From nobody Sat Feb 7 19:45:39 2026 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A856C77B7A for ; Thu, 25 May 2023 09:50:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240618AbjEYJu3 (ORCPT ); Thu, 25 May 2023 05:50:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38048 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240261AbjEYJu0 (ORCPT ); Thu, 25 May 2023 05:50:26 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AC24B191 for ; Thu, 25 May 2023 02:49:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1685008180; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=hAxjra5W1+1SvpBMN22QXJJOi5JB+teXZgPwJvUgVGE=; b=H5eCmI5ZjssqzzZPef2G9MeMirWeBvpgB42ph90+wq0JHNlgkrjIjNlJsOZTFfu7ONWP+M Q0aWm1eL9R9jB9KmuIf31QQq6/gw6wZ9LZHCoVsiaQBa0ta2GjzDVc3QO4bgsMfF103OMs D+eFVc/DBLhWApjVmJN9V/pIG2E5tgw= Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-44-FIiChdNTPFimlaeJDlZfEQ-1; Thu, 25 May 2023 05:49:38 -0400 X-MC-Unique: FIiChdNTPFimlaeJDlZfEQ-1 Received: by mail-pg1-f200.google.com with SMTP id 41be03b00d2f7-53425d37f33so902381a12.3 for ; Thu, 25 May 2023 02:49:38 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685008177; x=1687600177; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=hAxjra5W1+1SvpBMN22QXJJOi5JB+teXZgPwJvUgVGE=; b=DBtByHAon5EpSh1gm8P3J+SGoHiCHyLM7g5Za4T4EKbXQQTH9inFKr0TXA18gxwQ6y NnxBCt66lLfuMyJZhOtF+UcEmLTHMPR/3rue6Fiw7Lbv8uT5WtWeS++avJJtK5oW1Sb/ caaTFp1CE2oUStYBlP5M6QR0DoAjyQfWoxKHOnFZc0k/jclGDH/nHA3ngAFX6+dmZ8fu mI7ueoWqOXvOdwwDYXCmmHsPp/Cu8gafSzcf1imYPC0SYSU7Zbg4V6NxOSD+nXYK5qgY b2ojpWJzbC6DrnCgQ9UEH7Lz+CsbUu0OaAcprOFglYH9HqtwBpUZXAUvfOIac6Ccv9Yi WoBQ== X-Gm-Message-State: AC+VfDwVApH1RZKLNk/g34cpYMEd+VyP1bNoQFxSi1GI2/MBAuDwB6Bj rdUkGdG/+UItmx3qWbh+9xqzh80zENZlkrzIa/SMyZRaViNMWAKi4BTrjqPd2PS6AKYX7zQLO7s J2ARKigdy7Nf0kL8LkuLQcmGR X-Received: by 2002:a17:903:230f:b0:1af:a03:8d82 with SMTP id d15-20020a170903230f00b001af0a038d82mr1149855plh.57.1685008177412; Thu, 25 May 2023 02:49:37 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ64F7+wAhODeQTh71SkG9KiZ+8BDhumZp7KJkEik3KY4RGXnQjHL9XswjQ5pC+GeNWlMRi+Sg== X-Received: by 2002:a17:903:230f:b0:1af:a03:8d82 with SMTP id d15-20020a170903230f00b001af0a038d82mr1149833plh.57.1685008177110; Thu, 25 May 2023 02:49:37 -0700 (PDT) Received: from localhost.localdomain.com ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id c10-20020a170903234a00b001ab2b4105ddsm1008282plh.60.2023.05.25.02.49.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 25 May 2023 02:49:36 -0700 (PDT) From: Tao Liu To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com Cc: linux-kernel@vger.kernel.org, bhe@redhat.com, dyoung@redhat.com, kexec@lists.infradead.org, linux-efi@vger.kernel.org, Tao Liu Subject: [PATCH] x86/kexec: Add EFI config table identity mapping for kexec kernel Date: Thu, 25 May 2023 17:49:14 +0800 Message-Id: <20230525094914.23420-1-ltao@redhat.com> X-Mailer: git-send-email 2.33.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" A kexec kernel bootup hang is observed on Intel Atom cpu due to unmapped EFI config table. Currently EFI system table is identity-mapped for the kexec kernel, but EFI config table is not mapped explicitly: commit 6bbeb276b71f ("x86/kexec: Add the EFI system tables and ACPI tables to the ident map") Later in the following 2 commits, EFI config table will be accessed when enabling sev at kernel startup. This may result in a page fault due to EFI config table's unmapped address. Since the page fault occurs at an early stage, it is unrecoverable and kernel hangs. commit ec1c66af3a30 ("x86/compressed/64: Detect/setup SEV/SME features earlier during boot") commit c01fce9cef84 ("x86/compressed: Add SEV-SNP feature detection/setup") In addition, the issue doesn't appear on all systems, because the kexec kernel uses Page Size Extension (PSE) for identity mapping. In most cases, EFI config table can end up to be mapped into due to 1 GB page size. However if nogbpages is set, or cpu doesn't support pdpe1gb feature (e.g Intel Atom x6425RE cpu), EFI config table may not be mapped into due to 2 MB page size, thus a page fault hang is more likely to happen. In this patch, we will make sure the EFI config table is always mapped. Signed-off-by: Tao Liu --- arch/x86/kernel/machine_kexec_64.c | 35 ++++++++++++++++++++++++++---- 1 file changed, 31 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_k= exec_64.c index 1a3e2c05a8a5..755aa12f583f 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -28,6 +28,7 @@ #include #include #include +#include =20 #ifdef CONFIG_ACPI /* @@ -86,10 +87,12 @@ const struct kexec_file_ops * const kexec_file_loaders[= ] =3D { #endif =20 static int -map_efi_systab(struct x86_mapping_info *info, pgd_t *level4p) +map_efi_sys_cfg_tab(struct x86_mapping_info *info, pgd_t *level4p) { #ifdef CONFIG_EFI unsigned long mstart, mend; + void *kaddr; + int ret; =20 if (!efi_enabled(EFI_BOOT)) return 0; @@ -105,6 +108,30 @@ map_efi_systab(struct x86_mapping_info *info, pgd_t *l= evel4p) if (!mstart) return 0; =20 + ret =3D kernel_ident_mapping_init(info, level4p, mstart, mend); + if (ret) + return ret; + + kaddr =3D memremap(mstart, mend - mstart, MEMREMAP_WB); + if (!kaddr) { + pr_err("Could not map UEFI system table\n"); + return -ENOMEM; + } + + mstart =3D efi_config_table; + + if (efi_enabled(EFI_64BIT)) { + efi_system_table_64_t *stbl =3D (efi_system_table_64_t *)kaddr; + + mend =3D mstart + sizeof(efi_config_table_64_t) * stbl->nr_tables; + } else { + efi_system_table_32_t *stbl =3D (efi_system_table_32_t *)kaddr; + + mend =3D mstart + sizeof(efi_config_table_32_t) * stbl->nr_tables; + } + + memunmap(kaddr); + return kernel_ident_mapping_init(info, level4p, mstart, mend); #endif return 0; @@ -244,10 +271,10 @@ static int init_pgtable(struct kimage *image, unsigne= d long start_pgtable) } =20 /* - * Prepare EFI systab and ACPI tables for kexec kernel since they are - * not covered by pfn_mapped. + * Prepare EFI systab, config table and ACPI tables for kexec kernel + * since they are not covered by pfn_mapped. */ - result =3D map_efi_systab(&info, level4p); + result =3D map_efi_sys_cfg_tab(&info, level4p); if (result) return result; =20 --=20 2.33.1