From patchwork Sat Oct 23 18:05:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Brost X-Patchwork-Id: 12579703 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2961AC433F5 for ; Sat, 23 Oct 2021 18:10:11 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EC38F60ED5 for ; Sat, 23 Oct 2021 18:10:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org EC38F60ED5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 2FEF76E83D; Sat, 23 Oct 2021 18:09:54 +0000 (UTC) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by gabe.freedesktop.org (Postfix) with ESMTPS id 9D00989FAD; Sat, 23 Oct 2021 18:09:52 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10146"; a="209566138" X-IronPort-AV: E=Sophos;i="5.87,175,1631602800"; d="scan'208";a="209566138" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Oct 2021 11:09:52 -0700 X-IronPort-AV: E=Sophos;i="5.87,175,1631602800"; d="scan'208";a="528262359" Received: from jons-linux-dev-box.fm.intel.com ([10.1.27.20]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Oct 2021 11:09:51 -0700 From: Matthew Brost To: , Cc: , Date: Sat, 23 Oct 2021 11:05:08 -0700 Message-Id: <20211023180510.35152-2-matthew.brost@intel.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211023180510.35152-1-matthew.brost@intel.com> References: <20211023180510.35152-1-matthew.brost@intel.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 1/3] drm/i915/guc: Do error capture asynchronously X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" An error capture allocates memory, memory allocations depend on resets, and resets need to flush the G2H handlers to seal several races. If the error capture is done from the G2H handler this creates a circular dependency. To work around this, do a error capture in a work queue asynchronously from the G2H handler. This should be fine as (eventually) all register state is put into a buffer by the GuC so it is safe to restart the context before the error capture is complete. At worst, a full GT reset clobbers an error capture and some information is lost. Example of lockdep splat below: [ 154.625989] ====================================================== [ 154.632195] WARNING: possible circular locking dependency detected [ 154.638393] 5.14.0-rc5-guc+ #50 Tainted: G U [ 154.643991] ------------------------------------------------------ [ 154.650196] i915_selftest/1673 is trying to acquire lock: [ 154.655621] ffff8881079cb918 ((work_completion)(&ct->requests.worker)){+.+.}-{0:0}, at: __flush_work+0x350/0x4d0 [ 154.665826] but task is already holding lock: [ 154.671682] ffff8881079cbfb8 (>->reset.mutex){+.+.}-{3:3}, at: intel_gt_reset+0xf0/0x300 [i915] [ 154.680659] which lock already depends on the new lock. [ 154.688857] the existing dependency chain (in reverse order) is: [ 154.696365] -> #2 (>->reset.mutex){+.+.}-{3:3}: [ 154.702571] lock_acquire+0xd2/0x300 [ 154.706695] i915_gem_shrinker_taints_mutex+0x2d/0x50 [i915] [ 154.712959] intel_gt_init_reset+0x61/0x80 [i915] [ 154.718258] intel_gt_init_early+0xe6/0x120 [i915] [ 154.723648] i915_driver_probe+0x592/0xdc0 [i915] [ 154.728942] i915_pci_probe+0x43/0x1c0 [i915] [ 154.733891] pci_device_probe+0x9b/0x110 [ 154.738362] really_probe+0x1a6/0x3a0 [ 154.742568] __driver_probe_device+0xf9/0x170 [ 154.747468] driver_probe_device+0x19/0x90 [ 154.752114] __driver_attach+0x99/0x170 [ 154.756492] bus_for_each_dev+0x73/0xc0 [ 154.760870] bus_add_driver+0x14b/0x1f0 [ 154.765248] driver_register+0x67/0xb0 [ 154.769542] i915_init+0x18/0x8c [i915] [ 154.773964] do_one_initcall+0x53/0x2e0 [ 154.778343] do_init_module+0x56/0x210 [ 154.782639] load_module+0x25fc/0x29f0 [ 154.786934] __do_sys_finit_module+0xae/0x110 [ 154.791835] do_syscall_64+0x38/0xc0 [ 154.795958] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 154.801558] -> #1 (fs_reclaim){+.+.}-{0:0}: [ 154.807241] lock_acquire+0xd2/0x300 [ 154.811361] fs_reclaim_acquire+0x9e/0xd0 [ 154.815914] kmem_cache_alloc_trace+0x30/0x790 [ 154.820899] i915_gpu_coredump_alloc+0x53/0x1a0 [i915] [ 154.826649] i915_gpu_coredump+0x39/0x560 [i915] [ 154.831866] i915_capture_error_state+0xa/0x70 [i915] [ 154.837513] intel_guc_context_reset_process_msg+0x174/0x1f0 [i915] [ 154.844383] ct_incoming_request_worker_func+0x130/0x1b0 [i915] [ 154.850898] process_one_work+0x264/0x590 [ 154.855451] worker_thread+0x4b/0x3a0 [ 154.859655] kthread+0x147/0x170 [ 154.863428] ret_from_fork+0x1f/0x30 [ 154.867548] -> #0 ((work_completion)(&ct->requests.worker)){+.+.}-{0:0}: [ 154.875747] check_prev_add+0x90/0xc30 [ 154.880042] __lock_acquire+0x1643/0x2110 [ 154.884595] lock_acquire+0xd2/0x300 [ 154.888715] __flush_work+0x373/0x4d0 [ 154.892920] intel_guc_submission_reset_prepare+0xf3/0x340 [i915] [ 154.899606] intel_uc_reset_prepare+0x40/0x50 [i915] [ 154.905166] reset_prepare+0x55/0x60 [i915] [ 154.909946] intel_gt_reset+0x11c/0x300 [i915] [ 154.914984] do_device_reset+0x13/0x20 [i915] [ 154.919936] check_whitelist_across_reset+0x166/0x250 [i915] [ 154.926212] live_reset_whitelist.cold+0x6a/0x7a [i915] [ 154.932037] __i915_subtests.cold+0x20/0x74 [i915] [ 154.937428] __run_selftests.cold+0x96/0xee [i915] [ 154.942816] i915_live_selftests+0x2c/0x60 [i915] [ 154.948125] i915_pci_probe+0x93/0x1c0 [i915] [ 154.953076] pci_device_probe+0x9b/0x110 [ 154.957545] really_probe+0x1a6/0x3a0 [ 154.961749] __driver_probe_device+0xf9/0x170 [ 154.966653] driver_probe_device+0x19/0x90 [ 154.971290] __driver_attach+0x99/0x170 [ 154.975671] bus_for_each_dev+0x73/0xc0 [ 154.980053] bus_add_driver+0x14b/0x1f0 [ 154.984431] driver_register+0x67/0xb0 [ 154.988725] i915_init+0x18/0x8c [i915] [ 154.993149] do_one_initcall+0x53/0x2e0 [ 154.997527] do_init_module+0x56/0x210 [ 155.001822] load_module+0x25fc/0x29f0 [ 155.006118] __do_sys_finit_module+0xae/0x110 [ 155.011019] do_syscall_64+0x38/0xc0 [ 155.015139] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 155.020729] other info that might help us debug this: [ 155.028752] Chain exists of: (work_completion)(&ct->requests.worker) --> fs_reclaim --> >->reset.mutex [ 155.041294] Possible unsafe locking scenario: [ 155.047240] CPU0 CPU1 [ 155.051791] ---- ---- [ 155.056344] lock(>->reset.mutex); [ 155.060026] lock(fs_reclaim); [ 155.065706] lock(>->reset.mutex); [ 155.071912] lock((work_completion)(&ct->requests.worker)); [ 155.077595] *** DEADLOCK *** v2: - Resolve ce within lock, requeue workqueue if list not empty v3: (CI) - Only add ce to capture list if empty Signed-off-by: Matthew Brost --- drivers/gpu/drm/i915/gt/intel_context.c | 2 + drivers/gpu/drm/i915/gt/intel_context_types.h | 7 ++ drivers/gpu/drm/i915/gt/uc/intel_guc.h | 10 +++ .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 65 +++++++++++++++++-- 4 files changed, 78 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/intel_context.c b/drivers/gpu/drm/i915/gt/intel_context.c index 5634d14052bc..c8990d7c030a 100644 --- a/drivers/gpu/drm/i915/gt/intel_context.c +++ b/drivers/gpu/drm/i915/gt/intel_context.c @@ -406,6 +406,8 @@ intel_context_init(struct intel_context *ce, struct intel_engine_cs *engine) INIT_LIST_HEAD(&ce->parallel.child_list); + INIT_LIST_HEAD(&ce->guc_capture_link); + /* * Initialize fence to be complete as this is expected to be complete * unless there is a pending schedule disable outstanding. diff --git a/drivers/gpu/drm/i915/gt/intel_context_types.h b/drivers/gpu/drm/i915/gt/intel_context_types.h index 9e0177dc5484..ca714c866512 100644 --- a/drivers/gpu/drm/i915/gt/intel_context_types.h +++ b/drivers/gpu/drm/i915/gt/intel_context_types.h @@ -276,6 +276,13 @@ struct intel_context { } guc; } parallel; + /** + * @guc_capture_link: in guc->submission_state.capture_list when an + * error capture is pending on this context, protected by + * guc->submission_state.lock + */ + struct list_head guc_capture_link; + #ifdef CONFIG_DRM_I915_SELFTEST /** * @drop_schedule_enable: Force drop of schedule enable G2H for selftest diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc.h b/drivers/gpu/drm/i915/gt/uc/intel_guc.h index 31cf9fb48c7e..540a567268ef 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc.h +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc.h @@ -114,6 +114,16 @@ struct intel_guc { * function as it might be in an atomic context (no sleeping) */ struct work_struct destroyed_worker; + /** + * @capture_list: list of intel_context that need to capture + * error state + */ + struct list_head capture_list; + /** + * @capture_worker: worker to do error capture when the GuC + * signals a context has been reset + */ + struct work_struct capture_worker; } submission_state; /** diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c index d7710debcd47..9a5aeba033e0 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -91,8 +91,8 @@ * used for all of GuC submission but that could change in the future. * * guc->submission_state.lock - * Global lock for GuC submission state. Protects guc_ids and destroyed contexts - * list. + * Global lock for GuC submission state. Protects guc_ids, destroyed contexts + * list, and capture list. * * ce->guc_state.lock * Protects everything under ce->guc_state. Ensures that a context is in the @@ -1478,6 +1478,8 @@ void intel_guc_submission_reset_finish(struct intel_guc *guc) static void destroyed_worker_func(struct work_struct *w); +static void capture_worker_func(struct work_struct *w); + /* * Set up the memory resources to be shared with the GuC (via the GGTT) * at firmware loading time. @@ -1506,6 +1508,8 @@ int intel_guc_submission_init(struct intel_guc *guc) INIT_LIST_HEAD(&guc->submission_state.destroyed_contexts); INIT_WORK(&guc->submission_state.destroyed_worker, destroyed_worker_func); + INIT_LIST_HEAD(&guc->submission_state.capture_list); + INIT_WORK(&guc->submission_state.capture_worker, capture_worker_func); guc->submission_state.guc_ids_bitmap = bitmap_zalloc(NUMBER_MULTI_LRC_GUC_ID, GFP_KERNEL); @@ -3652,17 +3656,66 @@ int intel_guc_sched_done_process_msg(struct intel_guc *guc, return 0; } -static void capture_error_state(struct intel_guc *guc, - struct intel_context *ce) +static void capture_worker_func(struct work_struct *w) { + struct intel_guc *guc = container_of(w, struct intel_guc, + submission_state.capture_worker); struct intel_gt *gt = guc_to_gt(guc); struct drm_i915_private *i915 = gt->i915; - struct intel_engine_cs *engine = __context_to_physical_engine(ce); + struct intel_engine_cs *engine; + struct intel_context *ce; + unsigned long flags; intel_wakeref_t wakeref; + spin_lock_irqsave(&guc->submission_state.lock, flags); + ce = list_first_entry(&guc->submission_state.capture_list, + struct intel_context, guc_capture_link); + list_del_init(&ce->guc_capture_link); + spin_unlock_irqrestore(&guc->submission_state.lock, flags); + + engine = __context_to_physical_engine(ce); intel_engine_set_hung_context(engine, ce); with_intel_runtime_pm(&i915->runtime_pm, wakeref) - i915_capture_error_state(gt, engine->mask); + i915_capture_error_state(gt, ce->engine->mask); + + if (!list_empty(&guc->submission_state.capture_list)) + queue_work(system_unbound_wq, + &guc->submission_state.capture_worker); +} + +static void capture_error_state(struct intel_guc *guc, + struct intel_context *ce) +{ + struct intel_gt *gt = guc_to_gt(guc); + struct drm_i915_private *i915 = gt->i915; + struct intel_engine_cs *engine = __context_to_physical_engine(ce); + unsigned long flags; + + spin_lock_irqsave(&guc->submission_state.lock, flags); + /* + * Corner case where if resets happen faster than the error captures + * (selftests, igts that intentionally cause hangs), suppress 2nd the + * error capture. + */ + if (list_empty(&ce->guc_capture_link)) + list_add_tail(&guc->submission_state.capture_list, + &ce->guc_capture_link); + spin_unlock_irqrestore(&guc->submission_state.lock, flags); + + /* + * We do the error capture async as an error capture can allocate + * memory, the reset path must flush the G2H handler in order to seal + * several races, and the memory allocations depend on the reset path + * (circular dependecy if error capture done here in the G2H handler). + * Doing the error capture async should be ok, as (eventually) all + * register state is captured in buffer by the GuC (i.e. it is ok to + * restart the context before the error capture is complete). + * + * FIXME: Long term, fix the error capture to be able to allocate memory + * in a no sleep context 1 page at time so we can do the error capture + * immediately. + */ + queue_work(system_unbound_wq, &guc->submission_state.capture_worker); atomic_inc(&i915->gpu_error.reset_engine_count[engine->uabi_class]); } From patchwork Sat Oct 23 18:05:09 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Brost X-Patchwork-Id: 12579701 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 18C30C433EF for ; Sat, 23 Oct 2021 18:10:10 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CE5CB60ED5 for ; Sat, 23 Oct 2021 18:10:09 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org CE5CB60ED5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 001D46E0E7; Sat, 23 Oct 2021 18:09:54 +0000 (UTC) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by gabe.freedesktop.org (Postfix) with ESMTPS id C6A8789E9E; Sat, 23 Oct 2021 18:09:52 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10146"; a="209566139" X-IronPort-AV: E=Sophos;i="5.87,175,1631602800"; d="scan'208";a="209566139" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Oct 2021 11:09:52 -0700 X-IronPort-AV: E=Sophos;i="5.87,175,1631602800"; d="scan'208";a="528262362" Received: from jons-linux-dev-box.fm.intel.com ([10.1.27.20]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Oct 2021 11:09:52 -0700 From: Matthew Brost To: , Cc: , Date: Sat, 23 Oct 2021 11:05:09 -0700 Message-Id: <20211023180510.35152-3-matthew.brost@intel.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211023180510.35152-1-matthew.brost@intel.com> References: <20211023180510.35152-1-matthew.brost@intel.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 2/3] drm/i915/guc: Flush G2H work queue during reset X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" It isn't safe to scrub for missing G2H or continue with the reset until all G2H processing is complete. Flush the G2H work queue during reset to ensure it is done running. No need to call the IRQ handler directly either as the scrubbing code can deal with any missing G2H. Signed-off-by: Matthew Brost Reviewed-by: Daniele Ceraolo Spurio --- .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 18 +----------------- 1 file changed, 1 insertion(+), 17 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c index 9a5aeba033e0..5f584283631b 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -1128,8 +1128,6 @@ static void guc_flush_destroyed_contexts(struct intel_guc *guc); void intel_guc_submission_reset_prepare(struct intel_guc *guc) { - int i; - if (unlikely(!guc_submission_initialized(guc))) { /* Reset called during driver load? GuC not yet initialised! */ return; @@ -1145,21 +1143,7 @@ void intel_guc_submission_reset_prepare(struct intel_guc *guc) guc_flush_submissions(guc); guc_flush_destroyed_contexts(guc); - - /* - * Handle any outstanding G2Hs before reset. Call IRQ handler directly - * each pass as interrupt have been disabled. We always scrub for - * outstanding G2H as it is possible for outstanding_submission_g2h to - * be incremented after the context state update. - */ - for (i = 0; i < 4 && atomic_read(&guc->outstanding_submission_g2h); ++i) { - intel_guc_to_host_event_handler(guc); -#define wait_for_reset(guc, wait_var) \ - intel_guc_wait_for_pending_msg(guc, wait_var, false, (HZ / 20)) - do { - wait_for_reset(guc, &guc->outstanding_submission_g2h); - } while (!list_empty(&guc->ct.requests.incoming)); - } + flush_work(&guc->ct.requests.worker); scrub_guc_desc_for_outstanding_g2h(guc); } From patchwork Sat Oct 23 18:05:10 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Brost X-Patchwork-Id: 12579705 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 376AFC433FE for ; Sat, 23 Oct 2021 18:10:12 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0200060E9C for ; Sat, 23 Oct 2021 18:10:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0200060E9C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 663F76E84D; Sat, 23 Oct 2021 18:09:55 +0000 (UTC) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by gabe.freedesktop.org (Postfix) with ESMTPS id F041589FAD; Sat, 23 Oct 2021 18:09:52 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10146"; a="209566140" X-IronPort-AV: E=Sophos;i="5.87,175,1631602800"; d="scan'208";a="209566140" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Oct 2021 11:09:52 -0700 X-IronPort-AV: E=Sophos;i="5.87,175,1631602800"; d="scan'208";a="528262365" Received: from jons-linux-dev-box.fm.intel.com ([10.1.27.20]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Oct 2021 11:09:52 -0700 From: Matthew Brost To: , Cc: , Date: Sat, 23 Oct 2021 11:05:10 -0700 Message-Id: <20211023180510.35152-4-matthew.brost@intel.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211023180510.35152-1-matthew.brost@intel.com> References: <20211023180510.35152-1-matthew.brost@intel.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 3/3] drm/i915/guc: Refcount context during error capture X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" From: John Harrison When i915 receives a context reset notification from GuC, it triggers an error capture before resetting any outstanding requsts of that context. Unfortunately, the error capture is not a time bound operation. In certain situations it can take a long time, particularly when multiple large LMEM buffers must be read back and eoncoded. If this delay is longer than other timeouts (heartbeat, test recovery, etc.) then a full GT reset can be triggered in the middle. That can result in the context being reset by GuC actually being destroyed before the error capture completes and the GuC submission code resumes. Thus, the GuC side can start dereferencing stale pointers and Bad Things ensue. So add a refcount get of the context during the entire reset operation. That way, the context can't be destroyed part way through no matter what other resets or user interactions occur. v2: (Matthew Brost) - Update patch to work with async error capture Signed-off-by: John Harrison Signed-off-by: Matthew Brost Reviewed-by: Matthew Brost --- .../gpu/drm/i915/gt/uc/intel_guc_submission.c | 24 +++++++++++++++++-- 1 file changed, 22 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c index 5f584283631b..846c3dfcf146 100644 --- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c +++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c @@ -3662,6 +3662,8 @@ static void capture_worker_func(struct work_struct *w) with_intel_runtime_pm(&i915->runtime_pm, wakeref) i915_capture_error_state(gt, ce->engine->mask); + intel_context_put(ce); + if (!list_empty(&guc->submission_state.capture_list)) queue_work(system_unbound_wq, &guc->submission_state.capture_worker); @@ -3711,7 +3713,7 @@ static void guc_context_replay(struct intel_context *ce) tasklet_hi_schedule(&sched_engine->tasklet); } -static void guc_handle_context_reset(struct intel_guc *guc, +static bool guc_handle_context_reset(struct intel_guc *guc, struct intel_context *ce) { trace_intel_context_reset(ce); @@ -3724,7 +3726,11 @@ static void guc_handle_context_reset(struct intel_guc *guc, !context_blocked(ce))) { capture_error_state(guc, ce); guc_context_replay(ce); + + return false; } + + return true; } int intel_guc_context_reset_process_msg(struct intel_guc *guc, @@ -3732,6 +3738,7 @@ int intel_guc_context_reset_process_msg(struct intel_guc *guc, { struct intel_context *ce; int desc_idx; + unsigned long flags; if (unlikely(len != 1)) { drm_err(&guc_to_gt(guc)->i915->drm, "Invalid length %u", len); @@ -3739,11 +3746,24 @@ int intel_guc_context_reset_process_msg(struct intel_guc *guc, } desc_idx = msg[0]; + + /* + * The context lookup uses the xarray but lookups only require an RCU lock + * not the full spinlock. So take the lock explicitly and keep it until the + * context has been reference count locked to ensure it can't be destroyed + * asynchronously until the reset is done. + */ + xa_lock_irqsave(&guc->context_lookup, flags); ce = g2h_context_lookup(guc, desc_idx); + if (ce) + intel_context_get(ce); + xa_unlock_irqrestore(&guc->context_lookup, flags); + if (unlikely(!ce)) return -EPROTO; - guc_handle_context_reset(guc, ce); + if (guc_handle_context_reset(guc, ce)) + intel_context_put(ce); return 0; }