Implementing (and even advertising) 64bit PSCI functions to 32bit
guests is at least a bit odd, if not altogether violating the
spec which says ("5.2.1 Register usage in arguments and return values"):
"Adherence to the SMC Calling Conventions implies that any AArch32
caller of an SMC64 function will get a return code of 0xFFFFFFFF(int32).
This matches the NOT_SUPPORTED error code used in PSCI"
Tighten the implementation by pretending these functions are not
there for 32bit guests.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
virt/kvm/arm/psci.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/virt/kvm/arm/psci.c b/virt/kvm/arm/psci.c
index 69ff4a51ceb5..122795cdd984 100644
--- a/virt/kvm/arm/psci.c
+++ b/virt/kvm/arm/psci.c
@@ -199,6 +199,21 @@ static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
vcpu_set_reg(vcpu, i, (u32)vcpu_get_reg(vcpu, i));
}
+static unsigned long kvm_psci_check_allowed_function(struct kvm_vcpu *vcpu, u32 fn)
+{
+ switch(fn) {
+ case PSCI_0_2_FN64_CPU_SUSPEND:
+ case PSCI_0_2_FN64_CPU_ON:
+ case PSCI_0_2_FN64_AFFINITY_INFO:
+ /* Disallow these functions for 32bit guests */
+ if (vcpu_mode_is_32bit(vcpu))
+ return PSCI_RET_NOT_SUPPORTED;
+ break;
+ }
+
+ return 0;
+}
+
static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
{
struct kvm *kvm = vcpu->kvm;
@@ -206,6 +221,10 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
unsigned long val;
int ret = 1;
+ val = kvm_psci_check_allowed_function(vcpu, psci_fn);
+ if (val)
+ goto out;
+
switch (psci_fn) {
case PSCI_0_2_FN_PSCI_VERSION:
/*
@@ -273,6 +292,7 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
break;
}
+out:
smccc_set_retval(vcpu, val, 0, 0, 0);
return ret;
}
@@ -290,6 +310,10 @@ static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu)
break;
case PSCI_1_0_FN_PSCI_FEATURES:
feature = smccc_get_arg1(vcpu);
+ val = kvm_psci_check_allowed_function(vcpu, feature);
+ if (val)
+ break;
+
switch(feature) {
case PSCI_0_2_FN_PSCI_VERSION:
case PSCI_0_2_FN_CPU_SUSPEND:
--
2.25.0
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