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[209.85.220.65]) by mx.google.com with SMTPS id o198sor3415590pfd.60.2020.11.12.14.05.24 for (Google Transport Security); Thu, 12 Nov 2020 14:05:24 -0800 (PST) Received-SPF: pass (google.com: domain of john.stultz@linaro.org designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=pinvfDrD; spf=pass (google.com: domain of john.stultz@linaro.org designates 209.85.220.65 as permitted sender) smtp.mailfrom=john.stultz@linaro.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id; bh=slkfJzLThfnq7dp6T3hHJaR873aqxgp2bKc6BsX9aV0=; b=pinvfDrDrB6ctJHlCeWOYTxu5y04SDYjFnGR3GwyyCDGTbeCvS4VYROYFBfSi2WhCz KW8hlBAR3YFiOuLUNYTwBi+g9xr/VGgaTV2vWsnITUq9ZQfhas5xNg3/Wvr7gQtYykWF C3B5YcxnleGCEfOn0Zfx+3JoXDzz31JRxEVdZGfFXjiWK2kPeZShiRBZNDNR2dkccIHZ 09dI+FJpIwdTrg4w417/w3FRyR1QxjvsUHtxlGdjbN5GPCV2rGhtJCEskGqnB02OcG1R rmfQpkDGFfpQI0yg5p5VTLNbwQf16YFY5P5b+a5jjZmN8Lo4xmNb2kaSEa4ytkn2SBwv Nuzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=slkfJzLThfnq7dp6T3hHJaR873aqxgp2bKc6BsX9aV0=; b=P1sdklKqgbcZKkH+kK4Eh4DpOEwOD6sOPt6zOC/8qZ4IkosScMD+KQkbg2DaALmG9a gKj3RiebhECq9nkwCIeBMpJSndTrvuLSCwvEm7il23c0YgWbpEfZjxLQbRMgjXOvZ4L5 KTrr1ck89PJVB/hF4ak4vHJMon24Ati6x1VXXhkvjcM9hAxcVUxF7sXb7v5GF87UuazM uYRwyqQ4UwDp467Z7Cd2ZQ5UB6vQ+TvvYZ2/wmH1JtD/K3kLHa9Fb6xmT6DJC0IM6t0Y 8spvDOYEG+xaYWLKm4wGs0aRGK2P379rP3+VIsm0d3KKpVdsEBoOAw5L4R80qjG5frRf fRLw== X-Gm-Message-State: AOAM533m26oiiONXWuC7ixGudGMgaPs9hYrfr6nEfizW0rDziMjTVXFP W0zC9lfTJHtO7PmKnMDJb9I/pkIq X-Google-Smtp-Source: ABdhPJxfhZH/q5hThNOBnnLYhFe96bQakZ1Aix4ClMUJBa7gSEj5LlM3tIe7QGLlxguFwIACTomUHQ== X-Received: by 2002:aa7:9888:0:b029:18b:a9e2:dc7a with SMTP id r8-20020aa798880000b029018ba9e2dc7amr1335896pfl.67.1605218723741; Thu, 12 Nov 2020 14:05:23 -0800 (PST) Return-Path: Received: from localhost.localdomain ([2601:1c2:680:1319:692:26ff:feda:3a81]) by smtp.gmail.com with ESMTPSA id mv5sm7638976pjb.42.2020.11.12.14.05.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Nov 2020 14:05:22 -0800 (PST) From: John Stultz To: lkml 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 Subject: [RESEND][PATCH 1/2] arm-smmu-qcom: Ensure the qcom_scm driver has finished probing Date: Thu, 12 Nov 2020 22:05:19 +0000 Message-Id: <20201112220520.48159-1-john.stultz@linaro.org> X-Mailer: git-send-email 2.17.1 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. 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 Reported-by: Robin Murphy Signed-off-by: John Stultz --- drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c | 4 ++++ 1 file changed, 4 insertions(+) -- 2.17.1 diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c index 66ba4870659f4..ef37ccfa82562 100644 --- a/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c +++ b/drivers/iommu/arm/arm-smmu/arm-smmu-qcom.c @@ -159,6 +159,10 @@ 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);