static irqreturn_t prq_event_thread()

in intel/svm.c [909:1014]

• 75 lines of code
• 19 McCabe index (conditional complexity)

static irqreturn_t prq_event_thread(int irq, void *d)
{
	struct intel_svm_dev *sdev = NULL;
	struct intel_iommu *iommu = d;
	struct intel_svm *svm = NULL;
	struct page_req_dsc *req;
	int head, tail, handled;
	u64 address;

	/*
	 * Clear PPR bit before reading head/tail registers, to ensure that
	 * we get a new interrupt if needed.
	 */
	writel(DMA_PRS_PPR, iommu->reg + DMAR_PRS_REG);

	tail = dmar_readq(iommu->reg + DMAR_PQT_REG) & PRQ_RING_MASK;
	head = dmar_readq(iommu->reg + DMAR_PQH_REG) & PRQ_RING_MASK;
	handled = (head != tail);
	while (head != tail) {
		req = &iommu->prq[head / sizeof(*req)];
		address = (u64)req->addr << VTD_PAGE_SHIFT;

		if (unlikely(!req->pasid_present)) {
			pr_err("IOMMU: %s: Page request without PASID\n",
			       iommu->name);
bad_req:
			svm = NULL;
			sdev = NULL;
			handle_bad_prq_event(iommu, req, QI_RESP_INVALID);
			goto prq_advance;
		}

		if (unlikely(!is_canonical_address(address))) {
			pr_err("IOMMU: %s: Address is not canonical\n",
			       iommu->name);
			goto bad_req;
		}

		if (unlikely(req->pm_req && (req->rd_req | req->wr_req))) {
			pr_err("IOMMU: %s: Page request in Privilege Mode\n",
			       iommu->name);
			goto bad_req;
		}

		if (unlikely(req->exe_req && req->rd_req)) {
			pr_err("IOMMU: %s: Execution request not supported\n",
			       iommu->name);
			goto bad_req;
		}

		if (!svm || svm->pasid != req->pasid) {
			/*
			 * It can't go away, because the driver is not permitted
			 * to unbind the mm while any page faults are outstanding.
			 */
			svm = pasid_private_find(req->pasid);
			if (IS_ERR_OR_NULL(svm) || (svm->flags & SVM_FLAG_SUPERVISOR_MODE))
				goto bad_req;
		}

		if (!sdev || sdev->sid != req->rid) {
			sdev = svm_lookup_device_by_sid(svm, req->rid);
			if (!sdev)
				goto bad_req;
		}

		sdev->prq_seq_number++;

		/*
		 * If prq is to be handled outside iommu driver via receiver of
		 * the fault notifiers, we skip the page response here.
		 */
		if (intel_svm_prq_report(iommu, sdev->dev, req))
			handle_bad_prq_event(iommu, req, QI_RESP_INVALID);

		trace_prq_report(iommu, sdev->dev, req->qw_0, req->qw_1,
				 req->priv_data[0], req->priv_data[1],
				 sdev->prq_seq_number);
prq_advance:
		head = (head + sizeof(*req)) & PRQ_RING_MASK;
	}

	dmar_writeq(iommu->reg + DMAR_PQH_REG, tail);

	/*
	 * Clear the page request overflow bit and wake up all threads that
	 * are waiting for the completion of this handling.
	 */
	if (readl(iommu->reg + DMAR_PRS_REG) & DMA_PRS_PRO) {
		pr_info_ratelimited("IOMMU: %s: PRQ overflow detected\n",
				    iommu->name);
		head = dmar_readq(iommu->reg + DMAR_PQH_REG) & PRQ_RING_MASK;
		tail = dmar_readq(iommu->reg + DMAR_PQT_REG) & PRQ_RING_MASK;
		if (head == tail) {
			iopf_queue_discard_partial(iommu->iopf_queue);
			writel(DMA_PRS_PRO, iommu->reg + DMAR_PRS_REG);
			pr_info_ratelimited("IOMMU: %s: PRQ overflow cleared",
					    iommu->name);
		}
	}

	if (!completion_done(&iommu->prq_complete))
		complete(&iommu->prq_complete);

	return IRQ_RETVAL(handled);
}