linux-kernel - [PATCH v5 42/44] KVM: nSVM: Disable PMU MSR interception as appropriate while running L2

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Message-ID: <20250806195706.1650976-43-seanjc@google.com>
Date: Wed,  6 Aug 2025 12:57:04 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Tianrui Zhao <zhaotianrui@...ngson.cn>, Bibo Mao <maobibo@...ngson.cn>, 
	Huacai Chen <chenhuacai@...nel.org>, Anup Patel <anup@...infault.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Xin Li <xin@...or.com>, "H. Peter Anvin" <hpa@...or.com>, 
	Andy Lutomirski <luto@...nel.org>, 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: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	kvm@...r.kernel.org, loongarch@...ts.linux.dev, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-perf-users@...r.kernel.org, Kan Liang <kan.liang@...ux.intel.com>, 
	Yongwei Ma <yongwei.ma@...el.com>, Mingwei Zhang <mizhang@...gle.com>, 
	Xiong Zhang <xiong.y.zhang@...ux.intel.com>, Sandipan Das <sandipan.das@....com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>
Subject: [PATCH v5 42/44] KVM: nSVM: Disable PMU MSR interception as
 appropriate while running L2

Add MSRs that might be passed through to L1 when running with a mediated
PMU to the nested SVM's set of to-be-merged MSR indices, i.e. disable
interception of PMU MSRs when running L2 if both KVM (L0) and L1 disable
interception.  There is no need for KVM to interpose on such MSR accesses,
e.g. if L1 exposes a mediated PMU (or equivalent) to L2.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/nested.c | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index b7fd2e869998..de2b9db2d0ba 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -194,7 +194,7 @@ void recalc_intercepts(struct vcpu_svm *svm)
  * Hardcode the capacity of the array based on the maximum number of _offsets_.
  * MSRs are batched together, so there are fewer offsets than MSRs.
  */
-static int nested_svm_msrpm_merge_offsets[7] __ro_after_init;
+static int nested_svm_msrpm_merge_offsets[10] __ro_after_init;
 static int nested_svm_nr_msrpm_merge_offsets __ro_after_init;
 typedef unsigned long nsvm_msrpm_merge_t;
 
@@ -222,6 +222,22 @@ int __init nested_svm_init_msrpm_merge_offsets(void)
 		MSR_IA32_LASTBRANCHTOIP,
 		MSR_IA32_LASTINTFROMIP,
 		MSR_IA32_LASTINTTOIP,
+
+		MSR_K7_PERFCTR0,
+		MSR_K7_PERFCTR1,
+		MSR_K7_PERFCTR2,
+		MSR_K7_PERFCTR3,
+		MSR_F15H_PERF_CTR0,
+		MSR_F15H_PERF_CTR1,
+		MSR_F15H_PERF_CTR2,
+		MSR_F15H_PERF_CTR3,
+		MSR_F15H_PERF_CTR4,
+		MSR_F15H_PERF_CTR5,
+
+		MSR_AMD64_PERF_CNTR_GLOBAL_CTL,
+		MSR_AMD64_PERF_CNTR_GLOBAL_STATUS,
+		MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR,
+		MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_SET,
 	};
 	int i, j;
 
-- 
2.50.1.565.gc32cd1483b-goog