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* [PATCH 0/3 v4] mmu_notifier: Allow to manage CPU external TLBs
@ 2014-10-28 17:13 Joerg Roedel
       [not found] ` <1414516440-910-1-git-send-email-joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
  0 siblings, 1 reply; 7+ messages in thread
From: Joerg Roedel @ 2014-10-28 17:13 UTC (permalink / raw)
  To: Andrew Morton, Andrea Arcangeli, Peter Zijlstra, Rik van Riel,
	Hugh Dickins, Mel Gorman, Johannes Weiner
  Cc: Jerome Glisse, Jay.Cornwall, Oded.Gabbay, John.Bridgman,
	Suravee.Suthikulpanit, ben.sander, Jesse Barnes, David Woodhouse,
	linux-kernel, linux-mm, iommu, jroedel, joro

From: Joerg Roedel <jroedel@suse.de>

Changes V3->V4:

* Rebased to v3.18-rc2
* Updated patch description and some comments

Changes V2->V3:

* Rebased to v3.17-rc4
* Fixed compile error because pmdp_get_and_clear_notify was
  missing

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 v4 of my patch-set which extends the mmu-notifiers
to allow managing CPU external TLBs. A more in-depth
description on the How and Why of this patch-set can be
found in the description of patch 1/3.

Any comments and review appreciated!

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 | 88 +++++++++++++++++++++++++++++++++++++++++---
 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, 128 insertions(+), 17 deletions(-)

-- 
1.8.4.5

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^ permalink raw reply	[flat|nested] 7+ messages in thread
* [PATCH 0/3 v3] mmu_notifier: Allow to manage CPU external TLBs
@ 2014-09-09 15:43 Joerg Roedel
       [not found] ` <1410277434-3087-1-git-send-email-joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
  0 siblings, 1 reply; 7+ messages in thread
From: Joerg Roedel @ 2014-09-09 15:43 UTC (permalink / raw)
  To: Andrew Morton, Andrea Arcangeli, Peter Zijlstra, Rik van Riel,
	Hugh Dickins, Mel Gorman, Johannes Weiner
  Cc: Jerome Glisse, jroedel, joro, Jay.Cornwall, Oded.Gabbay,
	John.Bridgman, Suravee.Suthikulpanit, ben.sander, Jesse Barnes,
	David Woodhouse, linux-kernel, linux-mm, iommu

Changes V2->V3:

* Rebased to v3.17-rc4
* Fixed compile error because pmdp_get_and_clear_notify was
  missing

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!

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 | 88 +++++++++++++++++++++++++++++++++++++++++---
 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, 128 insertions(+), 17 deletions(-)

-- 
1.9.1

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
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^ permalink raw reply	[flat|nested] 7+ messages in thread
* [PATCH 0/3 v2] mmu_notifier: Allow to manage CPU external TLBs
@ 2014-07-29 16:18 Joerg Roedel
  2014-07-29 16:18 ` [PATCH 3/3] mmu_notifier: Add the call-back for mmu_notifier_invalidate_range() Joerg Roedel
  0 siblings, 1 reply; 7+ messages in thread
From: Joerg Roedel @ 2014-07-29 16:18 UTC (permalink / raw)
  To: Andrew Morton, Andrea Arcangeli, Peter Zijlstra, Rik van Riel,
	Hugh Dickins, Mel Gorman, Johannes Weiner
  Cc: Jerome Glisse, jroedel, Jay.Cornwall, Oded.Gabbay, John.Bridgman,
	Suravee.Suthikulpanit, ben.sander, Jesse Barnes, David Woodhouse,
	linux-kernel, linux-mm, iommu, Joerg Roedel

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!

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@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

^ permalink raw reply	[flat|nested] 7+ messages in thread
* [PATCH 0/3] mmu_notifier: Allow to manage CPU external TLBs
@ 2014-07-24 14:35 Joerg Roedel
       [not found] ` <1406212541-25975-1-git-send-email-joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
  0 siblings, 1 reply; 7+ messages in thread
From: Joerg Roedel @ 2014-07-24 14:35 UTC (permalink / raw)
  To: Andrew Morton, Andrea Arcangeli, Peter Zijlstra, Rik van Riel,
	Hugh Dickins, Mel Gorman, Johannes Weiner
  Cc: Jay.Cornwall-5C7GfCeVMHo, John.Bridgman-5C7GfCeVMHo,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA,
	iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg, Jerome Glisse,
	jroedel-l3A5Bk7waGM, Jesse Barnes, David Woodhouse,
	ben.sander-5C7GfCeVMHo

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.

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!

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 | 66 ++++++++++++++++++++++++++++++++++++++++----
 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            | 15 ++++++++++
 mm/rmap.c                    |  2 +-
 10 files changed, 95 insertions(+), 18 deletions(-)

-- 
1.9.1

^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2014-10-28 17:14 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2014-10-28 17:13 [PATCH 0/3 v4] mmu_notifier: Allow to manage CPU external TLBs Joerg Roedel
     [not found] ` <1414516440-910-1-git-send-email-joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2014-10-28 17:13   ` [PATCH 1/3] mmu_notifier: Add mmu_notifier_invalidate_range() Joerg Roedel
2014-10-28 17:13   ` [PATCH 2/3] mmu_notifier: Call mmu_notifier_invalidate_range() from VMM Joerg Roedel
2014-10-28 17:14   ` [PATCH 3/3] mmu_notifier: Add the call-back for mmu_notifier_invalidate_range() Joerg Roedel
  -- strict thread matches above, loose matches on Subject: below --
2014-09-09 15:43 [PATCH 0/3 v3] mmu_notifier: Allow to manage CPU external TLBs Joerg Roedel
     [not found] ` <1410277434-3087-1-git-send-email-joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2014-09-09 15:43   ` [PATCH 3/3] mmu_notifier: Add the call-back for mmu_notifier_invalidate_range() Joerg Roedel
2014-07-29 16:18 [PATCH 0/3 v2] mmu_notifier: Allow to manage CPU external TLBs Joerg Roedel
2014-07-29 16:18 ` [PATCH 3/3] mmu_notifier: Add the call-back for mmu_notifier_invalidate_range() Joerg Roedel
2014-07-24 14:35 [PATCH 0/3] mmu_notifier: Allow to manage CPU external TLBs Joerg Roedel
     [not found] ` <1406212541-25975-1-git-send-email-joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2014-07-24 14:35   ` [PATCH 3/3] mmu_notifier: Add the call-back for mmu_notifier_invalidate_range() Joerg Roedel

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