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Diffstat (limited to 'Documentation/ABI/testing/sysfs-driver-uio_pci_sva-pasid')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-driver-uio_pci_sva-pasid | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-driver-uio_pci_sva-pasid b/Documentation/ABI/testing/sysfs-driver-uio_pci_sva-pasid new file mode 100644 index 000000000000..6892fe46cea8 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-driver-uio_pci_sva-pasid @@ -0,0 +1,29 @@ +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; |