From 6ed7abdfb185933b5985bfd97cf8b2e475c3473d Mon Sep 17 00:00:00 2001
From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Date: Wed, 28 Nov 2012 20:54:14 +0800
Subject: [PATCH] --- yaml --- r: 343550 b: refs/heads/master c:
 5a560f8b5ed361c7be783d5a671ea26ca4d6fa01 h: refs/heads/master v: v3

---
 [refs]                   |  2 +-
 trunk/arch/x86/kvm/vmx.c | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 07cf96fc58d7..7decedd47073 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: e6c7d32172f10b68fa9a3be05aa1231352a52171
+refs/heads/master: 5a560f8b5ed361c7be783d5a671ea26ca4d6fa01
diff --git a/trunk/arch/x86/kvm/vmx.c b/trunk/arch/x86/kvm/vmx.c
index 4406374e3b6d..3606154bbc8b 100644
--- a/trunk/arch/x86/kvm/vmx.c
+++ b/trunk/arch/x86/kvm/vmx.c
@@ -1002,6 +1002,15 @@ static void __loaded_vmcs_clear(void *arg)
 	if (per_cpu(current_vmcs, cpu) == loaded_vmcs->vmcs)
 		per_cpu(current_vmcs, cpu) = NULL;
 	list_del(&loaded_vmcs->loaded_vmcss_on_cpu_link);
+
+	/*
+	 * we should ensure updating loaded_vmcs->loaded_vmcss_on_cpu_link
+	 * is before setting loaded_vmcs->vcpu to -1 which is done in
+	 * loaded_vmcs_init. Otherwise, other cpu can see vcpu = -1 fist
+	 * then adds the vmcs into percpu list before it is deleted.
+	 */
+	smp_wmb();
+
 	loaded_vmcs_init(loaded_vmcs);
 }
 
@@ -1537,6 +1546,14 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 
 		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
 		local_irq_disable();
+
+		/*
+		 * Read loaded_vmcs->cpu should be before fetching
+		 * loaded_vmcs->loaded_vmcss_on_cpu_link.
+		 * See the comments in __loaded_vmcs_clear().
+		 */
+		smp_rmb();
+
 		list_add(&vmx->loaded_vmcs->loaded_vmcss_on_cpu_link,
 			 &per_cpu(loaded_vmcss_on_cpu, cpu));
 		local_irq_enable();