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iommu: io-pgtable-arm: Fix unmap optimization for pagetable boundaries

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The last level optimization for __arm_lpae_unmap assumes that
consecutive blocks of 2MB addresses are located in the same
1GB mapping but this isn't always true - if the address spans
a 1GB boundary the next iova is in a different pagetable.

Only perform the optimization for the current pagetable entry and
then kick it back for the loop in arm_lpae_unmap to try again
with the updated iova.  All this means that __arm_lpae_unmap may
not unmap all of the size that it was given. This is okay assuming
at least something was unmapped so don't jump out of the loop
in arm_lpae_unmap until the child function returns 0 or the entire
block is freed, whichever comes first.

CRs-Fixed: 867143
Change-Id: Ic0dedbad407d60365a95afdaf03ec3b91f53960d
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
This commit is contained in:
Jordan Crouse 2015-07-07 12:55:48 -06:00 • committed by David Keitel
parent d295004695
commit fd7077c385
1 changed files with 15 additions and 24 deletions
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39
drivers/iommu/io-pgtable-arm.c
View file

@ -494,36 +494,27 @@ static int __arm_lpae_unmap(struct arm_lpae_io_pgtable *data,
return size;
} else if ((lvl == ARM_LPAE_MAX_LEVELS - 2) && !iopte_leaf(pte, lvl)) {
size_t remaining = size;
arm_lpae_iopte *table = iopte_deref(pte, data);
int tl_offset = ARM_LPAE_LVL_IDX(iova, lvl + 1, data);
int entry_size = (1 << data->pg_shift);
int max_entries = ARM_LPAE_BLOCK_SIZE(lvl, data) / entry_size;
int entries = min_t(int, size / entry_size,
max_entries - tl_offset);
int table_len = entries * sizeof(*table);
/*
* This isn't a block mapping so it must be a table mapping
* and since it's the 2nd-to-last level the next level has
* to be all page mappings. Zero them all out in one fell
* swoop.
*/
for (;;) {
arm_lpae_iopte *table = iopte_deref(pte, data);
int table_len;
size_t unmapped;
int tl_offset = ARM_LPAE_LVL_IDX(iova, lvl + 1, data);
int entry_size = (1 << data->pg_shift);
int max_entries =
ARM_LPAE_BLOCK_SIZE(lvl, data) / entry_size;
int entries = min_t(int, remaining / entry_size,
max_entries - tl_offset);
table += tl_offset;
table_len = entries * sizeof(*table);
memset(table, 0, table_len);
tlb->flush_pgtable(table, table_len, cookie);
unmapped = entries * entry_size;
iova += unmapped;
remaining -= unmapped;
if (!remaining)
break;
pte = *++ptep;
}
return size;
table += tl_offset;
memset(table, 0, table_len);
tlb->flush_pgtable(table, table_len, cookie);
return entries * entry_size;
} else if (iopte_leaf(pte, lvl)) {
/*
* Insert a table at the next level to map the old region,
@ -556,7 +547,7 @@ static size_t arm_lpae_unmap(struct io_pgtable_ops *ops, unsigned long iova,
? remaining
: iommu_pgsize(data->iop.cfg.pgsize_bitmap, iova, size);
ret = __arm_lpae_unmap(data, iova, size_to_unmap, lvl, ptep);
if (ret != size_to_unmap)
if (ret == 0)
break;
unmapped += ret;
iova += ret;