RE: [PATCH v5 06/15] iommupt: Add unmap_pages op

From: Jason Gunthorpe jgg@nvidia.com Sent: Thursday, September 4, 2025 1:47 AM

+static __maybe_unused int __unmap_range(struct pt_range *range, void *arg,

• 			unsigned int level,
  

• 			struct pt_table_p *table)
  

+{

• struct pt_state pts = pt_init(range, level, table);
• struct pt_unmap_args *unmap = arg;
• unsigned int num_oas = 0;
• unsigned int start_index;
• int ret = 0;
• _pt_iter_first(&pts);
• start_index = pts.index;
• pts.type = pt_load_entry_raw(&pts);
• /*

• * A starting index is in the middle of a contiguous entry
  

• *
  

• * The IOMMU API does not require drivers to support unmapping
  

parts of

• * large pages. Long ago VFIO would try to split maps but the current
  

• * version never does.
  

• *
  

• * Instead when unmap reaches a partial unmap of the start of a
  

large

• * IOPTE it should remove the entire IOPTE and return that size to the
  

• * caller.
  

• */
  

• if (pts.type == PT_ENTRY_OA) {

• if (log2_mod(range->va, pt_entry_oa_lg2sz(&pts)))
  

• 	return -EINVAL;
  

• goto start_oa;
  

• }

it's not typical goto a location inside a loop.

Actually even w/o that goto, the flow will continue to...

• do {

• if (pts.type != PT_ENTRY_OA) {
  

• 	bool fully_covered;
  

• 	if (pts.type != PT_ENTRY_TABLE) {
  

• 		ret = -EINVAL;
  

• 		break;
  

• 	}
  

• 	if (pts.index != start_index)
  

• 		pt_index_to_va(&pts);
  

• 	pts.table_lower = pt_table_ptr(&pts);
  

• 	fully_covered = pt_item_fully_covered(
  

• 		&pts, pt_table_item_lg2sz(&pts));
  

• 	ret = pt_descend(&pts, arg, __unmap_range);
  

• 	if (ret)
  

• 		break;
  

• 	/*
  

• 	 * If the unmapping range fully covers the table then
  

we

• 	 * can free it as well. The clear is delayed until we
  

• 	 * succeed in clearing the lower table levels.
  

• 	 */
  

• 	if (fully_covered) {
  

• 		iommu_pages_list_add(&unmap->free_list,
  

• 				     pts.table_lower);
  

• 		pt_clear_entry(&pts, ilog2(1));
  

• 	}
  

• 	pts.index++;
  

• } else {
  

• 	unsigned int num_contig_lg2;
  

...here naturally.

+start_oa:

• 	/*
  

• 	 * If the caller requested an last that falls within a
  

• 	 * single entry then the entire entry is unmapped and
  

• 	 * the length returned will be larger than requested.
  

• 	 */
  

• 	num_contig_lg2 = pt_entry_num_contig_lg2(&pts);
  

• 	pt_clear_entry(&pts, num_contig_lg2);
  

• 	num_oas += log2_to_int(num_contig_lg2);
  

• 	pts.index += log2_to_int(num_contig_lg2);
  

• }
  

• if (pts.index >= pts.end_index)
  

• 	break;
  

• pts.type = pt_load_entry_raw(&pts);
  

• } while (true);
• unmap->unmapped += log2_mul(num_oas,

pt_table_item_lg2sz(&pts));

• return ret;

+}

the rest looks good:

Reviewed-by: Kevin Tian kevin.tian@intel.com