Commit 827c2ab3 authored Mar 22, 2022 by Oliver Upton Committed by Marc Zyngier Apr 06, 2022

KVM: arm64: Actually prevent SMC64 SYSTEM_RESET2 from AArch32



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.

Hoist the check to see if the requested function is allowed into
kvm_psci_call(), thereby preventing SMC64 calls from AArch32 for all
PSCI versions.

Fixes: d43583b8 ("KVM: arm64: Expose PSCI SYSTEM_RESET2 call to the guest")
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Reiji Watanabe <reijiw@google.com>
Signed-off-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220322183538.2757758-3-oupton@google.com

parent 2da0aebc

arch/arm64/kvm/psci.c

+9 −5

Original line number	Diff line number	Diff line
		@@ -231,10 +231,6 @@ 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:
		/*
		@@ -302,7 +298,6 @@ static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
		break;
		}

		out:
		smccc_set_retval(vcpu, val, 0, 0, 0);
		return ret;
		}
		@@ -422,6 +417,15 @@ static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
		*/
		int kvm_psci_call(struct kvm_vcpu *vcpu)
		{
		u32 psci_fn = smccc_get_function(vcpu);
		unsigned long val;

		val = kvm_psci_check_allowed_function(vcpu, psci_fn);
		if (val) {
		smccc_set_retval(vcpu, val, 0, 0, 0);
		return 1;
		}

		switch (kvm_psci_version(vcpu)) {
		case KVM_ARM_PSCI_1_1:
		return kvm_psci_1_x_call(vcpu, 1);