int vfio_pci_core_mmap()

in pci/vfio_pci_core.c [1446:1515]

• 52 lines of code
• 14 McCabe index (conditional complexity)

int vfio_pci_core_mmap(struct vfio_device *core_vdev, struct vm_area_struct *vma)
{
	struct vfio_pci_core_device *vdev =
		container_of(core_vdev, struct vfio_pci_core_device, vdev);
	struct pci_dev *pdev = vdev->pdev;
	unsigned int index;
	u64 phys_len, req_len, pgoff, req_start;
	int ret;

	index = vma->vm_pgoff >> (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT);

	if (index >= VFIO_PCI_NUM_REGIONS + vdev->num_regions)
		return -EINVAL;
	if (vma->vm_end < vma->vm_start)
		return -EINVAL;
	if ((vma->vm_flags & VM_SHARED) == 0)
		return -EINVAL;
	if (index >= VFIO_PCI_NUM_REGIONS) {
		int regnum = index - VFIO_PCI_NUM_REGIONS;
		struct vfio_pci_region *region = vdev->region + regnum;

		if (region->ops && region->ops->mmap &&
		    (region->flags & VFIO_REGION_INFO_FLAG_MMAP))
			return region->ops->mmap(vdev, region, vma);
		return -EINVAL;
	}
	if (index >= VFIO_PCI_ROM_REGION_INDEX)
		return -EINVAL;
	if (!vdev->bar_mmap_supported[index])
		return -EINVAL;

	phys_len = PAGE_ALIGN(pci_resource_len(pdev, index));
	req_len = vma->vm_end - vma->vm_start;
	pgoff = vma->vm_pgoff &
		((1U << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
	req_start = pgoff << PAGE_SHIFT;

	if (req_start + req_len > phys_len)
		return -EINVAL;

	/*
	 * Even though we don't make use of the barmap for the mmap,
	 * we need to request the region and the barmap tracks that.
	 */
	if (!vdev->barmap[index]) {
		ret = pci_request_selected_regions(pdev,
						   1 << index, "vfio-pci");
		if (ret)
			return ret;

		vdev->barmap[index] = pci_iomap(pdev, index, 0);
		if (!vdev->barmap[index]) {
			pci_release_selected_regions(pdev, 1 << index);
			return -ENOMEM;
		}
	}

	vma->vm_private_data = vdev;
	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
	vma->vm_pgoff = (pci_resource_start(pdev, index) >> PAGE_SHIFT) + pgoff;

	/*
	 * See remap_pfn_range(), called from vfio_pci_fault() but we can't
	 * change vm_flags within the fault handler.  Set them now.
	 */
	vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
	vma->vm_ops = &vfio_pci_mmap_ops;

	return 0;
}