linux-kernel - [PATCH] KVM: x86/pmu: Distinguish EVENTSEL bitmasks for uniform event creation and filtering

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Message-Id: <20220210102603.42764-1-likexu@tencent.com>
Date:   Thu, 10 Feb 2022 18:26:03 +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>,
        Wanpeng Li <wanpengli@...cent.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Joerg Roedel <joro@...tes.org>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] KVM: x86/pmu: Distinguish EVENTSEL bitmasks for uniform event creation and filtering

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

The current usage of EVENTSEL_* macro is a mess in the KVM context. Partly
because we have a conceptual ambiguity when choosing to create a RAW or
HARDWARE event: when bits other than HARDWARE_EVENT_MASK are set,
the pmc_reprogram_counter() will use the RAW type.

By introducing the new macro AMD64_EXTRA_EVENTSEL_EVENT to simplify,
the following three issues can be addressed in one go:

- the 12 selection bits are used as comparison keys for allow or deny;
- NON_HARDWARE_EVENT_MASK is only used to determine if a HARDWARE
  event is programmed or not, a 12-bit selected event will be a RAW event;
  (jmattson helped report this issue)
- by reusing AMD64_RAW_EVENT_MASK, the extra 4 selection bits (if set) are
  passed to the perf correctly and not filtered out by X86_RAW_EVENT_MASK;.

Signed-off-by: Like Xu <likexu@...cent.com>
---
 arch/x86/include/asm/perf_event.h |  3 ++-
 arch/x86/kvm/pmu.c                | 11 ++++-------
 arch/x86/kvm/pmu.h                |  6 ++++++
 3 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 8fc1b5003713..bd068fd19043 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -43,8 +43,9 @@
 #define AMD64_EVENTSEL_INT_CORE_SEL_MASK		\
 	(0xFULL << AMD64_EVENTSEL_INT_CORE_SEL_SHIFT)
 
+#define AMD64_EXTRA_EVENTSEL_EVENT				(0x0FULL << 32)
 #define AMD64_EVENTSEL_EVENT	\
-	(ARCH_PERFMON_EVENTSEL_EVENT | (0x0FULL << 32))
+	(ARCH_PERFMON_EVENTSEL_EVENT | AMD64_EXTRA_EVENTSEL_EVENT)
 #define INTEL_ARCH_EVENT_MASK	\
 	(ARCH_PERFMON_EVENTSEL_UMASK | ARCH_PERFMON_EVENTSEL_EVENT)
 
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 2c98f3ee8df4..99426a8d7f18 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -198,7 +198,8 @@ void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)
 
 	filter = srcu_dereference(kvm->arch.pmu_event_filter, &kvm->srcu);
 	if (filter) {
-		__u64 key = eventsel & AMD64_RAW_EVENT_MASK_NB;
+		__u64 key = eventsel & (INTEL_ARCH_EVENT_MASK |
+					AMD64_EXTRA_EVENTSEL_EVENT);
 
 		if (bsearch(&key, filter->events, filter->nevents,
 			    sizeof(__u64), cmp_u64))
@@ -209,18 +210,14 @@ void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)
 	if (!allow_event)
 		return;
 
-	if (!(eventsel & (ARCH_PERFMON_EVENTSEL_EDGE |
-			  ARCH_PERFMON_EVENTSEL_INV |
-			  ARCH_PERFMON_EVENTSEL_CMASK |
-			  HSW_IN_TX |
-			  HSW_IN_TX_CHECKPOINTED))) {
+	if (!(eventsel & NON_HARDWARE_EVENT_MASK)) {
 		config = kvm_x86_ops.pmu_ops->pmc_perf_hw_id(pmc);
 		if (config != PERF_COUNT_HW_MAX)
 			type = PERF_TYPE_HARDWARE;
 	}
 
 	if (type == PERF_TYPE_RAW)
-		config = eventsel & X86_RAW_EVENT_MASK;
+		config = eventsel & AMD64_RAW_EVENT_MASK;
 
 	if (pmc->current_config == eventsel && pmc_resume_counter(pmc))
 		return;
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 7a7b8d5b775e..48d867e250bc 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -17,6 +17,12 @@
 
 #define MAX_FIXED_COUNTERS	3
 
+#define KVM_ARCH_PERFMON_EVENTSEL_IGNORE \
+	(ARCH_PERFMON_EVENTSEL_ANY | ARCH_PERFMON_EVENTSEL_PIN_CONTROL)
+
+#define NON_HARDWARE_EVENT_MASK	(AMD64_EXTRA_EVENTSEL_EVENT | \
+	 (X86_ALL_EVENT_FLAGS & ~KVM_ARCH_PERFMON_EVENTSEL_IGNORE))
+
 struct kvm_event_hw_type_mapping {
 	u8 eventsel;
 	u8 unit_mask;
-- 
2.35.0