[PATCH 2/2] KVM: arm64: Actually prevent SMC64 SYSTEM_RESET2 from AArch32

[Oliver Upton]

The SMCCC does not allow the SMC64 calling convention to be used from
AArch32. While KVM checks to see if the calling convention is allowed in
PSCI_1_0_FN_PSCI_FEATURES, it does not actually prevent calls to
unadvertised PSCI v1.0+ functions.

Check to see if the requested function is allowed from the guest's
execution state. Deny the call if it is not.

Fixes: d43583b890e7 ("KVM: arm64: Expose PSCI SYSTEM_RESET2 call to the guest")
Cc: Will Deacon <will at kernel.org>
Signed-off-by: Oliver Upton <oupton at google.com>
---
 arch/arm64/kvm/psci.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/arm64/kvm/psci.c b/arch/arm64/kvm/psci.c
index cd3ee947485f..0d771468b708 100644
--- a/arch/arm64/kvm/psci.c
+++ b/arch/arm64/kvm/psci.c
@@ -318,6 +318,10 @@ static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor)
 	if (minor > 1)
 		return -EINVAL;
 
+	val = kvm_psci_check_allowed_function(vcpu, psci_fn);
+	if (val)
+		goto out;
+
 	switch(psci_fn) {
 	case PSCI_0_2_FN_PSCI_VERSION:
 		val = minor == 0 ? KVM_ARM_PSCI_1_0 : KVM_ARM_PSCI_1_1;
@@ -378,6 +382,7 @@ static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor)
 		return kvm_psci_0_2_call(vcpu);
 	}
 
+out:
 	smccc_set_retval(vcpu, val, 0, 0, 0);
 	return ret;
 }
-- 
2.35.1.894.gb6a874cedc-goog