When a guest delibarately uses an SSMC32 function number (which is allowed),
we should make sure we drop the top 32bits from the input arguments, as they
could legitimately be junk.
Reported-by: Christoffer Dall <christoffer.dall@xxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
virt/kvm/arm/psci.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
index 17e2bdd4b76f..69ff4a51ceb5 100644
--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/psci.c
@@ -187,6 +187,18 @@ static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
}
+static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
+{
+ int i;
+
+ /*
+ * Zero the input registers' upper 32 bits. They will be fully
+ * zeroed on exit, so we're fine changing them in place.
+ */
+ for (i = 1; i < 4; i++)
+ vcpu_set_reg(vcpu, i, (u32)vcpu_get_reg(vcpu, i));
+}
+
static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
{
struct kvm *kvm = vcpu->kvm;
@@ -211,12 +223,16 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
val = PSCI_RET_SUCCESS;
break;
case PSCI_0_2_FN_CPU_ON:
+ kvm_psci_narrow_to_32bit(vcpu);
+ fallthrough;
case PSCI_0_2_FN64_CPU_ON:
mutex_lock(&kvm->lock);
val = kvm_psci_vcpu_on(vcpu);
mutex_unlock(&kvm->lock);
break;
case PSCI_0_2_FN_AFFINITY_INFO:
+ kvm_psci_narrow_to_32bit(vcpu);
+ fallthrough;
case PSCI_0_2_FN64_AFFINITY_INFO:
val = kvm_psci_vcpu_affinity_info(vcpu);
break;
--
2.25.0
