Patch "KVM: x86: block guest protection keys unless the host has them enabled" has been added to the 4.12-stable tree

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 4.12-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-4.12 subdirectory.

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

From: Paolo Bonzini <[email protected]>
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 <[email protected]>

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.

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

@@ -469,7 +469,7 @@ 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);
 			entry->edx &= kvm_cpuid_7_0_edx_x86_features;
 			entry->edx &= get_scattered_cpuid_leaf(7, 0, CPUID_EDX);

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

queue-4.12/kvm-x86-block-guest-protection-keys-unless-the-host-has-them-enabled.patch queue-4.12/kvm-pkeys-do-not-use-pkru-value-in-vcpu-arch.guest_fpu.state.patch queue-4.12/kvm-x86-simplify-handling-of-pkru.patch