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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 3ED44C5519F for ; Thu, 19 Nov 2020 02:40:00 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 9117B246B8 for ; Thu, 19 Nov 2020 02:39:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9117B246B8 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 hemlock.osuosl.org (Postfix) with ESMTP id 080CC872F7; Thu, 19 Nov 2020 02:39:59 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 5py87m6G4DRB; Thu, 19 Nov 2020 02:39:58 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by hemlock.osuosl.org (Postfix) with ESMTP id 47ED8872F1; Thu, 19 Nov 2020 02:39:58 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 3CEC5C0891; Thu, 19 Nov 2020 02:39:58 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 3843FC07FF for ; Thu, 19 Nov 2020 02:39:57 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 26671864F2 for ; Thu, 19 Nov 2020 02:39:57 +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 WEAJ_kOtY5Ap for ; Thu, 19 Nov 2020 02:39:55 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by fraxinus.osuosl.org (Postfix) with ESMTPS id 9E6AE8648E for ; Thu, 19 Nov 2020 02:39:55 +0000 (UTC) IronPort-SDR: JrHtf+OHeqP8PiAb1GxJuS0oxdkcDBKnvRBC0eYvrVJYbcUD77+H+m1TAVsELtDt5rbDJ0bcAA wXD/EfVbuCuw== X-IronPort-AV: E=McAfee;i="6000,8403,9809"; a="158993007" X-IronPort-AV: E=Sophos;i="5.77,489,1596524400"; d="scan'208";a="158993007" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Nov 2020 18:39:54 -0800 IronPort-SDR: BBenq/SihesJuC5zUQrFMO0X4viqEH0dctidJ2WXPZ5JLGDNZbjFiU2s/XHaVqQep32MF37lZD /UhtlFfFTLUg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.77,489,1596524400"; d="scan'208";a="431084885" Received: from allen-box.sh.intel.com (HELO [10.239.159.28]) ([10.239.159.28]) by fmsmga001.fm.intel.com with ESMTP; 18 Nov 2020 18:39:52 -0800 Subject: Re: [Patch V8 3/3] iommu: Document usage of "/sys/kernel/iommu_groups//type" file To: Will Deacon , Ashok Raj References: <20200925190620.18732-1-ashok.raj@intel.com> <20200925190620.18732-4-ashok.raj@intel.com> <20201118135137.GA2177@willie-the-truck> From: Lu Baolu Message-ID: <7eeae289-070f-c5c9-aff5-edbb8437ef69@linux.intel.com> Date: Thu, 19 Nov 2020 10:32:43 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201118135137.GA2177@willie-the-truck> Content-Language: en-US Cc: Will Deacon , iommu@lists.linux-foundation.org, 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" Hi Will, On 11/18/20 9:51 PM, Will Deacon wrote: > On Fri, Sep 25, 2020 at 12:06:20PM -0700, Ashok Raj wrote: >> From: Sai Praneeth Prakhya >> >> 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 >> Cc: Sohil Mehta >> Cc: Robin Murphy >> Cc: Jacob Pan >> Reviewed-by: Lu Baolu >> 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..effde9d23f4f 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: September 2020 >> +KernelVersion: v5.10 > > ^^ Please can you update these two lines? Sure. > >> +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 > > Can we avoid assuming gender here and just use "they" instead of "he", please? > Same thing for the "Caution" note below. Yes, absolutely. > >> + just a write only value. > > I can't figure out from this description what string is returned to > userspace in the case that the group is configured as blocked or unmanaged. This series only enables switching a default domain in use between DMA and IDENTITY. Other cases will result in write failures. > >> + Note: >> + ----- >> + A group type could be modified only when > > s/could be/may be/ > >> + 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. > > Thanks, > > Will Best regards, baolu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu