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=-8.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, T_DKIMWL_WL_HIGH,USER_AGENT_MUTT 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 7B274C6786F for ; Fri, 2 Nov 2018 19:59:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 45E2720833 for ; Fri, 2 Nov 2018 19:59:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="zwmlpB+Q" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 45E2720833 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 S1726917AbeKCFH6 (ORCPT ); Sat, 3 Nov 2018 01:07:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:46112 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726106AbeKCFH6 (ORCPT ); Sat, 3 Nov 2018 01:07:58 -0400 Received: from localhost (unknown [69.71.4.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B900C2081B; Fri, 2 Nov 2018 19:59:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541188767; bh=liSUcXWJy0aGb9Dr/w+lxSwtMCU7z5euI7DsIO4eMFE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=zwmlpB+QE650NorjxNp88N+Rj5S/VO1Ufs1j/gr2b6PAh8PVo+HpZdBc3OmoRYDTn CCkpYyacrWOKmrtQ9OUOJt9k8jZRsAu94kbIfD20orQjVt8Dj6EmxMZ5Xs1Zt85JuX oOs1nOesXo5cekr43z2debVfAARzXPUdu+DCFh3Y= Date: Fri, 2 Nov 2018 14:59:25 -0500 From: Bjorn Helgaas To: "Woods, Brian" Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , "x86@kernel.org" , Clemens Ladisch , Jean Delvare , Guenter Roeck , Pu Wen , Jia Zhang , "linux-kernel@vger.kernel.org" , "linux-hwmon@vger.kernel.org" , "linux-pci@vger.kernel.org" Subject: Re: [PATCH 2/4] x86/amd_nb: add support for newer PCI topologies Message-ID: <20181102195925.GB160487@google.com> References: <20181102181055.130531-1-brian.woods@amd.com> <20181102181055.130531-3-brian.woods@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181102181055.130531-3-brian.woods@amd.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 02, 2018 at 06:11:07PM +0000, Woods, Brian wrote: > Add support for new processors which have multiple PCI root complexes > per data fabric/SMN interface. The interfaces per root complex are > redundant and should be skipped. This makes sure the DF/SMN interfaces > get accessed via the correct root complex. SMN? > Ex: > DF/SMN 0 -> 60 > 40 > 20 > 00 > DF/SMN 1 -> e0 > c0 > a0 > 80 This isn't my code, and I'm not really objecting to these changes, but from where I sit, the fact that you need this sort of vendor-specific topology discovery is a little bit ugly and seems like something of a maintenance issue. You could argue that this is sort of an "AMD CPU driver", which is entitled to be device-specific, and that does make some sense. But device-specific code is typically packaged as a driver that uses driver registration interfaces like acpi_bus_register_driver(), pci_register_driver(), etc. That gives you a consistent structure and, more importantly, a framework for dealing with hotplug. It doesn't look like amd_nb.c would deal well with hot-add of CPUs. > Signed-off-by: Brian Woods > --- > arch/x86/kernel/amd_nb.c | 41 +++++++++++++++++++++++++++++++++++------ > 1 file changed, 35 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c > index 19d489ee2b1e..c0bf26aeb7c3 100644 > --- a/arch/x86/kernel/amd_nb.c > +++ b/arch/x86/kernel/amd_nb.c > @@ -213,7 +213,10 @@ int amd_cache_northbridges(void) > const struct pci_device_id *root_ids = amd_root_ids; > struct pci_dev *root, *misc, *link; > struct amd_northbridge *nb; > - u16 i = 0; > + u16 roots_per_misc = 0; > + u16 misc_count = 0; > + u16 root_count = 0; > + u16 i, j; > > if (amd_northbridges.num) > return 0; > @@ -226,26 +229,52 @@ int amd_cache_northbridges(void) > > misc = NULL; > while ((misc = next_northbridge(misc, misc_ids)) != NULL) > - i++; > + misc_count++; > > - if (!i) > + root = NULL; > + while ((root = next_northbridge(root, root_ids)) != NULL) > + root_count++; > + > + if (!misc_count) > return -ENODEV; > > - nb = kcalloc(i, sizeof(struct amd_northbridge), GFP_KERNEL); > + if (root_count) { > + roots_per_misc = root_count / misc_count; > + > + /* > + * There should be _exactly_ N roots for each DF/SMN > + * interface. > + */ > + if (!roots_per_misc || (root_count % roots_per_misc)) { > + pr_info("Unsupported AMD DF/PCI configuration found\n"); > + return -ENODEV; > + } > + } > + > + nb = kcalloc(misc_count, sizeof(struct amd_northbridge), GFP_KERNEL); > if (!nb) > return -ENOMEM; > > amd_northbridges.nb = nb; > - amd_northbridges.num = i; > + amd_northbridges.num = misc_count; > > link = misc = root = NULL; > - for (i = 0; i != amd_northbridges.num; i++) { > + for (i = 0; i < amd_northbridges.num; i++) { > node_to_amd_nb(i)->root = root = > next_northbridge(root, root_ids); > node_to_amd_nb(i)->misc = misc = > next_northbridge(misc, misc_ids); > node_to_amd_nb(i)->link = link = > next_northbridge(link, link_ids); > + > + /* > + * If there are more root devices than data fabric/SMN, > + * interfaces, then the root devices per DF/SMN > + * interface are redundant and N-1 should be skipped so > + * they aren't mapped incorrectly. > + */ > + for (j = 1; j < roots_per_misc; j++) > + root = next_northbridge(root, root_ids); > } > > if (amd_gart_present()) > -- > 2.11.0 >