From patchwork Mon Jan 22 14:04:42 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Janusz Krzysztofik X-Patchwork-Id: 13525531 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id A1B2BC4725D for ; Mon, 22 Jan 2024 14:10:39 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id F3DDC10EF52; Mon, 22 Jan 2024 14:10:35 +0000 (UTC) Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) by gabe.freedesktop.org (Postfix) with ESMTPS id 1D4B010EF51; Mon, 22 Jan 2024 14:10:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1705932635; x=1737468635; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=5hMM6tw8Hj4p36VWRMe/wtk/W5Jj2d61sdh0gCgRqoU=; b=X4gw+9m5olD8l1hzX8t5wCcLh0QMfDM6i301DBSzby4wi4ubfVYHwCfM fwfjtDM2O5O5+nuGSZsH2dFFIq33BcJq7qTZJIIug1aD7nPbpq/3DQqct JPHJkEBjZ1EoRaD35/zVhfxUYBGN7he/YmEUv/MPlDXFTGTd222jd8M1J 7PKiUDBZMC2E457qj95oS56juV5kgnpsuvAUDK38m7FZrujvf5ZUToErP 6mm6pS0uAithOklEUvdsKVgH/9VuBrJGJpKIwJtP2l6un1cPlyv914e5X hMoCHjA7aT/3bulSAcPT9TMpH8V4PjozkwRQM/ljsPRZjxv48DTg6Ec5o w==; X-IronPort-AV: E=McAfee;i="6600,9927,10961"; a="8313812" X-IronPort-AV: E=Sophos;i="6.05,211,1701158400"; d="scan'208";a="8313812" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jan 2024 06:10:35 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10961"; a="855943792" X-IronPort-AV: E=Sophos;i="6.05,211,1701158400"; d="scan'208";a="855943792" Received: from jkrzyszt-mobl2.ger.corp.intel.com ([10.213.20.214]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jan 2024 06:10:29 -0800 From: Janusz Krzysztofik To: intel-gfx@lists.freedesktop.org Subject: [PATCH v4 1/3] drm/i915/vma: Fix UAF on destroy against retire race Date: Mon, 22 Jan 2024 15:04:42 +0100 Message-ID: <20240122141007.401490-6-janusz.krzysztofik@linux.intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240122141007.401490-5-janusz.krzysztofik@linux.intel.com> References: <20240122141007.401490-5-janusz.krzysztofik@linux.intel.com> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tvrtko Ursulin , Andi Shyti , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Chris Wilson , Andrzej Hajda , dri-devel@lists.freedesktop.org, Daniel Vetter , Rodrigo Vivi , Janusz Krzysztofik , David Airlie , Nirmoy Das Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Object debugging tools were sporadically reporting illegal attempts to free a still active i915 VMA object when parking a GPU tile believed to be idle. [161.359441] ODEBUG: free active (active state 0) object: ffff88811643b958 object type: i915_active hint: __i915_vma_active+0x0/0x50 [i915] [161.360082] WARNING: CPU: 5 PID: 276 at lib/debugobjects.c:514 debug_print_object+0x80/0xb0 ... [161.360304] CPU: 5 PID: 276 Comm: kworker/5:2 Not tainted 6.5.0-rc1-CI_DRM_13375-g003f860e5577+ #1 [161.360314] Hardware name: Intel Corporation Rocket Lake Client Platform/RocketLake S UDIMM 6L RVP, BIOS RKLSFWI1.R00.3173.A03.2204210138 04/21/2022 [161.360322] Workqueue: i915-unordered __intel_wakeref_put_work [i915] [161.360592] RIP: 0010:debug_print_object+0x80/0xb0 ... [161.361347] debug_object_free+0xeb/0x110 [161.361362] i915_active_fini+0x14/0x130 [i915] [161.361866] release_references+0xfe/0x1f0 [i915] [161.362543] i915_vma_parked+0x1db/0x380 [i915] [161.363129] __gt_park+0x121/0x230 [i915] [161.363515] ____intel_wakeref_put_last+0x1f/0x70 [i915] That has been tracked down to be happening when another thread is deactivating the VMA inside __active_retire() helper, after the VMA's active counter has been already decremented to 0, but before deactivation of the VMA's object is reported to the object debugging tool. We could prevent from that race by serializing i915_active_fini() with __active_retire() via ref->tree_lock, but that wouldn't stop the VMA from being used, e.g. from __i915_vma_retire() called at the end of __active_retire(), after that VMA has been already freed by a concurrent i915_vma_destroy() on return from the i915_active_fini(). Then, we should rather fix the issue at the VMA level, not in i915_active. Since __i915_vma_parked() is called from __gt_park() on last put of the GT's wakeref, the issue could be addressed by holding the GT wakeref long enough for __active_retire() to complete before that wakeref is released and the GT parked. A VMA associated with a request doesn't acquire a GT wakeref by itself. Instead, it depends on a wakeref held directly by the request's active intel_context for a GT associated with its VM, and indirectly on that intel_context's engine wakeref if the engine belongs to the same GT as the VMA's VM. In case of single-tile platforms, at least one of those wakerefs is usually held long enough for the request's VMA to be deactivated on time, before it is destroyed on last put of its VM GT wakeref. However, on multi-tile platforms, a request may use a VMA from a tile other than the one that hosts the request's engine, then it is protected only with the intel_context's VM GT wakeref. There was an attempt to fix this issue on 2-tile Meteor Lake by acquiring an extra wakeref for a Primary GT from i915_gem_do_execbuffer() -- see commit f56fe3e91787 ("drm/i915: Fix a VMA UAF for multi-gt platform"). However, it occurred insufficient -- the issue was still reported by CI. That wakeref was released on exit from i915_gem_do_execbuffer(), then potentially before completion of the request and deactivation of its associated VMAs. OTOH, CI reports indicate that single-tile platforms also suffer sporadically from the same race. I believe the issue was introduced by commit d93939730347 ("drm/i915: Remove the vma refcount") which moved a call to i915_active_fini() from a dropped i915_vma_release(), called on last put of the removed VMA kref, to i915_vma_parked() processing path called on last put of a GT wakeref. However, its visibility to the object debugging tool was suppressed by a bug in i915_active that was fixed two weeks later with commit e92eb246feb9 ("drm/i915/active: Fix missing debug object activation"). Fix the issue by getting a wakeref for the VMA's tile when activating it, and putting that wakeref only after the VMA is deactivated. However, exclude global GTT from that processing path, otherwise the GPU never goes idle. Since __i915_vma_retire() may be called from atomic contexts, use async variant of wakeref put. v4: Refresh on top of commit 5e4e06e4087e ("drm/i915: Track gt pm wakerefs") (Andi), - for more easy backporting, split out removal of former insufficient workarounds and move them to separate patches (Nirmoy). - clean up commit message and description a bit. v3: Identify root cause more precisely, and a commit to blame, - identify and drop former workarounds, - update commit message and description. v2: Get the wakeref before VM mutex to avoid circular locking dependency, - drop questionable Fixes: tag. Fixes: d93939730347 ("drm/i915: Remove the vma refcount") Closes: https://gitlab.freedesktop.org/drm/intel/issues/8875 Signed-off-by: Janusz Krzysztofik Cc: Thomas Hellström Cc: Nirmoy Das Cc: Andi Shyti Cc: stable@vger.kernel.org # v5.19+ --- drivers/gpu/drm/i915/i915_vma.c | 26 +++++++++++++++++++------- drivers/gpu/drm/i915/i915_vma_types.h | 1 + 2 files changed, 20 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c index d09aad34ba37f..604d420b9e1fd 100644 --- a/drivers/gpu/drm/i915/i915_vma.c +++ b/drivers/gpu/drm/i915/i915_vma.c @@ -34,6 +34,7 @@ #include "gt/intel_engine.h" #include "gt/intel_engine_heartbeat.h" #include "gt/intel_gt.h" +#include "gt/intel_gt_pm.h" #include "gt/intel_gt_requests.h" #include "gt/intel_tlb.h" @@ -103,12 +104,25 @@ static inline struct i915_vma *active_to_vma(struct i915_active *ref) static int __i915_vma_active(struct i915_active *ref) { - return i915_vma_tryget(active_to_vma(ref)) ? 0 : -ENOENT; + struct i915_vma *vma = active_to_vma(ref); + + if (!i915_vma_tryget(vma)) + return -ENOENT; + + if (!i915_vma_is_ggtt(vma)) + vma->wakeref = intel_gt_pm_get(vma->vm->gt); + + return 0; } static void __i915_vma_retire(struct i915_active *ref) { - i915_vma_put(active_to_vma(ref)); + struct i915_vma *vma = active_to_vma(ref); + + if (!i915_vma_is_ggtt(vma)) + intel_gt_pm_put_async(vma->vm->gt, vma->wakeref); + + i915_vma_put(vma); } static struct i915_vma * @@ -1404,7 +1418,7 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww, struct i915_vma_work *work = NULL; struct dma_fence *moving = NULL; struct i915_vma_resource *vma_res = NULL; - intel_wakeref_t wakeref = 0; + intel_wakeref_t wakeref; unsigned int bound; int err; @@ -1424,8 +1438,7 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww, if (err) return err; - if (flags & PIN_GLOBAL) - wakeref = intel_runtime_pm_get(&vma->vm->i915->runtime_pm); + wakeref = intel_runtime_pm_get(&vma->vm->i915->runtime_pm); if (flags & vma->vm->bind_async_flags) { /* lock VM */ @@ -1561,8 +1574,7 @@ int i915_vma_pin_ww(struct i915_vma *vma, struct i915_gem_ww_ctx *ww, if (work) dma_fence_work_commit_imm(&work->base); err_rpm: - if (wakeref) - intel_runtime_pm_put(&vma->vm->i915->runtime_pm, wakeref); + intel_runtime_pm_put(&vma->vm->i915->runtime_pm, wakeref); if (moving) dma_fence_put(moving); diff --git a/drivers/gpu/drm/i915/i915_vma_types.h b/drivers/gpu/drm/i915/i915_vma_types.h index 64472b7f0e770..f0086fadff4d3 100644 --- a/drivers/gpu/drm/i915/i915_vma_types.h +++ b/drivers/gpu/drm/i915/i915_vma_types.h @@ -264,6 +264,7 @@ struct i915_vma { #define I915_VMA_SCANOUT ((int)BIT(I915_VMA_SCANOUT_BIT)) struct i915_active active; + intel_wakeref_t wakeref; #define I915_VMA_PAGES_BIAS 24 #define I915_VMA_PAGES_ACTIVE (BIT(24) | 1)