[PATCH 3/4] KVM: arm64: Allow PtrAuth to be enabled from userspace on non-VHE systems

Marc Zyngier
2020-06-15T08:20:13Z

Now that the scene is set for enabling PtrAuth on non-VHE, drop
the restrictions preventing userspace from enabling it.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kvm/reset.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index d3b209023727..2a929789fe2e 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -42,6 +42,11 @@ static u32 kvm_ipa_limit;
#define VCPU_RESET_PSTATE_SVC (PSR_AA32_MODE_SVC | PSR_AA32_A_BIT | \
PSR_AA32_I_BIT | PSR_AA32_F_BIT)

+static bool system_has_full_ptr_auth(void)
+{
+ return system_supports_address_auth() && system_supports_generic_auth();
+}
+
/**
* kvm_arch_vm_ioctl_check_extension
*
@@ -80,8 +85,7 @@ int kvm_arch_vm_ioctl_check_extension(struct kvm *kvm, long ext)
break;
case KVM_CAP_ARM_PTRAUTH_ADDRESS:
case KVM_CAP_ARM_PTRAUTH_GENERIC:
- r = has_vhe() && system_supports_address_auth() &&
- system_supports_generic_auth();
+ r = system_has_full_ptr_auth();
break;
default:
r = 0;
@@ -205,19 +209,14 @@ static void kvm_vcpu_reset_sve(struct kvm_vcpu *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.
+ * features are requested by the userspace together and the system
+ * supports these capabilities.
*/
if (!test_bit(KVM_ARM_VCPU_PTRAUTH_ADDRESS, vcpu->arch.features) ||
- !test_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, vcpu->arch.features))
+ !test_bit(KVM_ARM_VCPU_PTRAUTH_GENERIC, vcpu->arch.features) ||
+ !system_has_full_ptr_auth())
return -EINVAL;

vcpu->arch.flags |= KVM_ARM64_GUEST_HAS_PTRAUTH;
--
2.27.0