iommufd/iova_bitmap: Remove iterator logic

The newly introduced dynamic pinning/windowing greatly simplifies the code
and there's no obvious performance advantage that has been identified that
justifies maintinaing both schemes.

Remove the iterator logic and have iova_bitmap_for_each() just invoke the
callback with the total iova/length.

Fixes: 2780025e01e2 ("iommufd/iova_bitmap: Handle recording beyond the mapped pages")
Link: https://lore.kernel.org/r/20240627110105.62325-12-joao.m.martins@oracle.com
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Matt Ochs <mochs@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/iommu/iommufd/iova_bitmap.c b/drivers/iommu/iommufd/iova_bitmap.c
index b047e1e180be73eb844c5d41c7062c95e4e29617..b9e964b1ad5cc15c24263c241f7ef80573bd76f9 100644 (file)
--- a/drivers/iommu/iommufd/iova_bitmap.c
+++ b/drivers/iommu/iommufd/iova_bitmap.c
@@ -116,12 +116,6 @@ struct iova_bitmap {
 
        /* length of the IOVA range for the whole bitmap */
        size_t length;
-
-       /* length of the IOVA range set ahead the pinned pages */
-       unsigned long set_ahead_length;
-
-       /* true if it using the iterator otherwise it pins dynamically */
-       bool iterator;
 };
 
 /*
@@ -354,40 +348,6 @@ static bool iova_bitmap_mapped_range(struct iova_bitmap_map *mapped,
                 (iova + length - 1) <= (mapped->iova + mapped->length - 1));
 }
 
-/*
- * Returns true if there's not more data to iterate.
- */
-static bool iova_bitmap_done(struct iova_bitmap *bitmap)
-{
-       return bitmap->mapped_base_index >= bitmap->mapped_total_index;
-}
-
-static int iova_bitmap_set_ahead(struct iova_bitmap *bitmap,
-                                size_t set_ahead_length)
-{
-       int ret = 0;
-
-       while (set_ahead_length > 0 && !iova_bitmap_done(bitmap)) {
-               unsigned long length = iova_bitmap_mapped_length(bitmap);
-               unsigned long iova = iova_bitmap_mapped_iova(bitmap);
-
-               ret = iova_bitmap_get(bitmap);
-               if (ret)
-                       break;
-
-               length = min(length, set_ahead_length);
-               iova_bitmap_set(bitmap, iova, length);
-
-               set_ahead_length -= length;
-               bitmap->mapped_base_index +=
-                       iova_bitmap_offset_to_index(bitmap, length - 1) + 1;
-               iova_bitmap_put(bitmap);
-       }
-
-       bitmap->set_ahead_length = 0;
-       return ret;
-}
-
 /*
  * Advances to a selected range, releases the current pinned
  * pages and pins the next set of bitmap pages.
@@ -409,36 +369,6 @@ static int iova_bitmap_advance_to(struct iova_bitmap *bitmap,
        return iova_bitmap_get(bitmap);
 }
 
-/*
- * Advances to the next range, releases the current pinned
- * pages and pins the next set of bitmap pages.
- * Returns 0 on success or otherwise errno.
- */
-static int iova_bitmap_advance(struct iova_bitmap *bitmap)
-{
-       unsigned long iova = iova_bitmap_mapped_length(bitmap) - 1;
-       unsigned long count = iova_bitmap_offset_to_index(bitmap, iova) + 1;
-
-       bitmap->mapped_base_index += count;
-
-       iova_bitmap_put(bitmap);
-
-       /* Iterate, set and skip any bits requested for next iteration */
-       if (bitmap->set_ahead_length) {
-               int ret;
-
-               ret = iova_bitmap_set_ahead(bitmap, bitmap->set_ahead_length);
-               if (ret)
-                       return ret;
-       }
-
-       if (iova_bitmap_done(bitmap))
-               return 0;
-
-       /* When advancing the index we pin the next set of bitmap pages */
-       return iova_bitmap_get(bitmap);
-}
-
 /**
  * iova_bitmap_for_each() - Iterates over the bitmap
  * @bitmap: IOVA bitmap to iterate
@@ -455,23 +385,7 @@ static int iova_bitmap_advance(struct iova_bitmap *bitmap)
 int iova_bitmap_for_each(struct iova_bitmap *bitmap, void *opaque,
                         iova_bitmap_fn_t fn)
 {
-       int ret = 0;
-
-       ret = iova_bitmap_get(bitmap);
-       if (ret)
-               return ret;
-
-       bitmap->iterator = true;
-       for (; !iova_bitmap_done(bitmap) && !ret;
-            ret = iova_bitmap_advance(bitmap)) {
-               ret = fn(bitmap, iova_bitmap_mapped_iova(bitmap),
-                        iova_bitmap_mapped_length(bitmap), opaque);
-               if (ret)
-                       break;
-       }
-       bitmap->iterator = false;
-
-       return ret;
+       return fn(bitmap, bitmap->iova, bitmap->length, opaque);
 }
 EXPORT_SYMBOL_NS_GPL(iova_bitmap_for_each, IOMMUFD);
 
@@ -492,15 +406,12 @@ void iova_bitmap_set(struct iova_bitmap *bitmap,
        unsigned long cur_bit, last_bit, last_page_idx;
 
 update_indexes:
-       if (unlikely(!bitmap->iterator &&
-                    !iova_bitmap_mapped_range(mapped, iova, length))) {
+       if (unlikely(!iova_bitmap_mapped_range(mapped, iova, length))) {
 
                /*
                 * The attempt to advance the base index to @iova
                 * may fail if it's out of bounds, or pinning the pages
                 * returns an error.
-                *
-                * It is a no-op if within a iova_bitmap_for_each() closure.
                 */
                if (iova_bitmap_advance_to(bitmap, iova))
                        return;
@@ -523,10 +434,6 @@ update_indexes:
                        unsigned long left =
                                ((last_bit - cur_bit + 1) << mapped->pgshift);
 
-                       if (bitmap->iterator) {
-                               bitmap->set_ahead_length = left;
-                               return;
-                       }
                        iova += (length - left);
                        length = left;
                        goto update_indexes;