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    Subject[PATCH 3/7] Intel pci: Dont cache iova above 32bit
    Mike Travis and Mike Habeck reported an issue where iova allocation
    would return a range that was larger than a device's dma mask.

    The dmar initialization code will reserve all PCI MMIO regions and copy
    those reservations into a domain specific iova tree. It is possible for
    one of those regions to be above the dma mask of a device. It is typical
    to allocate iovas with a 32bit mask (despite device's dma mask possibly
    being larger) and cache the result until it exhausts the lower 32bit
    address space. Freeing the iova range that is >= the last iova in the
    lower 32bit range when there is still an iova above the 32bit range will
    corrupt the cached iova by pointing it to a region that is above 32bit.
    If that region is also larger than the device's dma mask, a subsequent
    allocation will return an unusable iova and cause dma failure.

    Simply don't cache an iova that is above the 32bit caching boundary.

    From: Chris Wright <>
    Reported-by: Mike Travis <>
    Reported-by: Mike Habeck <>
    Cc: David Woodhouse <>
    Acked-by: Mike Travis <>
    Tested-by: Mike Habeck <>
    Signed-off-by: Chris Wright <>

    v3: rb_next() can return NULL, found when testing on my hw

    David, Mike Travis will collect and resumbit full series when he's back.

    drivers/pci/iova.c | 12 ++++++++++--
    1 file changed, 10 insertions(+), 2 deletions(-)

    --- linux.orig/drivers/pci/iova.c
    +++ linux/drivers/pci/iova.c
    @@ -63,8 +63,16 @@ __cached_rbnode_delete_update(struct iov
    curr = iovad->cached32_node;
    cached_iova = container_of(curr, struct iova, node);

    - if (free->pfn_lo >= cached_iova->pfn_lo)
    - iovad->cached32_node = rb_next(&free->node);
    + if (free->pfn_lo >= cached_iova->pfn_lo) {
    + struct rb_node *node = rb_next(&free->node);
    + struct iova *iova = container_of(node, struct iova, node);
    + /* only cache if it's below 32bit pfn */
    + if (node && iova->pfn_lo < iovad->dma_32bit_pfn)
    + iovad->cached32_node = node;
    + else
    + iovad->cached32_node = NULL;
    + }

    /* Computes the padding size required, to make the

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      Last update: 2011-05-28 20:19    [W:0.020 / U:48.268 seconds]
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