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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 8F55AC28CC5 for ; Sat, 8 Jun 2019 18:42:08 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 69201214C6 for ; Sat, 8 Jun 2019 18:42:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 69201214C6 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 mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 20BEE16AA; Sat, 8 Jun 2019 18:42:08 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id F304C16A9 for ; Sat, 8 Jun 2019 18:42:06 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 5BEDC711 for ; Sat, 8 Jun 2019 18:42:04 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga105.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 08 Jun 2019 11:42:03 -0700 X-ExtLoop1: 1 Received: from sai-dev-mach.sc.intel.com ([143.183.140.153]) by fmsmga004.fm.intel.com with ESMTP; 08 Jun 2019 11:42:03 -0700 Message-ID: <0467c18559982ca9fd2c9ed4f3cf826fd3487dab.camel@intel.com> Subject: Re: Device specific pass through in host systems - discuss user interface From: Sai Praneeth Prakhya To: "hch@lst.de" Date: Sat, 08 Jun 2019 11:38:58 -0700 In-Reply-To: <20190608072751.GA18928@lst.de> References: <3fa16135-b2bb-03b5-833a-bce8cc68f35f@arm.com> <12f8c572074b7963705ba066fdde0f9fdf0bfc62.camel@intel.com> <20190608072751.GA18928@lst.de> User-Agent: Evolution 3.30.5-0ubuntu0.18.10.1 MIME-Version: 1.0 Cc: "Shankar, Ravi V" , "Tian, Kevin" , "jroedel@suse.de" , "Raj, Ashok" , Will Deacon , "iommu@lists.linux-foundation.org" , "Pan, Jacob jun" , Robin Murphy , "Lu, Baolu" X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Sat, 2019-06-08 at 09:27 +0200, hch@lst.de wrote: > Just curious, what exactly is the use case? Explaining how someone > would wan to use this should drive the way we design an interface for it. Makes sense. Some example use cases: 1. Assume an SR-IOV device and if the admin decides to use some VF's natively (i.e. they are available only to host) and he wants them to be high performing and also believes that his OS is secure enough (so decides to by pass IOMMU). Presently, we don't support this use case because "iommu=pt" kernel command line argument is an all or none feature i.e. either all BDF's are translated through IOMMU or none. So, we would like to propose a per-BDF on/off feature. We would also want it to be run-time (i.e. sysfs based interface) rather than just boot-time interface (kernel command line argument). Also, want to be clear that it's not just SR-IOV devices that we are looking at but could be any unrelated PCIe devices i.e. a SATA device, USB, NIC or GFx. Wherein the admin wants to selectively put NIC and GFx through IOMMU and does not want transactions by SATA and USB to be translated by IOMMU. Regards, Sai _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu