Patch "Revert "KVM: nested VMX: disable perf cpuid reporting"" has been added to the 4.9-stable tree

Patch "Revert "KVM: nested VMX: disable perf cpuid reporting"" has been added to the 4.9-stable tree

[gregkh]

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

    Revert "KVM: nested VMX: disable perf cpuid reporting"

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:
     revert-kvm-nested-vmx-disable-perf-cpuid-reporting.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 <stable@vger.kernel.org> know about it.


>From 0b4c208d443ba2af82b4c70f99ca8df31e9a0020 Mon Sep 17 00:00:00 2001
From: Jim Mattson <jmattson@google.com>
Date: Tue, 20 Dec 2016 16:34:50 -0800
Subject: Revert "KVM: nested VMX: disable perf cpuid reporting"
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

From: Jim Mattson <jmattson@google.com>

commit 0b4c208d443ba2af82b4c70f99ca8df31e9a0020 upstream.

This reverts commit bc6134942dbbf31c25e9bd7c876be5da81c9e1ce.

A CPUID instruction executed in VMX non-root mode always causes a
VM-exit, regardless of the leaf being queried.

Fixes: bc6134942dbb ("KVM: nested VMX: disable perf cpuid reporting")
Signed-off-by: Jim Mattson <jmattson@google.com>
[The issue solved by bc6134942dbb has been resolved with ff651cb613b4
 ("KVM: nVMX: Add nested msr load/restore algorithm").]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/x86/kvm/cpuid.c |    6 ------
 arch/x86/kvm/vmx.c   |    2 --
 2 files changed, 8 deletions(-)

--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -846,12 +846,6 @@ void kvm_cpuid(struct kvm_vcpu *vcpu, u3
 	if (!best)
 		best = check_cpuid_limit(vcpu, function, index);
 
-	/*
-	 * Perfmon not yet supported for L2 guest.
-	 */
-	if (is_guest_mode(vcpu) && function == 0xa)
-		best = NULL;
-
 	if (best) {
 		*eax = best->eax;
 		*ebx = best->ebx;
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8051,8 +8051,6 @@ static bool nested_vmx_exit_handled(stru
 	case EXIT_REASON_TASK_SWITCH:
 		return true;
 	case EXIT_REASON_CPUID:
-		if (kvm_register_read(vcpu, VCPU_REGS_RAX) == 0xa)
-			return false;
 		return true;
 	case EXIT_REASON_HLT:
 		return nested_cpu_has(vmcs12, CPU_BASED_HLT_EXITING);


Patches currently in stable-queue which might be from jmattson@google.com are

queue-4.9/revert-kvm-nested-vmx-disable-perf-cpuid-reporting.patch