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ANDROID: iommu/pkvm-iommu: Fix locking in maple tree usage

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There are some problems with the maple tree usage at the moment:
- pviommu_domain_find() uses mas_find() which must be locked.
- pviommu_domain_remove_map() had a similar problem, but also it explicitly
  calls find and erase/insert non-atomically, so convert all of those to the
  unlocked version and use the tree lock on them.
- All allocations from unmap must be atomic

Bug: 357781595
Bug: 348382247
Signed-off-by: Mostafa Saleh <smostafa@google.com>
Reported-by: Aashish Sharma <shraash@google.com>
Change-Id: Ida8cfcfe3dc34ba7574d06eb1970602ab160173c
This commit is contained in:
Mostafa Saleh
2025-06-12 10:22:27 +00:00
parent e6f1cbbab1
commit 8e7a03dcb9
1 changed files with 17 additions and 11 deletions
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28
drivers/iommu/pkvm-pviommu.c
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@@ -92,21 +92,24 @@ static void pviommu_domain_remove_map(struct pviommu_domain *pv_domain,
/* Range can cover multiple entries. */
while (start < end) {
MA_STATE(mas, &pv_domain->mappings, start, end);
u64 entry = xa_to_value(mas_find(&mas, start));
u64 entry;
u64 old_start, old_end;
mtree_lock(mas.tree);
entry = xa_to_value(mas_find(&mas, start));
old_start = mas.index;
old_end = mas.last;
mas_erase(&mas);
/* Insert the rest if not removed. */
if (start > old_start)
mtree_store_range(&pv_domain->mappings, old_start, start - 1,
xa_mk_value(entry), GFP_KERNEL);
if (old_end > end)
mtree_store_range(&pv_domain->mappings, end + 1, old_end,
xa_mk_value(entry + end - old_start + 1), GFP_KERNEL);
if (start > old_start) {
MA_STATE(mas_border, &pv_domain->mappings, old_start, start - 1);
WARN_ON(mas_store_gfp(&mas_border, xa_mk_value(entry), GFP_ATOMIC));
}
if (old_end > end) {
MA_STATE(mas_border, &pv_domain->mappings, end + 1, old_end);
WARN_ON(mas_store_gfp(&mas_border, xa_mk_value(entry + end - old_start + 1),
GFP_ATOMIC));
}
mtree_unlock(mas.tree);
start = old_end + 1;
}
}
@@ -114,8 +117,11 @@ static void pviommu_domain_remove_map(struct pviommu_domain *pv_domain,
static u64 pviommu_domain_find(struct pviommu_domain *pv_domain, u64 key)
{
MA_STATE(mas, &pv_domain->mappings, key, key);
void *entry = mas_find(&mas, key);
void *entry;
mtree_lock(mas.tree);
entry = mas_find(&mas, key);
mtree_unlock(mas.tree);
/* No entry. */
if (!xa_is_value(entry))
return 0;