On Thu, Apr 23, 2015 at 6:09 PM, Daniel Kurtz <djku...@chromium.org> wrote: > On Mon, Apr 20, 2015 at 7:43 PM, Tomasz Figa <tf...@chromium.org> wrote: >> To flush created mappings, current mapping code relies on the fact that >> during unmap the driver zaps every IOVA being unmapped and that it is >> enough to zap a single IOVA of page table to remove the entire page >> table from IOMMU cache. Based on these assumptions the driver was made to >> simply zap the first IOVA of the mapping being created. This is enough >> to invalidate first page table, which could be shared with another >> mapping (and thus could be already present in IOMMU cache), but >> unfortunately it does not do anything about the last page table that >> could be shared with other mappings as well. >> >> Moreover, the flushing is performed before page table contents are >> actually modified, so there is a race between the CPU updating the page >> tables and hardware that could be possibly running at the same time and >> triggering IOMMU look-ups, which could bring back the page tables back >> to the cache. >> >> To fix both issues, this patch makes the mapping code zap first and last >> (if they are different) IOVAs of new mapping after the page table is >> updated. >> >> Signed-off-by: Tomasz Figa <tf...@chromium.org> >> Reviewed-by: Daniel Kurtz <djku...@chromium.org> >> Tested-by: Heiko Stuebner <he...@sntech.de> > > You probably want to remove the "CHROMIUM: " label in the subject.
Sorry, I removed gerrit tags, but hurrying up too much, I missed the label. I see, though, that Joerg has applied this patch already with this fixed up. Thanks. Best regards, Tomasz _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
