From patchwork Wed Jul 21 14:20:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joerg Roedel X-Patchwork-Id: 484582 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 7EE90C12002 for ; Wed, 21 Jul 2021 14:20:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6652A61246 for ; Wed, 21 Jul 2021 14:20:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239172AbhGUNkD (ORCPT ); Wed, 21 Jul 2021 09:40:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239071AbhGUNkA (ORCPT ); Wed, 21 Jul 2021 09:40:00 -0400 Received: from theia.8bytes.org (8bytes.org [IPv6:2a01:238:4383:600:38bc:a715:4b6d:a889]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 64248C061575; Wed, 21 Jul 2021 07:20:36 -0700 (PDT) Received: from cap.home.8bytes.org (p4ff2b1ea.dip0.t-ipconnect.de [79.242.177.234]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by theia.8bytes.org (Postfix) with ESMTPSA id A5417926; Wed, 21 Jul 2021 16:20:23 +0200 (CEST) From: Joerg Roedel To: x86@kernel.org, Eric Biederman Cc: kexec@lists.infradead.org, Joerg Roedel , stable@vger.kernel.org, hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , David Rientjes , Cfir Cohen , Erdem Aktas , Masami Hiramatsu , Mike Stunes , Sean Christopherson , Martin Radev , Arvind Sankar , Joerg Roedel , linux-coco@lists.linux.dev, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: [PATCH 01/12] kexec: Allow architecture code to opt-out at runtime Date: Wed, 21 Jul 2021 16:20:04 +0200 Message-Id: <20210721142015.1401-2-joro@8bytes.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210721142015.1401-1-joro@8bytes.org> References: <20210721142015.1401-1-joro@8bytes.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Joerg Roedel Allow a runtime opt-out of kexec support for architecture code in case the kernel is running in an environment where kexec is not properly supported yet. This will be used on x86 when the kernel is running as an SEV-ES guest. SEV-ES guests need special handling for kexec to hand over all CPUs to the new kernel. This requires special hypervisor support and handling code in the guest which is not yet implemented. Cc: stable@vger.kernel.org # v5.10+ Signed-off-by: Joerg Roedel --- include/linux/kexec.h | 1 + kernel/kexec.c | 14 ++++++++++++++ kernel/kexec_file.c | 9 +++++++++ 3 files changed, 24 insertions(+) diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 0c994ae37729..85c30dcd0bdc 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -201,6 +201,7 @@ int arch_kexec_kernel_verify_sig(struct kimage *image, void *buf, unsigned long buf_len); #endif int arch_kexec_locate_mem_hole(struct kexec_buf *kbuf); +bool arch_kexec_supported(void); extern int kexec_add_buffer(struct kexec_buf *kbuf); int kexec_locate_mem_hole(struct kexec_buf *kbuf); diff --git a/kernel/kexec.c b/kernel/kexec.c index c82c6c06f051..d03134160458 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -195,11 +195,25 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments, * that to happen you need to do that yourself. */ +bool __weak arch_kexec_supported(void) +{ + return true; +} + static inline int kexec_load_check(unsigned long nr_segments, unsigned long flags) { int result; + /* + * The architecture may support kexec in general, but the kernel could + * run in an environment where it is not (yet) possible to execute a new + * kernel. Allow the architecture code to opt-out of kexec support when + * it is running in such an environment. + */ + if (!arch_kexec_supported()) + return -ENOSYS; + /* We only trust the superuser with rebooting the system. */ if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) return -EPERM; diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 33400ff051a8..96d08a512e9c 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -358,6 +358,15 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, int ret = 0, i; struct kimage **dest_image, *image; + /* + * The architecture may support kexec in general, but the kernel could + * run in an environment where it is not (yet) possible to execute a new + * kernel. Allow the architecture code to opt-out of kexec support when + * it is running in such an environment. + */ + if (!arch_kexec_supported()) + return -ENOSYS; + /* We only trust the superuser with rebooting the system. */ if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) return -EPERM;