Patch "KVM: x86: fix ordering of cr0 initialization code in vmx_cpu_reset" has been added to the 4.6-stable tree

This is a note to let you know that I've just added the patch titled

KVM: x86: fix ordering of cr0 initialization code in vmx_cpu_reset

to the 4.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
kvm-x86-fix-ordering-of-cr0-initialization-code-in-vmx_cpu_reset.patch
and it can be found in the queue-4.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Bruce Rogers <[email protected]>
Date: Thu, 28 Apr 2016 14:49:21 -0600
Subject: KVM: x86: fix ordering of cr0 initialization code in vmx_cpu_reset
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From: Bruce Rogers <[email protected]>

commit f24632475d4ffed5626abbfab7ef30a128dd1474 upstream.

Commit d28bc9dd25ce reversed the order of two lines which initialize cr0, allowing the current (old) cr0 value to mess up vcpu initialization. This was observed in the checks for cr0 X86_CR0_WP bit in the context of kvm_mmu_reset_context(). Besides, setting vcpu->arch.cr0 after vmx_set_cr0() is completely redundant. Change the order back to ensure proper vcpu initialization.

The combination of booting with ovmf firmware when guest vcpus > 1 and kvm's ept=N option being set results in a VM-entry failure. This patch fixes that.

---
 arch/x86/kvm/vmx.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

@@ -5050,8 +5050,8 @@ static void vmx_vcpu_reset(struct kvm_vc
 		vmcs_write16(VIRTUAL_PROCESSOR_ID, vmx->vpid);
 
 	cr0 = X86_CR0_NW | X86_CR0_CD | X86_CR0_ET;
-	vmx_set_cr0(vcpu, cr0); /* enter rmode */
 	vmx->vcpu.arch.cr0 = cr0;
+	vmx_set_cr0(vcpu, cr0); /* enter rmode */
 	vmx_set_cr4(vcpu, 0);
 	vmx_set_efer(vcpu, 0);
 	vmx_fpu_activate(vcpu);

Patches currently in stable-queue which might be from [email protected] are

queue-4.6/kvm-x86-fix-ordering-of-cr0-initialization-code-in-vmx_cpu_reset.patch