From: Zide Chen <zide.chen@intel.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: kvm@vger.kernel.org, Andi Kleen <ak@linux.intel.com>,
Jim Mattson <jmattson@google.com>,
Stephane Eranian <eranian@google.com>,
linux-kernel@vger.kernel.org, Mingwei Zhang <mizhang@google.com>,
Zide Chen <zide.chen@intel.com>,
Das Sandipan <Sandipan.Das@amd.com>,
Shukla Manali <Manali.Shukla@amd.com>,
Dapeng Mi <dapeng1.mi@linux.intel.com>,
Xudong Hao <xudong.hao@intel.com>
Subject: [PATCH v2 12/16] KVM: x86/pmu: Populate CPUID.0AH:ECX fixed-counter bitmap
Date: Thu, 27 Aug 2026 15:37:51 -0700 [thread overview]
Message-ID: <20260827223755.143247-13-zide.chen@intel.com> (raw)
In-Reply-To: <20260827223755.143247-1-zide.chen@intel.com>
PerfMon v5 adds a fixed-counter support bitmap in CPUID.0AH:ECX.
This is the superset of EDX[4:0] which indicates the contiguous
counters starting from 0. For backward compatibility, it's recommended
to use the following to determine if a fixed counter is supported:
FxCtr[i]_is_supported := ECX[i] || (EDX[4:0] > i);
Originally-by: Yang Weijiang <weijiang.yang@intel.com>
Signed-off-by: Zide Chen <zide.chen@intel.com>
---
arch/x86/kvm/cpuid.c | 5 ++++-
arch/x86/kvm/vmx/pmu_intel.c | 3 +++
2 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 106e719e7aee..63201d4ea4a1 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1547,7 +1547,10 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
entry->eax = eax.full;
entry->ebx = kvm_pmu_cap.events_mask;
- entry->ecx = 0;
+ if (kvm_pmu_cap.version >= 5)
+ entry->ecx &= (u32)kvm_pmu_cap.fixed_cntr_mask64;
+ else
+ entry->ecx = 0;
entry->edx = edx.full;
break;
}
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index a6d2ebff7cc9..1ce69e764ae1 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -585,7 +585,10 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
kvm_pmu_cap.events_mask_len);
pmu->available_event_types = ~entry->ebx & (BIT_ULL(eax.split.mask_length) - 1);
+ /* FxCtr[i]_is_supported := ECX[i] || (EDX[4:0] > i) */
fixed_cntr_mask = BIT_ULL(edx.split.num_counters_fixed) - 1;
+ if (pmu->version >= 5)
+ fixed_cntr_mask |= entry->ecx;
fixed_cntr_mask &= kvm_pmu_cap.fixed_cntr_mask64;
/*
--
2.55.0
next prev parent reply other threads:[~2026-08-27 22:48 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-27 22:37 [PATCH] KVM: x86/pmu: Add mediated vPMU PerfMon v5 support Zide Chen
2026-08-27 22:37 ` [PATCH v2 01/16] KVM: x86/pmu: Remove redundant Perf Global Status MSR bit definitions Zide Chen
2026-08-27 22:57 ` sashiko-bot
2026-08-28 13:51 ` Chen, Zide
2026-08-27 22:37 ` [PATCH v2 02/16] KVM: x86/pmu: Rename all_valid_pmc_idx to pmc_exists Zide Chen
2026-08-27 22:37 ` [PATCH v2 03/16] KVM: x86/pmu: Rename reserved_bits to eventsel_rsvd in kvm_pmu Zide Chen
2026-08-27 22:37 ` [PATCH v2 04/16] KVM: x86/pmu: Gate BUFFER_OVF reserved bit on guest DS Zide Chen
2026-08-27 22:37 ` [PATCH v2 05/16] KVM: x86/pmu: Add PMC bitmap accessor helpers Zide Chen
2026-08-27 22:37 ` [PATCH v2 06/16] KVM: x86/pmu: Drop nr_arch_{gp,fixed}_counters from kvm_pmu Zide Chen
2026-08-27 22:37 ` [PATCH v2 07/16] KVM: x86/pmu: Expose kvm_host_pmu to vendor modules Zide Chen
2026-08-27 22:37 ` [PATCH v2 08/16] perf/x86: Plumb counter bitmap from x86_pmu to x86_pmu_cap Zide Chen
2026-08-27 22:37 ` [PATCH v2 09/16] KVM: x86/pmu: Switch to bitmask-based KVM PMU capabilities Zide Chen
2026-08-27 22:37 ` [PATCH v2 10/16] perf/x86: Remove num_counters_{gp,fixed} from x86_pmu_capability Zide Chen
2026-08-27 22:37 ` [PATCH v2 11/16] KVM: x86/pmu: Emulate the GLOBAL_STATUS_SET and GLOBAL_INUSE MSRs Zide Chen
2026-08-27 23:05 ` sashiko-bot
2026-08-28 20:22 ` Chen, Zide
2026-08-27 22:37 ` Zide Chen [this message]
2026-08-27 22:37 ` [PATCH v2 13/16] KVM: x86/pmu: Factor out fixed counter control bit calculation Zide Chen
2026-08-27 22:37 ` [PATCH v2 14/16] KVM: x86/pmu: Ignore AnyThread bit if CPUID.0AH:EDX[15] is set Zide Chen
2026-08-27 22:37 ` [PATCH v2 15/16] KVM: x86/pmu: Advertise PerfMon version 5 on Intel hosts Zide Chen
2026-08-27 22:37 ` [PATCH v2 16/16] KVM: selftests: Support fixed counters bitmap in pmu_counters_test Zide Chen
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