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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 905B3C433F5 for ; Tue, 19 Oct 2021 21:55:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72A926134F for ; Tue, 19 Oct 2021 21:55:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229657AbhJSV5Z (ORCPT ); Tue, 19 Oct 2021 17:57:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:49614 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229544AbhJSV5V (ORCPT ); Tue, 19 Oct 2021 17:57:21 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2730161260; Tue, 19 Oct 2021 21:55:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1634680508; bh=k8/6DG7Gf2l0QXlkRyX6y3iUIQXOBGnkd5657VOQQA4=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=Fax3yqYqNGg3N08Y+4+3iEZixE+nIKZolAfgragJsxeDSoYNqsS8ZBnmsZYKw8mo4 zve70NBrjQnDfrFxB92w+w16AHTqikE+RZ1xPkHeKkCGiwAU09zMNimobQtnykFA8G M1ce2nnqRbr+P5eSqu6KHbGnH+0ud0uoMQbkCYh9v4OKLkO77PL7c3TqxuXEvYqYzO FEMbvzhAAvKb8wwzrQjasn3BnLK3hG5LOQi68ZtZTGec6mrY1xeEetZK6xFvA3DN+E IzWB1c8pW4PAyhN0QN5tjloz8TA/9B0+erE+czyyekpIv4WTvhShl4sOSE/JpWug7Z PcLWjJVxzXeag== Date: Tue, 19 Oct 2021 16:55:06 -0500 From: Bjorn Helgaas To: Hans de Goede Cc: "Rafael J . Wysocki" , Mika Westerberg , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , Bjorn Helgaas , Myron Stowe , Juha-Pekka Heikkila , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, Benoit =?iso-8859-1?Q?Gr=E9goire?= , Hui Wang , stable@vger.kernel.org, "Rafael J . Wysocki" Subject: Re: [PATCH v5 1/2] x86/PCI: Ignore E820 reservations for bridge windows on newer systems Message-ID: <20211019215506.GA2411878@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20211019215240.GA2411590@bhelgaas> Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Tue, Oct 19, 2021 at 04:52:42PM -0500, Bjorn Helgaas wrote: > On Thu, Oct 14, 2021 at 08:39:42PM +0200, Hans de Goede wrote: > > Some BIOS-es contain a bug where they add addresses which map to system > > RAM in the PCI host bridge window returned by the ACPI _CRS method, see > > commit 4dc2287c1805 ("x86: avoid E820 regions when allocating address > > space"). > > > > To work around this bug Linux excludes E820 reserved addresses when > > allocating addresses from the PCI host bridge window since 2010. > > > > Recently (2020) some systems have shown-up with E820 reservations which > > cover the entire _CRS returned PCI bridge memory window, causing all > > attempts to assign memory to PCI BARs which have not been setup by the > > BIOS to fail. For example here are the relevant dmesg bits from a > > Lenovo IdeaPad 3 15IIL 81WE: > > > > [mem 0x000000004bc50000-0x00000000cfffffff] reserved > > pci_bus 0000:00: root bus resource [mem 0x65400000-0xbfffffff window] > > > > The ACPI specifications appear to allow this new behavior: > > > > The relationship between E820 and ACPI _CRS is not really very clear. > > ACPI v6.3, sec 15, table 15-374, says AddressRangeReserved means: > > > > This range of addresses is in use or reserved by the system and is > > not to be included in the allocatable memory pool of the operating > > system's memory manager. > > > > and it may be used when: > > > > The address range is in use by a memory-mapped system device. > > > > Furthermore, sec 15.2 says: > > > > Address ranges defined for baseboard memory-mapped I/O devices, such > > as APICs, are returned as reserved. > > > > A PCI host bridge qualifies as a baseboard memory-mapped I/O device, > > and its apertures are in use and certainly should not be included in > > the general allocatable pool, so the fact that some BIOS-es reports > > the PCI aperture as "reserved" in E820 doesn't seem like a BIOS bug. > > > > So it seems that the excluding of E820 reserved addresses is a mistake. > > > > Ideally Linux would fully stop excluding E820 reserved addresses, > > but then the old systems this was added for will regress. > > Instead keep the old behavior for old systems, while ignoring > > the E820 reservations for any systems from now on. > > > > Old systems are defined here as BIOS year < 2018, this was chosen to > > make sure that pci_use_e820 will not be set on the currently affected > > systems, while at the same time also taking into account that the > > systems for which the E820 checking was originally added may have > > received BIOS updates for quite a while (esp. CVE related ones), > > giving them a more recent BIOS year then 2010. > > > > Also add pci=no_e820 and pci=use_e820 options to allow overriding > > the BIOS year heuristic. > > > > BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=206459 > > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1868899 > > BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1871793 > > BugLink: https://bugs.launchpad.net/bugs/1878279 > > BugLink: https://bugs.launchpad.net/bugs/1931715 > > BugLink: https://bugs.launchpad.net/bugs/1932069 > > BugLink: https://bugs.launchpad.net/bugs/1921649 > > Cc: Benoit Grégoire > > Cc: Hui Wang > > Cc: stable@vger.kernel.org > > Reviewed-by: Mika Westerberg > > Acked-by: Rafael J. Wysocki > > Signed-off-by: Hans de Goede > > I haven't seen anybody else eager to merge this, so I guess I'll stick > my neck out here. > > I applied this to my for-linus branch for v5.15. (I only applied patch 1/2, to fix the PCI BAR assignments. The 2/2 patch to convert printk to pr_info might be nice, but definitely not -rc7 material. I'm hesitant enough about 1/2.)