@@ -87,7 +87,21 @@ used to get and set the keys for a thread.
Virtualization
--------------
-Pointer authentication is not currently supported in KVM guests. KVM
-will mask the feature bits from ID_AA64ISAR1_EL1, and attempted use of
-the feature will result in an UNDEFINED exception being injected into
-the guest.
+Pointer authentication is enabled in KVM guest when each virtual cpu is
+initialised by passing flags KVM_ARM_VCPU_PTRAUTH_[ADDRESS/GENERIC] and
+requesting these two separate cpu features to be enabled. The current KVM
+guest implementation works by enabling both features together, so both
+these userspace flags are checked before enabling pointer authentication.
+The separate userspace flag will allow to have no userspace ABI changes
+if support is added in the future to allow these two features to be
+enabled independently of one another.
+
+As Arm Architecture specifies that Pointer Authentication feature is
+implemented along with the VHE feature so KVM arm64 ptrauth code relies
+on VHE mode to be present.
+
+Additionally, when these vcpu feature flags are not set then KVM will
+filter out the Pointer Authentication system key registers from
+KVM_GET/SET_REG_* ioctls and mask those features from cpufeature ID
+register. Any attempt to use the Pointer Authentication instructions will
+result in an UNDEFINED exception being injected into the guest.
@@ -2761,6 +2761,16 @@ Possible features:
- KVM_ARM_VCPU_PMU_V3: Emulate PMUv3 for the CPU.
Depends on KVM_CAP_ARM_PMU_V3.
+ - KVM_ARM_VCPU_PTRAUTH_ADDRESS: Enables Address Pointer authentication
+ for arm64 only.
+ Both KVM_ARM_VCPU_PTRAUTH_ADDRESS and KVM_ARM_VCPU_PTRAUTH_GENERIC
+ must be requested or neither must be requested.
+
+ - KVM_ARM_VCPU_PTRAUTH_GENERIC: Enables Generic Pointer authentication
+ for arm64 only.
+ Both KVM_ARM_VCPU_PTRAUTH_ADDRESS and KVM_ARM_VCPU_PTRAUTH_GENERIC
+ must be requested or neither must be requested.
+
- KVM_ARM_VCPU_SVE: Enables SVE for the CPU (arm64 only).
Depends on KVM_CAP_ARM_SVE.
Requires KVM_ARM_VCPU_FINALIZE(KVM_ARM_VCPU_SVE):
@@ -49,7 +49,7 @@
#define KVM_MAX_VCPUS VGIC_V3_MAX_CPUS
-#define KVM_VCPU_MAX_FEATURES 5
+#define KVM_VCPU_MAX_FEATURES 7
#define KVM_REQ_SLEEP \
KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP)
@@ -104,6 +104,8 @@ struct kvm_regs {
#define KVM_ARM_VCPU_PSCI_0_2 2 /* CPU uses PSCI v0.2 */
#define KVM_ARM_VCPU_PMU_V3 3 /* Support guest PMUv3 */
#define KVM_ARM_VCPU_SVE 4 /* enable SVE for this CPU */
+#define KVM_ARM_VCPU_PTRAUTH_ADDRESS 5 /* VCPU uses address authentication */
+#define KVM_ARM_VCPU_PTRAUTH_GENERIC 6 /* VCPU uses generic authentication */
struct kvm_vcpu_init {
__u32 target;
@@ -221,6 +221,27 @@ static void kvm_vcpu_reset_sve(struct kvm_vcpu *vcpu)
memset(vcpu->arch.sve_state, 0, vcpu_sve_state_size(vcpu));
}
+static int kvm_vcpu_enable_ptrauth(struct kvm_vcpu *vcpu)
+{
+ /* Support ptrauth only if the system supports these capabilities. */
+ if (!has_vhe())
+ return -EINVAL;
+
+ if (!system_supports_address_auth() ||
+ !system_supports_generic_auth())
+ return -EINVAL;
+ /*
+ * For now make sure that both address/generic pointer authentication
+ * features are requested by the userspace together.
+ */
+ if (!test_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, vcpu->arch.features) ||
+ !test_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, vcpu->arch.features))
+ return -EINVAL;
+
+ vcpu->arch.flags |= KVM_ARM64_GUEST_HAS_PTRAUTH;
+ return 0;
+}
+
/**
* kvm_reset_vcpu - sets core registers and sys_regs to reset value
* @vcpu: The VCPU pointer
@@ -261,6 +282,12 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu)
kvm_vcpu_reset_sve(vcpu);
}
+ if (test_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, vcpu->arch.features) ||
+ test_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, vcpu->arch.features)) {
+ if (kvm_vcpu_enable_ptrauth(vcpu))
+ goto out;
+ }
+
switch (vcpu->arch.target) {
default:
if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features)) {