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kvm: x86: Update tsc multiplier on change.

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vmx.c writes the TSC_MULTIPLIER field in vmx_vcpu_load, but only when a
vcpu has migrated physical cpus. Record the last value written and
update in vmx_vcpu_load on any change, otherwise a cpu migration must
occur for TSC frequency scaling to take effect.

Cc: stable@vger.kernel.org
Fixes: ff2c3a1803775cc72dc6f624b59554956396b0ee
Signed-off-by: Owen Hofmann <osh@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Owen Hofmann 2016-03-01 13:36:13 -08:00 committed by Paolo Bonzini
parent 0178fd7dcc
commit 2680d6da45
1 changed files with 9 additions and 5 deletions
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14
arch/x86/kvm/vmx.c
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@ -596,6 +596,8 @@ struct vcpu_vmx {
/* Support for PML */
#define PML_ENTITY_NUM 512
struct page *pml_pg;
u64 current_tsc_ratio;
};
enum segment_cache_field {
@ -2127,14 +2129,16 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp);
vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */
/* Setup TSC multiplier */
if (cpu_has_vmx_tsc_scaling())
vmcs_write64(TSC_MULTIPLIER,
vcpu->arch.tsc_scaling_ratio);
vmx->loaded_vmcs->cpu = cpu;
}
/* Setup TSC multiplier */
if (kvm_has_tsc_control &&
vmx->current_tsc_ratio != vcpu->arch.tsc_scaling_ratio) {
vmx->current_tsc_ratio = vcpu->arch.tsc_scaling_ratio;
vmcs_write64(TSC_MULTIPLIER, vmx->current_tsc_ratio);
}
vmx_vcpu_pi_load(vcpu, cpu);
}