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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 3F96FCA9EC5 for ; Wed, 30 Oct 2019 12:07:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1C70120862 for ; Wed, 30 Oct 2019 12:07:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726175AbfJ3MHJ (ORCPT ); Wed, 30 Oct 2019 08:07:09 -0400 Received: from mga17.intel.com ([192.55.52.151]:20792 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726088AbfJ3MHJ (ORCPT ); Wed, 30 Oct 2019 08:07:09 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga107.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 30 Oct 2019 05:07:09 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,247,1569308400"; d="scan'208";a="211309534" Received: from lahna.fi.intel.com (HELO lahna) ([10.237.72.157]) by fmsmga001.fm.intel.com with SMTP; 30 Oct 2019 05:07:06 -0700 Received: by lahna (sSMTP sendmail emulation); Wed, 30 Oct 2019 14:07:05 +0200 Date: Wed, 30 Oct 2019 14:07:05 +0200 From: "mika.westerberg@linux.intel.com" To: Nicholas Johnson Cc: "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" , "bhelgaas@google.com" , "corbet@lwn.net" , "benh@kernel.crashing.org" , "logang@deltatee.com" Subject: Re: [PATCH v9 4/4] PCI: Allow extend_bridge_window() to shrink resource if necessary Message-ID: <20191030120705.GC2593@lahna.fi.intel.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Oct 29, 2019 at 03:29:21PM +0000, Nicholas Johnson wrote: > Remove checks for resource size in extend_bridge_window(). This is > necessary to allow the pci_bus_distribute_available_resources() to > function when the kernel parameter pci=hpmemsize=nn[KMG] is used to > allocate resources. Because the kernel parameter sets the size of all > hotplug bridges to be the same, there are problems when nested hotplug > bridges are encountered. Fitting a downstream hotplug bridge with size X > and normal bridges with non-zero size Y into parent hotplug bridge with > size X is impossible, and hence the downstream hotplug bridge needs to > shrink to fit into its parent. > > Add check for if bridge is extended or shrunken and adjust pci_dbg to > reflect this. > > Reset the resource if its new size is zero (if we have run out of a > bridge window resource) to prevent the PCI resource assignment code from > attempting to assign a zero-sized resource. > > Rename extend_bridge_window() to adjust_bridge_window() to reflect the > fact that the window can now shrink. > > Signed-off-by: Nicholas Johnson > --- > drivers/pci/setup-bus.c | 23 +++++++++++++++-------- > 1 file changed, 15 insertions(+), 8 deletions(-) > > diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c > index fe8b2c715..f8cd54584 100644 > --- a/drivers/pci/setup-bus.c > +++ b/drivers/pci/setup-bus.c > @@ -1814,7 +1814,7 @@ void __init pci_assign_unassigned_resources(void) > } > } > > -static void extend_bridge_window(struct pci_dev *bridge, struct resource *res, > +static void adjust_bridge_window(struct pci_dev *bridge, struct resource *res, > struct list_head *add_list, > resource_size_t new_size) > { > @@ -1823,13 +1823,20 @@ static void extend_bridge_window(struct pci_dev *bridge, struct resource *res, > if (res->parent) > return; > > - if (resource_size(res) >= new_size) > - return; > + if (new_size > resource_size(res)) { > + add_size = new_size - resource_size(res); > + pci_dbg(bridge, "bridge window %pR extended by %pa\n", res, > + &add_size); > + } else if (new_size < resource_size(res)) { > + add_size = resource_size(res) - new_size; > + pci_dbg(bridge, "bridge window %pR shrunken by %pa\n", res, > + &add_size); > + } Do we need to care about new_size == resource_size(res)? Also there are several calls of resource_size(res) above so probably worth storing it into a helper variable. > - add_size = new_size - resource_size(res); > - pci_dbg(bridge, "bridge window %pR extended by %pa\n", res, &add_size); > res->end = res->start + new_size - 1; > remove_from_list(add_list, res); > + if (!new_size) > + reset_resource(res); > }