--- /dev/null
+What: /sys/bus/pci/drivers/uio_pci_sva/<pci_dev>/pasid
+Date: September 2025
+Contact: Yaxing Guo <guoyaxing@bosc.ac.cn>
+Description:
+ Process Address Space ID (PASID) assigned by IOMMU driver to
+ the device for use with Shared Virtual Addressing (SVA).
+
+ This read-only attribute exposes the PASID (A 20-bit identifier
+ used in PCIe Address Translation Services and iommu table walks)
+ allocated by the IOMMU driver during sva device binding.
+
+ User-space UIO applications must read this attribute to obtain
+ the PASID and program it into the device's configuration registers.
+ This enables the device to perform DMA using user-space virtual
+ address, with address translation handled by IOMMU.
+
+ UIO User-space applications must:
+ - Opening device and Mapping the device's register space via /dev/uioX
+ (This triggers the IOMMU driver to allocate the PASID)
+ - Reading the PASID from sysfs
+ - Writing the PASID to a device-specific register (with example offset)
+ The code may be like:
+
+ map = mmap(..., "/dev/uio0", ...);
+
+ f = fopen("/sys/.../pasid", "r");
+ fscanf(f, "%d", &pasid);
+
+ map[REG_PASID_OFFSET] = pasid;
--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * UIO PCI Express sva driver
+ *
+ * Copyright (c) 2025 Beijing Institute of Open Source Chip (BOSC)
+ */
+
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/uio_driver.h>
+#include <linux/iommu.h>
+
+struct uio_pci_sva_dev {
+ struct pci_dev *pdev;
+ struct uio_info info;
+ struct iommu_sva *sva_handle;
+ int pasid;
+};
+
+static irqreturn_t irq_handler(int irq, struct uio_info *dev_info)
+{
+ return IRQ_HANDLED;
+}
+
+static int uio_pci_sva_open(struct uio_info *info, struct inode *inode)
+{
+ struct iommu_sva *handle;
+ struct uio_pci_sva_dev *udev = info->priv;
+ struct iommu_domain *domain;
+
+ if (!udev && !udev->pdev)
+ return -ENODEV;
+
+ domain = iommu_get_domain_for_dev(&udev->pdev->dev);
+ if (domain)
+ iommu_detach_device(domain, &udev->pdev->dev);
+
+ handle = iommu_sva_bind_device(&udev->pdev->dev, current->mm);
+ if (IS_ERR(handle))
+ return -EINVAL;
+
+ udev->pasid = iommu_sva_get_pasid(handle);
+
+ udev->sva_handle = handle;
+
+ return 0;
+}
+
+static int uio_pci_sva_release(struct uio_info *info, struct inode *inode)
+{
+ struct uio_pci_sva_dev *udev = info->priv;
+
+ if (!udev && !udev->pdev)
+ return -ENODEV;
+
+ iommu_sva_unbind_device(udev->sva_handle);
+
+ return 0;
+}
+
+static int probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+ struct uio_pci_sva_dev *udev;
+ int ret, i, irq = 0;
+
+ ret = pci_enable_device(pdev);
+ if (ret) {
+ dev_err(&pdev->dev, "pci_enable_device failed: %d\n", ret);
+ return ret;
+ }
+
+ ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+ if (ret)
+ goto out_disable;
+
+ pci_set_master(pdev);
+
+ ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_MSIX | PCI_IRQ_MSI);
+ if (ret > 0) {
+ irq = pci_irq_vector(pdev, 0);
+ if (irq < 0) {
+ dev_err(&pdev->dev, "Failed to get MSI vector\n");
+ ret = irq;
+ goto out_disable;
+ }
+ } else
+ dev_warn(&pdev->dev,
+ "No IRQ vectors available (%d), using polling\n", ret);
+
+ udev = devm_kzalloc(&pdev->dev, sizeof(struct uio_pci_sva_dev),
+ GFP_KERNEL);
+ if (!udev) {
+ ret = -ENOMEM;
+ goto out_disable;
+ }
+
+ udev->pdev = pdev;
+ udev->info.name = "uio_pci_sva";
+ udev->info.version = "0.0.1";
+ udev->info.open = uio_pci_sva_open;
+ udev->info.release = uio_pci_sva_release;
+ udev->info.irq = irq;
+ udev->info.handler = irq_handler;
+ udev->info.priv = udev;
+
+ for (i = 0; i < MAX_UIO_MAPS; i++) {
+ struct resource *r = &pdev->resource[i];
+ struct uio_mem *uiomem = &udev->info.mem[i];
+
+ if (r->flags != (IORESOURCE_SIZEALIGN | IORESOURCE_MEM))
+ continue;
+
+ if (uiomem >= &udev->info.mem[MAX_UIO_MAPS]) {
+ dev_warn(&pdev->dev, "Do not support more than %d iomem\n",
+ MAX_UIO_MAPS);
+ break;
+ }
+
+ uiomem->memtype = UIO_MEM_PHYS;
+ uiomem->addr = r->start & PAGE_MASK;
+ uiomem->offs = r->start & ~PAGE_MASK;
+ uiomem->size =
+ (uiomem->offs + resource_size(r) + PAGE_SIZE - 1) &
+ PAGE_MASK;
+ uiomem->name = r->name;
+ }
+
+ ret = devm_uio_register_device(&pdev->dev, &udev->info);
+ if (ret) {
+ dev_err(&pdev->dev, "Failed to register uio device\n");
+ goto out_free;
+ }
+
+ pci_set_drvdata(pdev, udev);
+
+ return 0;
+
+out_free:
+ kfree(udev);
+out_disable:
+ pci_disable_device(pdev);
+
+ return ret;
+}
+
+static void remove(struct pci_dev *pdev)
+{
+ struct uio_pci_sva_dev *udev = pci_get_drvdata(pdev);
+
+ pci_release_regions(pdev);
+ pci_disable_device(pdev);
+ kfree(udev);
+}
+
+static ssize_t pasid_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct pci_dev *pdev = to_pci_dev(dev);
+ struct uio_pci_sva_dev *udev = pci_get_drvdata(pdev);
+
+ return sysfs_emit(buf, "%d\n", udev->pasid);
+}
+static DEVICE_ATTR_RO(pasid);
+
+static struct attribute *uio_pci_sva_attrs[] = {
+ &dev_attr_pasid.attr,
+ NULL
+};
+
+static const struct attribute_group uio_pci_sva_attr_group = {
+ .attrs = uio_pci_sva_attrs,
+};
+
+static const struct attribute_group *uio_pci_sva_attr_groups[] = {
+ &uio_pci_sva_attr_group,
+ NULL
+};
+
+static struct pci_driver uio_pci_generic_sva_driver = {
+ .name = "uio_pci_sva",
+ .dev_groups = uio_pci_sva_attr_groups,
+ .id_table = NULL,
+ .probe = probe,
+ .remove = remove,
+};
+
+module_pci_driver(uio_pci_generic_sva_driver);
+MODULE_VERSION("0.0.01");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Yaxing Guo <guoyaxing@bosc.ac.cn>");
+MODULE_DESCRIPTION("Generic UIO sva driver for PCI");
projects / thirdparty / linux.git / commitdiff
