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=-17.4 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 8A2E0C433E2 for ; Tue, 15 Sep 2020 23:02:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 52703208E4 for ; Tue, 15 Sep 2020 23:02:41 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="ZVyYyQFG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727330AbgIOXCi (ORCPT ); Tue, 15 Sep 2020 19:02:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58140 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727368AbgIOXCY (ORCPT ); Tue, 15 Sep 2020 19:02:24 -0400 Received: from mail-lj1-x244.google.com (mail-lj1-x244.google.com [IPv6:2a00:1450:4864:20::244]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE370C061788 for ; Tue, 15 Sep 2020 16:02:23 -0700 (PDT) Received: by mail-lj1-x244.google.com with SMTP id k25so4241329ljg.9 for ; Tue, 15 Sep 2020 16:02:23 -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=/9scBHPNix+y6Pwr8cQyVX+xDYS3UrPPXINpHzBknN4=; b=ZVyYyQFG1iBiLFuKDDQuAPmiBZLpB11LhmJ8YIOtjnryLAEf3A4zUrMoifNnYRWJlf 8GcDcZvPM6I43fh/hfWt5Ij4L0sml+BEcbwcrw9YG7Yv4MCF4a3iTKVN2+zx/6t1Ok/U EztiiWABfLBG0/pmN5Vl7Cj2fE6WIAdiGdue7cOiCXYCIRSnnNjhvCG039/GlTc80TRj aqwQ3MOyvtANK7SvVzqwtpY0bPLrbyc56t1ojaXcJdWtPVCALRtamlRtUIQUeZZ3HY8z BDvzFgB0IjGoamrNzKeAtkR8T1BKPA8B09P9hDpTiuNjtQyYdb12iJHIbtSbTSRWvjFY sX3A== 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=/9scBHPNix+y6Pwr8cQyVX+xDYS3UrPPXINpHzBknN4=; b=V0WNdUOhufoiYoJGYZCJuih0TJGqp4Pyo+H6HEOt3x2i6rYPpAqMJ5J6no0NSuQIwR 5iOfi0cKRb2hJtEF+LcaH0LYDmKNL0GLY+NUHlqt1Eqm9dxEQtAH0+3ehe0SEdvWA5Qz DO3Tg8JLHoikBVd4gIT/lOi8bAAWjtqxh2Pe5b6hLyTfPS5/KL9qEV4OdDFHCw17JyCt nb1Urior46JmtlF1iwCxzlbG/LyDZEh/RlRxA7DofU3B6eMNgs4v5fXdC9LQ0787oGBU KQ+JePZqE23008uG7MCJsQ5DgaSvVwf859zuuwmw+F6B3yjPb9xHl+rBRYohyMnl/RPF IgLg== X-Gm-Message-State: AOAM532ODpowsWj3mL3aBCGGBGyXuGS5PETZPtsQcROa4MVJ/Oy788gS 6WWhrcMBWEirWCbA8qJTpU6Ld7oP7sVbun34v2v1UQ== X-Google-Smtp-Source: ABdhPJysOqFs8iJIdAa5maQ13XMna1CrI/NRUUz9V4/qRiA3nA6/D4LifyuPbfI1VmRc64fhlM/srS8bqKradXWp+OM= X-Received: by 2002:a2e:9992:: with SMTP id w18mr7963973lji.301.1600210941914; Tue, 15 Sep 2020 16:02:21 -0700 (PDT) MIME-Version: 1.0 References: <20200711195346.GA132330@bjorn-Precision-5520> In-Reply-To: From: Rajat Jain Date: Tue, 15 Sep 2020 16:01:45 -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 Hello Bjorn, On Tue, Jul 14, 2020 at 1:19 PM Rajat Jain wrote: > > 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/ Any feedback on the patch above? It has been waiting for feedback.... Thanks & Best Regards,, Rajat > > 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