From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.8 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 0FF137D072 for ; Tue, 17 Jul 2018 17:49:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730718AbeGQSWn convert rfc822-to-8bit (ORCPT ); Tue, 17 Jul 2018 14:22:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55638 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729730AbeGQSWn (ORCPT ); Tue, 17 Jul 2018 14:22:43 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DB4DC307D84A; Tue, 17 Jul 2018 17:48:59 +0000 (UTC) Received: from t450s.home (ovpn-116-29.phx2.redhat.com [10.3.116.29]) by smtp.corp.redhat.com (Postfix) with ESMTP id D1536608EF; Tue, 17 Jul 2018 17:48:58 +0000 (UTC) Date: Tue, 17 Jul 2018 11:48:48 -0600 From: Alex Williamson To: Logan Gunthorpe Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org, linux-doc@vger.kernel.org, Stephen Bates , Christoph Hellwig , Bjorn Helgaas , Jonathan Corbet , Ingo Molnar , Thomas Gleixner , "Paul E. McKenney" , Marc Zyngier , Kai-Heng Feng , Frederic Weisbecker , Dan Williams , =?UTF-8?B?SsOpcsO0bWU=?= Glisse , Benjamin Herrenschmidt , Christian =?UTF-8?B?S8O2bmln?= , Matthew Wilcox Subject: Re: [PATCH v7 4/4] PCI: Introduce the disable_acs_redir parameter Message-ID: <20180717114848.2914d547@t450s.home> In-Reply-To: <20180717170204.30470-5-logang@deltatee.com> References: <20180717170204.30470-1-logang@deltatee.com> <20180717170204.30470-5-logang@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Tue, 17 Jul 2018 17:49:00 +0000 (UTC) Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Tue, 17 Jul 2018 11:02:04 -0600 Logan Gunthorpe wrote: > In order to support P2P traffic on a segment of the PCI hierarchy, > we must be able to disable the ACS redirect bits for select > PCI bridges. The bridges must be selected before the devices are > discovered by the kernel and the IOMMU groups created. Therefore, > a kernel command line parameter is created to specify devices > which must have their ACS bits disabled. > > The new parameter takes a list of devices separated by a semicolon. > Each device specified will have it's ACS redirect bits disabled. > This is similar to the existing 'resource_alignment' parameter. > > The ACS Request P2P Request Redirect, P2P Completion Redirect and P2P > Egress Control bits are disabled which is sufficient to always allow > passing P2P traffic uninterrupted. The bits are set after the kernel > (optionally) enables the ACS bits itself. It is also done regardless of > whether the kernel sets the bits or not seeing some BIOS firmware is known > to set the bits on boot. > > If the user tries to disable the ACS redirct for a device without the > ACS capability, a warning is printed to dmesg. > > Signed-off-by: Logan Gunthorpe > Reviewed-by: Stephen Bates > Acked-by: Christian König > --- > Documentation/admin-guide/kernel-parameters.txt | 9 +++ > drivers/pci/pci.c | 76 ++++++++++++++++++++++++- > 2 files changed, 83 insertions(+), 2 deletions(-) Thanks for the re-spins! Reviewed-by: Alex Williamson -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html