static int vfio_iommu_type1_dirty_pages()

in vfio_iommu_type1.c [2878:2980]

• 84 lines of code
• 23 McCabe index (conditional complexity)

static int vfio_iommu_type1_dirty_pages(struct vfio_iommu *iommu,
					unsigned long arg)
{
	struct vfio_iommu_type1_dirty_bitmap dirty;
	uint32_t mask = VFIO_IOMMU_DIRTY_PAGES_FLAG_START |
			VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP |
			VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP;
	unsigned long minsz;
	int ret = 0;

	if (!iommu->v2)
		return -EACCES;

	minsz = offsetofend(struct vfio_iommu_type1_dirty_bitmap, flags);

	if (copy_from_user(&dirty, (void __user *)arg, minsz))
		return -EFAULT;

	if (dirty.argsz < minsz || dirty.flags & ~mask)
		return -EINVAL;

	/* only one flag should be set at a time */
	if (__ffs(dirty.flags) != __fls(dirty.flags))
		return -EINVAL;

	if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_START) {
		size_t pgsize;

		mutex_lock(&iommu->lock);
		pgsize = 1 << __ffs(iommu->pgsize_bitmap);
		if (!iommu->dirty_page_tracking) {
			ret = vfio_dma_bitmap_alloc_all(iommu, pgsize);
			if (!ret)
				iommu->dirty_page_tracking = true;
		}
		mutex_unlock(&iommu->lock);
		return ret;
	} else if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP) {
		mutex_lock(&iommu->lock);
		if (iommu->dirty_page_tracking) {
			iommu->dirty_page_tracking = false;
			vfio_dma_bitmap_free_all(iommu);
		}
		mutex_unlock(&iommu->lock);
		return 0;
	} else if (dirty.flags & VFIO_IOMMU_DIRTY_PAGES_FLAG_GET_BITMAP) {
		struct vfio_iommu_type1_dirty_bitmap_get range;
		unsigned long pgshift;
		size_t data_size = dirty.argsz - minsz;
		size_t iommu_pgsize;

		if (!data_size || data_size < sizeof(range))
			return -EINVAL;

		if (copy_from_user(&range, (void __user *)(arg + minsz),
				   sizeof(range)))
			return -EFAULT;

		if (range.iova + range.size < range.iova)
			return -EINVAL;
		if (!access_ok((void __user *)range.bitmap.data,
			       range.bitmap.size))
			return -EINVAL;

		pgshift = __ffs(range.bitmap.pgsize);
		ret = verify_bitmap_size(range.size >> pgshift,
					 range.bitmap.size);
		if (ret)
			return ret;

		mutex_lock(&iommu->lock);

		iommu_pgsize = (size_t)1 << __ffs(iommu->pgsize_bitmap);

		/* allow only smallest supported pgsize */
		if (range.bitmap.pgsize != iommu_pgsize) {
			ret = -EINVAL;
			goto out_unlock;
		}
		if (range.iova & (iommu_pgsize - 1)) {
			ret = -EINVAL;
			goto out_unlock;
		}
		if (!range.size || range.size & (iommu_pgsize - 1)) {
			ret = -EINVAL;
			goto out_unlock;
		}

		if (iommu->dirty_page_tracking)
			ret = vfio_iova_dirty_bitmap(range.bitmap.data,
						     iommu, range.iova,
						     range.size,
						     range.bitmap.pgsize);
		else
			ret = -EINVAL;
out_unlock:
		mutex_unlock(&iommu->lock);

		return ret;
	}

	return -EINVAL;
}