int intel_svm_page_response()

in intel/svm.c [1079:1181]

• 77 lines of code
• 18 McCabe index (conditional complexity)

int intel_svm_page_response(struct device *dev,
			    struct iommu_fault_event *evt,
			    struct iommu_page_response *msg)
{
	struct iommu_fault_page_request *prm;
	struct intel_svm_dev *sdev = NULL;
	struct intel_svm *svm = NULL;
	struct intel_iommu *iommu;
	bool private_present;
	bool pasid_present;
	bool last_page;
	u8 bus, devfn;
	int ret = 0;
	u16 sid;

	if (!dev || !dev_is_pci(dev))
		return -ENODEV;

	iommu = device_to_iommu(dev, &bus, &devfn);
	if (!iommu)
		return -ENODEV;

	if (!msg || !evt)
		return -EINVAL;

	mutex_lock(&pasid_mutex);

	prm = &evt->fault.prm;
	sid = PCI_DEVID(bus, devfn);
	pasid_present = prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID;
	private_present = prm->flags & IOMMU_FAULT_PAGE_REQUEST_PRIV_DATA;
	last_page = prm->flags & IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE;

	if (!pasid_present) {
		ret = -EINVAL;
		goto out;
	}

	if (prm->pasid == 0 || prm->pasid >= PASID_MAX) {
		ret = -EINVAL;
		goto out;
	}

	ret = pasid_to_svm_sdev(dev, prm->pasid, &svm, &sdev);
	if (ret || !sdev) {
		ret = -ENODEV;
		goto out;
	}

	/*
	 * For responses from userspace, need to make sure that the
	 * pasid has been bound to its mm.
	 */
	if (svm->flags & SVM_FLAG_GUEST_MODE) {
		struct mm_struct *mm;

		mm = get_task_mm(current);
		if (!mm) {
			ret = -EINVAL;
			goto out;
		}

		if (mm != svm->mm) {
			ret = -ENODEV;
			mmput(mm);
			goto out;
		}

		mmput(mm);
	}

	/*
	 * Per VT-d spec. v3.0 ch7.7, system software must respond
	 * with page group response if private data is present (PDP)
	 * or last page in group (LPIG) bit is set. This is an
	 * additional VT-d requirement beyond PCI ATS spec.
	 */
	if (last_page || private_present) {
		struct qi_desc desc;

		desc.qw0 = QI_PGRP_PASID(prm->pasid) | QI_PGRP_DID(sid) |
				QI_PGRP_PASID_P(pasid_present) |
				QI_PGRP_PDP(private_present) |
				QI_PGRP_RESP_CODE(msg->code) |
				QI_PGRP_RESP_TYPE;
		desc.qw1 = QI_PGRP_IDX(prm->grpid) | QI_PGRP_LPIG(last_page);
		desc.qw2 = 0;
		desc.qw3 = 0;

		if (private_present) {
			desc.qw2 = prm->private_data[0];
			desc.qw3 = prm->private_data[1];
		} else if (prm->private_data[0]) {
			dmar_latency_update(iommu, DMAR_LATENCY_PRQ,
				ktime_to_ns(ktime_get()) - prm->private_data[0]);
		}

		qi_submit_sync(iommu, &desc, 1, 0);
	}
out:
	mutex_unlock(&pasid_mutex);
	return ret;
}