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=-3.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS autolearn=no 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 A3435C2D0CE for ; Mon, 30 Dec 2019 09:42:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6BD5B20658 for ; Mon, 30 Dec 2019 09:42:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="TyjztaV0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727352AbfL3JmX (ORCPT ); Mon, 30 Dec 2019 04:42:23 -0500 Received: from mail-ot1-f67.google.com ([209.85.210.67]:43099 "EHLO mail-ot1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727162AbfL3JmW (ORCPT ); Mon, 30 Dec 2019 04:42:22 -0500 Received: by mail-ot1-f67.google.com with SMTP id p8so9197509oth.10 for ; Mon, 30 Dec 2019 01:42:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=7aJ1y7kojlezhXxwCAdzL2Cz1fpp5Mlwq/T9MyJ5Ytc=; b=TyjztaV08AZvzV59Zdl0SvtbkaC827fqWnZXdmVUUkgIQIbcjIxa+85MPylZdoHwoD aG6NlJEh5syG7O4b2m3q2Ue05RwU7M3fTzuLhRNNm8o9fT6kwWBeOZH7igbgIZbypV/9 TzMjIpuwu1AevS5HIURy7SeRvS+tHdQJfhlZeK2ZJlemKchV6LFMmw3r1W6M3HHpyUww ZfUJ3X/6Ku0vmWSIwDPre0OycgeA+5o54gRpf/AhgLGSfuoc/c0xzHT6MVHdQiP6+tKZ 1OvDJnpMr6/nPpKAuWGDylu9LfRplJuzl5G4um8Pc2peacY/9D9UiUU/c/7aN3gav5Zl P5+A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7aJ1y7kojlezhXxwCAdzL2Cz1fpp5Mlwq/T9MyJ5Ytc=; b=JO/LcT+yXg8p2KfsZq9LHST7VKItoWuwJq46uVx5kQwUnU/NM0qrt6NtYhyHBs3jVo VPy8solscSqk2NcG8PtvctpkPXzzn7R+DcjgNd/9lRhDuW02WpfajS0mwe0nFaDQ90RG 41IOj1rlxXEKRsJamD6Q6bf2Kj3OpJ1Eb06VnR12HyIP+YSrnPfzk9mmhqqxO7A2+CW1 GyKCtomCXaBK0wL3SI7pAmyj1PKdFyyt4fc2SKQUyVScMjMaCAvcA9Ye8jc08G51Y7iP RKcyA//enzoW/IT4DzpJ8z+goqiG2BV7c0HqgCIOUVDp9R6VdkmT45l2zmMw/Htfx60B djTw== X-Gm-Message-State: APjAAAWA97AdmNKK6Njh71ogp3JB2LoM1oPHtqIupy2olvi9jJkGpZhf +FNRNKjxmOfWFriaaVoh3+cbXbJqrMa/NcMR8cW1SQ== X-Google-Smtp-Source: APXvYqzTYr6aV+rPI0Pmwpf+N298DKL88SZz9iyTWr2mhh+zFVppiuaocEDoNMW1GBuinPaNQ1q4OK5ewnpeCvMxXXs= X-Received: by 2002:a9d:68d3:: with SMTP id i19mr18735495oto.71.1577698941942; Mon, 30 Dec 2019 01:42:21 -0800 (PST) MIME-Version: 1.0 References: <20191204075233.GA10520@dhcp-128-65.nay.redhat.com> In-Reply-To: From: Dan Williams Date: Mon, 30 Dec 2019 01:42:10 -0800 Message-ID: Subject: Re: [PATCH] x86/efi: update e820 about reserved EFI boot services data to fix kexec breakage To: Dan Williams Cc: Dave Young , linux-efi , X86 ML , Linux Kernel Mailing List , Michael Weiser , Ard Biesheuvel , kexec@lists.infradead.org, Ingo Molnar , Borislav Petkov , "Eric W. Biederman" , "H. Peter Anvin" , Thomas Gleixner Content-Type: text/plain; charset="UTF-8" Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Sat, Dec 28, 2019 at 10:13 PM Dan Williams wrote: > > On Sat, Dec 28, 2019 at 12:54 PM Dan Williams > wrote: > > > > On Tue, Dec 3, 2019 at 11:53 PM Dave Young wrote: > > > > > > Michael Weiser reported he got below error during a kexec rebooting: > > > esrt: Unsupported ESRT version 2904149718861218184. > > > > > > The ESRT memory stays in EFI boot services data, and it was reserved > > > in kernel via efi_mem_reserve(). The initial purpose of the reservation > > > is to reuse the EFI boot services data across kexec reboot. For example > > > the BGRT image data and some ESRT memory like Michael reported. > > > > > > But although the memory is reserved it is not updated in X86 e820 table. > > > And kexec_file_load iterate system ram in io resource list to find places > > > for kernel, initramfs and other stuff. In Michael's case the kexec loaded > > > initramfs overwritten the ESRT memory and then the failure happened. > > > > > > Since kexec_file_load depends on the e820 to be updated, just fix this > > > by updating the reserved EFI boot services memory as reserved type in e820. > > > > > > Originally any memory descriptors with EFI_MEMORY_RUNTIME attribute are > > > bypassed in the reservation code path because they are assumed as reserved. > > > But the reservation is still needed for multiple kexec reboot. > > > And it is the only possible case we come here thus just drop the code > > > chunk then everything works without side effects. > > > > > > On my machine the ESRT memory sits in an EFI runtime data range, it does > > > not trigger the problem, but I successfully tested with BGRT instead. > > > both kexec_load and kexec_file_load work and kdump works as well. > > > > > > Signed-off-by: Dave Young > > > --- > > > arch/x86/platform/efi/quirks.c | 6 ++---- > > > 1 file changed, 2 insertions(+), 4 deletions(-) > > > > > > --- linux-x86.orig/arch/x86/platform/efi/quirks.c > > > +++ linux-x86/arch/x86/platform/efi/quirks.c > > > @@ -260,10 +260,6 @@ void __init efi_arch_mem_reserve(phys_ad > > > return; > > > } > > > > > > - /* No need to reserve regions that will never be freed. */ > > > - if (md.attribute & EFI_MEMORY_RUNTIME) > > > - return; > > > - > > > size += addr % EFI_PAGE_SIZE; > > > size = round_up(size, EFI_PAGE_SIZE); > > > addr = round_down(addr, EFI_PAGE_SIZE); > > > @@ -293,6 +289,8 @@ void __init efi_arch_mem_reserve(phys_ad > > > early_memunmap(new, new_size); > > > > > > efi_memmap_install(new_phys, num_entries); > > > + e820__range_update(addr, size, E820_TYPE_RAM, E820_TYPE_RESERVED); > > > + e820__update_table(e820_table); > > > } > > > > > > /* > > > > > > > Bisect says this change (commit af1648984828) is triggering a > > regression, likely not urgent, in my testing of the new efi_fake_mem= > > facility to allow memory to be marked "soft reserved" via the kernel > > command line (commit 199c84717612 x86/efi: Add efi_fake_mem support > > for EFI_MEMORY_SP). The following command line triggers the crash > > signature below: > > > > efi_fake_mem=4G@9G:0x40000,4G@13G:0x40000 > > > > However, this command line works ok: > > > > efi_fake_mem=8G@9G:0x40000 > > > > So, something about multiple efi_fake_mem statements interacts badly > > with this change. Nothing obvious occurs to me at the moment, I'll > > keep debugging, but wanted to highlight this in the meantime in case > > someone else sees a deeper issue or the root cause. > > Still looking, but this failure does not seem to be specific to the > "soft reservation" changes. Any update to the efi memmap that pushes > it over a page boundary triggers this failure. I.e. I can fix the > problem by over-allocating the efi memmap and then page aligning the > result. __early_ioremap "should" be handling this case, but it appears > something else is messing this up. Found it. Neither this patch nor the soft reservation changes are at fault, they are just helping to trigger a long standing bug in efi_fake_memmap(). Its usage of efi_memmap_split_count() can over count the number of splits needed for new entries. Consider the case of 2 contiguous fake entries intersecting the end of a single entry. The first call to efi_memmap_split_count() determines the resulting split will be (old1, new1, old2), the second call determines (old1, new2). The result is 2 splits when only 1 is needed to get a result of (old1, new1, new2) and the new map ends up with an empty entry. efi_memmap_install() interprets an empty entry as start = 0 end = 0xffffffffffffffff and attempts an extra split / copy past the end of the new map. I'll send a patch to fix up efi_fake_memmap().