static int arm_smmu_handle_evt()

in arm/arm-smmu-v3/arm-smmu-v3.c [1444:1536]

• 80 lines of code
• 15 McCabe index (conditional complexity)

static int arm_smmu_handle_evt(struct arm_smmu_device *smmu, u64 *evt)
{
	int ret;
	u32 reason;
	u32 perm = 0;
	struct arm_smmu_master *master;
	bool ssid_valid = evt[0] & EVTQ_0_SSV;
	u32 sid = FIELD_GET(EVTQ_0_SID, evt[0]);
	struct iommu_fault_event fault_evt = { };
	struct iommu_fault *flt = &fault_evt.fault;

	switch (FIELD_GET(EVTQ_0_ID, evt[0])) {
	case EVT_ID_TRANSLATION_FAULT:
		reason = IOMMU_FAULT_REASON_PTE_FETCH;
		break;
	case EVT_ID_ADDR_SIZE_FAULT:
		reason = IOMMU_FAULT_REASON_OOR_ADDRESS;
		break;
	case EVT_ID_ACCESS_FAULT:
		reason = IOMMU_FAULT_REASON_ACCESS;
		break;
	case EVT_ID_PERMISSION_FAULT:
		reason = IOMMU_FAULT_REASON_PERMISSION;
		break;
	default:
		return -EOPNOTSUPP;
	}

	/* Stage-2 is always pinned at the moment */
	if (evt[1] & EVTQ_1_S2)
		return -EFAULT;

	if (evt[1] & EVTQ_1_RnW)
		perm |= IOMMU_FAULT_PERM_READ;
	else
		perm |= IOMMU_FAULT_PERM_WRITE;

	if (evt[1] & EVTQ_1_InD)
		perm |= IOMMU_FAULT_PERM_EXEC;

	if (evt[1] & EVTQ_1_PnU)
		perm |= IOMMU_FAULT_PERM_PRIV;

	if (evt[1] & EVTQ_1_STALL) {
		flt->type = IOMMU_FAULT_PAGE_REQ;
		flt->prm = (struct iommu_fault_page_request) {
			.flags = IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE,
			.grpid = FIELD_GET(EVTQ_1_STAG, evt[1]),
			.perm = perm,
			.addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
		};

		if (ssid_valid) {
			flt->prm.flags |= IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
			flt->prm.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]);
		}
	} else {
		flt->type = IOMMU_FAULT_DMA_UNRECOV;
		flt->event = (struct iommu_fault_unrecoverable) {
			.reason = reason,
			.flags = IOMMU_FAULT_UNRECOV_ADDR_VALID,
			.perm = perm,
			.addr = FIELD_GET(EVTQ_2_ADDR, evt[2]),
		};

		if (ssid_valid) {
			flt->event.flags |= IOMMU_FAULT_UNRECOV_PASID_VALID;
			flt->event.pasid = FIELD_GET(EVTQ_0_SSID, evt[0]);
		}
	}

	mutex_lock(&smmu->streams_mutex);
	master = arm_smmu_find_master(smmu, sid);
	if (!master) {
		ret = -EINVAL;
		goto out_unlock;
	}

	ret = iommu_report_device_fault(master->dev, &fault_evt);
	if (ret && flt->type == IOMMU_FAULT_PAGE_REQ) {
		/* Nobody cared, abort the access */
		struct iommu_page_response resp = {
			.pasid		= flt->prm.pasid,
			.grpid		= flt->prm.grpid,
			.code		= IOMMU_PAGE_RESP_FAILURE,
		};
		arm_smmu_page_response(master->dev, &fault_evt, &resp);
	}

out_unlock:
	mutex_unlock(&smmu->streams_mutex);
	return ret;
}