From: Dapeng Mi Date: Fri, 10 Oct 2025 00:52:39 +0000 (+0800) Subject: KVM: x86/pmu: Don't try to get perf capabilities for hybrid CPUs X-Git-Tag: v6.18-rc2~13^2^2~13 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=034417c1439a533a315562a57bd340d963eaac6b;p=thirdparty%2Fkernel%2Flinux.git KVM: x86/pmu: Don't try to get perf capabilities for hybrid CPUs Explicitly zero kvm_host_pmu instead of attempting to get the perf PMU capabilities when running on a hybrid CPU to avoid running afoul of perf's sanity check. ------------[ cut here ]------------ WARNING: arch/x86/events/core.c:3089 at perf_get_x86_pmu_capability+0xd/0xc0, Call Trace: kvm_x86_vendor_init+0x1b0/0x1a40 [kvm] vmx_init+0xdb/0x260 [kvm_intel] vt_init+0x12/0x9d0 [kvm_intel] do_one_initcall+0x60/0x3f0 do_init_module+0x97/0x2b0 load_module+0x2d08/0x2e30 init_module_from_file+0x96/0xe0 idempotent_init_module+0x117/0x330 __x64_sys_finit_module+0x73/0xe0 Always read the capabilities for non-hybrid CPUs, i.e. don't entirely revert to reading capabilities if and only if KVM wants to use a PMU, as it may be useful to have the host PMU capabilities available, e.g. if only or debug. Reported-by: Chaitanya Kumar Borah Closes: https://lore.kernel.org/all/70b64347-2aca-4511-af78-a767d5fa8226@intel.com/ Fixes: 51f34b1e650f ("KVM: x86/pmu: Snapshot host (i.e. perf's) reported PMU capabilities") Suggested-by: Sean Christopherson Signed-off-by: Dapeng Mi Link: https://lore.kernel.org/r/20251010005239.146953-1-dapeng1.mi@linux.intel.com [sean: rework changelog, call out hybrid CPUs in shortlog] Signed-off-by: Sean Christopherson --- diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 40ac4cb44ed2..487ad19a236e 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -108,16 +108,18 @@ void kvm_init_pmu_capability(const struct kvm_pmu_ops *pmu_ops) bool is_intel = boot_cpu_data.x86_vendor == X86_VENDOR_INTEL; int min_nr_gp_ctrs = pmu_ops->MIN_NR_GP_COUNTERS; - perf_get_x86_pmu_capability(&kvm_host_pmu); - /* * Hybrid PMUs don't play nice with virtualization without careful * configuration by userspace, and KVM's APIs for reporting supported * vPMU features do not account for hybrid PMUs. Disable vPMU support * for hybrid PMUs until KVM gains a way to let userspace opt-in. */ - if (cpu_feature_enabled(X86_FEATURE_HYBRID_CPU)) + if (cpu_feature_enabled(X86_FEATURE_HYBRID_CPU)) { enable_pmu = false; + memset(&kvm_host_pmu, 0, sizeof(kvm_host_pmu)); + } else { + perf_get_x86_pmu_capability(&kvm_host_pmu); + } if (enable_pmu) { /*