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[POWERPC] Fix G5 DART (IOMMU) race causing occasional data corruption

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It seems that the occasional data corruption observed with the tg3
driver wasn't due to missing barriers after all, but rather seems to
be due to the DART (= IOMMU) in the U4 northbridge reading stale
IOMMU table entries from memory due to a race.  This fixes it by
making the CPU read the entry back from memory before using it.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Benjamin Herrenschmidt 2006-09-13 22:12:52 +10:00 committed by Paul Mackerras
parent f007cacffc
commit eeac5c142b
1 changed files with 6 additions and 1 deletions
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7
arch/powerpc/sysdev/dart_iommu.c
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@ -139,6 +139,7 @@ static inline void dart_tlb_invalidate_one(unsigned long bus_rpn)
static void dart_flush(struct iommu_table *tbl) static void dart_flush(struct iommu_table *tbl)
{ {
mb();
if (dart_dirty) { if (dart_dirty) {
dart_tlb_invalidate_all(); dart_tlb_invalidate_all();
dart_dirty = 0; dart_dirty = 0;
@ -172,9 +173,13 @@ static void dart_build(struct iommu_table *tbl, long index,
uaddr += DART_PAGE_SIZE; uaddr += DART_PAGE_SIZE;
} }
/* make sure all updates have reached memory */
mb();
in_be32((unsigned __iomem *)dp);
mb();
if (dart_is_u4) { if (dart_is_u4) {
rpn = index; rpn = index;
mb(); /* make sure all updates have reached memory */
while (npages--) while (npages--)
dart_tlb_invalidate_one(rpn++); dart_tlb_invalidate_one(rpn++);
} else { } else {