmu.max_events;
+
+	if (hw_event < max)
+		return x86_pmu.event_map(array_index_nospec(hw_event, max));
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(perf_get_hw_event_config);
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index dc295b8c8def..396f0ce7a0f4 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -478,6 +478,7 @@ struct x86_pmu_lbr {
 };
 
 extern void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap);
+extern u64 perf_get_hw_event_config(int hw_event);
 extern void perf_check_microcode(void);
 extern void perf_clear_dirty_counters(void);
 extern int x86_perf_rdpmc_index(struct perf_event *event);
@@ -487,6 +488,11 @@ static inline void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap)
 	memset(cap, 0, sizeof(*cap));
 }
 
+static inline u64 perf_get_hw_event_config(int hw_event)
+{
+	return 0;
+}
+
 static inline void perf_events_lapic_init(void)	{ }
 static inline void perf_check_microcode(void) { }
 #endif
-- 
2.36.1