From: Benjamin Herrenschmidt Date: Wed, 13 Sep 2006 12:12:52 +0000 (+1000) Subject: [POWERPC] Fix G5 DART (IOMMU) race causing occasional data corruption X-Git-Tag: v2.6.18~13^2~7^2 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=eeac5c142b8687e35780b11b54b4c2f95b1a2436;p=linux-2.6 [POWERPC] Fix G5 DART (IOMMU) race causing occasional data corruption 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 Signed-off-by: Paul Mackerras --- diff --git a/arch/powerpc/sysdev/dart_iommu.c b/arch/powerpc/sysdev/dart_iommu.c index e32fadde1f..03b4477dd7 100644 --- a/arch/powerpc/sysdev/dart_iommu.c +++ b/arch/powerpc/sysdev/dart_iommu.c @@ -139,6 +139,7 @@ wait_more: static void dart_flush(struct iommu_table *tbl) { + mb(); if (dart_dirty) { dart_tlb_invalidate_all(); dart_dirty = 0; @@ -172,9 +173,13 @@ static void dart_build(struct iommu_table *tbl, long index, uaddr += DART_PAGE_SIZE; } + /* make sure all updates have reached memory */ + mb(); + in_be32((unsigned __iomem *)dp); + mb(); + if (dart_is_u4) { rpn = index; - mb(); /* make sure all updates have reached memory */ while (npages--) dart_tlb_invalidate_one(rpn++); } else {