From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-17.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AF526C8448F for ; Thu, 3 Dec 2020 13:39:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B5F6420449 for ; Thu, 3 Dec 2020 13:39:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437205AbgLCNgP (ORCPT ); Thu, 3 Dec 2020 08:36:15 -0500 Received: from mail.kernel.org ([198.145.29.99]:48858 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2436667AbgLCNak (ORCPT ); Thu, 3 Dec 2020 08:30:40 -0500 From: Sasha Levin Authentication-Results: mail.kernel.org; dkim=permerror (bad message/signature format) To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: John Stultz , Robin Murphy , Will Deacon , Andy Gross , Maulik Shah , Bjorn Andersson , Saravana Kannan , Marc Zyngier , Lina Iyer , iommu@lists.linux-foundation.org, linux-arm-msm , Sasha Levin , linux-arm-kernel@lists.infradead.org Subject: [PATCH AUTOSEL 5.9 22/39] arm-smmu-qcom: Ensure the qcom_scm driver has finished probing Date: Thu, 3 Dec 2020 08:28:16 -0500 Message-Id: <20201203132834.930999-22-sashal@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20201203132834.930999-1-sashal@kernel.org> References: <20201203132834.930999-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: John Stultz [ Upstream commit 72b55c96f3a5ae6e486c20b5dacf5114060ed042 ] Robin Murphy pointed out that if the arm-smmu driver probes before the qcom_scm driver, we may call qcom_scm_qsmmu500_wait_safe_toggle() before the __scm is initialized. Now, getting this to happen is a bit contrived, as in my efforts it required enabling asynchronous probing for both drivers, moving the firmware dts node to the end of the dtsi file, as well as forcing a long delay in the qcom_scm_probe function. With those tweaks we ran into the following crash: [ 2.631040] arm-smmu 15000000.iommu: Stage-1: 48-bit VA -> 48-bit IPA [ 2.633372] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 ... [ 2.633402] [0000000000000000] user address but active_mm is swapper [ 2.633409] Internal error: Oops: 96000005 [#1] PREEMPT SMP [ 2.633415] Modules linked in: [ 2.633427] CPU: 5 PID: 117 Comm: kworker/u16:2 Tainted: G W 5.10.0-rc1-mainline-00025-g272a618fc36-dirty #3971 [ 2.633430] Hardware name: Thundercomm Dragonboard 845c (DT) [ 2.633448] Workqueue: events_unbound async_run_entry_fn [ 2.633456] pstate: 80c00005 (Nzcv daif +PAN +UAO -TCO BTYPE=--) [ 2.633465] pc : qcom_scm_qsmmu500_wait_safe_toggle+0x78/0xb0 [ 2.633473] lr : qcom_smmu500_reset+0x58/0x78 [ 2.633476] sp : ffffffc0105a3b60 ... [ 2.633567] Call trace: [ 2.633572] qcom_scm_qsmmu500_wait_safe_toggle+0x78/0xb0 [ 2.633576] qcom_smmu500_reset+0x58/0x78 [ 2.633581] arm_smmu_device_reset+0x194/0x270 [ 2.633585] arm_smmu_device_probe+0xc94/0xeb8 [ 2.633592] platform_drv_probe+0x58/0xa8 [ 2.633597] really_probe+0xec/0x398 [ 2.633601] driver_probe_device+0x5c/0xb8 [ 2.633606] __driver_attach_async_helper+0x64/0x88 [ 2.633610] async_run_entry_fn+0x4c/0x118 [ 2.633617] process_one_work+0x20c/0x4b0 [ 2.633621] worker_thread+0x48/0x460 [ 2.633628] kthread+0x14c/0x158 [ 2.633634] ret_from_fork+0x10/0x18 [ 2.633642] Code: a9034fa0 d0007f73 29107fa0 91342273 (f9400020) To avoid this, this patch adds a check on qcom_scm_is_available() in the qcom_smmu_impl_init() function, returning -EPROBE_DEFER if its not ready. This allows the driver to try to probe again later after qcom_scm has finished probing. Reported-by: Robin Murphy Signed-off-by: John Stultz Reviewed-by: Robin Murphy Cc: Robin Murphy Cc: Will Deacon Cc: Andy Gross Cc: Maulik Shah Cc: Bjorn Andersson Cc: Saravana Kannan Cc: Marc Zyngier Cc: Lina Iyer Cc: iommu@lists.linux-foundation.org Cc: linux-arm-msm Link: https://lore.kernel.org/r/20201112220520.48159-1-john.stultz@linaro.org Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c index be4318044f96c..702fbaa6c9ada 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c @@ -69,6 +69,10 @@ struct arm_smmu_device *qcom_smmu_impl_init(struct arm_smmu_device *smmu) { struct qcom_smmu *qsmmu; + /* Check to make sure qcom_scm has finished probing */ + if (!qcom_scm_is_available()) + return ERR_PTR(-EPROBE_DEFER); + qsmmu = devm_kzalloc(smmu->dev, sizeof(*qsmmu), GFP_KERNEL); if (!qsmmu) return ERR_PTR(-ENOMEM); -- 2.27.0