linux-kernel - [PATCH v2 5/6] KVM: x86/pmu: Update sample period in pmc_write

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Date:   Fri,  3 Nov 2023 16:05:40 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dapeng Mi <dapeng1.mi@...ux.intel.com>,
        Mingwei Zhang <mizhang@...gle.com>,
        Roman Kagan <rkagan@...zon.de>,
        Jim Mattson <jmattson@...gle.com>,
        Like Xu <like.xu.linux@...il.com>
Subject: [PATCH v2 5/6] KVM: x86/pmu: Update sample period in pmc_write_counter()

Update a PMC's sample period in pmc_write_counter() to deduplicate code
across all callers of pmc_write_counter().  Opportunistically move
pmc_write_counter() into pmc.c now that it's doing more work.  WRMSR isn't
such a hot path that an extra CALL+RET pair will be problematic, and the
order of function definitions needs to be changed anyways, i.e. now is a
convenient time to eat the churn.

Reviewed-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/pmu.c           | 27 +++++++++++++++++++++++++++
 arch/x86/kvm/pmu.h           | 25 +------------------------
 arch/x86/kvm/svm/pmu.c       |  1 -
 arch/x86/kvm/vmx/pmu_intel.c |  2 --
 4 files changed, 28 insertions(+), 27 deletions(-)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index c06090196b00..3725d001239d 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -161,6 +161,15 @@ static u64 pmc_get_pebs_precise_level(struct kvm_pmc *pmc)
 	return 1;
 }
 
+static u64 get_sample_period(struct kvm_pmc *pmc, u64 counter_value)
+{
+	u64 sample_period = (-counter_value) & pmc_bitmask(pmc);
+
+	if (!sample_period)
+		sample_period = pmc_bitmask(pmc) + 1;
+	return sample_period;
+}
+
 static int pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type, u64 config,
 				 bool exclude_user, bool exclude_kernel,
 				 bool intr)
@@ -268,6 +277,24 @@ static void pmc_stop_counter(struct kvm_pmc *pmc)
 	}
 }
 
+static void pmc_update_sample_period(struct kvm_pmc *pmc)
+{
+	if (!pmc->perf_event || pmc->is_paused ||
+	    !is_sampling_event(pmc->perf_event))
+		return;
+
+	perf_event_period(pmc->perf_event,
+			  get_sample_period(pmc, pmc->counter));
+}
+
+void pmc_write_counter(struct kvm_pmc *pmc, u64 val)
+{
+	pmc->counter += val - pmc_read_counter(pmc);
+	pmc->counter &= pmc_bitmask(pmc);
+	pmc_update_sample_period(pmc);
+}
+EXPORT_SYMBOL_GPL(pmc_write_counter);
+
 static int filter_cmp(const void *pa, const void *pb, u64 mask)
 {
 	u64 a = *(u64 *)pa & mask;
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index db9a12c0a2ef..cae85e550f60 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -74,11 +74,7 @@ static inline u64 pmc_read_counter(struct kvm_pmc *pmc)
 	return counter & pmc_bitmask(pmc);
 }
 
-static inline void pmc_write_counter(struct kvm_pmc *pmc, u64 val)
-{
-	pmc->counter += val - pmc_read_counter(pmc);
-	pmc->counter &= pmc_bitmask(pmc);
-}
+void pmc_write_counter(struct kvm_pmc *pmc, u64 val);
 
 static inline bool pmc_is_gp(struct kvm_pmc *pmc)
 {
@@ -128,25 +124,6 @@ static inline struct kvm_pmc *get_fixed_pmc(struct kvm_pmu *pmu, u32 msr)
 	return NULL;
 }
 
-static inline u64 get_sample_period(struct kvm_pmc *pmc, u64 counter_value)
-{
-	u64 sample_period = (-counter_value) & pmc_bitmask(pmc);
-
-	if (!sample_period)
-		sample_period = pmc_bitmask(pmc) + 1;
-	return sample_period;
-}
-
-static inline void pmc_update_sample_period(struct kvm_pmc *pmc)
-{
-	if (!pmc->perf_event || pmc->is_paused ||
-	    !is_sampling_event(pmc->perf_event))
-		return;
-
-	perf_event_period(pmc->perf_event,
-			  get_sample_period(pmc, pmc->counter));
-}
-
 static inline bool pmc_speculative_in_use(struct kvm_pmc *pmc)
 {
 	struct kvm_pmu *pmu = pmc_to_pmu(pmc);
diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index 3fd47de14b38..b6a7ad4d6914 100644
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -161,7 +161,6 @@ static int amd_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 	pmc = get_gp_pmc_amd(pmu, msr, PMU_TYPE_COUNTER);
 	if (pmc) {
 		pmc_write_counter(pmc, data);
-		pmc_update_sample_period(pmc);
 		return 0;
 	}
 	/* MSR_EVNTSELn */
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 90c1f7f07e53..a6216c874729 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -437,11 +437,9 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 			    !(msr & MSR_PMC_FULL_WIDTH_BIT))
 				data = (s64)(s32)data;
 			pmc_write_counter(pmc, data);
-			pmc_update_sample_period(pmc);
 			break;
 		} else if ((pmc = get_fixed_pmc(pmu, msr))) {
 			pmc_write_counter(pmc, data);
-			pmc_update_sample_period(pmc);
 			break;
 		} else if ((pmc = get_gp_pmc(pmu, msr, MSR_P6_EVNTSEL0))) {
 			reserved_bits = pmu->reserved_bits;
-- 
2.42.0.869.gea05f2083d-goog