Patch "KVM: x86: block guest protection keys unless the host has them enabled" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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

    KVM: x86: block guest protection keys unless the host has them enabled

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-x86-block-guest-protection-keys-unless-the-host-has-them-enabled.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 c469268cd523245cc58255f6696e0c295485cb0b Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Thu, 24 Aug 2017 11:59:31 +0200
Subject: KVM: x86: block guest protection keys unless the host has them enabled

From: Paolo Bonzini <pbonzini@redhat.com>

commit c469268cd523245cc58255f6696e0c295485cb0b upstream.

If the host has protection keys disabled, we cannot read and write the
guest PKRU---RDPKRU and WRPKRU fail with #GP(0) if CR4.PKE=0.  Block
the PKU cpuid bit in that case.

This ensures that guest_CR4.PKE=1 implies host_CR4.PKE=1.

Fixes: 1be0e61c1f255faaeab04a390e00c8b9b9042870
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -456,7 +456,7 @@ static inline int __do_cpuid_ent(struct
 			entry->ecx &= kvm_cpuid_7_0_ecx_x86_features;
 			cpuid_mask(&entry->ecx, CPUID_7_ECX);
 			/* PKU is not yet implemented for shadow paging. */
-			if (!tdp_enabled)
+			if (!tdp_enabled || !boot_cpu_has(X86_FEATURE_OSPKE))
 				entry->ecx &= ~F(PKU);
 		} else {
 			entry->ebx = 0;


Patches currently in stable-queue which might be from pbonzini@redhat.com are

queue-4.9/kvm-x86-block-guest-protection-keys-unless-the-host-has-them-enabled.patch
queue-4.9/kvm-pkeys-do-not-use-pkru-value-in-vcpu-arch.guest_fpu.state.patch