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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 581AAECDFB1 for ; Tue, 17 Jul 2018 17:50:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1DB7D206B8 for ; Tue, 17 Jul 2018 17:50:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1DB7D206B8 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=deltatee.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731023AbeGQSXw (ORCPT ); Tue, 17 Jul 2018 14:23:52 -0400 Received: from ale.deltatee.com ([207.54.116.67]:45146 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729980AbeGQSXw (ORCPT ); Tue, 17 Jul 2018 14:23:52 -0400 Received: from guinness.priv.deltatee.com ([172.16.1.162]) by ale.deltatee.com with esmtp (Exim 4.89) (envelope-from ) id 1ffU6P-00077P-1J; Tue, 17 Jul 2018 11:49:33 -0600 To: Alex Williamson 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?SsOpcsO0bWUgR2xpc3Nl?= , Benjamin Herrenschmidt , =?UTF-8?Q?Christian_K=c3=b6nig?= , Matthew Wilcox References: <20180717170204.30470-1-logang@deltatee.com> <20180717170204.30470-5-logang@deltatee.com> <20180717114848.2914d547@t450s.home> From: Logan Gunthorpe Message-ID: Date: Tue, 17 Jul 2018 11:49:22 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180717114848.2914d547@t450s.home> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 172.16.1.162 X-SA-Exim-Rcpt-To: willy@infradead.org, christian.koenig@amd.com, benh@kernel.crashing.org, jglisse@redhat.com, dan.j.williams@intel.com, frederic@kernel.org, kai.heng.feng@canonical.com, marc.zyngier@arm.com, paulmck@linux.vnet.ibm.com, tglx@linutronix.de, mingo@kernel.org, corbet@lwn.net, bhelgaas@google.com, hch@lst.de, sbates@raithlin.com, linux-doc@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, alex.williamson@redhat.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [PATCH v7 4/4] PCI: Introduce the disable_acs_redir parameter X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 17/07/18 11:48 AM, Alex Williamson wrote: > 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 Thanks for all the thorough review! Logan