linux-kernel - [PATCH v4 17/38] KVM: x86/pmu: Add perf_capabilities field in struct kvm_host

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Message-ID: <20250324173121.1275209-18-mizhang@google.com>
Date: Mon, 24 Mar 2025 17:30:57 +0000
From: Mingwei Zhang <mizhang@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, Liang@...gle.com, 
	Kan <kan.liang@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	kvm@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	Mingwei Zhang <mizhang@...gle.com>, Yongwei Ma <yongwei.ma@...el.com>, 
	Xiong Zhang <xiong.y.zhang@...ux.intel.com>, Dapeng Mi <dapeng1.mi@...ux.intel.com>, 
	Jim Mattson <jmattson@...gle.com>, Sandipan Das <sandipan.das@....com>, 
	Zide Chen <zide.chen@...el.com>, Eranian Stephane <eranian@...gle.com>, 
	Das Sandipan <Sandipan.Das@....com>, Shukla Manali <Manali.Shukla@....com>, 
	Nikunj Dadhania <nikunj.dadhania@....com>
Subject: [PATCH v4 17/38] KVM: x86/pmu: Add perf_capabilities field in struct kvm_host_values{}

From: Dapeng Mi <dapeng1.mi@...ux.intel.com>

Add perf_capabilities in kvm_host_values{} structure to record host perf
capabilities. KVM needs to know if host supports some PMU capabilities
and then decide if passthrough or intercept some PMU MSRs or instruction
like rdpmc, e.g. If host supports PERF_METRICES, but guest is configured
not to support it, then rdpmc instruction needs to be intercepted.

Co-developed-by: Mingwei Zhang <mizhang@...gle.com>
Signed-off-by: Mingwei Zhang <mizhang@...gle.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@...ux.intel.com>
---
 arch/x86/kvm/vmx/vmx.c | 8 ++------
 arch/x86/kvm/x86.c     | 3 +++
 arch/x86/kvm/x86.h     | 1 +
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index acd3582874b9..ca1c53f855e0 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7908,14 +7908,10 @@ void vmx_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu)
 static __init u64 vmx_get_perf_capabilities(void)
 {
 	u64 perf_cap = PMU_CAP_FW_WRITES;
-	u64 host_perf_cap = 0;
 
 	if (!enable_pmu)
 		return 0;
 
-	if (boot_cpu_has(X86_FEATURE_PDCM))
-		rdmsrl(MSR_IA32_PERF_CAPABILITIES, host_perf_cap);
-
 	if (!cpu_feature_enabled(X86_FEATURE_ARCH_LBR) &&
 	    !enable_mediated_pmu) {
 		x86_perf_get_lbr(&vmx_lbr_caps);
@@ -7928,11 +7924,11 @@ static __init u64 vmx_get_perf_capabilities(void)
 		if (!vmx_lbr_caps.has_callstack)
 			memset(&vmx_lbr_caps, 0, sizeof(vmx_lbr_caps));
 		else if (vmx_lbr_caps.nr)
-			perf_cap |= host_perf_cap & PMU_CAP_LBR_FMT;
+			perf_cap |= kvm_host.perf_capabilities & PMU_CAP_LBR_FMT;
 	}
 
 	if (vmx_pebs_supported()) {
-		perf_cap |= host_perf_cap & PERF_CAP_PEBS_MASK;
+		perf_cap |= kvm_host.perf_capabilities & PERF_CAP_PEBS_MASK;
 
 		/*
 		 * Disallow adaptive PEBS as it is functionally broken, can be
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1ebe169b88b6..578e5f110b6c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9786,6 +9786,9 @@ int kvm_x86_vendor_init(struct kvm_x86_init_ops *ops)
 	if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES))
 		rdmsrl(MSR_IA32_ARCH_CAPABILITIES, kvm_host.arch_capabilities);
 
+	if (boot_cpu_has(X86_FEATURE_PDCM))
+		rdmsrl(MSR_IA32_PERF_CAPABILITIES, kvm_host.perf_capabilities);
+
 	r = ops->hardware_setup();
 	if (r != 0)
 		goto out_mmu_exit;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index dbf9973b3d09..b1df4ad2341b 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -46,6 +46,7 @@ struct kvm_host_values {
 	u64 xcr0;
 	u64 xss;
 	u64 arch_capabilities;
+	u64 perf_capabilities;
 };
 
 void kvm_spurious_fault(void);
-- 
2.49.0.395.g12beb8f557-goog