Commit 2eec7343 authored Nov 01, 2010 by Jan Kiszka Committed by Avi Kivity Jan 12, 2011

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>

parent aac87636

arch/x86/kvm/x86.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -4007,12 +4007,14 @@ 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);
		}
		} else
		wbinvd();
		return X86EMUL_CONTINUE;
		}