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Author SHA1 Message Date
Andi Shyti
fc58c693bc drm/i915/gem: Replace dev_priv with i915
Anyone using 'dev_priv' instead of 'i915' in a cleaned-up area
should be fined and required to do community service for a few
days.

Using 'i915' instead of 'dev_priv' has been the preferred
practice over the past years and some effort has been spent to
replace 'dev_priv' with 'i915'. Therefore, 'dev_priv' should
almost never be used (unless it breaks some defines which are
dependent on the naming).

I thought I had cleaned up the 'gem/' directory in the past, but
still, old aficionados of the 'dev_priv' name keep sneaking it
in.

Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Tvrtko Ursulin <tursulin@ursulin.net>
Reviewed-by: Tvrtko Ursulin <tursulin@ursulin.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20240328071833.664001-1-andi.shyti@linux.intel.com
2024-03-28 20:41:04 +01:00
Nirmoy Das
db7bbd13f0 drm/i915: Check before removing mm notifier
Error in mmu_interval_notifier_insert() can leave a NULL
notifier.mm pointer. Catch that and return early.

Fixes: ed29c26911 ("drm/i915: Fix userptr so we do not have to worry about obj->mm.lock, v7.")
Cc: <stable@vger.kernel.org> # v5.13+
[tursulin: Added Fixes and cc stable.]
Cc: Andi Shyti <andi.shyti@linux.intel.com>
Cc: Shawn Lee <shawn.c.lee@intel.com>
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240219125047.28906-1-nirmoy.das@intel.com
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
2024-02-28 13:11:32 +00:00
Jonathan Cavitt
86ceaaaec5 drm/i915/gem: Atomically invalidate userptr on mmu-notifier
Never block for outstanding work on userptr object upon receipt of a
mmu-notifier. The reason we originally did so was to immediately unbind
the userptr and unpin its pages, but since that has been dropped in
commit b4b9731b02 ("drm/i915: Simplify userptr locking"), we never
return the pages to the system i.e. never drop our page->mapcount and so
do not allow the page and CPU PTE to be revoked. Based on this history,
we know we are safe to drop the wait entirely.

Upon return from mmu-notifier, we will still have the userptr pages
pinned preventing the following PTE operation (such as try_to_unmap)
adjusting the vm_area_struct, so it is safe to keep the pages around for
as long as we still have i/o pending.

We do not have any means currently to asynchronously revalidate the
userptr pages, that is always prior to next use.

Signed-off-by: Chris Wilson <chris.p.wilson@linux.intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Reviewed-by: Andi Shyti <andi.shyti@linux.intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231128162505.3493942-1-jonathan.cavitt@intel.com
2023-12-19 16:56:39 +01:00
Chris Wilson
c3bfba9a22 drm/i915: Check for integer truncation on scatterlist creation
There is an impedance mismatch between the scatterlist API using unsigned
int and our memory/page accounting in unsigned long. That is we may try
to create a scatterlist for a large object that overflows returning a
small table into which we try to fit very many pages. As the object size
is under the control of userspace, we have to be prudent and catch the
conversion errors.

To catch the implicit truncation we check before calling scattterlist
creation Apis. we use overflows_type check and report E2BIG if the
overflows may raise. When caller does not return errno, use WARN_ON to
report a problem.

This is already used in our create ioctls to indicate if the uABI request
is simply too large for the backing store. Failing that type check,
we have a second check at sg_alloc_table time to make sure the values
we are passing into the scatterlist API are not truncated.

v2: Move added i915_utils's macro into drm_util header (Jani N)
v5: Fix macros to be enclosed in parentheses for complex values
    Fix too long line warning
v8: Replace safe_conversion() with check_assign() (Kees)
v14: Remove shadowing macros of scatterlist creation api and fix to
     explicitly overflow check where the scatterlist creation APIs are
     called. (Jani)
v15: Add missing returning of error code when the WARN_ON() has been
     detected. (Jani)

Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Brian Welty <brian.welty@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Co-developed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221228192252.917299-3-gwan-gyeong.mun@intel.com
2022-12-30 04:19:18 -05:00
Matthew Auld
8c94951560 drm/i915: use i915_sg_dma_sizes() for all backends
We rely on page_sizes.sg in setup_scratch_page() reporting the correct
value if the underlying sgl is not contiguous, however in
get_pages_internal() we are only looking at the layout of the created
pages when calculating the sg_page_sizes, and not the final sgl, which
could in theory be completely different. In such a situation we might
incorrectly think we have a 64K scratch page, when it is actually only
4K or similar split over multiple non-contiguous entries, which could
lead to broken behaviour when touching the scratch space within the
padding of a 64K GTT page-table. For most of the other backends we
already just call i915_sg_dma_sizes() on the final mapping, so rather
just move that into __i915_gem_object_set_pages() to avoid such issues
coming back to bite us later.

v2: Update missing conversion in gvt

Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Stuart Summers <stuart.summers@intel.com>
Cc: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221108103238.165447-1-matthew.auld@intel.com
2022-11-09 10:07:22 +00:00
Matthew Auld
6f7de35b50 drm/i915/userptr: restore probe_range behaviour
The conversion looks harmless, however the addr value is updated inside
the loop with the previous vm_end, which then incorrectly leads to
for_each_vma_range() iterating over stuff outside the range we care
about. Fix this by storing the end value separately. Also fix the case
where the range doesn't intersect with any vma, or if the vma itself
doesn't extend the entire range, which must mean we have hole at the
end. Both should result in an error, as per the previous behaviour.

v2: Fix the cases where the range is empty, or if there's a hole at
the end of the range

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/7247
Testcase: igt@gem_userptr_blits@probe
Fixes: f683b9d613 ("i915: use the VMA iterator")
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yu Zhao <yuzhao@google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221028130635.465839-1-matthew.auld@intel.com
2022-11-04 13:49:43 +00:00
Dave Airlie
60ba8c5bd9 Merge tag 'drm-intel-gt-next-2022-11-03' of git://anongit.freedesktop.org/drm/drm-intel into drm-next
Driver Changes:

- Fix for #7306: [Arc A380] white flickering when using arc as a
  secondary gpu (Matt A)
- Add Wa_18017747507 for DG2 (Wayne)
- Avoid spurious WARN on DG1 due to incorrect cache_dirty flag
  (Niranjana, Matt A)
- Corrections to CS timestamp support for Gen5 and earlier (Ville)

- Fix a build error used with clang compiler on hwmon (GG)
- Improvements to LMEM handling with RPM (Anshuman, Matt A)
- Cleanups in dmabuf code (Mike)

- Selftest improvements (Matt A)

Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/Y2N11wu175p6qeEN@jlahtine-mobl.ger.corp.intel.com
2022-11-04 17:33:34 +10:00
Robert Beckett
78a07fe777 drm/i915: stop abusing swiotlb_max_segment
swiotlb_max_segment used to return either the maximum size that swiotlb
could bounce, or for Xen PV PAGE_SIZE even if swiotlb could bounce buffer
larger mappings.  This made i915 on Xen PV work as it bypasses the
coherency aspect of the DMA API and can't cope with bounce buffering
and this avoided bounce buffering for the Xen/PV case.

So instead of adding this hack back, check for Xen/PV directly in i915
for the Xen case and otherwise use the proper DMA API helper to query
the maximum mapping size.

Replace swiotlb_max_segment() calls with dma_max_mapping_size().
In i915_gem_object_get_pages_internal() no longer consider max_segment
only if CONFIG_SWIOTLB is enabled. There can be other (iommu related)
causes of specific max segment sizes.

Fixes: a2daa27c0c ("swiotlb: simplify swiotlb_max_segment")
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Robert Beckett <bob.beckett@collabora.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
[hch: added the Xen hack, rewrote the changelog]
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221020110308.1582518-1-hch@lst.de
2022-10-27 10:10:05 +01:00
Colin Ian King
178ce94a15 drm/i915/gem: remove redundant assignments to variable ret
The variable ret is being assigned with a value that is never read
both before and after a while-loop. The variable is being re-assigned
inside the while-loop and afterwards on the call to the function
i915_gem_object_lock_interruptible. Remove the redundants assignments.

Cleans up clang scan-build warnings:

warning: Although the value stored to 'ret' is used in the
enclosing expression, the value is never actually read
from 'ret' [deadcode.DeadStores]

warning: Value stored to 'ret' is never read [deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221007194745.2749277-1-colin.i.king@gmail.com
2022-10-10 09:14:50 +01:00
Matthew Wilcox (Oracle)
f683b9d613 i915: use the VMA iterator
Replace the linked list in probe_range() with the VMA iterator.

Link: https://lkml.kernel.org/r/20220906194824.2110408-65-Liam.Howlett@oracle.com
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-09-26 19:46:25 -07:00
Matthew Wilcox (Oracle)
541846502f mm/migrate: Convert migrate_page() to migrate_folio()
Convert all callers to pass a folio.  Most have the folio
already available.  Switch all users from aops->migratepage to
aops->migrate_folio.  Also turn the documentation into kerneldoc.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: David Sterba <dsterba@suse.com>
2022-08-02 12:34:04 -04:00
Christian König
0cc848a75b dma-buf: add DMA_RESV_USAGE_BOOKKEEP v3
Add an usage for submissions independent of implicit sync but still
interesting for memory management.

v2: cleanup the kerneldoc a bit
v3: separate amdgpu changes from this

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220407085946.744568-10-christian.koenig@amd.com
2022-04-07 12:53:54 +02:00
Christian König
7bc80a5462 dma-buf: add enum dma_resv_usage v4
This change adds the dma_resv_usage enum and allows us to specify why a
dma_resv object is queried for its containing fences.

Additional to that a dma_resv_usage_rw() helper function is added to aid
retrieving the fences for a read or write userspace submission.

This is then deployed to the different query functions of the dma_resv
object and all of their users. When the write paratermer was previously
true we now use DMA_RESV_USAGE_WRITE and DMA_RESV_USAGE_READ otherwise.

v2: add KERNEL/OTHER in separate patch
v3: some kerneldoc suggestions by Daniel
v4: some more kerneldoc suggestions by Daniel, fix missing cases lost in
    the rebase pointed out by Bas.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20220407085946.744568-2-christian.koenig@amd.com
2022-04-07 12:53:53 +02:00
Rodrigo Vivi
063565aca3 Merge drm/drm-next into drm-intel-next
Catch-up with 5.17-rc2 and trying to align with drm-intel-gt-next
for a possible topic branch for merging the split of i915_regs...

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
2022-01-31 13:19:33 -05:00
Jani Nikula
db583eea5a drm/i915: split out gem/i915_gem_userptr.h from i915_drv.h
We already have the gem/i915_gem_userptr.c file.

Acked-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/c29f66604ebd973b8eff1cce7d7c53615a26480f.1641561552.git.jani.nikula@intel.com
2022-01-10 15:43:19 +02:00
Michał Winiarski
1a9c4db4ca drm/i915/gem: Use to_gt() helper
Use to_gt() helper consistently throughout the codebase.
Pure mechanical s/i915->gt/to_gt(i915). No functional changes.

Signed-off-by: Michał Winiarski <michal.winiarski@intel.com>
Signed-off-by: Andi Shyti <andi.shyti@linux.intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211214193346.21231-6-andi.shyti@linux.intel.com
2021-12-17 21:50:32 -08:00
Matthew Auld
6343034771 drm/i915/userptr: add paranoid flush-on-acquire
Even though userptr objects are always coherent with the GPU, with no
way for userspace to change this with the set_caching ioctl, even on
non-LLC platforms, there is still the 'Bypass LCC' mocs setting, which
might permit reading the contents of main memory directly.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211018174508.2137279-5-matthew.auld@intel.com
2021-10-20 16:50:21 +01:00
Matthew Auld
f7858cb48b drm/i915: mark userptr objects as ALLOC_USER
These are userspace objects, so mark them as such. In a later patch it's
useful to determine how paranoid we need to be when managing cache
flushes. In theory no functional changes.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211018174508.2137279-2-matthew.auld@intel.com
2021-10-20 16:50:17 +01:00
Linus Torvalds
23852bec53 RDMA v5.15 merge window Pull Request
- Various cleanup and small features for rtrs
 
 - kmap_local_page() conversions
 
 - Driver updates and fixes for: efa, rxe, mlx5, hfi1, qed, hns
 
 - Cache the IB subnet prefix
 
 - Rework how CRC is calcuated in rxe
 
 - Clean reference counting in iwpm's netlink
 
 - Pull object allocation and lifecycle for user QPs to the uverbs core
   code
 
 - Several small hns features and continued general code cleanups
 
 - Fix the scatterlist confusion of orig_nents/nents introduced in an
   earlier patch creating the append operation
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma

Pull rdma updates from Jason Gunthorpe:
 "This is quite a small cycle, no major series stands out. The HNS and
  rxe drivers saw the most activity this cycle, with rxe being broken
  for a good chunk of time. The significant deleted line count is due to
  a SPDX cleanup series.

  Summary:

   - Various cleanup and small features for rtrs

   - kmap_local_page() conversions

   - Driver updates and fixes for: efa, rxe, mlx5, hfi1, qed, hns

   - Cache the IB subnet prefix

   - Rework how CRC is calcuated in rxe

   - Clean reference counting in iwpm's netlink

   - Pull object allocation and lifecycle for user QPs to the uverbs
     core code

   - Several small hns features and continued general code cleanups

   - Fix the scatterlist confusion of orig_nents/nents introduced in an
     earlier patch creating the append operation"

* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma: (90 commits)
  RDMA/mlx5: Relax DCS QP creation checks
  RDMA/hns: Delete unnecessary blank lines.
  RDMA/hns: Encapsulate the qp db as a function
  RDMA/hns: Adjust the order in which irq are requested and enabled
  RDMA/hns: Remove RST2RST error prints for hw v1
  RDMA/hns: Remove dqpn filling when modify qp from Init to Init
  RDMA/hns: Fix QP's resp incomplete assignment
  RDMA/hns: Fix query destination qpn
  RDMA/hfi1: Convert to SPDX identifier
  IB/rdmavt: Convert to SPDX identifier
  RDMA/hns: Bugfix for incorrect association between dip_idx and dgid
  RDMA/hns: Bugfix for the missing assignment for dip_idx
  RDMA/hns: Bugfix for data type of dip_idx
  RDMA/hns: Fix incorrect lsn field
  RDMA/irdma: Remove the repeated declaration
  RDMA/core/sa_query: Retry SA queries
  RDMA: Use the sg_table directly and remove the opencoded version from umem
  lib/scatterlist: Fix wrong update of orig_nents
  lib/scatterlist: Provide a dedicated function to support table append
  RDMA/hns: Delete unused hns bitmap interface
  ...
2021-09-02 14:47:21 -07:00
Maor Gottlieb
90e7a6de62 lib/scatterlist: Provide a dedicated function to support table append
RDMA is the only in-kernel user that uses __sg_alloc_table_from_pages to
append pages dynamically. In the next patch. That mode will be extended
and that function will get more parameters. So separate it into a unique
function to make such change more clear.

Link: https://lore.kernel.org/r/20210824142531.3877007-2-maorg@nvidia.com
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
2021-08-24 15:21:14 -03:00
Chris Wilson
b65a948973 drm/i915/userptr: Probe existence of backing struct pages upon creation
Jason Ekstrand requested a more efficient method than userptr+set-domain
to determine if the userptr object was backed by a complete set of pages
upon creation. To be more efficient than simply populating the userptr
using get_user_pages() (as done by the call to set-domain or execbuf),
we can walk the tree of vm_area_struct and check for gaps or vma not
backed by struct page (VM_PFNMAP). The question is how to handle
VM_MIXEDMAP which may be either struct page or pfn backed...

With discrete we are going to drop support for set_domain(), so offering
a way to probe the pages, without having to resort to dummy batches has
been requested.

v2:
- add new query param for the PROBE flag, so userspace can easily
  check if the kernel supports it(Jason).
- use mmap_read_{lock, unlock}.
- add some kernel-doc.
v3:
- In the docs also mention that PROBE doesn't guarantee that the pages
  will remain valid by the time they are actually used(Tvrtko).
- Add a small comment for the hole finding logic(Jason).
- Move the param next to all the other params which just return true.

Testcase: igt/gem_userptr_blits/probe
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Kenneth Graunke <kenneth@whitecape.org>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Ramalingam C <ramalingam.c@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Acked-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210723113405.427004-1-matthew.auld@intel.com
2021-08-05 11:34:00 +02:00
Thomas Hellström
0ff375759f drm/i915: Update object placement flags to be mutable
The object ops i915_GEM_OBJECT_HAS_IOMEM and the object
I915_BO_ALLOC_STRUCT_PAGE flags are considered immutable by
much of our code. Introduce a new mem_flags member to hold these
and make sure checks for these flags being set are either done
under the object lock or with pages properly pinned. The flags
will change during migration under the object lock.

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210624084240.270219-2-thomas.hellstrom@linux.intel.com
2021-06-24 18:50:56 +01:00
Thomas Hellström
b4b9731b02 drm/i915: Simplify userptr locking
Use an rwlock instead of spinlock for the global notifier lock
to reduce risk of contention in execbuf.

Protect object state with the object lock whenever possible rather
than with the global notifier lock

Don't take an explicit page_ref in userptr_submit_init() but rather
call get_pages() after obtaining the page list so that
get_pages() holds the page_ref. This means we don't need to call
userptr_submit_fini(), which is needed to avoid awkward locking
in our upcoming VM_BIND code.

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210610143525.624677-1-thomas.hellstrom@linux.intel.com
2021-06-14 12:23:49 +01:00
Dave Airlie
2a7005c8a3 Merge tag 'drm-intel-gt-next-2021-06-10' of git://anongit.freedesktop.org/drm/drm-intel into drm-next
UAPI Changes:

- Disable mmap ioctl for gen12+ (excl. TGL-LP)
- Start enabling HuC loading by default for upcoming Gen12+
  platforms (excludes TGL and RKL)

Core Changes:

- Backmerge of drm-next

Driver Changes:

- Revert "i915: use io_mapping_map_user" (Eero, Matt A)
- Initialize the TTM device and memory managers (Thomas)
- Major rework to the GuC submission backend to prepare
  for enabling on new platforms (Michal Wa., Daniele,
  Matt B, Rodrigo)
- Fix i915_sg_page_sizes to record dma segments rather
  than physical pages (Thomas)

- Locking rework to prep for TTM conversion (Thomas)
- Replace IS_GEN and friends with GRAPHICS_VER (Lucas)
- Use DEVICE_ATTR_RO macro (Yue)
- Static code checker fixes (Zhihao)

Signed-off-by: Dave Airlie <airlied@redhat.com>
From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/YMHeDxg9VLiFtyn3@jlahtine-mobl.ger.corp.intel.com
2021-06-11 13:37:34 +10:00
Christian König
d3fae3b3da dma-buf: drop the _rcu postfix on function names v3
The functions can be called both in _rcu context as well
as while holding the lock.

v2: add some kerneldoc as suggested by Daniel
v3: fix indentation

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210602111714.212426-7-christian.koenig@amd.com
2021-06-06 11:19:51 +02:00
Thomas Hellström
62445a97c5 drm/i915: Fix i915_sg_page_sizes to record dma segments rather than physical pages
All users of this function actually want the dma segment sizes, but that's
not what's calculated. Fix that and rename the function to
i915_sg_dma_sizes to reflect what's calculated.

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210601074654.3103-4-thomas.hellstrom@linux.intel.com
2021-06-01 09:33:08 +01:00
Dave Airlie
41d1d0c51f Merge tag 'drm-intel-gt-next-2021-04-06' of git://anongit.freedesktop.org/drm/drm-intel into drm-next
Driver Changes:

- Prepare for local/device memory support on DG1 by starting
  to use it for kernel internal allocations: context, ring
  and engine scratch (Matt A, CQ, Abdiel, Imre)
- Sandybridge fix to avoid hard hang on ring resume (Chris)
- Limit imported dma-buf size to int32 (Matt A)
- Double check heartbeat timeout before resetting (Chris)

- Use new tasklet API for execution list (Emil)
- Fix SPDX checkpats warnings (Chris)
- Fixes for various checkpatch warnings (Chris)
- Selftest improvements (Chris)
- Move the defer_request waiter active assertion to correct spot (Chris)
- Make local-memory probing a GT operation (Matt, Tvrtko)
- Protect against request freeing during cancellation on wedging (Chris)
- Retire unexpected starting state error dumping (Chris)
- Distinction of memory regions in debugging (Zbigniew)
- Always flush the submission queue on checking for idle (Chris)

- Consolidate 2big error check to helper (Matt)
- Decrease number of subplatform bits (Tvrtko)
- Remove unused internal request priority levels (Chris)
- Document the unused internal header bits in buddy allocator (Matt)
- Cleanup the region class/instance encoding (Matt)

Signed-off-by: Dave Airlie <airlied@redhat.com>

From: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/YGxksaZGXHnFxlwg@jlahtine-mobl.ger.corp.intel.com
2021-04-08 12:46:12 +10:00
Matthew Auld
ae2fb480f3 drm/i915/gem: consolidate 2big error checking for object sizes
Throw it into a simple helper, and throw a warning if we encounter an
object which has been initialised with an object size that exceeds our
limit of INT_MAX pages.

Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20210122181514.541436-2-matthew.auld@intel.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
2021-03-24 19:30:35 +01:00
Maarten Lankhorst
fd995a3cc4 drm/i915: Keep userpointer bindings if seqcount is unchanged, v2.
Instead of force unbinding and rebinding every time, we try to check
if our notifier seqcount is still correct when pages are bound. This
way we only rebind userptr when we need to, and prevent stalls.

Changes since v1:
- Missing mutex_unlock, reported by kbuild.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-63-maarten.lankhorst@linux.intel.com
2021-03-24 17:48:11 +01:00
Maarten Lankhorst
cf41a8f1dc drm/i915: Finally remove obj->mm.lock.
With all callers and selftests fixed to use ww locking, we can now
finally remove this lock.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-62-maarten.lankhorst@linux.intel.com
2021-03-24 17:47:20 +01:00
Maarten Lankhorst
abd2f57717 drm/i915: Flatten obj->mm.lock
With userptr fixed, there is no need for all separate lockdep classes
now, and we can remove all lockdep tricks used. A trylock in the
shrinker is all we need now to flatten the locking hierarchy.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
[danvet: Resolve conflict because we don't have the patch from Chris
to rebrand i915_gem_shrinker_taints_mutex to fs_reclaim_taints_mutex.
It's not a bad idea, but if we do it, it should be moved to the right
header. See
https://lore.kernel.org/intel-gfx/20210202154318.19246-1-chris@chris-wilson.co.uk/]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-18-maarten.lankhorst@linux.intel.com
2021-03-24 17:27:19 +01:00
Maarten Lankhorst
ed29c26911 drm/i915: Fix userptr so we do not have to worry about obj->mm.lock, v7.
Instead of doing what we do currently, which will never work with
PROVE_LOCKING, do the same as AMD does, and something similar to
relocation slowpath. When all locks are dropped, we acquire the
pages for pinning. When the locks are taken, we transfer those
pages in .get_pages() to the bo. As a final check before installing
the fences, we ensure that the mmu notifier was not called; if it is,
we return -EAGAIN to userspace to signal it has to start over.

Changes since v1:
- Unbinding is done in submit_init only. submit_begin() removed.
- MMU_NOTFIER -> MMU_NOTIFIER
Changes since v2:
- Make i915->mm.notifier a spinlock.
Changes since v3:
- Add WARN_ON if there are any page references left, should have been 0.
- Return 0 on success in submit_init(), bug from spinlock conversion.
- Release pvec outside of notifier_lock (Thomas).
Changes since v4:
- Mention why we're clearing eb->[i + 1].vma in the code. (Thomas)
- Actually check all invalidations in eb_move_to_gpu. (Thomas)
- Do not wait when process is exiting to fix gem_ctx_persistence.userptr.
Changes since v5:
- Clarify why check on PF_EXITING is (temporarily) required.
Changes since v6:
- Ensure userptr validity is checked in set_domain through a special path.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Dave Airlie <airlied@redhat.com>
[danvet: s/kfree/kvfree/ in i915_gem_object_userptr_drop_ref in the
previous review round, but which got lost. The other open questions
around page refcount are imo better discussed in a separate series,
with amdgpu folks involved].
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-17-maarten.lankhorst@linux.intel.com
2021-03-24 17:27:19 +01:00
Maarten Lankhorst
20ee27bd84 drm/i915: Make compilation of userptr code depend on MMU_NOTIFIER.
Now that unsynchronized mappings are removed, the only time userptr
works is when the MMU notifier is enabled. Put all of the userptr
code behind a mmu notifier ifdef.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-16-maarten.lankhorst@linux.intel.com
2021-03-24 17:27:19 +01:00
Maarten Lankhorst
c6bcc0c2fd drm/i915: Reject UNSYNCHRONIZED for userptr, v2.
We should not allow this any more, as it will break with the new userptr
implementation, it could still be made to work, but there's no point in
doing so.

Inspection of the beignet opencl driver shows that it's only used
when normal userptr is not available, which means for new kernels
you will need CONFIG_I915_USERPTR.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-15-maarten.lankhorst@linux.intel.com
2021-03-24 17:27:19 +01:00
Maarten Lankhorst
02b64a4a0c drm/i915: Reject more ioctls for userptr, v2.
There are a couple of ioctl's related to tiling and cache placement,
that make no sense for userptr, reject those:
- i915_gem_set_tiling_ioctl()
    Tiling should always be linear for userptr. Changing placement will
    fail with -ENXIO.
- i915_gem_set_caching_ioctl()
    Userptr memory should always be cached. Changing caching mode will
    fail with -ENXIO.
- i915_gem_set_domain_ioctl()
    Still temporarily allowed to work as intended, it's used to check
    userptr validity. With the reworked userptr code, it will keep
    working for this usecase.

This plus the previous changes have been tested against beignet
by using its own unit tests, and intel-video-compute by using
piglit's opencl tests.

Changes since v1:
- set_domain was apparently used in iris for checking userptr validity,
  keep it working as intended.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-14-maarten.lankhorst@linux.intel.com
2021-03-24 17:27:19 +01:00
Maarten Lankhorst
ae4e55b894 drm/i915: No longer allow exporting userptr through dma-buf
It doesn't make sense to export a memory address, we will prevent
allowing access this way to different address spaces when we
rework userptr handling, so best to explicitly disable it.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-13-maarten.lankhorst@linux.intel.com
2021-03-24 17:27:19 +01:00
Maarten Lankhorst
ae30af84ed drm/i915: Disable userptr pread/pwrite support.
Userptr should not need the kernel for a userspace memcpy, userspace
needs to call memcpy directly.

Specifically, disable i915_gem_pwrite_ioctl() and i915_gem_pread_ioctl().

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: Jason Ekstrand <jason@jlekstrand.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-12-maarten.lankhorst@linux.intel.com
2021-03-24 17:27:03 +01:00
Maarten Lankhorst
c471748dc7 drm/i915: Move HAS_STRUCT_PAGE to obj->flags
We want to remove the changing of ops structure for attaching
phys pages, so we need to kill off HAS_STRUCT_PAGE from ops->flags,
and put it in the bo.

This will remove a potential race of dereferencing the wrong obj->ops
without ww mutex held.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
[danvet: apply with wiggle]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210323155059.628690-8-maarten.lankhorst@linux.intel.com
2021-03-24 11:47:37 +01:00
Maor Gottlieb
07da1223ec lib/scatterlist: Add support in dynamic allocation of SG table from pages
Extend __sg_alloc_table_from_pages to support dynamic allocation of
SG table from pages. It should be used by drivers that can't supply
all the pages at one time.

This function returns the last populated SGE in the table. Users should
pass it as an argument to the function from the second call and forward.
As before, nents will be equal to the number of populated SGEs (chunks).

With this new extension, drivers can benefit the optimization of merging
contiguous pages without a need to allocate all pages in advance and
hold them in a large buffer.

E.g. with the Infiniband driver that allocates a single page for hold the
pages. For 1TB memory registration, the temporary buffer would consume only
4KB, instead of 2GB.

Link: https://lore.kernel.org/r/20201004154340.1080481-2-leon@kernel.org
Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
2020-10-05 20:45:45 -03:00
Linus Torvalds
b25d1dc947 Merge branch 'simplify-do_wp_page'
Merge emailed patches from Peter Xu:
 "This is a small series that I picked up from Linus's suggestion to
  simplify cow handling (and also make it more strict) by checking
  against page refcounts rather than mapcounts.

  This makes uffd-wp work again (verified by running upmapsort)"

Note: this is horrendously bad timing, and making this kind of
fundamental vm change after -rc3 is not at all how things should work.
The saving grace is that it really is a a nice simplification:

 8 files changed, 29 insertions(+), 120 deletions(-)

The reason for the bad timing is that it turns out that commit
17839856fd ("gup: document and work around 'COW can break either way'
issue" broke not just UFFD functionality (as Peter noticed), but Mikulas
Patocka also reports that it caused issues for strace when running in a
DAX environment with ext4 on a persistent memory setup.

And we can't just revert that commit without re-introducing the original
issue that is a potential security hole, so making COW stricter (and in
the process much simpler) is a step to then undoing the forced COW that
broke other uses.

Link: https://lore.kernel.org/lkml/alpine.LRH.2.02.2009031328040.6929@file01.intranet.prod.int.rdu2.redhat.com/

* emailed patches from Peter Xu <peterx@redhat.com>:
  mm: Add PGREUSE counter
  mm/gup: Remove enfornced COW mechanism
  mm/ksm: Remove reuse_ksm_page()
  mm: do_wp_page() simplification
2020-09-04 09:31:54 -07:00
Peter Xu
a308c71bf1 mm/gup: Remove enfornced COW mechanism
With the more strict (but greatly simplified) page reuse logic in
do_wp_page(), we can safely go back to the world where cow is not
enforced with writes.

This essentially reverts commit 17839856fd ("gup: document and work
around 'COW can break either way' issue").  There are some context
differences due to some changes later on around it:

  2170ecfa76 ("drm/i915: convert get_user_pages() --> pin_user_pages()", 2020-06-03)
  376a34efa4 ("mm/gup: refactor and de-duplicate gup_fast() code", 2020-06-03)

Some lines moved back and forth with those, but this revert patch should
have striped out and covered all the enforced cow bits anyways.

Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-09-04 09:25:20 -07:00
Peter Xu
64019a2e46 mm/gup: remove task_struct pointer for all gup code
After the cleanup of page fault accounting, gup does not need to pass
task_struct around any more.  Remove that parameter in the whole gup
stack.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Link: http://lkml.kernel.org/r/20200707225021.200906-26-peterx@redhat.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 10:58:04 -07:00
Chris Wilson
040e123c0b drm/i915/gem: Avoid kmalloc under i915->mm_lock
Rearrange the allocation of the mm_struct registration to avoid
allocating underneath the i915->mm_lock, so that we avoid tainting the
lock (and in turn many other locks that may be held as i915->mm_lock is
taken, and those locks we may want on the free [shrinker] paths). In
doing so, we convert the lookup to be RCU protected by courtesy of
converting the free-worker to be an rcu_work.

v2: Remember to use hash_rcu variants to protect the list iteration from
concurrent add/del.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200619194038.5088-1-chris@chris-wilson.co.uk
2020-06-30 19:36:16 +01:00
Jani Nikula
0f69403d25 Merge drm/drm-next into drm-intel-next-queued
Catch up with upstream, in particular to get c1e8d7c6a7 ("mmap locking
API: convert mmap_sem comments").

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
2020-06-25 18:05:03 +03:00
Michel Lespinasse
c1e8d7c6a7 mmap locking API: convert mmap_sem comments
Convert comments that reference mmap_sem to reference mmap_lock instead.

[akpm@linux-foundation.org: fix up linux-next leftovers]
[akpm@linux-foundation.org: s/lockaphore/lock/, per Vlastimil]
[akpm@linux-foundation.org: more linux-next fixups, per Michel]

Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ying Han <yinghan@google.com>
Link: http://lkml.kernel.org/r/20200520052908.204642-13-walken@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-09 09:39:14 -07:00
Michel Lespinasse
d8ed45c5dc mmap locking API: use coccinelle to convert mmap_sem rwsem call sites
This change converts the existing mmap_sem rwsem calls to use the new mmap
locking API instead.

The change is generated using coccinelle with the following rule:

// spatch --sp-file mmap_lock_api.cocci --in-place --include-headers --dir .

@@
expression mm;
@@
(
-init_rwsem
+mmap_init_lock
|
-down_write
+mmap_write_lock
|
-down_write_killable
+mmap_write_lock_killable
|
-down_write_trylock
+mmap_write_trylock
|
-up_write
+mmap_write_unlock
|
-downgrade_write
+mmap_write_downgrade
|
-down_read
+mmap_read_lock
|
-down_read_killable
+mmap_read_lock_killable
|
-down_read_trylock
+mmap_read_trylock
|
-up_read
+mmap_read_unlock
)
-(&mm->mmap_sem)
+(mm)

Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Reviewed-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Davidlohr Bueso <dbueso@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Liam Howlett <Liam.Howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ying Han <yinghan@google.com>
Link: http://lkml.kernel.org/r/20200520052908.204642-5-walken@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-09 09:39:14 -07:00
John Hubbard
2170ecfa76 drm/i915: convert get_user_pages() --> pin_user_pages()
This code was using get_user_pages*(), in a "Case 2" scenario (DMA/RDMA),
using the categorization from [1].  That means that it's time to convert
the get_user_pages*() + put_page() calls to pin_user_pages*() +
unpin_user_pages() calls.

There is some helpful background in [2]: basically, this is a small part
of fixing a long-standing disconnect between pinning pages, and file
systems' use of those pages.

[1] Documentation/core-api/pin_user_pages.rst

[2] "Explicit pinning of user-space pages":
    https://lwn.net/Articles/807108/

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: "Joonas Lahtinen" <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Link: http://lkml.kernel.org/r/20200519002124.2025955-5-jhubbard@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-03 20:09:42 -07:00
Linus Torvalds
17839856fd gup: document and work around "COW can break either way" issue
Doing a "get_user_pages()" on a copy-on-write page for reading can be
ambiguous: the page can be COW'ed at any time afterwards, and the
direction of a COW event isn't defined.

Yes, whoever writes to it will generally do the COW, but if the thread
that did the get_user_pages() unmapped the page before the write (and
that could happen due to memory pressure in addition to any outright
action), the writer could also just take over the old page instead.

End result: the get_user_pages() call might result in a page pointer
that is no longer associated with the original VM, and is associated
with - and controlled by - another VM having taken it over instead.

So when doing a get_user_pages() on a COW mapping, the only really safe
thing to do would be to break the COW when getting the page, even when
only getting it for reading.

At the same time, some users simply don't even care.

For example, the perf code wants to look up the page not because it
cares about the page, but because the code simply wants to look up the
physical address of the access for informational purposes, and doesn't
really care about races when a page might be unmapped and remapped
elsewhere.

This adds logic to force a COW event by setting FOLL_WRITE on any
copy-on-write mapping when FOLL_GET (or FOLL_PIN) is used to get a page
pointer as a result.

The current semantics end up being:

 - __get_user_pages_fast(): no change. If you don't ask for a write,
   you won't break COW. You'd better know what you're doing.

 - get_user_pages_fast(): the fast-case "look it up in the page tables
   without anything getting mmap_sem" now refuses to follow a read-only
   page, since it might need COW breaking.  Which happens in the slow
   path - the fast path doesn't know if the memory might be COW or not.

 - get_user_pages() (including the slow-path fallback for gup_fast()):
   for a COW mapping, turn on FOLL_WRITE for FOLL_GET/FOLL_PIN, with
   very similar semantics to FOLL_FORCE.

If it turns out that we want finer granularity (ie "only break COW when
it might actually matter" - things like the zero page are special and
don't need to be broken) we might need to push these semantics deeper
into the lookup fault path.  So if people care enough, it's possible
that we might end up adding a new internal FOLL_BREAK_COW flag to go
with the internal FOLL_COW flag we already have for tracking "I had a
COW".

Alternatively, if it turns out that different callers might want to
explicitly control the forced COW break behavior, we might even want to
make such a flag visible to the users of get_user_pages() instead of
using the above default semantics.

But for now, this is mostly commentary on the issue (this commit message
being a lot bigger than the patch, and that patch in turn is almost all
comments), with that minimal "enable COW breaking early" logic using the
existing FOLL_WRITE behavior.

[ It might be worth noting that we've always had this ambiguity, and it
  could arguably be seen as a user-space issue.

  You only get private COW mappings that could break either way in
  situations where user space is doing cooperative things (ie fork()
  before an execve() etc), but it _is_ surprising and very subtle, and
  fork() is supposed to give you independent address spaces.

  So let's treat this as a kernel issue and make the semantics of
  get_user_pages() easier to understand. Note that obviously a true
  shared mapping will still get a page that can change under us, so this
  does _not_ mean that get_user_pages() somehow returns any "stable"
  page ]

Reported-by: Jann Horn <jannh@google.com>
Tested-by: Christoph Hellwig <hch@lst.de>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Kirill Shutemov <kirill@shutemov.name>
Acked-by: Jan Kara <jack@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-06-02 10:19:17 -07:00
Chris Wilson
7d192daa73 drm/i915/gem: Give each object class a friendly name
Name the object classes and their offspring for easier lockdep
debugging.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200529183204.16850-2-chris@chris-wilson.co.uk
2020-05-29 23:38:29 +01:00
Chris Wilson
ea97c4ca54 drm/i915/gem: Suppress some random warnings
Leave the error propagation in place, but limit the warnings to only
show up in CI if the unlikely errors are hit.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200525141957.3061-2-chris@chris-wilson.co.uk
2020-05-25 16:45:18 +01:00