From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AF651288505 for ; Mon, 13 Jul 2026 01:57:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783907823; cv=none; b=qRHGFeBys0/yxr6LfR/w7LdX6v3tDYVaUTz6X4qrm7vN/Ngk7ua+T6pyClZ2W9H0QnzhA64V4iy5HWJrpkQEobPbponWLcmbcWr/cHK2Pd30A5PKAWbUoZyD+FKxNDGOPAqd0wO/Fr00NrcImRx+mRF/h5kuVmMmX3xFMCJmkEI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783907823; c=relaxed/simple; bh=x16NHzTAXMochQ5afCRZ2hNgR3hhog0+bvy7u90uH8Y=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Uc/Hmqlu12rAZ8PjfJfEBu/bD9b9B1FRbfEHhKo+pdph3FRSSftq3Mv252omkE8W6NNiMUvrPDEwlAZB5uUTsquznN0OxwO6Y6P56xsFLCiYW4NubWKLuMb3Ckzrn281GwCliky/MWwB+HTzgluUTAfptl07Ba8pQB6LTyNSINM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=N+G5W2r4; arc=none smtp.client-ip=192.198.163.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="N+G5W2r4" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1783907821; x=1815443821; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=x16NHzTAXMochQ5afCRZ2hNgR3hhog0+bvy7u90uH8Y=; b=N+G5W2r45KTVdGvq1VDDEtVM0UyxehKgAVzKOtQ1AlCnjAEG2s3amgtj zdE7chWSInncCyc8zFWWt7k8Fp3vBnMcqM/PloLdeyzfTG3d6iDUzLLTR vYP91NxsN5rhBoeCUxCyPavjvFYG0pNIuxSco1ySVcTTNlKA7sfJTva/G NwTGiyVoO6DFdaHSWBmBygLchF+iTpYDxZKTeOktXKL13cAeWQkKXCSo6 DLV5NXhIja62gLKdcu+u0SlLeP3oCEFdOV07ZxdO0EO/5f9y0YUUtgfX+ 4svn7yK4KHBFt62d9z3WqDlwyQoClv6cI1ueSWi4SJXdRlccA+p4yKixA A==; X-CSE-ConnectionGUID: ncXv0F0YQyWapCC2nyYoqQ== X-CSE-MsgGUID: l5Mm81tUTYODih6u4iPXSg== X-IronPort-AV: E=McAfee;i="6800,10657,11841"; a="88340080" X-IronPort-AV: E=Sophos;i="6.25,154,1779174000"; d="scan'208";a="88340080" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by fmvoesa106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jul 2026 18:57:00 -0700 X-CSE-ConnectionGUID: KHL5G0gCSwu610MMDkoghA== X-CSE-MsgGUID: HoCWIW4RSNe6gEKpwAEGXw== X-ExtLoop1: 1 Received: from allen-sbox.sh.intel.com (HELO [10.239.159.30]) ([10.239.159.30]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jul 2026 18:56:59 -0700 Message-ID: <775d3d16-f43d-4a5f-9629-4912a4cabd91@linux.intel.com> Date: Mon, 13 Jul 2026 09:55:16 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] iommu/vt-d: Disable IOMMU by default on Lenovo ThinkPad P50s To: Oliver Lin Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org, joro@8bytes.org, robin.murphy@arm.com, will@kernel.org References: <20260703092348.17583-1-oliver@liuxiaozhen.dev> Content-Language: en-US From: Baolu Lu In-Reply-To: <20260703092348.17583-1-oliver@liuxiaozhen.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/3/26 17:23, Oliver Lin wrote: > Lenovo ThinkPad P50s exhibits firmware issues when Intel VT-d is enabled. Why not fix the firmware issue instead? > With IOMMU enabled, the system reports DMAR DMA faults during boot, > TPM 2.0 (tpm_crb) fails to initialize with timeout errors, and the > machine cannot shut down or resume reliably. Booting with > intel_iommu=off avoids these issues. So the driver already provides a command-line workaround for this firmware issue, right? Why is a hardcoded kernel quirk necessary here? > > Add a DMI quirk to disable Intel IOMMU by default on this platform. > If the user explicitly specifies intel_iommu=on on the kernel command > line, do not apply the quirk so that VT-d can still be enabled for > testing and debugging. > > Signed-off-by: Oliver Lin > --- > drivers/iommu/intel/iommu.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) [..snip...] Thanks, baolu