[PATCH 1/8] KVM: arm64: nv: Disallow KVM_CAP_ARM_MTE + FEAT_EL2

[Oliver Upton <oupton@kernel.org>]

KVM's nested implementation already hides FEAT_MTE and its laundry list
of derivatives from an NV guest. While good, this is insonsistent with
the UAPI which does not explicitly prevent the combination of MTE and
NV.

Bite the bullet and refuse to create a nested VM if KVM_CAP_ARM_MTE has
been enabled.

Cc: stable@vger.kernel.org
Fixes: a7484c80e5ca ("KVM: arm64: Allow userspace to request KVM_ARM_VCPU_EL2*")
Signed-off-by: Oliver Upton <oupton@kernel.org>
---
 arch/arm64/kvm/arm.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 157bf4b81202..a750413c684b 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1793,13 +1793,15 @@ static int kvm_vcpu_init_check_features(struct kvm_vcpu *vcpu,
 	    !test_bit(KVM_ARM_VCPU_PMU_V3, &features))
 		return -EINVAL;
 
+	/* MTE is incompatible with AArch32 and nested virt */
+	if (kvm_has_mte(vcpu->kvm) &&
+	    (test_bit(KVM_ARM_VCPU_EL1_32BIT, &features) ||
+	     test_bit(KVM_ARM_VCPU_HAS_EL2, &features)))
+		return -EINVAL;
+
 	if (!test_bit(KVM_ARM_VCPU_EL1_32BIT, &features))
 		return 0;
 
-	/* MTE is incompatible with AArch32 */
-	if (kvm_has_mte(vcpu->kvm))
-		return -EINVAL;
-
 	/* NV is incompatible with AArch32 */
 	if (test_bit(KVM_ARM_VCPU_HAS_EL2, &features))
 		return -EINVAL;
-- 
2.47.3