--- /dev/null
+From acfb3b883f6d6a4b5d27ad7fdded11f6a09ae6dd Mon Sep 17 00:00:00 2001
+From: Marc Zyngier <marc.zyngier@arm.com>
+Date: Tue, 16 Jan 2018 10:23:47 +0000
+Subject: arm64: KVM: Fix SMCCC handling of unimplemented SMC/HVC calls
+
+From: Marc Zyngier <marc.zyngier@arm.com>
+
+commit acfb3b883f6d6a4b5d27ad7fdded11f6a09ae6dd upstream.
+
+KVM doesn't follow the SMCCC when it comes to unimplemented calls,
+and inject an UNDEF instead of returning an error. Since firmware
+calls are now used for security mitigation, they are becoming more
+common, and the undef is counter productive.
+
+Instead, let's follow the SMCCC which states that -1 must be returned
+to the caller when getting an unknown function number.
+
+Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
+Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/arm64/kvm/handle_exit.c | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+--- a/arch/arm64/kvm/handle_exit.c
++++ b/arch/arm64/kvm/handle_exit.c
+@@ -34,7 +34,7 @@ static int handle_hvc(struct kvm_vcpu *v
+
+ ret = kvm_psci_call(vcpu);
+ if (ret < 0) {
+- kvm_inject_undefined(vcpu);
++ *vcpu_reg(vcpu, 0) = ~0UL;
+ return 1;
+ }
+
+@@ -43,7 +43,7 @@ static int handle_hvc(struct kvm_vcpu *v
+
+ static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
+ {
+- kvm_inject_undefined(vcpu);
++ *vcpu_reg(vcpu, 0) = ~0UL;
+ return 1;
+ }
+