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KVM: x86: Avoid issuing wbinvd twice 

Micro optimization to avoid calling wbinvd twice on the CPU that has to
emulate it. As we might be preempted between smp_call_function_many and
the local wbinvd, the cache might be filled again so that real work
could be done uselessly.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
hifive-unleashed-5.1
Jan Kiszka 2010-11-01 14:01:29 +01:00 committed by Avi Kivity
parent aac8763697
commit 2eec734374
1 changed files with 6 additions and 4 deletions
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10
arch/x86/kvm/x86.c
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@ -4007,13 +4007,15 @@ int kvm_emulate_wbinvd(struct kvm_vcpu *vcpu)
return X86EMUL_CONTINUE;
if (kvm_x86_ops->has_wbinvd_exit()) {
preempt_disable();
int cpu = get_cpu();
cpumask_set_cpu(cpu, vcpu->arch.wbinvd_dirty_mask);
smp_call_function_many(vcpu->arch.wbinvd_dirty_mask,
wbinvd_ipi, NULL, 1);
preempt_enable();
put_cpu();
cpumask_clear(vcpu->arch.wbinvd_dirty_mask);
}
wbinvd();
} else
wbinvd();
return X86EMUL_CONTINUE;
}
EXPORT_SYMBOL_GPL(kvm_emulate_wbinvd);