A subsequent patch will flip the locking hierarchy from
ce->guc_state.lock -> sched_engine->lock to sched_engine->lock ->
ce->guc_state.lock. As such we need to release the submit fence for a
request from an IRQ to break a lock inversion - i.e. the fence must be
release went holding ce->guc_state.lock and the releasing of the can
acquire sched_engine->lock.
v2:
(Daniele)
- Delete request from list before calling irq_work_queue
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-16-matthew.brost@intel.com
While debugging an issue with full GT resets I went down a rabbit hole
thinking the scrubbing of lost G2H wasn't working correctly. This proved
to be incorrect as this was working just fine but this chase inspired me
to write a selftest to prove that this works. This simple selftest
injects errors dropping various G2H and then issues a full GT reset
proving that the scrubbing of these G2H doesn't blow up.
v2:
(Daniel Vetter)
- Use ifdef instead of macros for selftests
v3:
(Checkpatch)
- A space after 'switch' statement
v4:
(Daniele)
- A comment saying GT won't idle if G2H are lost
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-12-matthew.brost@intel.com
When the GuC does a media reset, it copies a golden context state back
into the corrupted context's state. The address of the golden context
and the size of the engine state restore are passed in via the GuC ADS.
The i915 had a bug where it passed in the whole size of the golden
context, not the size of the engine state to restore resulting in a
memory corruption.
Also copy the entire golden context on init rather than just the engine
state that is restored.
v2 (Daniele): use defines to avoid duplicated const variables (John).
Fixes: 481d458cae ("drm/i915/guc: Add golden context to GuC ADS")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-11-matthew.brost@intel.com
Propagating errors to dependent fences is broken and can lead to errors
from one client ending up in another. In commit 3761baae90 ("Revert
"drm/i915: Propagate errors on awaiting already signaled fences""), we
attempted to get rid of fence error propagation but missed the case
added in commit 8e9f84cf5c ("drm/i915/gt: Propagate change in error
status to children on unhold"). Revert that one too. This error was
found by an up-and-coming selftest which triggers a reset during
request cancellation and verifies that subsequent requests complete
successfully.
v2:
(Daniel Vetter)
- Use revert
v3:
(Jason)
- Update commit message
v4 (Daniele):
- fix checkpatch error in commit message.
References: '3761baae908a ("Revert "drm/i915: Propagate errors on awaiting already signaled fences"")'
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-8-matthew.brost@intel.com
If the context is reset as a result of the request cancellation the
context reset G2H is received after schedule disable done G2H which is
the wrong order. The schedule disable done G2H release the waiting
request cancellation code which resubmits the context. This races
with the context reset G2H which also wants to resubmit the context but
in this case it really should be a NOP as request cancellation code owns
the resubmit. Use some clever tricks of checking the context state to
seal this race until the GuC firmware is fixed.
v2:
(Checkpatch)
- Fix typos
v3:
(Daniele)
- State that is a bug in the GuC firmware
Fixes: 62eaf0ae21 ("drm/i915/guc: Support request cancellation")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-7-matthew.brost@intel.com
A small race that could result in incorrect accounting of the number
of outstanding G2H. Basically prior to this patch we did not increment
the number of outstanding G2H if we encoutered a GT reset while sending
a H2G. This was incorrect as the context state had already been updated
to anticipate a G2H response thus the counter should be incremented.
As part of this change we remove a legacy (now unused) path that was the
last caller requiring a G2H response that was not guaranteed to loop.
This allows us to simplify the accounting as we don't need to handle the
case where the send fails due to the channel being busy.
Also always use helper when decrementing this value.
v2 (Daniele): update GEM_BUG_ON check, pull in dead code removal from
later patch, remove loop param from context_deregister.
Fixes: f4eb1f3fe9 ("drm/i915/guc: Ensure G2H response has space in buffer")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909164744.31249-3-matthew.brost@intel.com
Usage of Transparent Hugepages was disabled in 9987da4b5d
("drm/i915: Disable THP until we have a GPU read BW W/A"), but since it
appears majority of performance regressions reported with an enabled IOMMU
can be almost eliminated by turning them on, lets just do that.
To err on the side of safety we keep the current default in cases where
IOMMU is not active, and only when it is default to the "huge=within_size"
mode. Although there probably would be wins to enable them throughout,
more extensive testing across benchmarks and platforms would need to be
done.
With the patch and IOMMU enabled my local testing on a small Skylake part
shows OglVSTangent regression being reduced from ~14% (IOMMU on versus
IOMMU off) to ~2% (same comparison but with THP on).
More detailed testing done in the below referenced Gitlab issue by Eero:
Skylake GT4e:
Performance drops from enabling IOMMU:
30-35% SynMark CSDof
20-25% Unigine Heaven, MemBW GPU write, SynMark VSTangent
~20% GLB Egypt (1/2 screen window)
10-15% GLB T-Rex (1/2 screen window)
8-10% GfxBench T-Rex, MemBW GPU blit
7-8% SynMark DeferredAA + TerrainFly* + ZBuffer
6-7% GfxBench Manhattan 3.0 + 3.1, SynMark TexMem128 & CSCloth
5-6% GfxBench CarChase, Unigine Valley
3-5% GfxBench Vulkan & GL AztecRuins + ALU2, MemBW GPU texture,
SynMark Fill*, Deferred, TerrainPan*
1-2% Most of the other tests
With the patch drops become:
20-25% SynMark TexMem*
15-20% GLB Egypt (1/2 screen window)
10-15% GLB T-Rex (1/2 screen window)
4-7% GfxBench T-Rex, GpuTest Triangle
1-8% GfxBench ALU2 (offscreen 1%, onscreen 8%)
3% GfxBench Manhattan 3.0, SynMark CSDof
2-3% Unigine Heaven + Valley, MemBW GPU texture
1-3 GfxBench Manhattan 3.1 + CarChase + Vulkan & GL AztecRuins
Broxton:
Performance drops from IOMMU, without patch:
30% MemBW GPU write
25% SynMark ZBuffer + Fill*
20% MemBW GPU blit
15% MemBW GPU blend, GpuTest Triangle
10-15% MemBW GPU texture
10% GLB Egypt, Unigine Heaven (had hangs), SynMark TerrainFly*
7-9% GLB T-Rex, GfxBench Manhattan 3.0 + T-Rex,
SynMark Deferred* + TexMem*
6-8% GfxBench CarChase, Unigine Valley,
SynMark CSCloth + ShMapVsm + TerrainPan*
5-6% GfxBench Manhattan 3.1 + GL AztecRuins,
SynMark CSDof + TexFilterTri
2-4% GfxBench ALU2, SynMark DrvRes + GSCloth + ShMapPcf + Batch[0-5] +
TexFilterAniso, GpuTest GiMark + 32-bit Julia
And with patch:
15-20% MemBW GPU texture
10% SynMark TexMem*
8-9% GLB Egypt (1/2 screen window)
4-5% GLB T-Rex (1/2 screen window)
3-6% GfxBench Manhattan 3.0, GpuTest FurMark,
SynMark Deferred + TexFilterTri
3-4% GfxBench Manhattan 3.1 + T-Rex, SynMark VSInstancing
2-4% GpuTest Triangle, SynMark DeferredAA
2-3% Unigine Heaven + Valley
1-3% SynMark Terrain*
1-2% GfxBench CarChase, SynMark TexFilterAniso + ZBuffer
Tigerlake-H:
20-25% MemBW GPU texture
15-20% GpuTest Triangle
13-15% SynMark TerrainFly* + DeferredAA + HdrBloom
8-10% GfxBench Manhattan 3.1, SynMark TerrainPan* + DrvRes
6-7% GfxBench Manhattan 3.0, SynMark TexMem*
4-8% GLB onscreen Fill + T-Rex + Egypt (more in onscreen than
offscreen versions of T-Rex/Egypt)
4-6% GfxBench CarChase + GLES AztecRuins + ALU2, GpuTest 32-bit Julia,
SynMark CSDof + DrvState
3-5% GfxBench T-Rex + Egypt, Unigine Heaven + Valley, GpuTest Plot3D
1-7% Media tests
2-3% MemBW GPU blit
1-3% Most of the rest of 3D tests
With the patch:
6-8% MemBW GPU blend => the only regression in these tests (compared
to IOMMU without THP)
4-6% SynMark DrvState (not impacted) + HdrBloom (improved)
3-4% GLB T-Rex
~3% GLB Egypt, SynMark DrvRes
1-3% GfxBench T-Rex + Egypt, SynMark TexFilterTri
1-2% GfxBench CarChase + GLES AztecRuins, Unigine Valley,
GpuTest Triangle
~1% GfxBench Manhattan 3.0/3.1, Unigine Heaven
Perf of several tests actually improved with IOMMU + THP, compared to no
IOMMU / no THP:
10-15% SynMark Batch[0-3]
5-10% MemBW GPU texture, SynMark ShMapVsm
3-4% SynMark Fill* + Geom*
2-3% SynMark TexMem512 + CSCloth
1-2% SynMark TexMem128 + DeferredAA
As a summary across all platforms, these are the benchmarks where enabling
THP on top of IOMMU enabled brings regressions:
* Skylake GT4e:
20-25% SynMark TexMem*
(whereas all MemBW GPU tests either improve or are not affected)
* Broxton J4205:
7% MemBW GPU texture
2-3% SynMark TexMem*
* Tigerlake-H:
7% MemBW GPU blend
Other benchmarks show either lowering of regressions or improvements.
v2:
* Add Kconfig dependency to transparent hugepages and some help text.
* Move to helper for easier handling of kernel build options.
v3:
* Drop Kconfig. (Daniel)
v4:
* Add some benchmark results to commit message.
v5:
* Add explicit regression summary to commit message. (Eero)
References: b901bb8932 ("drm/i915/gemfs: enable THP")
References: 9987da4b5d ("drm/i915: Disable THP until we have a GPU read BW W/A")
References: https://gitlab.freedesktop.org/drm/intel/-/issues/430
Co-developed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Eero Tamminen <eero.t.tamminen@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210909114448.508493-1-tvrtko.ursulin@linux.intel.com
The full audit is quite a bit of work:
- i915_dpt has very simple lifetime (somehow we create a display pagetable vm
per object, so its _very_ simple, there's only ever a single vma in there),
and uses i915_vm_close(), which internally does a i915_vm_put(). No rcu.
Aside: wtf is i915_dpt doing in the intel_display.c garbage collector as a new
feature, instead of added as a separate file with some clean-ish interface.
Also, i915_dpt unfortunately re-introduces some coding patterns from
pre-dma_resv_lock conversion times.
- i915_gem_proto_ctx is fully refcounted and no rcu, all protected by
fpriv->proto_context_lock.
- i915_gem_context is itself rcu protected, and that might leak to anything it
points at. Before
commit cf977e1861
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed Dec 2 11:21:40 2020 +0000
drm/i915/gem: Spring clean debugfs
and
commit db80a1294c
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon Jan 18 11:08:54 2021 +0000
drm/i915/gem: Remove per-client stats from debugfs/i915_gem_objects
we had a bunch of debugfs files that relied on rcu protecting everything, but
those are gone now. The main one was removed even earlier with
There doesn't seem to be anything left that's actually protecting
stuff now that the ctx->vm itself is invariant. See
commit ccbc1b9794
Author: Jason Ekstrand <jason@jlekstrand.net>
Date: Thu Jul 8 10:48:30 2021 -0500
drm/i915/gem: Don't allow changing the VM on running contexts (v4)
Note that we drop the vm refcount before the final release of the gem context
refcount, so this is all very dangerous even without rcu. Note that aside from
later on creating new engines (a defunct feature) and debug output we're never
looked at gem_ctx->vm for anything functional, hence why this is ok.
Fingers crossed.
Preceeding patches removed all vestiges of rcu use from gem_ctx->vm
derferencing to make it clear it's really not used.
The gem_ctx->rcu protection was introduced in
commit a4e7ccdac3
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri Oct 4 14:40:09 2019 +0100
drm/i915: Move context management under GEM
The commit message is somewhat entertaining because it fails to
mention this fact completely, and compensates that by an in-commit
changelog entry that claims that ctx->vm is protected by ctx->mutex.
Which was the case _before_ this commit, but no longer after it.
- intel_context holds a full reference. Unfortunately intel_context is also rcu
protected and the reference to the ->vm is dropped before the
rcu barrier - only the kfree is delayed. So again we need to check
whether that leaks anywhere on the intel_context->vm. RCU is only
used to protect intel_context sitting on the breadcrumb lists, which
don't look at the vm anywhere, so we are fine.
Nothing else relies on rcu protection of intel_context and hence is
fully protected by the kref refcount alone, which protects
intel_context->vm in turn.
The breadcrumbs rcu usage was added in
commit c744d50363
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu Nov 26 14:04:06 2020 +0000
drm/i915/gt: Split the breadcrumb spinlock between global and contexts
its parent commit added the intel_context rcu protection:
commit 14d1eaf088
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu Nov 26 14:04:05 2020 +0000
drm/i915/gt: Protect context lifetime with RCU
given some credence to my claim that I've actually caught them all.
- drm_i915_gem_object's shares_resv_from pointer has a full refcount to the
dma_resv, which is a sub-refcount that's released after the final
i915_vm_put() has been called. Safe.
Aside: Maybe we should have a struct dma_resv_shared which is just dma_resv +
kref as a stand-alone thing. It's a pretty useful pattern which other drivers
might want to copy.
For a bit more context see
commit 4d8151ae53
Author: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Date: Tue Jun 1 09:46:41 2021 +0200
drm/i915: Don't free shared locks while shared
- the fpriv->vm_xa was relying on rcu_read_lock for lookup, but that
was updated in a prep patch too to just be a spinlock-protected
lookup.
- intel_gt->vm is set at driver load in intel_gt_init() and released
in intel_gt_driver_release(). There seems to be some issue that
in some error paths this is called twice, but otherwise no rcu to be
found anywhere. This was added in the below commit, which
unfortunately doesn't explain why this complication exists.
commit e6ba764802
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Sat Dec 21 16:03:24 2019 +0000
drm/i915: Remove i915->kernel_context
The proper fix most likely for this is to start using drmm_ at large
scale, but that's also huge amounts of work.
- i915_vma->vm is some real pain, because rcu is rcu protected, at
least in the vma lookup in the context lookup cache in
eb_lookup_vma(). This was added in
commit 4ff4b44cbb
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri Jun 16 15:05:16 2017 +0100
drm/i915: Store a direct lookup from object handle to vma
This was changed to a radix tree from the hashtable in, but with the
locking unchanged, in
commit d1b48c1e71
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed Aug 16 09:52:08 2017 +0100
drm/i915: Replace execbuf vma ht with an idr
In
commit 93159e1235
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon Mar 23 09:28:41 2020 +0000
drm/i915/gem: Avoid gem_context->mutex for simple vma lookup
the locking was changed from dev->struct_mutex to rcu, which added
the requirement to rcu protect i915_vma. Somehow this was missed in
review (or I'm completely blind).
Irrespective of all that the vma lookup cache rcu_read_lock grabs a
full reference of the vma and the rcu doesn't leak further. So no
impact on i915_address_space from that.
I have not found any other rcu use for i915_vma, but given that it
seems broken I also didn't bother to do a careful in-depth audit.
Alltogether there's nothing left in-tree anymore which requires that a
pointer deref to an i915_address_space is safe undre rcu_read_lock
only.
rcu protection of i915_address_space was introduced in
commit b32fa81115
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu Jun 20 19:37:05 2019 +0100
drm/i915/gtt: Defer address space cleanup to an RCU worker
by mixing up a bugfixing (i915_address_space needs to be released from
a worker) with enabling rcu support. The commit message also seems
somewhat confused, because it talks about cleanup of WC pages
requiring sleep, while the code and linked bugzilla are about a
requirement to take dev->struct_mutex (which yes sleeps but it's a
much more specific problem). Since final kref_put can be called from
pretty much anywhere (including hardirq context through the
scheduler's i915_active cleanup) we need a worker here. Hence that
part must be kept.
Ideally all these reclaim workers should have some kind of integration
with our shrinkers, but for some of these it's rather tricky. Anyway,
that's a preexisting condition in the codeebase that we wont fix in
this patch here.
We also remove the rcu_barrier in ggtt_cleanup_hw added in
commit 60a4233a49
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon Jul 29 14:24:12 2019 +0100
drm/i915: Flush the i915_vm_release before ggtt shutdown
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20210902142057.929669-11-daniel.vetter@ffwll.ch
It's been invariant since
commit ccbc1b9794
Author: Jason Ekstrand <jason@jlekstrand.net>
Date: Thu Jul 8 10:48:30 2021 -0500
drm/i915/gem: Don't allow changing the VM on running contexts (v4)
this just completes the deed. I've tried to split out prep work for
more careful review as much as possible, this is what's left:
- get_ppgtt gets simplified since we don't need to grab a temporary
reference - we can rely on the temporary reference for the gem_ctx
while we inspect the vm. The new vm_id still needs a full
i915_vm_open ofc. This also removes the final caller of context_get_vm_rcu
- A pile of selftests can now just look at ctx->vm instead of
rcu_dereference_protected( , true) or similar things.
- All callers of i915_gem_context_vm also disappear.
- I've changed the hugepage selftest to set scrub_64K without any
locking, because when we inspect that setting we're also not taking
any locks either. It works because it's a selftests that's careful
(single threaded gives you nice ordering) and not a live driver
where races can happen from anywhere.
These can only be split up further if we have some intermediate state
with a bunch more rcu_dereference_protected(ctx->vm, true), just to
shut up lockdep and sparse.
The conversion to __rcu happened in
commit a4e7ccdac3
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri Oct 4 14:40:09 2019 +0100
drm/i915: Move context management under GEM
Note that we're not breaking the actual bugfix in there: The real
bugfix is pushing the i915_vm_relase onto a separate worker, to avoid
locking inversion issues. The rcu conversion was just thrown in for
entertainment value on top (no vm lookup isn't even close to anything
that's a hotpath where removing the single spinlock can be measured).
v2: Rebase over the change to move the i915_vm_put() into
i915_gem_context_release().
v3: Trivial conflict against repainted shed.
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Jon Bloomfield <jon.bloomfield@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Link: https://patchwork.freedesktop.org/patch/msgid/20210902142057.929669-9-daniel.vetter@ffwll.ch
The comment added in
commit b81dde7194
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Tue May 21 22:11:29 2019 +0100
drm/i915: Allow userspace to clone contexts on creation
and moved in
commit 27dbae8f36
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Wed Nov 6 09:13:12 2019 +0000
drm/i915/gem: Safely acquire the ctx->vm when copying
suggested that i915_address_space were at least intended to be managed
through SLAB_TYPESAFE_BY_RCU:
* This ppgtt may have be reallocated between
* the read and the kref, and reassigned to a third
* context. In order to avoid inadvertent sharing
* of this ppgtt with that third context (and not
* src), we have to confirm that we have the same
* ppgtt after passing through the strong memory
* barrier implied by a successful
* kref_get_unless_zero().
But extensive git history search has not brough any such reuse to
light.
What has come to light though is that ever since
commit 2850748ef8
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri Oct 4 14:39:58 2019 +0100
drm/i915: Pull i915_vma_pin under the vm->mutex
(yes this commit is earlier) the final i915_vma_put call has been
moved from i915_gem_context_free (now called _release) to
context_close, which means it's not actually safe anymore to access
the ctx->vm pointer without lock helds, because it might disappear at
any moment. Note that superficially things all still work, because the
i915_address_space is RCU protected since
commit b32fa81115
Author: Chris Wilson <chris@chris-wilson.co.uk>
Date: Thu Jun 20 19:37:05 2019 +0100
drm/i915/gtt: Defer address space cleanup to an RCU worker
except the very clever macro above (which is designed to protected
against object reuse due to SLAB_TYPESAFE_BY_RCU or similar tricks)
results in an endless loop if the refcount of the ctx->vm ever
permanently drops to 0. Which it totally now can.
Fix that by moving the final i915_vm_put to where it should be.
Note that i915_gem_context is rcu protected, but _only_ the final
kfree. This means anyone who chases a pointer to a gem ctx solely
under the protection can pretty only call kref_get_unless_zero(). This
seems to be pretty much the case, aside from a bunch of cases that
consult the scheduling information without any further protection.
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Jason Ekstrand <jason@jlekstrand.net>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: "Thomas Hellström" <thomas.hellstrom@intel.com>
Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Fixes: 2850748ef8 ("drm/i915: Pull i915_vma_pin under the vm->mutex")
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210902142057.929669-3-daniel.vetter@ffwll.ch
Historically we've initialized all undefined/reserved entries in
a platform's MOCS table to the contents of table entry #1 (i.e.,
I915_MOCS_PTE).
Going forward, we can't assume that table entry #1 will always
contain suitable values to use for undefined/reserved table
indices. We'll allow a platform-specific table index to be
selected at table initialization time in these cases.
This new mechanism to select L3 WB entry will be applicable for
all the Gen12+ platforms except TGL and RKL.
Since TGL and RLK are already in production so their mocs settings
are intact to avoid ABI break.
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Ayaz A Siddiqui <ayaz.siddiqui@intel.com>
Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210903092153.535736-5-ayaz.siddiqui@intel.com
Using the I915_MMAP_TYPE_FIXED mmap type requires the TTM backend, so
for that mmap type, use __i915_gem_object_create_user() instead of
i915_gem_object_create_internal(), as we really want to tests objects
mmap-able by user-space.
This also means that the out-of-space error happens at object creation
and returns -ENXIO rather than -ENOSPC, so fix the code up to expect
that on out-of-offset-space errors.
Finally only use I915_MMAP_TYPE_FIXED for LMEM and SMEM for now if
testing on LMEM-capable devices. For stolen LMEM, we still take the
same path as for integrated, as that haven't been moved over to TTM yet,
and user-space should not be able to create out of stolen LMEM anyway.
v2:
- Check the presence of the obj->ops->mmap_offset callback rather than
hardcoding the supported mmap regions in can_mmap() (Maarten Lankhorst)
Fixes: 7961c5b60f ("drm/i915: Add TTM offset argument to mmap.")
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210831122931.157536-1-thomas.hellstrom@linux.intel.com
A recent restructuring of our context workaround list initialization
added an early return for non-render engines; this caused us to
potentially miss the wa_init_finish() call at the end of the function.
The mistake is pretty harmless --- the only impact is that non-render
engines on graphics version 12.50+ platforms we don't trim down the
workaround list to reclaim some memory, and we don't print the usual
"Initialized 1 context workaround" message in dmesg. Let's change the
early return to a jump down to the wa_init_finish() call at the bottom
of the function.
Reported-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Fixes: 9e9dfd0802 ("drm/i915/dg2: Maintain backward-compatible nested batch behavior")
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210826033559.1209020-1-matthew.d.roper@intel.com
Clang warns:
In file included from drivers/gpu/drm/i915/gt/intel_reset.c:1514:
drivers/gpu/drm/i915/gt/selftest_hangcheck.c:465:62: warning: variable
'err' is uninitialized when used here [-Wuninitialized]
pr_err("[%s] Create context failed: %d!\n", engine->name, err);
^~~
...
drivers/gpu/drm/i915/gt/selftest_hangcheck.c:580:62: warning: variable
'err' is uninitialized when used here [-Wuninitialized]
pr_err("[%s] Create context failed: %d!\n", engine->name, err);
^~~
...
2 warnings generated.
This appears to be a copy and paste issue. Use ce directly using the %pe
specifier to pretty print the error code so that err is not used
uninitialized in these functions.
Fixes: 3a7b72665e ("drm/i915/selftest: Bump selftest timeouts for hangcheck")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210813171158.2665823-1-nathan@kernel.org
