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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 85C1DC47420 for ; Fri, 25 Sep 2020 19:06:34 +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 2AD35221E5 for ; Fri, 25 Sep 2020 19:06:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2AD35221E5 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=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 CB76C86D8B; Fri, 25 Sep 2020 19:06:33 +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 s1DAiwQZJ4aQ; Fri, 25 Sep 2020 19:06:31 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id 5504A86D8D; Fri, 25 Sep 2020 19:06:31 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 3B9D8C0891; Fri, 25 Sep 2020 19:06:31 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists.linuxfoundation.org (Postfix) with ESMTP id E8C45C0051 for ; Fri, 25 Sep 2020 19:06:28 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id E34FE872C7 for ; Fri, 25 Sep 2020 19:06:28 +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 EcFkoX0dRBPJ for ; Fri, 25 Sep 2020 19:06:28 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by hemlock.osuosl.org (Postfix) with ESMTPS id 15D0487322 for ; Fri, 25 Sep 2020 19:06:28 +0000 (UTC) IronPort-SDR: eyrXMAZjXt9EaZYYO32OhlepceHsMfHrOgTXx31YmgfAnExHNokmNjUfOpC4vHRKGOOQlq76ws N7GKDnavn7oQ== X-IronPort-AV: E=McAfee;i="6000,8403,9755"; a="162505421" X-IronPort-AV: E=Sophos;i="5.77,303,1596524400"; d="scan'208";a="162505421" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Sep 2020 12:06:27 -0700 IronPort-SDR: hyZXh2U2XdMDR+yitQyAytpiS/aRm/9ZAfMWsKTkUj1p05/5iF3vCMeLcTMdCzQnUQtSDqAr0v WniiPnpZC4Ug== X-IronPort-AV: E=Sophos;i="5.77,303,1596524400"; d="scan'208";a="310944880" Received: from araj-mobl1.jf.intel.com (HELO localhost) ([10.254.96.12]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Sep 2020 12:06:26 -0700 From: Ashok Raj To: Joerg Roedel , iommu@lists.linux-foundation.org Subject: [Patch V8 3/3] iommu: Document usage of "/sys/kernel/iommu_groups//type" file Date: Fri, 25 Sep 2020 12:06:20 -0700 Message-Id: <20200925190620.18732-4-ashok.raj@intel.com> X-Mailer: git-send-email 2.13.6 In-Reply-To: <20200925190620.18732-1-ashok.raj@intel.com> References: <20200925190620.18732-1-ashok.raj@intel.com> 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: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" 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 +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. -- 2.7.4 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu