@@ -218,6 +218,40 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
kvm_arm_teardown_hypercalls(kvm);
}
+static bool kvm_has_full_ptr_auth(void)
+{
+ bool apa, gpa, api, gpi, apa3, gpa3;
+ u64 isar1, isar2, val;
+
+ /*
+ * Check that:
+ *
+ * - both Address and Generic auth are implemented for a given
+ * algorithm (Q5, IMPDEF or Q3)
+ * - only a single algorithm is implemented.
+ */
+ if (!system_has_full_ptr_auth())
+ return false;
+
+ isar1 = read_sanitised_ftr_reg(SYS_ID_AA64ISAR1_EL1);
+ isar2 = read_sanitised_ftr_reg(SYS_ID_AA64ISAR2_EL1);
+
+ apa = !!FIELD_GET(ID_AA64ISAR1_EL1_APA_MASK, isar1);
+ val = FIELD_GET(ID_AA64ISAR1_EL1_GPA_MASK, isar1);
+ gpa = (val == ID_AA64ISAR1_EL1_GPA_IMP);
+
+ api = !!FIELD_GET(ID_AA64ISAR1_EL1_API_MASK, isar1);
+ val = FIELD_GET(ID_AA64ISAR1_EL1_GPI_MASK, isar1);
+ gpi = (val == ID_AA64ISAR1_EL1_GPI_IMP);
+
+ apa3 = !!FIELD_GET(ID_AA64ISAR2_EL1_APA3_MASK, isar2);
+ val = FIELD_GET(ID_AA64ISAR2_EL1_GPA3_MASK, isar2);
+ gpa3 = (val == ID_AA64ISAR2_EL1_GPA3_IMP);
+
+ return (apa == gpa && api == gpi && apa3 == gpa3 &&
+ (apa + api + apa3) == 1);
+}
+
int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
{
int r;
@@ -311,7 +345,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
break;
case KVM_CAP_ARM_PTRAUTH_ADDRESS:
case KVM_CAP_ARM_PTRAUTH_GENERIC:
- r = system_has_full_ptr_auth();
+ r = kvm_has_full_ptr_auth();
break;
case KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE:
if (kvm)
@@ -1270,7 +1304,7 @@ static unsigned long system_supported_vcpu_features(void)
if (!system_supports_sve())
clear_bit(KVM_ARM_VCPU_SVE, &features);
- if (!system_has_full_ptr_auth()) {
+ if (!kvm_has_full_ptr_auth()) {
clear_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, &features);
clear_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, &features);
}
PAuth comes it two parts: address authentication, and generic authentication. So far, KVM mandates that both are implemented. PAuth also comes in three flavours: Q5, Q3, and IMPDEF. Only one can be implemented for any of address and generic authentication. Crucially, the architecture doesn't mandate that address and generic authentication implement the *same* flavour. This would make implementing ERETAx very difficult for NV, something we are not terribly keen on. So only allow PAuth support for KVM on systems that are not totally insane. Which is so far 100% of the known HW. Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/arm64/kvm/arm.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-)