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arm64: KVM: Fix SMCCC handling of unimplemented SMC/HVC calls

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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.

Cc: <stable@vger.kernel.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
This commit is contained in:
Marc Zyngier 2018-01-16 10:23:47 +00:00 committed by Christoffer Dall
parent f8f85dc00b
commit acfb3b883f
1 changed files with 2 additions and 2 deletions
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4
arch/arm64/kvm/handle_exit.c
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@ -45,7 +45,7 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
ret = kvm_psci_call(vcpu);
if (ret < 0) {
kvm_inject_undefined(vcpu);
vcpu_set_reg(vcpu, 0, ~0UL);
return 1;
}
@ -54,7 +54,7 @@ static int handle_hvc(struct kvm_vcpu *vcpu, struct kvm_run *run)
static int handle_smc(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
kvm_inject_undefined(vcpu);
vcpu_set_reg(vcpu, 0, ~0UL);
return 1;
}