Patch "KVM: nVMX: Fix nested VPID vmx exec control" has been added to the 4.9-stable tree

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

KVM: nVMX: Fix nested VPID vmx exec control

to the 4.9-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-nvmx-fix-nested-vpid-vmx-exec-control.patch
and it can be found in the queue-4.9 subdirectory.

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

From: Wanpeng Li <[email protected]>
Date: Mon, 20 Mar 2017 21:18:53 -0700
Subject: KVM: nVMX: Fix nested VPID vmx exec control
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Wanpeng Li <[email protected]>

commit 63cb6d5f004ca44f9b8e562b6dd191f717a4960e upstream.

This can be reproduced by running kvm-unit-tests/vmx.flat on L0 w/ vpid disabled.

Test suite: VPID
Unhandled exception 6 #UD at ip 00000000004051a6
error_code=0000 rflags=00010047 cs=00000008
rax=0000000000000000 rcx=0000000000000001 rdx=0000000000000047 rbx=0000000000402f79 rbp=0000000000456240 rsi=0000000000000001 rdi=0000000000000000 r8=000000000000000a r9=00000000000003f8 r10=0000000080010011 r11=0000000000000000 r12=0000000000000003 r13=0000000000000708 r14=0000000000000000 r15=0000000000000000 cr0=0000000080010031 cr2=0000000000000000 cr3=0000000007fff000 cr4=0000000000002020 cr8=0000000000000000
STACK: @4051a6 40523e 400f7f 402059 40028f

We should hide and forbid VPID in L1 if it is disabled on L0. However, nested VPID enable bit is set unconditionally during setup nested vmx exec controls though VPID is not exposed through nested VMX capablity. This patch fixes it by don't set nested VPID enable bit if it is disabled on L0.

---
 arch/x86/kvm/vmx.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

@@ -2787,7 +2787,6 @@ static void nested_vmx_setup_ctls_msrs(s
 		SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
 		SECONDARY_EXEC_RDTSCP |
 		SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
-		SECONDARY_EXEC_ENABLE_VPID |
 		SECONDARY_EXEC_APIC_REGISTER_VIRT |
 		SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
 		SECONDARY_EXEC_WBINVD_EXITING |

@@ -2815,10 +2814,12 @@ static void nested_vmx_setup_ctls_msrs(s
 	 * though it is treated as global context.  The alternative is
 	 * not failing the single-context invvpid, and it is worse.
 	 */
-	if (enable_vpid)
+	if (enable_vpid) {
+		vmx->nested.nested_vmx_secondary_ctls_high |=
+			SECONDARY_EXEC_ENABLE_VPID;
 		vmx->nested.nested_vmx_vpid_caps = VMX_VPID_INVVPID_BIT |
 			VMX_VPID_EXTENT_SUPPORTED_MASK;
-	else
+	} else
 		vmx->nested.nested_vmx_vpid_caps = 0;
 
 	if (enable_unrestricted_guest)

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

queue-4.9/kvm-nvmx-fix-nested-vpid-vmx-exec-control.patch