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=-17.6 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 32345C433E0 for ; Tue, 14 Jul 2020 20:19:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0241120890 for ; Tue, 14 Jul 2020 20:19:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ktzGRdNH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728672AbgGNUTp (ORCPT ); Tue, 14 Jul 2020 16:19:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53018 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725955AbgGNUTp (ORCPT ); Tue, 14 Jul 2020 16:19:45 -0400 Received: from mail-lj1-x243.google.com (mail-lj1-x243.google.com [IPv6:2a00:1450:4864:20::243]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 94FFFC061755 for ; Tue, 14 Jul 2020 13:19:44 -0700 (PDT) Received: by mail-lj1-x243.google.com with SMTP id f5so25210689ljj.10 for ; Tue, 14 Jul 2020 13:19:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=XWpCwFxzq2ITP3K2PgbPEPYflHGc9CASEeamyGhecg4=; b=ktzGRdNHxUc/NOjGB1vSjjeBZhP/eN1zV/MJ3JD8wmxjdxCf0IQ+zpHExTOeKFCy+a lkIxtWm6PjqYkFHafKjnDH7YyMKXwotc5q6DnqSw3TopHIRLxHCs+deg6PTyFFdIXYFv k7EKTWOzzY2ectIvYgQJoT3PC8WtQ36MwQGEEdeS4yRKsH7OHceijsqk6ydBx4RUmYvR IZrllP4JBOp0cXppgKAXu1mmq6yPSvexe7a431gzpco6kw0dfLio0xngHrY49l7HSD+o /v/hKsd9rStGhPgfKDu4Tzc6hz5W+DzX3Fs66+EIKtMQGOTLMOIPGhjlXHu/EB8LfYrq 3KdQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=XWpCwFxzq2ITP3K2PgbPEPYflHGc9CASEeamyGhecg4=; b=JtXHOIE01hoT165OeRqJD2oxULXpy0l7Jy/v8SrO5ZIPOGH4NJ8G51iYjEwzP0gnWJ ZBADe1PgOJdLsQ6fEdePaMytpquijan/jfgRwo3WDmevFhUyM/3ydhcD7vz20qqjeOgf 3H0PD6fz1uZ5JketWj2318Xgfa+e+6rXk82yu1QKGIz5tv+/huy0aIL6IiXzarSH4Y7g xDthN8BzGh6yc7lUI7q/6e1s4OtjXtrN6jv2nHvsszZ6BuUmx/CVlgL6zqpk02QvJMhx AK48P0s62PvNxrffJBSyXF6Gjn3w2xeZtIdO18iPMDL3MaF+YuP+QpmOj59+i2sy6huO eDeA== X-Gm-Message-State: AOAM5322/+bOQAcX/bNfLeccI69qMx7JcAV6K1I2LZp2NjO/X1BW+lCs PhG6kZ2fZYGa4FBxBqSX/3cew5pF+ObR5u5qyNnIrg== X-Google-Smtp-Source: ABdhPJyog1559G29m5pJ504Xf+0cH4eNg4/1fwwOhATAWoZMeuV+BZE2PrcQIEm6ttR2VLYvOaa4/0qm67q9Isa6wdw= X-Received: by 2002:a2e:8199:: with SMTP id e25mr2844648ljg.307.1594757982632; Tue, 14 Jul 2020 13:19:42 -0700 (PDT) MIME-Version: 1.0 References: <20200711195346.GA132330@bjorn-Precision-5520> In-Reply-To: <20200711195346.GA132330@bjorn-Precision-5520> From: Rajat Jain Date: Tue, 14 Jul 2020 13:19:05 -0700 Message-ID: Subject: Re: [PATCH v4 4/4] PCI/ACS: Enable PCI_ACS_TB for untrusted/external-facing devices To: Bjorn Helgaas Cc: "Raj, Ashok" , David Woodhouse , Lu Baolu , Joerg Roedel , Bjorn Helgaas , "Rafael J. Wysocki" , Len Brown , "open list:AMD IOMMU (AMD-VI)" , Linux Kernel Mailing List , linux-pci , ACPI Devel Maling List , "Krishnakumar, Lalithambika" , Mika Westerberg , Jean-Philippe Brucker , Prashant Malani , Benson Leung , Todd Broch , Alex Levin , Mattias Nissler , Rajat Jain , Bernie Keany , Aaron Durbin , Diego Rivas , Duncan Laurie , Furquan Shaikh , Jesse Barnes , Christian Kellner , Alex Williamson , Greg Kroah-Hartman , "Oliver O'Halloran" , Saravana Kannan , Suzuki K Poulose , Arnd Bergmann , Heikki Krogerus Content-Type: text/plain; charset="UTF-8" Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Sat, Jul 11, 2020 at 12:53 PM Bjorn Helgaas wrote: > > On Fri, Jul 10, 2020 at 03:53:59PM -0700, Rajat Jain wrote: > > On Fri, Jul 10, 2020 at 2:29 PM Raj, Ashok wrote: > > > On Fri, Jul 10, 2020 at 03:29:22PM -0500, Bjorn Helgaas wrote: > > > > On Tue, Jul 07, 2020 at 03:46:04PM -0700, Rajat Jain wrote: > > > > > When enabling ACS, enable translation blocking for external facing ports > > > > > and untrusted devices. > > > > > > > > > > Signed-off-by: Rajat Jain > > > > > --- > > > > > v4: Add braces to avoid warning from kernel robot > > > > > print warning for only external-facing devices. > > > > > v3: print warning if ACS_TB not supported on external-facing/untrusted ports. > > > > > Minor code comments fixes. > > > > > v2: Commit log change > > > > > > > > > > drivers/pci/pci.c | 8 ++++++++ > > > > > drivers/pci/quirks.c | 15 +++++++++++++++ > > > > > 2 files changed, 23 insertions(+) > > > > > > > > > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > > > > > index 73a8627822140..a5a6bea7af7ce 100644 > > > > > --- a/drivers/pci/pci.c > > > > > +++ b/drivers/pci/pci.c > > > > > @@ -876,6 +876,14 @@ static void pci_std_enable_acs(struct pci_dev *dev) > > > > > /* Upstream Forwarding */ > > > > > ctrl |= (cap & PCI_ACS_UF); > > > > > > > > > > + /* Enable Translation Blocking for external devices */ > > > > > + if (dev->external_facing || dev->untrusted) { > > > > > + if (cap & PCI_ACS_TB) > > > > > + ctrl |= PCI_ACS_TB; > > > > > + else if (dev->external_facing) > > > > > + pci_warn(dev, "ACS: No Translation Blocking on external-facing dev\n"); > > > > > + } > > > > > > > > IIUC, this means that external devices can *never* use ATS and > > > > can never cache translations. > > > > Yes, but it already exists today (and this patch doesn't change that): > > 521376741b2c2 "PCI/ATS: Only enable ATS for trusted devices" > > > > IMHO any external device trying to send ATS traffic despite having ATS > > disabled should count as a bad intent. And this patch is trying to > > plug that loophole, by blocking the AT traffic from devices that we do > > not expect to see AT from anyway. > > Thinking about this some more, I wonder if Linux should: > > - Explicitly disable ATS for every device at enumeration-time, e.g., > in pci_init_capabilities(), > > - Enable PCI_ACS_TB for every device (not just external-facing or > untrusted ones), > > - Disable PCI_ACS_TB for the relevant devices along the path only > when enabling ATS. > > One nice thing about doing that is that the "untrusted" test would be > only in pci_enable_ats(), and we wouldn't need one in > pci_std_enable_acs(). Sent out v5 with this approach here: https://patchwork.kernel.org/patch/11663515/ Thanks, Rajat > > > It's possible BIOS gives us devices with ATS enabled, and this might > break them, but that seems like something we'd want to find out about. > > Bjorn