diff options
Diffstat (limited to 'arch/x86/kvm/x86.c')
| -rw-r--r-- | arch/x86/kvm/x86.c | 44 |
1 files changed, 33 insertions, 11 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ef12747ecb63..152ea4993b76 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -2974,6 +2974,22 @@ static void kvm_update_masterclock(struct kvm *kvm) kvm_end_pvclock_update(kvm); } +/* + * Use the kernel's tsc_khz directly if the TSC is constant, otherwise use KVM's + * per-CPU value (which may be zero if a CPU is going offline). Note, tsc_khz + * can change during boot even if the TSC is constant, as it's possible for KVM + * to be loaded before TSC calibration completes. Ideally, KVM would get a + * notification when calibration completes, but practically speaking calibration + * will complete before userspace is alive enough to create VMs. + */ +static unsigned long get_cpu_tsc_khz(void) +{ + if (static_cpu_has(X86_FEATURE_CONSTANT_TSC)) + return tsc_khz; + else + return __this_cpu_read(cpu_tsc_khz); +} + /* Called within read_seqcount_begin/retry for kvm->pvclock_sc. */ static void __get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data) { @@ -2984,7 +3000,8 @@ static void __get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data) get_cpu(); data->flags = 0; - if (ka->use_master_clock && __this_cpu_read(cpu_tsc_khz)) { + if (ka->use_master_clock && + (static_cpu_has(X86_FEATURE_CONSTANT_TSC) || __this_cpu_read(cpu_tsc_khz))) { #ifdef CONFIG_X86_64 struct timespec64 ts; @@ -2998,7 +3015,7 @@ static void __get_kvmclock(struct kvm *kvm, struct kvm_clock_data *data) data->flags |= KVM_CLOCK_TSC_STABLE; hv_clock.tsc_timestamp = ka->master_cycle_now; hv_clock.system_time = ka->master_kernel_ns + ka->kvmclock_offset; - kvm_get_time_scale(NSEC_PER_SEC, __this_cpu_read(cpu_tsc_khz) * 1000LL, + kvm_get_time_scale(NSEC_PER_SEC, get_cpu_tsc_khz() * 1000LL, &hv_clock.tsc_shift, &hv_clock.tsc_to_system_mul); data->clock = __pvclock_read_cycles(&hv_clock, data->host_tsc); @@ -3108,7 +3125,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) /* Keep irq disabled to prevent changes to the clock */ local_irq_save(flags); - tgt_tsc_khz = __this_cpu_read(cpu_tsc_khz); + tgt_tsc_khz = get_cpu_tsc_khz(); if (unlikely(tgt_tsc_khz == 0)) { local_irq_restore(flags); kvm_make_request(KVM_REQ_CLOCK_UPDATE, v); @@ -9038,9 +9055,11 @@ static void tsc_khz_changed(void *data) struct cpufreq_freqs *freq = data; unsigned long khz = 0; + WARN_ON_ONCE(boot_cpu_has(X86_FEATURE_CONSTANT_TSC)); + if (data) khz = freq->new; - else if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) + else khz = cpufreq_quick_get(raw_smp_processor_id()); if (!khz) khz = tsc_khz; @@ -9061,8 +9080,10 @@ static void kvm_hyperv_tsc_notifier(void) hyperv_stop_tsc_emulation(); /* TSC frequency always matches when on Hyper-V */ - for_each_present_cpu(cpu) - per_cpu(cpu_tsc_khz, cpu) = tsc_khz; + if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) { + for_each_present_cpu(cpu) + per_cpu(cpu_tsc_khz, cpu) = tsc_khz; + } kvm_caps.max_guest_tsc_khz = tsc_khz; list_for_each_entry(kvm, &vm_list, vm_list) { @@ -9199,10 +9220,10 @@ static void kvm_timer_init(void) } cpufreq_register_notifier(&kvmclock_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER); - } - cpuhp_setup_state(CPUHP_AP_X86_KVM_CLK_ONLINE, "x86/kvm/clk:online", - kvmclock_cpu_online, kvmclock_cpu_down_prep); + cpuhp_setup_state(CPUHP_AP_X86_KVM_CLK_ONLINE, "x86/kvm/clk:online", + kvmclock_cpu_online, kvmclock_cpu_down_prep); + } } #ifdef CONFIG_X86_64 @@ -9362,10 +9383,11 @@ void kvm_arch_exit(void) #endif kvm_lapic_exit(); - if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) + if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) { cpufreq_unregister_notifier(&kvmclock_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER); - cpuhp_remove_state_nocalls(CPUHP_AP_X86_KVM_CLK_ONLINE); + cpuhp_remove_state_nocalls(CPUHP_AP_X86_KVM_CLK_ONLINE); + } #ifdef CONFIG_X86_64 pvclock_gtod_unregister_notifier(&pvclock_gtod_notifier); irq_work_sync(&pvclock_irq_work); |