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

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

[gregkh]

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 <stable@vger.kernel.org> know about it.


>From f24632475d4ffed5626abbfab7ef30a128dd1474 Mon Sep 17 00:00:00 2001
From: Bruce Rogers <brogers@suse.com>
Date: Thu, 28 Apr 2016 14:49:21 -0600
Subject: KVM: x86: fix ordering of cr0 initialization code in vmx_cpu_reset
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Bruce Rogers <brogers@suse.com>

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.

Fixes: d28bc9dd25ce ("KVM: x86: INIT and reset sequences are different")
Signed-off-by: Bruce Rogers <brogers@suse.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -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 brogers@suse.com are

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