On Tue, Jul 29, 2014 at 06:18:10PM +0200, Joerg Roedel wrote: > Changes V1->V2: > > * Rebase to v3.16-rc7 > * Added call of ->invalidate_range to > __mmu_notifier_invalidate_end() so that the subsystem > doesn't need to register an ->invalidate_end() call-back, > subsystems will likely either register > invalidate_range_start/end or invalidate_range, so that > should be fine. > * Re-orded declarations a bit to reflect that > invalidate_range is not only called between > invalidate_range_start/end > * Updated documentation to cover the case where > invalidate_range is called outside of > invalidate_range_start/end to flush page-table pages out > of the TLB > > Hi, > > here is a patch-set to extend the mmu_notifiers in the Linux > kernel to allow managing CPU external TLBs. Those TLBs may > be implemented in IOMMUs or any other external device, e.g. > ATS/PRI capable PCI devices. > > The problem with managing these TLBs are the semantics of > the invalidate_range_start/end call-backs currently > available. Currently the subsystem using mmu_notifiers has > to guarantee that no new TLB entries are established between > invalidate_range_start/end. Furthermore the > invalidate_range_start() function is called when all pages > are still mapped and invalidate_range_end() when the pages > are unmapped an already freed. > > So both call-backs can't be used to safely flush any non-CPU > TLB because _start() is called too early and _end() too > late. > > In the AMD IOMMUv2 driver this is currently implemented by > assigning an empty page-table to the external device between > _start() and _end(). But as tests have shown this doesn't > work as external devices don't re-fault infinitly but enter > a failure state after some time. > > Next problem with this solution is that it causes an > interrupt storm for IO page faults to be handled when an > empty page-table is assigned. > > Furthermore the _start()/end() notifiers only catch the > moment when page mappings are released, but not page-table > pages. But this is necessary for managing external TLBs when > the page-table is shared with the CPU. > > To solve this situation I wrote a patch-set to introduce a > new notifier call-back: mmu_notifer_invalidate_range(). This > notifier lifts the strict requirements that no new > references are taken in the range between _start() and > _end(). When the subsystem can't guarantee that any new > references are taken is has to provide the > invalidate_range() call-back to clear any new references in > there. > > It is called between invalidate_range_start() and _end() > every time the VMM has to wipe out any references to a > couple of pages. This are usually the places where the CPU > TLBs are flushed too and where its important that this > happens before invalidate_range_end() is called. > > Any comments and review appreciated! For the series : Reviewed-by: Jérôme Glisse <jglisse@xxxxxxxxxx> > > Thanks, > > Joerg > > Joerg Roedel (3): > mmu_notifier: Add mmu_notifier_invalidate_range() > mmu_notifier: Call mmu_notifier_invalidate_range() from VMM > mmu_notifier: Add the call-back for mmu_notifier_invalidate_range() > > include/linux/mmu_notifier.h | 75 +++++++++++++++++++++++++++++++++++++++++--- > kernel/events/uprobes.c | 2 +- > mm/fremap.c | 2 +- > mm/huge_memory.c | 9 +++--- > mm/hugetlb.c | 7 ++++- > mm/ksm.c | 4 +-- > mm/memory.c | 3 +- > mm/migrate.c | 3 +- > mm/mmu_notifier.c | 25 +++++++++++++++ > mm/rmap.c | 2 +- > 10 files changed, 115 insertions(+), 17 deletions(-) > > -- > 1.9.1 > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>