From patchwork Thu Jan 23 07:40:40 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 11346909 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 0DE0013A4 for ; Thu, 23 Jan 2020 07:40:59 +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 CB0A224125 for ; Thu, 23 Jan 2020 07:40:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CB0A224125 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 629266F9BA; Thu, 23 Jan 2020 07:40:58 +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 D111B6F9BA for ; Thu, 23 Jan 2020 07:40:56 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 19978082-1500050 for multiple; Thu, 23 Jan 2020 07:40:41 +0000 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Thu, 23 Jan 2020 07:40:40 +0000 Message-Id: <20200123074040.1212192-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200122210216.912207-1-chris@chris-wilson.co.uk> References: <20200122210216.912207-1-chris@chris-wilson.co.uk> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] drm/i915/gt: Poison GTT scratch pages 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" Using a clear page for scratch means that we have relatively benign errors in case it is accidentally used, but that can be rather too benign for debugging. If we poison the scratch, ideally it quickly results in an obvious error. Suggested-by: Mika Kuoppala Signed-off-by: Chris Wilson Cc: Mika Kuoppala --- .../drm/i915/gem/selftests/i915_gem_context.c | 30 ++++++++++++++++++- drivers/gpu/drm/i915/gt/intel_gtt.c | 19 ++++++++++++ 2 files changed, 48 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c index 7fc46861a54d..62c2babf2bd3 100644 --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_context.c @@ -1686,6 +1686,24 @@ static int read_from_scratch(struct i915_gem_context *ctx, return err; } +static int check_scratch_page(struct i915_gem_context *ctx, u32 *out) +{ + struct page *page = ctx_vm(ctx)->scratch[0].base.page; + unsigned long size = 1ul << (ctx_vm(ctx)->scratch_order + PAGE_SHIFT); + u32 *vaddr; + int err = 0; + + vaddr = kmap(page); + memcpy(out, vaddr, sizeof(*out)); + if (memchr_inv(vaddr, *out, size)) { + pr_err("Inconsistent initial state of scratch page!\n"); + err = -EINVAL; + } + kunmap(page); + + return err; +} + static int igt_vm_isolation(void *arg) { struct drm_i915_private *i915 = arg; @@ -1696,6 +1714,7 @@ static int igt_vm_isolation(void *arg) I915_RND_STATE(prng); struct file *file; u64 vm_total; + u32 expected; int err; if (INTEL_GEN(i915) < 7) @@ -1720,12 +1739,21 @@ static int igt_vm_isolation(void *arg) goto out_file; } + /* Read the initial state of the scratch page */ + err = check_scratch_page(ctx_a, &expected); + if (err) + goto out_file; + ctx_b = live_context(i915, file); if (IS_ERR(ctx_b)) { err = PTR_ERR(ctx_b); goto out_file; } + err = check_scratch_page(ctx_b, &expected); + if (err) + goto out_file; + /* We can only test vm isolation, if the vm are distinct */ if (ctx_vm(ctx_a) == ctx_vm(ctx_b)) goto out_file; @@ -1760,7 +1788,7 @@ static int igt_vm_isolation(void *arg) if (err) goto out_file; - if (value) { + if (value != expected) { pr_err("%s: Read %08x from scratch (offset 0x%08x_%08x), after %lu reads!\n", engine->name, value, upper_32_bits(offset), diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.c b/drivers/gpu/drm/i915/gt/intel_gtt.c index 45d8e0019a8e..804da478d8f9 100644 --- a/drivers/gpu/drm/i915/gt/intel_gtt.c +++ b/drivers/gpu/drm/i915/gt/intel_gtt.c @@ -299,6 +299,14 @@ fill_page_dma(const struct i915_page_dma *p, const u64 val, unsigned int count) kunmap_atomic(memset64(kmap_atomic(p->page), val, count)); } +static void poison_scratch_page(struct page *page, unsigned long size) +{ + if (!IS_ENABLED(CONFIG_DRM_I915_DEBUG_GEM)) + return; + + kunmap_atomic(memset(kmap_atomic(page), POISON_FREE, size)); +} + int setup_scratch_page(struct i915_address_space *vm, gfp_t gfp) { unsigned long size; @@ -331,6 +339,17 @@ int setup_scratch_page(struct i915_address_space *vm, gfp_t gfp) if (unlikely(!page)) goto skip; + /* + * Use a non-zero scratch page for debugging. + * + * We want a value that should be reasonably obvious + * to spot in the error state, while also causing a GPU hang + * if executed. We prefer using a clear page in production, so + * should it ever be accidentally used, the effect should be + * fairly benign. + */ + poison_scratch_page(page, size); + addr = dma_map_page_attrs(vm->dma, page, 0, size, PCI_DMA_BIDIRECTIONAL,