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KVM: x86: Harden against cpufreq

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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 <zamsden@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Zachary Amsden 2009-10-09 16:26:08 -10:00 committed by Avi Kivity
parent 565d0998ec
commit 6b7d7e762b
1 changed files with 12 additions and 4 deletions
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16
arch/x86/kvm/x86.c
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@ -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;