iommu/iova: Fix alloc iova overflows issue

In __alloc_and_insert_iova_range, there is an issue that retry_pfn
overflows. The value of iovad->anchor.pfn_hi is ~0UL, then when
iovad->cached_node is iovad->anchor, curr_iova->pfn_hi + 1 will
overflow. As a result, if the retry logic is executed, low_pfn is
updated to 0, and then new_pfn < low_pfn returns false to make the
allocation successful.

This issue occurs in the following two situations:
1. The first iova size exceeds the domain size. When initializing
iova domain, iovad->cached_node is assigned as iovad->anchor. For
example, the iova domain size is 10M, start_pfn is 0x1_F000_0000,
and the iova size allocated for the first time is 11M. The
following is the log information, new->pfn_lo is smaller than
iovad->cached_node.

Example log as follows:
[ 223.798112][T1705487] sh: [name:iova&]__alloc_and_insert_iova_range
start_pfn:0x1f0000,retry_pfn:0x0,size:0xb00,limit_pfn:0x1f0a00
[ 223.799590][T1705487] sh: [name:iova&]__alloc_and_insert_iova_range
success start_pfn:0x1f0000,new->pfn_lo:0x1efe00,new->pfn_hi:0x1f08ff

2. The node with the largest iova->pfn_lo value in the iova domain
is deleted, iovad->cached_node will be updated to iovad->anchor,
and then the alloc iova size exceeds the maximum iova size that can
be allocated in the domain.

After judging that retry_pfn is less than limit_pfn, call retry_pfn+1
to fix the overflow issue.

Signed-off-by: jianjiao zeng <[e-mail]>
Signed-off-by: Yunfei Wang <[e-mail]>
Cc: <[e-mail]> # 5.15.*
Fixes: 4e89dce72521 ("iommu/iova: Retry from last rb tree node if iova search fails")
Acked-by: Robin Murphy <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Joerg Roedel <[e-mail]>

drivers/iommu/iova.c

···
 
 	curr = __get_cached_rbnode(iovad, limit_pfn);
 	curr_iova = to_iova(curr);
-	retry_pfn = curr_iova->pfn_hi + 1;
+	retry_pfn = curr_iova->pfn_hi;
 
 retry:
 	do {
···
 	if (high_pfn < size || new_pfn < low_pfn) {
 		if (low_pfn == iovad->start_pfn && retry_pfn < limit_pfn) {
 			high_pfn = limit_pfn;
-			low_pfn = retry_pfn;
+			low_pfn = retry_pfn + 1;
 			curr = iova_find_limit(iovad, limit_pfn);
 			curr_iova = to_iova(curr);
 			goto retry;