From: Sean Christopherson Date: Tue, 24 Jan 2023 23:49:03 +0000 (+0000) Subject: KVM: x86/pmu: Don't tell userspace to save PMU MSRs if PMU is disabled X-Git-Tag: v6.3-rc1~85^2~9^2~4 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=c3531edc79a7adbe4451d34084e8bf227c022872;p=thirdparty%2Flinux.git KVM: x86/pmu: Don't tell userspace to save PMU MSRs if PMU is disabled Omit all PMU MSRs from the "MSRs to save" list if the PMU is disabled so that userspace doesn't waste time saving and restoring dummy values. KVM provides "error" semantics (read zeros, drop writes) for such known-but- unsupported MSRs, i.e. has fudged around this issue for quite some time. Keep the "error" semantics as-is for now, the logic will be cleaned up in a separate patch. Cc: Aaron Lewis Cc: Weijiang Yang Link: https://lore.kernel.org/r/20230124234905.3774678-5-seanjc@google.com Signed-off-by: Sean Christopherson --- diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 9b6e1af63531f..25da2cc09e558 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7081,8 +7081,10 @@ static void kvm_init_msr_list(void) for (i = 0; i < ARRAY_SIZE(msrs_to_save_base); i++) kvm_probe_msr_to_save(msrs_to_save_base[i]); - for (i = 0; i < ARRAY_SIZE(msrs_to_save_pmu); i++) - kvm_probe_msr_to_save(msrs_to_save_pmu[i]); + if (enable_pmu) { + for (i = 0; i < ARRAY_SIZE(msrs_to_save_pmu); i++) + kvm_probe_msr_to_save(msrs_to_save_pmu[i]); + } for (i = 0; i < ARRAY_SIZE(emulated_msrs_all); i++) { if (!static_call(kvm_x86_has_emulated_msr)(NULL, emulated_msrs_all[i]))