From 6b7d7e762b238f908fe4c3345c2c6eb5c3fdbd59 Mon Sep 17 00:00:00 2001 From: Zachary Amsden Date: Fri, 9 Oct 2009 16:26:08 -1000 Subject: [PATCH] KVM: x86: Harden against cpufreq If cpufreq can't determine the CPU khz, or cpufreq is not compiled in, we should fallback to the measured TSC khz. Signed-off-by: Zachary Amsden Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/x86.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 098e7f886306..3cffa2cac70b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -1348,8 +1348,12 @@ out: void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) { kvm_x86_ops->vcpu_load(vcpu, cpu); - if (unlikely(per_cpu(cpu_tsc_khz, cpu) == 0)) - per_cpu(cpu_tsc_khz, cpu) = cpufreq_quick_get(cpu); + if (unlikely(per_cpu(cpu_tsc_khz, cpu) == 0)) { + unsigned long khz = cpufreq_quick_get(cpu); + if (!khz) + khz = tsc_khz; + per_cpu(cpu_tsc_khz, cpu) = khz; + } kvm_request_guest_time_update(vcpu); } @@ -3144,8 +3148,12 @@ static void kvm_timer_init(void) if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC)) { cpufreq_register_notifier(&kvmclock_cpufreq_notifier_block, CPUFREQ_TRANSITION_NOTIFIER); - for_each_online_cpu(cpu) - per_cpu(cpu_tsc_khz, cpu) = cpufreq_get(cpu); + for_each_online_cpu(cpu) { + unsigned long khz = cpufreq_get(cpu); + if (!khz) + khz = tsc_khz; + per_cpu(cpu_tsc_khz, cpu) = khz; + } } else { for_each_possible_cpu(cpu) per_cpu(cpu_tsc_khz, cpu) = tsc_khz; -- 2.39.2