From patchwork Tue Mar 5 14:35:06 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Janusz Krzysztofik X-Patchwork-Id: 13582526 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 C66B9C54E41 for ; Tue, 5 Mar 2024 14:38:21 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 5E41B112B57; Tue, 5 Mar 2024 14:38:16 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=intel.com header.i=@intel.com header.b="WSAJVCN+"; dkim-atps=neutral Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.10]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3AD47112B58; Tue, 5 Mar 2024 14:38:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1709649495; x=1741185495; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=dSbTmoVhJvrjxpkvz1Xr2BX0CfO/pQfB0Ll5jWT27lM=; b=WSAJVCN+ID0pgoD8+9KyZVugFNE04j7i6VxiliEto5H6SYQRAjmJvtSO 3pfcsqvDHpb5ELSlKw/y7oUHLjG6/6XZwpO2+3ePydrKpnlwdLussFJlG 3Mdojcf6Sr+rDiCaRyOawRqN91jvmfjcm/XuVduVDH5ukyaJni6U+HWBp 3lptiajgi3FkZkbOtrs7rARWNMAdnO+GkD45VDvb813HxeUYICHzazaP1 SZJDwM7NICWFE8FSWff4z882WNOdicyLxHmD+FWZ8GvAYvf/wJSp06kLP GyQVghiFMHPO8f94q6vLgxUch3oOWgnIt6WXDegpFpQQ77cWsTuO9vC9D g==; X-IronPort-AV: E=McAfee;i="6600,9927,11003"; a="21662439" X-IronPort-AV: E=Sophos;i="6.06,205,1705392000"; d="scan'208";a="21662439" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by orvoesa102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Mar 2024 06:38:15 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,205,1705392000"; d="scan'208";a="13959926" Received: from jkrzyszt-mobl2.ger.corp.intel.com (HELO jkrzyszt-mobl2.intranet) ([10.213.25.18]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Mar 2024 06:38:12 -0800 From: Janusz Krzysztofik To: intel-gfx@lists.freedesktop.org Cc: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , dri-devel@lists.freedesktop.org, Andi Shyti , Andrzej Hajda , Nirmoy Das , Jonathan Cavitt , =?utf-8?q?Thomas_Hellstr=C3=B6?= =?utf-8?q?m?= , Niranjana Vishwanathapura , Janusz Krzysztofik Subject: [PATCH v7 1/3] drm/i915/vma: Fix UAF on destroy against retire race Date: Tue, 5 Mar 2024 15:35:06 +0100 Message-ID: <20240305143747.335367-6-janusz.krzysztofik@linux.intel.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240305143747.335367-5-janusz.krzysztofik@linux.intel.com> References: <20240305143747.335367-5-janusz.krzysztofik@linux.intel.com> MIME-Version: 1.0 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" Object debugging tools were sporadically reporting illegal attempts to free a still active i915 VMA object when parking a GT 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. 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"). 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. Those wakerefs are released asynchronously to VMA deactivation. Fix the issue by getting a wakeref for the VMA's GT 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. Also, to avoid circular locking dependency, take care of acquiring the wakeref before VM mutex when both are needed. v7: Add inline comments with justifications for: - using untracked variants of intel_gt_pm_get/put() (Nirmoy), - using async variant of _put(), - not getting the wakeref in case of a global GTT, - always getting the first wakeref outside vm->mutex. v6: Since __i915_vma_active/retire() callbacks are not serialized, storing a wakeref tracking handle inside struct i915_vma is not safe, and there is no other good place for that. Use untracked variants of intel_gt_pm_get/put_async(). v5: Replace "tile" with "GT" across commit description (Rodrigo), - avoid mentioning multi-GT case in commit description (Rodrigo), - explain why we need to take a temporary wakeref unconditionally inside i915_vma_pin_ww() (Rodrigo). 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: Rodrigo Vivi Cc: stable@vger.kernel.org # v5.19+ Reviewed-by: Nirmoy Das --- drivers/gpu/drm/i915/i915_vma.c | 50 ++++++++++++++++++++++++++++----- 1 file changed, 43 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c index d09aad34ba37f..b70715b1411d6 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 +104,42 @@ 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; + + /* + * Exclude global GTT VMA from holding a GT wakeref + * while active, otherwise GPU never goes idle. + */ + if (!i915_vma_is_ggtt(vma)) { + /* + * Since we and our _retire() counterpart can be + * called asynchronously, storing a wakeref tracking + * handle inside struct i915_vma is not safe, and + * there is no other good place for that. Hence, + * use untracked variants of intel_gt_pm_get/put(). + */ + intel_gt_pm_get_untracked(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)) { + /* + * Since we can be called from atomic contexts, + * use an async variant of intel_gt_pm_put(). + */ + intel_gt_pm_put_async_untracked(vma->vm->gt); + } + + i915_vma_put(vma); } static struct i915_vma * @@ -1404,7 +1435,7 @@ 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 +1455,14 @@ 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); + /* + * In case of a global GTT, we must hold a runtime-pm wakeref + * while global PTEs are updated. In other cases, we hold + * the rpm reference while the VMA is active. Since runtime + * resume may require allocations, which are forbidden inside + * vm->mutex, get the first rpm wakeref outside of the mutex. + */ + wakeref = intel_runtime_pm_get(&vma->vm->i915->runtime_pm); if (flags & vma->vm->bind_async_flags) { /* lock VM */ @@ -1561,8 +1598,7 @@ 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);