Mike Travis and Mike Habeck reported an issue where iova allocation would return a range that was larger than a device's dma mask. https://lkml.org/lkml/2011/3/29/423 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 <chrisw@xxxxxxxxxxxx> Reported-by: Mike Travis <travis@xxxxxxx> Reported-by: Mike Habeck <habeck@xxxxxxx> Cc: David Woodhouse <dwmw2@xxxxxxxxxxxxx> Cc: stable@xxxxxxxxxx Acked-by: Mike Travis <travis@xxxxxxx> Tested-by: Mike Habeck <habeck@xxxxxxx> Signed-off-by: Chris Wright <chrisw@xxxxxxxxxxxx> --- 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 -- -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
