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=-5.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 D4A4FC433E1 for ; Mon, 13 Jul 2020 08:01:52 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (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 A64712072D for ; Mon, 13 Jul 2020 08:01:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A64712072D 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 whitealder.osuosl.org (Postfix) with ESMTP id 66BEA88744; Mon, 13 Jul 2020 08:01:52 +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 1xrZtzUv+e9r; Mon, 13 Jul 2020 08:01:50 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by whitealder.osuosl.org (Postfix) with ESMTP id F143F88EFA; Mon, 13 Jul 2020 08:01:28 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id E32E6C0888; Mon, 13 Jul 2020 08:01:28 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) by lists.linuxfoundation.org (Postfix) with ESMTP id F3FEDC0733 for ; Mon, 13 Jul 2020 08:01:27 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id DD5B322011 for ; Mon, 13 Jul 2020 08:01:27 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Q1UA5D6L5GW6 for ; Mon, 13 Jul 2020 08:01:25 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from theia.8bytes.org (8bytes.org [81.169.241.247]) by silver.osuosl.org (Postfix) with ESMTPS id 5FAF920366 for ; Mon, 13 Jul 2020 08:01:25 +0000 (UTC) Received: by theia.8bytes.org (Postfix, from userid 1000) id EBC6136B; Mon, 13 Jul 2020 10:01:19 +0200 (CEST) Date: Mon, 13 Jul 2020 10:01:15 +0200 From: Joerg Roedel To: Bjorn Helgaas Subject: Re: [PATCH v4 4/4] PCI/ACS: Enable PCI_ACS_TB for untrusted/external-facing devices Message-ID: <20200713080115.GN27672@8bytes.org> References: <20200712025838.GA147150@bjorn-Precision-5520> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200712025838.GA147150@bjorn-Precision-5520> User-Agent: Mutt/1.10.1 (2018-07-13) Cc: Todd Broch , linux-pci , "Krishnakumar, Lalithambika" , Heikki Krogerus , Diego Rivas , Rajat Jain , Jean-Philippe Brucker , Furquan Shaikh , "Raj, Ashok" , Saravana Kannan , ACPI Devel Maling List , Christian Kellner , Mattias Nissler , Jesse Barnes , Len Brown , Rajat Jain , Prashant Malani , Suzuki K Poulose , Aaron Durbin , Alex Williamson , Bjorn Helgaas , Mika Westerberg , Bernie Keany , Duncan Laurie , Greg Kroah-Hartman , "Rafael J. Wysocki" , Linux Kernel Mailing List , "open list:AMD IOMMU \(AMD-VI\)" , Arnd Bergmann , Oliver O'Halloran , Benson Leung , David Woodhouse , Alex Levin 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" On Sat, Jul 11, 2020 at 09:58:38PM -0500, Bjorn Helgaas wrote: > If BIOS handed off with ATS enabled and we somehow relied on it being > already enabled, something might break if we start disabling ATS. > Just a theoretical possibility, doesn't seem likely to me. I don't think this will be a problem. When the BIOS enables ATS for a device it also needs to enable the IOMMU already, an we are not handling an already enabled IOMMU (outside of kdump kernels) very well. Regards, Joerg _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu