arm: KVM: Fix SMCCC handling of unimplemented SMC/HVC calls (20e8175d) · Commits · 戴 / test

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> Tested-by:

Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by:

Marc Zyngier <marc.zyngier@arm.com> Signed-off-by:

Catalin Marinas <catalin.marinas@arm.com>

arch/arm/kvm/handle_exit.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -38,7 +38,7 @@ 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;
		}

		@@ -47,7 +47,16 @@ 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);
		/*
		* "If an SMC instruction executed at Non-secure EL1 is
		* trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
		* Trap exception, not a Secure Monitor Call exception [...]"
		*
		* We need to advance the PC after the trap, as it would
		* otherwise return to the same address...
		*/
		vcpu_set_reg(vcpu, 0, ~0UL);
		kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
		return 1;
		}

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