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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7F29C43334 for ; Thu, 23 Jun 2022 04:43:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231963AbiFWEn3 (ORCPT ); Thu, 23 Jun 2022 00:43:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241110AbiFWDik (ORCPT ); Wed, 22 Jun 2022 23:38:40 -0400 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CE10435271 for ; Wed, 22 Jun 2022 20:38:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655955519; x=1687491519; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=U5JwulRGEY1I1BJUk8tkPc0NZfI5FzapZ/tvQYnIU7A=; b=L6TQ795FlAUEmi45WH7cVPx001dKc11mPcKdjeFpStuMaqF1RrkgG4yy DP2S+MKNaniSQwufKomiW8xtYScyLBGZFIz+YBqTImOqOvq8mQq3jXMzo v2fpSUi3eyzI9f9QGrq2LYds37+r5M0pfnoryQHxDg9qfzGcRwrpjBD5h AO3OlbV9wYrxQW/DNNN6n0rsEpFSBpH/j3ytsOPlYGPOQQeWghO6gKdHc T9s7Ay4IDTyTSUTB6hfNzKbux07M+sYQFd9ibcJ7LkL+wgHBZw6rV4bcf hNzp/lxQuQcqVTyLnLl5mIRZnJEBy+i82reS5WtBtg8vpqooli8EcBt9Y g==; X-IronPort-AV: E=McAfee;i="6400,9594,10386"; a="281342007" X-IronPort-AV: E=Sophos;i="5.92,215,1650956400"; d="scan'208";a="281342007" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2022 20:38:39 -0700 X-IronPort-AV: E=Sophos;i="5.92,215,1650956400"; d="scan'208";a="644525123" Received: from yutaoxu-mobl.ccr.corp.intel.com (HELO [10.249.172.190]) ([10.249.172.190]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2022 20:38:36 -0700 Message-ID: Date: Thu, 23 Jun 2022 11:38:34 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Cc: baolu.lu@linux.intel.com, Steve Wahl , Joerg Roedel , Kyung Min Park , David Woodhouse , Will Deacon , iommu , Kevin Tian , Mike Travis , Dimitri Sivanich , Russ Anderson , Linux List Kernel Mailing Subject: Re: [PATCH v3] iommu/vt-d: Make DMAR_UNITS_SUPPORTED a config setting Content-Language: en-US To: Jerry Snitselaar References: <9d6177ac-802f-eb11-4307-b0e49d8126b5@linux.intel.com> <20220615183650.32075-1-steve.wahl@hpe.com> <96984350-3a04-812a-60f1-a09138014fac@linux.intel.com> <20220623025126.ld45k72c2okodvvk@cantor> From: Baolu Lu In-Reply-To: <20220623025126.ld45k72c2okodvvk@cantor> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/6/23 10:51, Jerry Snitselaar wrote: >> The real problem here is that the iommu sequence ID overflows if >> DMAR_UNITS_SUPPORTED is not big enough. This is purely a software >> implementation issue, I am not sure whether user opt-in when building a >> kernel package could help a lot here. >> > Is this something that could be figured out when parsing the dmar > table? It looks like currently iommu_refcnt[], iommu_did[], and > dmar_seq_ids[] depend on it. That's definitely a better solution. Best regards, baolu