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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 80723C3F2D1 for ; Mon, 2 Mar 2020 15:08:47 +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 2C550214DB for ; Mon, 2 Mar 2020 15:08:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2C550214DB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=8bytes.org 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 C54908593F; Mon, 2 Mar 2020 15:08:46 +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 M5ZNwNMN5t14; Mon, 2 Mar 2020 15:08:46 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by fraxinus.osuosl.org (Postfix) with ESMTP id 5BE7D858A6; Mon, 2 Mar 2020 15:08:46 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 3FCEAC1AE2; Mon, 2 Mar 2020 15:08:46 +0000 (UTC) Received: from fraxinus.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by lists.linuxfoundation.org (Postfix) with ESMTP id 765C1C013E for ; Mon, 2 Mar 2020 15:08:45 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by fraxinus.osuosl.org (Postfix) with ESMTP id 65060858A6 for ; Mon, 2 Mar 2020 15:08:45 +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 hcpSBvX3mzD9 for ; Mon, 2 Mar 2020 15:08:43 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) by fraxinus.osuosl.org (Postfix) with ESMTPS id B7ECA8589C for ; Mon, 2 Mar 2020 15:08:43 +0000 (UTC) Received: by theia.8bytes.org (Postfix, from userid 1000) id A5A462AF; Mon, 2 Mar 2020 16:08:37 +0100 (CET) Date: Mon, 2 Mar 2020 16:08:34 +0100 From: Joerg Roedel To: Sai Praneeth Prakhya Subject: Re: [PATCH V2 3/5] iommu: Add support to change default domain of an iommu_group Message-ID: <20200302150833.GA6540@8bytes.org> References: <5aa5ef20ff81f706aafa9a6af68cef98fe60ad0f.1581619464.git.sai.praneeth.prakhya@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <5aa5ef20ff81f706aafa9a6af68cef98fe60ad0f.1581619464.git.sai.praneeth.prakhya@intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Cc: Ashok Raj , 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hello Sai, Baolu, On Sun, Feb 16, 2020 at 01:57:26PM -0800, Sai Praneeth Prakhya wrote: > Hence it will be helpful if there is some way to change the default > domain of a B:D.F dynamically. Since, linux iommu subsystem prefers to > deal at iommu_group level instead of B:D.F level, it might be helpful > if there is some way to change the default domain of a *iommu_group* > dynamically. Hence, add such support. The question is how this plays together with the per-device private domains in the Intel VT-d driver. I recently debugged an issue there and I think there are more. The overall code for this seems to be pretty fragile, so I had the idea to make the private default domains more general. IOMMU default domains don't necessarily need to stick to the iommu-group granularity, because the default domain is used by in-kernel drivers only, and the kernel trusts itself. So my idea was to make the private-domain concept of the VT-d driver more generic and move it to the iommu core code. With that we can configure real per-device default domain types and don't have the race condition with driver probing when changing the default domain of multiple devices. We have to limit the ability to change default domain types to devices with no PCI aliases, but that should not be a problem for the intended use-case. What do you think? Regards, Joerg _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu