From patchwork Fri May 8 09:29:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11536133 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 58C9614B4 for ; Fri, 8 May 2020 09:30:05 +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 3EAA32070B for ; Fri, 8 May 2020 09:30:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3EAA32070B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=chris-wilson.co.uk Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=intel-gfx-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id E192E6EAC3; Fri, 8 May 2020 09:30:03 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id 813506EAC4 for ; Fri, 8 May 2020 09:30:02 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from build.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 21148442-1500050 for multiple; Fri, 08 May 2020 10:29:37 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Fri, 8 May 2020 10:29:27 +0100 Message-Id: <20200508092933.738-3-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200508092933.738-1-chris@chris-wilson.co.uk> References: <20200508092933.738-1-chris@chris-wilson.co.uk> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 3/9] drm/i915: Prevent using semaphores to chain up to external fences 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: , Cc: Chris Wilson Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" The downside of using semaphores is that we lose metadata passing along the signaling chain. This is particularly nasty when we need to pass along a fatal error such as EFAULT or EDEADLK. For fatal errors we want to scrub the request before it is executed, which means that we cannot preload the request onto HW and have it wait upon a semaphore. Signed-off-by: Chris Wilson Reviewed-by: Mika Kuoppala --- drivers/gpu/drm/i915/i915_request.c | 26 +++++++++++++++++++++ drivers/gpu/drm/i915/i915_scheduler_types.h | 1 + 2 files changed, 27 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c index 94189c7d43cd..f0f9393e2ade 100644 --- a/drivers/gpu/drm/i915/i915_request.c +++ b/drivers/gpu/drm/i915/i915_request.c @@ -1002,6 +1002,15 @@ emit_semaphore_wait(struct i915_request *to, if (!rcu_access_pointer(from->hwsp_cacheline)) goto await_fence; + /* + * If this or its dependents are waiting on an external fence + * that may fail catastrophically, then we want to avoid using + * sempahores as they bypass the fence signaling metadata, and we + * lose the fence->error propagation. + */ + if (from->sched.flags & I915_SCHED_HAS_EXTERNAL_CHAIN) + goto await_fence; + /* Just emit the first semaphore we see as request space is limited. */ if (already_busywaiting(to) & mask) goto await_fence; @@ -1064,12 +1073,29 @@ i915_request_await_request(struct i915_request *to, struct i915_request *from) return ret; } + if (from->sched.flags & I915_SCHED_HAS_EXTERNAL_CHAIN) + to->sched.flags |= I915_SCHED_HAS_EXTERNAL_CHAIN; + return 0; } +static void mark_external(struct i915_request *rq) +{ + /* + * The downside of using semaphores is that we lose metadata passing + * along the signaling chain. This is particularly nasty when we + * need to pass along a fatal error such as EFAULT or EDEADLK. For + * fatal errors we want to scrub the request before it is executed, + * which means that we cannot preload the request onto HW and have + * it wait upon a semaphore. + */ + rq->sched.flags |= I915_SCHED_HAS_EXTERNAL_CHAIN; +} + static int i915_request_await_external(struct i915_request *rq, struct dma_fence *fence) { + mark_external(rq); return i915_sw_fence_await_dma_fence(&rq->submit, fence, fence->context ? I915_FENCE_TIMEOUT : 0, I915_FENCE_GFP); diff --git a/drivers/gpu/drm/i915/i915_scheduler_types.h b/drivers/gpu/drm/i915/i915_scheduler_types.h index 7186875088a0..6ab2c5289bed 100644 --- a/drivers/gpu/drm/i915/i915_scheduler_types.h +++ b/drivers/gpu/drm/i915/i915_scheduler_types.h @@ -66,6 +66,7 @@ struct i915_sched_node { struct i915_sched_attr attr; unsigned int flags; #define I915_SCHED_HAS_SEMAPHORE_CHAIN BIT(0) +#define I915_SCHED_HAS_EXTERNAL_CHAIN BIT(1) intel_engine_mask_t semaphores; };