- 15 Sep, 2020 6 commits
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Chris Wilson authored
On Tigerlake, we are seeing a repeat of commit d8f50531 ("drm/i915/icl: Forcibly evict stale csb entries") where, presumably, due to a missing Global Observation Point synchronisation, the write pointer of the CSB ringbuffer is updated _prior_ to the contents of the ringbuffer. That is we see the GPU report more context-switch entries for us to parse, but those entries have not been written, leading us to process stale events, and eventually report a hung GPU. However, this effect appears to be much more severe than we previously saw on Icelake (though it might be best if we try the same approach there as well and measure), and Bruce suggested the good idea of resetting the CSB entry after use so that we can detect when it has been updated by the GPU. By instrumenting how long that may be, we can set a reliable upper bound for how long we should wait for: 513 late, avg of 61 retries (590 ns), max of 1061 retries (10099 ns) Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2045 References: d8f50531 ("drm/i915/icl: Forcibly evict stale csb entries") References: HSDES#22011327657, HSDES#1508287568 Suggested-by:
Bruce Chang <yu.bruce.chang@intel.com> Signed-off-by:
Chris Wilson <chris@chris-wilson.co.uk> Cc: Bruce Chang <yu.bruce.chang@intel.com> Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com> Cc: stable@vger.kernel.org # v5.4 Reviewed-by:
Mika Kuoppala <mika.kuoppala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200915134923.30088-2-chris@chris-wilson.co.uk
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Chris Wilson authored
A CSB entry is 64b, and it is simpler for us to treat it as an array of 64b entries than as an array of pairs of 32b entries. Signed-off-by:
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Chris Wilson authored
If the ips module calls into the driver during an unbind/bind cycle, we may see the driver while it has unregistered itself from ips and try and dereference a NULL ips_mchdev pointer. <1> [211.928844] BUG: kernel NULL pointer dereference, address: 0000000000000014 <1> [211.928861] #PF: supervisor read access in kernel mode <1> [211.928871] #PF: error_code(0x0000) - not-present page <6> [211.928881] PGD 0 P4D 0 <4> [211.928890] Oops: 0000 [#1] PREEMPT SMP PTI <4> [211.928900] CPU: 3 PID: 327 Comm: ips-monitor Not tainted 5.9.0-rc5-CI-CI_DRM_9008+ #1 <4> [211.928914] Hardware name: Hewlett-Packard HP EliteBook 8440p/172A, BIOS 68CCU Ver. F.24 09/13/2013 <4> [211.929056] RIP: 0010:mchdev_get+0x5a/0x180 [i915] <4> [211.929067] Code: c0 5a 74 0d 80 3d f1 53 29 00 00 0f 84 ab 00 00 00 48 8b 1d c8 a8 29 00 e8 d3 18 89 e1 85 c0 74 09 80 3d d1 53 29 00 00 74 65 <8b> 4b 14 48 8d 7b 14 85 c9 0f 84 09 01 00 00 8d 51 01 89 c8 f0 0f <4> [211.929095] RSP: 0018:ffffc900002efe60 EFLAGS: 00010202 <4> [211.929105] RAX: 0000000000000001 RBX: 0000000000000000 RCX: ffff8881297acf40 <4> [211.929118] RDX: 0000000000000000 RSI: ffffffff8264e2c0 RDI: ffff8881297ad820 <4> [211.929130] RBP: ffffc900002efe68 R08: ffff8881297ad820 R09: 00000000fffffffe <4> [211.929143] R10: ffff8881297acf40 R11: 00000000fff74c96 R12: ffff8881294dfa18 <4> [211.929155] R13: 0000000000000067 R14: ffff888126eff640 R15: ffff888126efe840 <4> [211.929168] FS: 0000000000000000(0000) GS:ffff888133d80000(0000) knlGS:0000000000000000 <4> [211.929182] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 <4> [211.929194] CR2: 0000000000000014 CR3: 0000000002610000 CR4: 00000000000006e0 <4> [211.929206] Call Trace: <4> [211.929294] i915_read_mch_val+0x15/0x380 [i915] <4> [211.929309] ? ips_monitor+0x3fb/0x630 [intel_ips] <4> [211.929321] ips_monitor+0x53c/0x630 [intel_ips] <4> [211.929334] ? ips_gpu_lower+0x30/0x30 [intel_ips] <4> [211.929348] kthread+0x14d/0x170 <4> [211.929358] ? kthread_park+0x80/0x80 <4> [211.929369] ret_from_fork+0x22/0x30 <4> [211.929382] Modules linked in: vgem snd_hda_codec_hdmi snd_hda_codec_generic ledtrig_audio i915 coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_intel snd_intel_dspcfg snd_hda_codec snd_hwdep snd_hda_core e1000e snd_pcm mei_me mei intel_ips lpc_ich ptp prime_numbers pps_core <4> [211.929437] CR2: 0000000000000014 Signed-off-by:
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Chris Wilson authored
If we create a new node, it is possible for the slab allocator to return us a recently freed node. If that node was just retired, it will retain the current jiffy as its node->age. There is then a miniscule window, where as that node is retired, it will appear on the free list with an incorrect age and be eligible for reuse by one thread, and then by a second thread as the correct node->age is written. Fixes: 06b73c2d ("drm/i915/gt: Delay taking the spinlock for grabbing from the buffer pool") Signed-off-by:
Matthew Auld <matthew.auld@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200915091417.4086-3-chris@chris-wilson.co.uk
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Chris Wilson authored
Let's not try and use PAT attributes for I915_MAP_WC if the CPU doesn't support PAT. Fixes: 6056e500 ("drm/i915/gem: Support discontiguous lmem object maps") Signed-off-by:
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Chris Wilson authored
On 32b, highmem using a finite set of indirect PTE (i.e. vmap) to provide virtual mappings of the high pages. As these are finite, map_new_virtual() must wait for some other kmap() to finish when it runs out. If we map a large number of objects, there is no method for it to tell us to release the mappings, and we deadlock. However, if we make an explicit vmap of the page, that uses a larger vmalloc arena, and also has the ability to tell us to release unwanted mappings. Most importantly, it will fail and propagate an error instead of waiting forever. Fixes: fb8621d3 ("drm/i915: Avoid allocating a vmap arena for a single page") #x86-32 References: e87666b5 ("drm/i915/shrinker: Hook up vmap allocation failure notifier") Signed-off-by:
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- 07 Sep, 2020 34 commits
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Thomas Hellström authored
The hwsp_gtt object is used for sub-allocation and could therefore be shared by many contexts causing unnecessary contention during concurrent context pinning. However since we're currently locking it only for pinning, it remains resident until we unpin it, and therefore it's safe to drop the lock early, allowing for concurrent thread access. Signed-off-by:
Thomas Hellström <thomas.hellstrom@intel.com> Reviewed-by:
Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
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Chris Wilson authored
(NOTE: This is the minimal backportable fix, a full fix is being developed at https://patchwork.freedesktop.org/patch/388048/) The flags passed to the wait_entry.func are passed onwards to try_to_wake_up(), which has a very particular interpretation for its wake_flags. In particular, beyond the published WF_SYNC, it has a few internal flags as well. Since we passed the fence->error down the chain via the flags argument, these ended up in the default_wake_function confusing the kernel/sched. Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2110 Fixes: ef468849 ("drm/i915: Propagate fence errors") Signed-off-by:
Rodrigo Vivi <rodrigo.vivi@intel.com> [Joonas: Rebased and reordered into drm-intel-gt-next branch] [Joonas: Added a note and link about more complete fix] Signed-off-by:
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Chris Wilson authored
To implement preempt-to-busy (and so efficient timeslicing and best utilization of the hardware submission ports) we let the GPU run asynchronously in respect to the ELSP submission queue. This created challenges in keeping and accessing the driver state mirroring the asynchronous GPU execution. Previous fix 1d9221e9 ("drm/i915: Skip signaling a signaled request") however did not correctly serialize request retirement with the execution callbacks. We were using the i915_request.lock to serialise adding an execution callback with __i915_request_submit. However, if we use an atomic llist_add to serialise multiple waiters and then check to see if the request is already executing, we can remove the irq-spinlock and fix serialization between retirement and execution callbacks in one go. v2: Avoid using the irq_work when outside of the irq-spinlocks, where we can execute the callbacks immediately. v3: Pay close attention to the order of setting ACTIVE on retirement, we need to ensure the request is signaled and breadcrumbs detached before we finish removing the request from the engine. v4: Expanded commit message. Fixes: 1d9221e9 ("drm/i915: Skip signaling a signaled request") Signed-off-by:
Tvrtko Ursulin <tvrtko.ursulin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200716142207.13003-2-chris@chris-wilson.co.ukSigned-off-by:
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Chris Wilson authored
To implement preempt-to-busy (and so efficient timeslicing and best utilization of the hardware submission ports) we let the GPU run asynchronously in respect to the ELSP submission queue. This created challenges in keeping and accessing the driver state mirroring the asynchronous GPU execution. The latest occurence of this was spotted by KCSAN: [ 1413.563200] BUG: KCSAN: data-race in __await_execution+0x217/0x370 [i915] [ 1413.563221] [ 1413.563236] race at unknown origin, with read to 0xffff88885bb6c478 of 8 bytes by task 9654 on cpu 1: [ 1413.563548] __await_execution+0x217/0x370 [i915] [ 1413.563891] i915_request_await_dma_fence+0x4eb/0x6a0 [i915] [ 1413.564235] i915_request_await_object+0x421/0x490 [i915] [ 1413.564577] i915_gem_do_execbuffer+0x29b7/0x3c40 [i915] [ 1413.564967] i915_gem_execbuffer2_ioctl+0x22f/0x5c0 [i915] [ 1413.564998] drm_ioctl_kernel+0x156/0x1b0 [ 1413.565022] drm_ioctl+0x2ff/0x480 [ 1413.565046] __x64_sys_ioctl+0x87/0xd0 [ 1413.565069] do_syscall_64+0x4d/0x80 [ 1413.565094] entry_SYSCALL_64_after_hwframe+0x44/0xa9 To complicate matters, we have to both avoid the read tearing of *active and avoid any write tearing as perform the pending[] -> inflight[] promotion of the execlists. This is because we cannot rely on the memcpy doing u64 aligned copies on all kernels/platforms and so we opt to open-code it with explicit WRITE_ONCE annotations to satisfy KCSAN. v2: When in doubt, write the same comment again. v3: Expanded commit message. Fixes: b55230e5 ("drm/i915: Check for awaits on still currently executing requests") Signed-off-by:
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Maarten Lankhorst authored
Use ww locking for pin_to_display_plane for all the pinning and locking. With the locking removed from set_cache_level, we need to fix i915_gem_set_caching_ioctl to take the object reservation lock. As this is a single lock, we don't need to use the ww dance. Changes since v1: - Do not use ww locking in i915_gem_set_caching_ioctl (Thomas). Signed-off-by:
Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Reviewed-by:
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Maarten Lankhorst authored
We want to start requiring the reservation_lock instead of obj->mm.lock for pinning objects, take the ww lock inside vm_fault_gtt as a first step towards the legacy lock removal. Signed-off-by:
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Maarten Lankhorst authored
Make sure vma_lock is not used as inner lock when kernel context is used, and add ww handling where appropriate. Ensure that execbuf selftests keep passing by using ww handling. Changes since v2: - Fix i915_gem_context finally. Signed-off-by:
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Maarten Lankhorst authored
We want to get rid of intel_context_pin(), convert intel_context_create_request() first. :) Signed-off-by:
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Maarten Lankhorst authored
This function does not use intel_context_create_request, so it has to use the same locking order as normal code. This is required to shut up lockdep in selftests. Signed-off-by:
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Maarten Lankhorst authored
Some i915 selftests still use i915_vma_lock() as inner lock, and intel_context_create_request() intel_timeline->mutex as outer lock. Fortunately for selftests this is not an issue, they should be fixed but we can move ahead and cleanify lockdep now. Signed-off-by:
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Maarten Lankhorst authored
We have the ordering of timeline->mutex vs resv_lock wrong, convert the i915_pin_vma and intel_context_pin as well to future-proof this. We may need to do future changes to do this more transaction-like, and only get down to a single i915_gem_ww_ctx, but for now this should work. Signed-off-by:
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Maarten Lankhorst authored
Instead of using intel_context_create_request(), use intel_context_pin() and i915_create_request directly. Now all those calls are gone outside of selftests. :) Signed-off-by:
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Maarten Lankhorst authored
This is the last part outside of selftests that still don't use the correct lock ordering of timeline->mutex vs resv_lock. With gem fixed, there are a few places that still get locking wrong: - gvt/scheduler.c - i915_perf.c - Most if not all selftests. Changes since v1: - Add intel_engine_pm_get/put() calls to fix use-after-free when using intel_engine_get_pool(). Signed-off-by:
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Maarten Lankhorst authored
As a preparation step for full object locking and wait/wound handling during pin and object mapping, ensure that we always pass the ww context in i915_gem_execbuffer.c to i915_vma_pin, use lockdep to ensure this happens. This also requires changing the order of eb_parse slightly, to ensure we pass ww at a point where we could still handle -EDEADLK safely. Signed-off-by:
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Maarten Lankhorst authored
Instead of doing everything inside of pin_mutex, we move all pinning outside. Because i915_active has its own reference counting and pinning is also having the same issues vs mutexes, we make sure everything is pinned first, so the pinning in i915_active only needs to bump refcounts. This allows us to take pin refcounts correctly all the time. Signed-off-by:
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Maarten Lankhorst authored
We want to lock all gem objects, including the engine context objects, rework the throttling to ensure that we can do this. Now we only throttle once, but can take eb_pin_engine while acquiring objects. This means we will have to drop the lock to wait. If we don't have to throttle we can still take the fastpath, if not we will take the slowpath and wait for the throttle request while unlocked. The engine has to be pinned as first step, otherwise gpu relocations won't work. Changes since v1: - Only need to get a throttled request in the fastpath, no need for a global flag any more. - Always free the waited request correctly. Changes since v2: - Use intel_engine_pm_get()/put() to keeep engine pool alive during EDEADLK handling. Changes since v3: - Fix small rq leak. Changes since v4: - Use a single reloc_context, for intel_context_pin_ww(). Signed-off-by:
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Maarten Lankhorst authored
Those arguments are already set as eb.file and eb.args, so kill off the extra arguments. This will allow us to move eb_pin_engine() to after we reserved all BO's. Signed-off-by:
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Maarten Lankhorst authored
This is required if we want to pass a ww context in intel_context_pin and gen6_ppgtt_pin(). Signed-off-by:
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Maarten Lankhorst authored
We want to start using ww locking in intel_context_pin, for this we need to lock multiple objects, and the single i915_gem_object_lock is not enough. Convert to using ww-waiting, and make sure we always pin intel_context_state, even if we don't have a renderstate object. Signed-off-by:
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Maarten Lankhorst authored
Now that we changed execbuf submission slightly to allow us to do all pinning in one place, we can now simply add ww versions on top of struct_mutex. All we have to do is a separate path for -EDEADLK handling, which needs to unpin all gem bo's before dropping the lock, then starting over. This finally allows us to do parallel submission, but because not all of the pinning code uses the ww ctx yet, we cannot completely drop struct_mutex yet. Changes since v1: - Keep struct_mutex for now. :( Changes since v2: - Make sure we always lock the ww context in slowpath. Changes since v3: - Don't call __eb_unreserve_vma in eb_move_to_gpu now; this can be done on normal unlock path. - Unconditionally release vmas and context. Changes since v4: - Rebased on top of struct_mutex reduction. Changes since v5: - Remove training wheels. Changes since v6: - Fix accidentally broken -ENOSPC handling. Changes since v7: - Handle gt buffer pool better. Changes since v8: - Properly clear variables, to make -EDEADLK handling not BUG. Change since v9: - Fix unpinning fence on pnv and below. Changes since v10: - Make relocation gpu chaining working again. Changes since v11: - Remove relocation chaining, pain to make it work. Signed-off-by:
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Maarten Lankhorst authored
We want to introduce backoff logic, but we need to lock the pool object as well for command parsing. Because of this, we will need backoff logic for the engine pool obj, move the batch validation up slightly to eb_lookup_vmas, and the actual command parsing in a separate function which can get called from execbuf relocation fast and slowpath. Signed-off-by:
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Maarten Lankhorst authored
Execbuffer submission will perform its own WW locking, and we cannot rely on the implicit lock there. This also makes it clear that the GVT code will get a lockdep splat when multiple batchbuffer shadows need to be performed in the same instance, fix that up. Signed-off-by:
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Maarten Lankhorst authored
i915_gem_ww_ctx is used to lock all gem bo's for pinning and memory eviction. We don't use it yet, but lets start adding the definition first. To use it, we have to pass a non-NULL ww to gem_object_lock, and don't unlock directly. It is done in i915_gem_ww_ctx_fini. Changes since v1: - Change ww_ctx and obj order in locking functions (Jonas Lahtinen) Signed-off-by:
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Maarten Lankhorst authored
This reverts commit 0f1dd022 ("drm/i915/gem: Split eb_vma into its own allocation") and also moves all unreserving to a single place at the end, which is a minor simplification. With the WW locking, we will drop all references only at the end when unlocking, so refcounting can now be removed. Signed-off-by:
Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20200819140904.1708856-5-maarten.lankhorst@linux.intel.comSigned-off-by:
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Maarten Lankhorst authored
This reverts commit 7dc8f114 ("drm/i915/gem: Drop relocation slowpath"). We need the slowpath relocation for taking ww-mutex inside the page fault handler, and we will take this mutex when pinning all objects. We also functionally revert ef398881 ("drm/i915/gem: Limit struct_mutex to eb_reserve"), as we need the struct_mutex in the slowpath as well, and a tiny part of 003d8b91 ("drm/i915/gem: Only call eb_lookup_vma once during execbuf ioctl"). Specifically, we make the -EAGAIN handling part of fallback to slowpath again. With this, we have a proper working slowpath again, which will allow us to do fault handling with WW locks held. [mlankhorst: Adjusted for reloc_gpu_flush() changes] Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Matthew Auld <matthew.auld@intel.com> Signed-off-by:
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Maarten Lankhorst authored
This reverts commit 964a9b0f ("drm/i915/gem: Use chained reloc batches") and commit 0e97fbb0 ("drm/i915/gem: Use a single chained reloc batches for a single execbuf"). When adding ww locking to execbuf, it's hard enough to deal with a single BO that is part of relocation execution. Chaining is hard to get right, and with GPU relocation deprecated, it's best to drop this altogether, instead of trying to fix something we will remove. This is not a completely 1:1 revert, we reset rq_size to 0 in reloc_cache_init, this was from e3d29130 ("drm/i915/gem: Implement legacy MI_STORE_DATA_IMM"), because we don't want to break the selftests. (Daniel) Signed-off-by:
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Maarten Lankhorst authored
This reverts commit 9e0f9464 ("drm/i915/gem: Async GPU relocations only"), and related commit 7ac2d253 ("drm/i915/gem: Delete unused code"). Async GPU relocations are not the path forward, we want to remove GPU accelerated relocation support eventually when userspace is fixed to use VM_BIND, and this is the first step towards that. We will keep async gpu relocations around for now, until userspace is fixed. Relocation support will be disabled completely on platforms where there was never any userspace that depends on it, as the hardware doesn't require it from at least gen9+ onward. For older platforms, the plan is to use cpu relocations only. The igt side is fixed in igt commit 39e9aa1032a4e ("tests/i915: Remove subtests that rely on async relocation behavior"). Signed-off-by:
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Chris Wilson authored
If dma_fence_chain_find_seqno() reports an error, it does so in its preamble before it disposes of the input fence. On handling the error, we need to drop the reference to the fence. Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2292Signed-off-by:
Lionel Landwerlin <lionel.g.landwerlin@intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20200806161056.17593-1-chris@chris-wilson.co.ukSigned-off-by:
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Chris Wilson authored
As we now protect the timeline list using RCU, we can drop the timeline->mutex for guarding the list iteration during context close, as we are searching for an inflight request. Any new request will see the context is banned and not be submitted. In doing so, pull the checks for a concurrent submission of the request (notably the i915_request_completed()) under the engine spinlock, to fully serialise with __i915_request_submit()). That is in the case of preempt-to-busy where the request may be completed during the __i915_request_submit(), we need to be careful that we sample the request status after serialising so that we don't miss the request the engine is actually submitting. Fixes: 4a317415 ("drm/i915/gem: Refine occupancy test in kill_context()") References: d22d2d07 ("drm/i915: Protect i915_request_await_start from early waits") # rcu protection of timeline->requests References: https://gitlab.freedesktop.org/drm/intel/-/issues/1622 References: https://gitlab.freedesktop.org/drm/intel/-/issues/2158Signed-off-by:
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Chris Wilson authored
When igt_random_offset() is a given a range of [0, PAGE_SIZE], it is allowed to return 0. However, attempting to use a size of 0 for the igt_lmem_write_cpu() byte poking, leads to call igt_random_offset() with a range of [offset, offset + 0] and ask it to find a length of 4 within it. This triggers the bug on that the requested length should fit within the range! Signed-off-by:
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Chris Wilson authored
Currently we hold no actual reference to the request nor context while they are attached to a breadcrumb. To avoid freeing the request/context too early, we serialise with cancel-breadcrumbs by taking the irq spinlock in i915_request_retire(). The alternative is to take a reference for a new breadcrumb and release it upon signaling; removing the more frequently hit contention point in i915_request_retire(). Signed-off-by:
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Chris Wilson authored
Move the __intel_breadcrumbs_arm_irq earlier, next to the disarm_irq, so that we can make use of it in the following patch. Signed-off-by:
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Chris Wilson authored
kmalloc uses power-of-two slab buckets for small allocations (up to a few pages). Since i915_page_directory is a page of pointers, plus a couple more, this is rounded up to 8K, and we waste nearly 50% of that allocation. Long terms this leads to poor memory utilisation, bloating the kernel footprint, but the problem is exacerbated by our conservative preallocation scheme for binding VMA. As we are required to allocate all levels for each vma just in case we need to insert them upon binding, this leads to a large multiplication factor for a single page vma. By halving the allocation we need for the page directory structure, we halve the impact of that factor, bringing workloads that once fitted into memory, hopefully back to fitting into memory. We maintain the split between i915_page_directory and i915_page_table as we only need half the allocation for the lowest, most populous, level. Signed-off-by:
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Chris Wilson authored
The GEM object is grossly overweight for the practicality of tracking large numbers of individual pages, yet it is currently our only abstraction for tracking DMA allocations. Since those allocations need to be reserved upfront before an operation, and that we need to break away from simple system memory, we need to ditch using plain struct page wrappers. In the process, we drop the WC mapping as we ended up clflushing everything anyway due to various issues across a wider range of platforms. Though in a future step, we need to drop the kmap_atomic approach which suggests we need to pre-map all the pages and keep them mapped. v2: Verify our large scratch page is suitably DMA aligned; and manually clear the scratch since we are allocating plain struct pages full of prior content. Signed-off-by:
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