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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham 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 B60A1C433E0 for ; Mon, 8 Jun 2020 01:55:02 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 76B982063A for ; Mon, 8 Jun 2020 01:55:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 76B982063A Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 5219485BD3; Mon, 8 Jun 2020 01:55:02 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from fraxinus.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id iWJ3t7YzyDiw; Mon, 8 Jun 2020 01:55:01 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id AC5B0854CC; Mon, 8 Jun 2020 01:55:01 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 870B9C07FF; Mon, 8 Jun 2020 01:55:01 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 633E0C016F for ; Mon, 8 Jun 2020 01:54:59 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 5F59285A1D for ; Mon, 8 Jun 2020 01:54:59 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id HLOD3UvfdbIq for ; Mon, 8 Jun 2020 01:54:58 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by whitealder.osuosl.org (Postfix) with ESMTPS id 7780D866FC for ; Mon, 8 Jun 2020 01:54:58 +0000 (UTC) IronPort-SDR: SEyDMYfpFup2ICVA5qMdAEHbp6zTDM7OTgSVG0G5DylUmy8UqFQmsfafOruZQyvCvDlYoZb37M YeHGlB7hHccA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Jun 2020 18:54:57 -0700 IronPort-SDR: eGgx29V6/mGhV4quDChJ1q7EOPCwEM2ZGozBumO+2Pq6Gkp36lihZV1XF20/kKgyJe0cy6H7J/ p0+xKG2tnyYg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,486,1583222400"; d="scan'208";a="295297451" Received: from allen-box.sh.intel.com (HELO [10.239.159.139]) ([10.239.159.139]) by fmsmga004.fm.intel.com with ESMTP; 07 Jun 2020 18:54:53 -0700 Subject: Re: [PATCH V4 3/3] iommu: Document usage of "/sys/kernel/iommu_groups//type" file To: Sai Praneeth Prakhya , iommu@lists.linux-foundation.org References: <24102f22824b26cf4fa6ec1c84d176110b21c574.1591290586.git.sai.praneeth.prakhya@intel.com> From: Lu Baolu Message-ID: <41050628-4dd2-c31b-e870-36a40c5d9c7b@linux.intel.com> Date: Mon, 8 Jun 2020 09:50:58 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <24102f22824b26cf4fa6ec1c84d176110b21c574.1591290586.git.sai.praneeth.prakhya@intel.com> Content-Language: en-US Cc: Ashok Raj , Will Deacon , Robin Murphy , Christoph Hellwig X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 6/5/20 9:32 AM, Sai Praneeth Prakhya wrote: > The default domain type of an iommu group can be changed by writing to > "/sys/kernel/iommu_groups//type" file. Hence, document it's usage > and more importantly spell out its limitations. > > Cc: Christoph Hellwig > Cc: Joerg Roedel > Cc: Ashok Raj > Cc: Will Deacon > Cc: Lu Baolu Reviewed-by: Lu Baolu Best regards, baolu > Cc: Sohil Mehta > Cc: Robin Murphy > Cc: Jacob Pan > Signed-off-by: Sai Praneeth Prakhya > --- > .../ABI/testing/sysfs-kernel-iommu_groups | 30 +++++++++++++++++++ > 1 file changed, 30 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-kernel-iommu_groups b/Documentation/ABI/testing/sysfs-kernel-iommu_groups > index 017f5bc3920c..a498daffeb0c 100644 > --- a/Documentation/ABI/testing/sysfs-kernel-iommu_groups > +++ b/Documentation/ABI/testing/sysfs-kernel-iommu_groups > @@ -33,3 +33,33 @@ Description: In case an RMRR is used only by graphics or USB devices > it is now exposed as "direct-relaxable" instead of "direct". > In device assignment use case, for instance, those RMRR > are considered to be relaxable and safe. > + > +What: /sys/kernel/iommu_groups//type > +Date: June 2020 > +KernelVersion: v5.8 > +Contact: Sai Praneeth Prakhya > +Description: Let the user know the type of default domain in use by iommu > + for this group. A privileged user could request kernel to change > + the group type by writing to this file. Presently, only three > + types are supported > + 1. DMA: All the DMA transactions from the device in this group > + are translated by the iommu. > + 2. identity: All the DMA transactions from the device in this > + group are *not* translated by the iommu. > + 3. auto: Change to the type the device was booted with. When the > + user reads the file he would never see "auto". This is > + just a write only value. > + Note: > + ----- > + A group type could be modified only when > + 1. The group has *only* one device > + 2. The device in the group is not bound to any device driver. > + So, the user must first unbind the appropriate driver and > + then change the default domain type. > + Caution: > + -------- > + Unbinding a device driver will take away the driver's control > + over the device and if done on devices that host root file > + system could lead to catastrophic effects (the user might > + need to reboot the machine to get it to normal state). So, it's > + expected that the user understands what he is doing. > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu