[PATCH v3 6/8] KVM: arm64: Do not allow KVM_CAP_ARM_MTE for any guest in pKVM

[Fuad Tabba <tabba@google.com>]

Supporting MTE in pKVM introduces significant complexity to the
hypervisor at EL2, even for non-protected VMs, since it would require
EL2 to handle tag management.

For now, do not allow KVM_CAP_ARM_MTE for all VM types in protected
mode.

Signed-off-by: Fuad Tabba <tabba@google.com>
---
 arch/arm64/include/asm/kvm_pkvm.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h
index 7195be508d99..ea5d2275d16d 100644
--- a/arch/arm64/include/asm/kvm_pkvm.h
+++ b/arch/arm64/include/asm/kvm_pkvm.h
@@ -44,6 +44,9 @@ static inline bool kvm_pkvm_ext_allowed(struct kvm *kvm, long ext)
 	case KVM_CAP_ARM_PTRAUTH_ADDRESS:
 	case KVM_CAP_ARM_PTRAUTH_GENERIC:
 		return true;
+	case KVM_CAP_ARM_MTE:
+		/* Memory tagging is not supported at all in pKVM. */
+		return false;
 	default:
 		return !kvm || !kvm_vm_is_protected(kvm);
 	}
-- 
2.51.2.1041.gc1ab5b90ca-goog