[PATCH][v2] KVM: x86: directly call wbinvd for local cpu when emulate wbinvd

[Li RongQing <lirongqing@baidu.com>]

directly call wbinvd for local cpu, instead of calling atomic
cpumask_set_cpu to set local cpu, and then check if local cpu
needs to run in on_each_cpu_mask

on_each_cpu_mask is less efficient than smp_call_function_many,
since it will close preempt again and running call function by
checking flag with SCF_RUN_LOCAL. and here wbinvd can be called
directly

In fact, This change reverts commit 2eec73437487 ("KVM: x86: Avoid
issuing wbinvd twice"), since smp_call_function_many is skiping the
local cpu (as description of c2162e13d6e2f), wbinvd is not issued
twice

and reverts commit c2162e13d6e2f ("KVM: X86: Fix missing local pCPU
when executing wbinvd on all dirty pCPUs") too, which fixed the
previous patch, when revert previous patch, it is not needed.

Signed-off-by: Li RongQing <lirongqing@baidu.com>
---
diff v2: rewrite commit log

 arch/x86/kvm/x86.c |   13 ++++++-------
 1 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index aabd3a2..28c4c72 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6991,15 +6991,14 @@ static int kvm_emulate_wbinvd_noskip(struct kvm_vcpu *vcpu)
 		return X86EMUL_CONTINUE;
 
 	if (static_call(kvm_x86_has_wbinvd_exit)()) {
-		int cpu = get_cpu();
-
-		cpumask_set_cpu(cpu, vcpu->arch.wbinvd_dirty_mask);
-		on_each_cpu_mask(vcpu->arch.wbinvd_dirty_mask,
+		preempt_disable();
+		smp_call_function_many(vcpu->arch.wbinvd_dirty_mask,
 				wbinvd_ipi, NULL, 1);
-		put_cpu();
+		preempt_enable();
 		cpumask_clear(vcpu->arch.wbinvd_dirty_mask);
-	} else
-		wbinvd();
+	}
+
+	wbinvd();
 	return X86EMUL_CONTINUE;
 }
 
-- 
1.7.1