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xen: mapcache: Fix finding matching entry

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If we have request without lock and hit unlocked or invalid
entry during the search, we remap it immediately,
even if we have matching entry in next entries in bucket.
This leads to duplication of mappings of the same size,
and to possibility of selecting the wrong element
during invalidation and underflow it's entry->lock counter

Signed-off-by: Aleksandr Partanen <alex.pentagrid@gmail.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Reviewed-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
Signed-off-by: Edgar E. Iglesias <edgar.iglesias@amd.com>
(cherry picked from commit a4b20f737c)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
This commit is contained in:
Aleksandr Partanen 2025-04-10 17:46:04 +03:00 • committed by Michael Tokarev
parent 827be9d37a
commit a03d7d6e32
1 changed files with 3 additions and 3 deletions
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6
hw/xen/xen-mapcache.c
View file

@ -376,12 +376,12 @@ tryagain:
entry = &mc->entry[address_index % mc->nr_buckets];
while (entry && (lock || entry->lock) && entry->vaddr_base &&
(entry->paddr_index != address_index || entry->size != cache_size ||
while (entry && (!entry->vaddr_base ||
entry->paddr_index != address_index || entry->size != cache_size ||
!test_bits(address_offset >> XC_PAGE_SHIFT,
test_bit_size >> XC_PAGE_SHIFT,
entry->valid_mapping))) {
if (!free_entry && !entry->lock) {
if (!free_entry && (!entry->lock || !entry->vaddr_base)) {
free_entry = entry;
free_pentry = pentry;
}