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| author | Jason Gunthorpe <jgg@nvidia.com> | 2026-05-12 19:46:17 +0300 |
|---|---|---|
| committer | Joerg Roedel <joerg.roedel@amd.com> | 2026-05-15 08:29:16 +0300 |
| commit | 58829512ad461af8f35941069c209941e3a97b65 (patch) | |
| tree | b821e62afb5ebd5b8d7a711eac69f26cbc025175 | |
| parent | 8ef3f77c440005c7f04229a75976bfc078364247 (diff) | |
| download | linux-58829512ad461af8f35941069c209941e3a97b65.tar.xz | |
iommupt: Fix the end_index calculation in __map_range_leaf()
Sashiko noticed a mismatch of units in this math: num_leaves is
actually the number of leaf *entries* (so a 16-item contiguous leaf
is one num_leaves), while index is in items. The mismatch in maths
causes __map_range_leaf() to exit early instead of efficiently
filling a larger range of contiguous PTEs.
The early exit is caught by the functions above and then
__map_range_leaf() is re-invoked, so there is no functional issue.
Correct the misuse of units by adjusting num_leaves with the leaf
size and avoid the performance cost of looping externally.
There are also some mismatched types for num_leaves; simplify
things to remove the duplicated calculations.
Fixes: d6c65b0fd621 ("iommupt: Avoid rewalking during map")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Samiullah Khawaja <skhawaja@google.com>
Reviewd-by: Pranjal Shrivastava <praan@google.com>
Tested-by: Josua Mayer <josua@solid-run.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
| -rw-r--r-- | drivers/iommu/generic_pt/iommu_pt.h | 20 |
1 files changed, 13 insertions, 7 deletions
diff --git a/drivers/iommu/generic_pt/iommu_pt.h b/drivers/iommu/generic_pt/iommu_pt.h index 4877b05291c9..dc91fb4e2f61 100644 --- a/drivers/iommu/generic_pt/iommu_pt.h +++ b/drivers/iommu/generic_pt/iommu_pt.h @@ -534,10 +534,12 @@ static int __map_range_leaf(struct pt_range *range, void *arg, struct pt_state pts = pt_init(range, level, table); struct pt_iommu_map_args *map = arg; unsigned int leaf_pgsize_lg2 = map->leaf_pgsize_lg2; + unsigned int leaves_avail; unsigned int start_index; pt_oaddr_t oa = map->oa; - unsigned int num_leaves; + pt_vaddr_t num_leaves; unsigned int orig_end; + unsigned int step_lg2; pt_vaddr_t last_va; unsigned int step; bool need_contig; @@ -546,21 +548,25 @@ static int __map_range_leaf(struct pt_range *range, void *arg, PT_WARN_ON(map->leaf_level != level); PT_WARN_ON(!pt_can_have_leaf(&pts)); - step = log2_to_int_t(unsigned int, - leaf_pgsize_lg2 - pt_table_item_lg2sz(&pts)); - need_contig = leaf_pgsize_lg2 != pt_table_item_lg2sz(&pts); + step_lg2 = leaf_pgsize_lg2 - pt_table_item_lg2sz(&pts); + step = log2_to_int_t(unsigned int, step_lg2); + need_contig = step_lg2 != 0; _pt_iter_first(&pts); start_index = pts.index; orig_end = pts.end_index; - if (pts.index + map->num_leaves < pts.end_index) { + leaves_avail = + log2_div_t(unsigned int, pts.end_index - pts.index, step_lg2); + if (map->num_leaves <= leaves_avail) { /* Need to stop in the middle of the table to change sizes */ - pts.end_index = pts.index + map->num_leaves; + pts.end_index = pts.index + log2_mul(map->num_leaves, step_lg2); num_leaves = 0; } else { - num_leaves = map->num_leaves - (pts.end_index - pts.index); + num_leaves = map->num_leaves - leaves_avail; } + PT_WARN_ON( + log2_mod_t(unsigned int, pts.end_index - pts.index, step_lg2)); do { pts.type = pt_load_entry_raw(&pts); if (pts.type != PT_ENTRY_EMPTY || need_contig) { |