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=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 8905FC17441 for ; Tue, 12 Nov 2019 09:40:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 642AC21783 for ; Tue, 12 Nov 2019 09:40:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727176AbfKLJj7 (ORCPT ); Tue, 12 Nov 2019 04:39:59 -0500 Received: from mga02.intel.com ([134.134.136.20]:18473 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725834AbfKLJj6 (ORCPT ); Tue, 12 Nov 2019 04:39:58 -0500 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 orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Nov 2019 01:39:57 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.68,295,1569308400"; d="scan'208";a="214042274" Received: from lahna.fi.intel.com (HELO lahna) ([10.237.72.163]) by fmsmga001.fm.intel.com with SMTP; 12 Nov 2019 01:39:54 -0800 Received: by lahna (sSMTP sendmail emulation); Tue, 12 Nov 2019 11:39:53 +0200 Date: Tue, 12 Nov 2019 11:39:53 +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 1/1] PCI: Fix bug resulting in double hpmemsize being assigned to MMIO window Message-ID: <20191112093953.GD2644@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-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 07, 2019 at 01:50:57PM +0000, Nicholas Johnson wrote: > Currently, the kernel can sometimes assign the MMIO_PREF window > additional size into the MMIO window, resulting in extra MMIO additional > size, despite the MMIO_PREF additional size being assigned successfully > into the MMIO_PREF window. > > This happens if in the first pass, the MMIO_PREF succeeds but the MMIO > fails. In the next pass, because MMIO_PREF is already assigned, the > attempt to assign MMIO_PREF returns an error code instead of success > (nothing more to do, already allocated). Hence, the size which is > actually allocated, but thought to have failed, is placed in the MMIO > window. > > Example of problem (more context can be found in the bug report URL): > > Mainline kernel: > pci 0000:06:01.0: BAR 14: assigned [mem 0x90100000-0xa00fffff] = 256M > pci 0000:06:04.0: BAR 14: assigned [mem 0xa0200000-0xb01fffff] = 256M > > Patched kernel: > pci 0000:06:01.0: BAR 14: assigned [mem 0x90100000-0x980fffff] = 128M > pci 0000:06:04.0: BAR 14: assigned [mem 0x98200000-0xa01fffff] = 128M > > This was using pci=realloc,hpmemsize=128M,nocrs - on the same machine > with the same configuration, with a Ubuntu mainline kernel and a kernel > patched with this patch. > > The bug results in the MMIO_PREF being added to the MMIO window, which > means doubling if MMIO_PREF size = MMIO size. With a large MMIO_PREF, > the MMIO window will likely fail to be assigned altogether due to lack > of 32-bit address space. > > Change find_free_bus_resource() to do the following: > - Return first unassigned resource of the correct type. > - If none of the above, return first assigned resource of the correct type. > - If none of the above, return NULL. > > Returning an assigned resource of the correct type allows the caller to > distinguish between already assigned and no resource of the correct type. > > Rename find_free_bus_resource to find_bus_resource_of_type(). > > Add checks in pbus_size_io() and pbus_size_mem() to return success if > resource returned from find_free_bus_resource() is already allocated. > > This avoids pbus_size_io() and pbus_size_mem() returning error code to > __pci_bus_size_bridges() when a resource has been successfully assigned > in a previous pass. This fixes the existing behaviour where space for a > resource could be reserved multiple times in different parent bridge > windows. > > Link: https://lore.kernel.org/lkml/20190531171216.20532-2-logang@deltatee.com/T/#u > Link: https://bugzilla.kernel.org/show_bug.cgi?id=203243 > > Reported-by: Kit Chow > Reported-by: Nicholas Johnson > Signed-off-by: Nicholas Johnson Reviewed-by: Mika Westerberg Minor nits below. > --- > drivers/pci/setup-bus.c | 34 +++++++++++++++++++++++----------- > 1 file changed, 23 insertions(+), 11 deletions(-) > > diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c > index e7dbe2170..f97c36a1e 100644 > --- a/drivers/pci/setup-bus.c > +++ b/drivers/pci/setup-bus.c > @@ -752,24 +752,32 @@ static void pci_bridge_check_ranges(struct pci_bus *bus) > } > > /* > - * Helper function for sizing routines: find first available bus resource > - * of a given type. Note: we intentionally skip the bus resources which > - * have already been assigned (that is, have non-NULL parent resource). > + * Helper function for sizing routines. > + * Assigned resources have non-NULL parent resource. > + * > + * Return first unassigned resource of the correct type. > + * If none of the above, return first assigned resource of the correct type. > + * If none of the above, return NULL. > + * > + * Returning an assigned resource of the correct type allows the caller to > + * distinguish between already assigned and no resource of the correct type. > */ > -static struct resource *find_free_bus_resource(struct pci_bus *bus, > - unsigned long type_mask, > - unsigned long type) > +static struct resource *find_bus_resource_of_type(struct pci_bus *bus, > + unsigned long type_mask, > + unsigned long type) > { > int i; > - struct resource *r; > + struct resource *r, *r_assigned = NULL; Maybe order them struct resource *r, *r_assigned = NULL; int i; > > pci_bus_for_each_resource(bus, r, i) { > if (r == &ioport_resource || r == &iomem_resource) > continue; > if (r && (r->flags & type_mask) == type && !r->parent) > return r; > + if (r && (r->flags & type_mask) == type && !r_assigned) > + r_assigned = r; > } > - return NULL; > + return r_assigned; > } > > static resource_size_t calculate_iosize(resource_size_t size, > @@ -866,14 +874,16 @@ static void pbus_size_io(struct pci_bus *bus, resource_size_t min_size, > struct list_head *realloc_head) > { > struct pci_dev *dev; > - struct resource *b_res = find_free_bus_resource(bus, IORESOURCE_IO, > - IORESOURCE_IO); > + struct resource *b_res = find_bus_resource_of_type(bus, IORESOURCE_IO, > + IORESOURCE_IO); > resource_size_t size = 0, size0 = 0, size1 = 0; > resource_size_t children_add_size = 0; > resource_size_t min_align, align; > > if (!b_res) > return; I think it may be good to comment here that skip the resources that are assigned (->parent != NULL). > + if (b_res->parent) > + return; > > min_align = window_alignment(bus, IORESOURCE_IO); > list_for_each_entry(dev, &bus->devices, bus_list) { > @@ -978,7 +988,7 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, > resource_size_t min_align, align, size, size0, size1; > resource_size_t aligns[18]; /* Alignments from 1MB to 128GB */ > int order, max_order; > - struct resource *b_res = find_free_bus_resource(bus, > + struct resource *b_res = find_bus_resource_of_type(bus, > mask | IORESOURCE_PREFETCH, type); > resource_size_t children_add_size = 0; > resource_size_t children_add_align = 0; > @@ -986,6 +996,8 @@ static int pbus_size_mem(struct pci_bus *bus, unsigned long mask, > > if (!b_res) > return -ENOSPC; Ditto. > + if (b_res->parent) > + return 0; > > memset(aligns, 0, sizeof(aligns)); > max_order = 0; > -- > 2.23.0