int kvm_arm_set_fw_reg()

in kvm/psci.c [490:571]

• 60 lines of code
• 20 McCabe index (conditional complexity)

int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
{
	void __user *uaddr = (void __user *)(long)reg->addr;
	u64 val;
	int wa_level;

	if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
		return -EFAULT;

	switch (reg->id) {
	case KVM_REG_ARM_PSCI_VERSION:
	{
		bool wants_02;

		wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);

		switch (val) {
		case KVM_ARM_PSCI_0_1:
			if (wants_02)
				return -EINVAL;
			vcpu->kvm->arch.psci_version = val;
			return 0;
		case KVM_ARM_PSCI_0_2:
		case KVM_ARM_PSCI_1_0:
			if (!wants_02)
				return -EINVAL;
			vcpu->kvm->arch.psci_version = val;
			return 0;
		}
		break;
	}

	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
		if (val & ~KVM_REG_FEATURE_LEVEL_MASK)
			return -EINVAL;

		if (get_kernel_wa_level(reg->id) < val)
			return -EINVAL;

		return 0;

	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
		if (val & ~(KVM_REG_FEATURE_LEVEL_MASK |
			    KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED))
			return -EINVAL;

		/* The enabled bit must not be set unless the level is AVAIL. */
		if ((val & KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED) &&
		    (val & KVM_REG_FEATURE_LEVEL_MASK) != KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL)
			return -EINVAL;

		/*
		 * Map all the possible incoming states to the only two we
		 * really want to deal with.
		 */
		switch (val & KVM_REG_FEATURE_LEVEL_MASK) {
		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL:
		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN:
			wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
			break;
		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL:
		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
			wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
			break;
		default:
			return -EINVAL;
		}

		/*
		 * We can deal with NOT_AVAIL on NOT_REQUIRED, but not the
		 * other way around.
		 */
		if (get_kernel_wa_level(reg->id) < wa_level)
			return -EINVAL;

		return 0;
	default:
		return -ENOENT;
	}

	return -EINVAL;
}