From nobody Thu Dec 18 14:28:00 2025 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 B9506C4332F for ; Wed, 13 Dec 2023 07:02:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233007AbjLMHCl (ORCPT ); Wed, 13 Dec 2023 02:02:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235287AbjLMGku (ORCPT ); Wed, 13 Dec 2023 01:40:50 -0500 Received: from smtp-fw-52004.amazon.com (smtp-fw-52004.amazon.com [52.119.213.154]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6BB78AB for ; Tue, 12 Dec 2023 22:40:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1702449655; x=1733985655; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=94amqqZKB2zJhADw4oYeciSDrXheAqykdeuVtMiJBwE=; b=YewaEIIb3vMLMNA8xGcEHKQgCbXPhZe7rnM/9qasdjdcJS+UJjq3BO2k uueMVMAckvXiVBDmeJyIOigD7t7faqcMbWwELxFcVtENaUUufqjlJhDlR DDkc2gz8+UR4MTm71Gpio8MxUGvyIzBaAdUX5NNR+BlqSf3uOC8PTSCMG g=; X-IronPort-AV: E=Sophos;i="6.04,272,1695686400"; d="scan'208";a="171634859" Received: from iad12-co-svc-p1-lb1-vlan2.amazon.com (HELO email-inbound-relay-iad-1d-m6i4x-00fceed5.us-east-1.amazon.com) ([10.43.8.2]) by smtp-border-fw-52004.iad7.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Dec 2023 06:40:53 +0000 Received: from smtpout.prod.us-east-1.prod.farcaster.email.amazon.dev (iad7-ws-svc-p70-lb3-vlan3.iad.amazon.com [10.32.235.38]) by email-inbound-relay-iad-1d-m6i4x-00fceed5.us-east-1.amazon.com (Postfix) with ESMTPS id E9EAFA0B0C; Wed, 13 Dec 2023 06:40:48 +0000 (UTC) Received: from EX19MTAEUA002.ant.amazon.com [10.0.43.254:56758] by smtpin.naws.eu-west-1.prod.farcaster.email.amazon.dev [10.0.22.100:2525] with esmtp (Farcaster) id 9438de3e-ca1c-46b1-a8b0-23d75734eed4; Wed, 13 Dec 2023 06:40:47 +0000 (UTC) X-Farcaster-Flow-ID: 9438de3e-ca1c-46b1-a8b0-23d75734eed4 Received: from EX19D014EUC004.ant.amazon.com (10.252.51.182) by EX19MTAEUA002.ant.amazon.com (10.252.50.126) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Wed, 13 Dec 2023 06:40:47 +0000 Received: from u5d18b891348c5b.ant.amazon.com (10.146.13.114) by EX19D014EUC004.ant.amazon.com (10.252.51.182) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.40; Wed, 13 Dec 2023 06:40:37 +0000 From: James Gowans To: , Eric Biederman , "Sean Christopherson" CC: , , Paolo Bonzini , Marc Zyngier , Arnd Bergmann , Tony Luck , Borislav Petkov , Thomas Gleixner , Ingo Molnar , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , "Pavel Machek" , Sebastian Reichel , Orson Zhai , Alexander Graf , "Jan H . Schoenherr" Subject: [PATCH] kexec: do syscore_shutdown() in kernel_kexec Date: Wed, 13 Dec 2023 08:40:04 +0200 Message-ID: <20231213064004.2419447-1-jgowans@amazon.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.146.13.114] X-ClientProxiedBy: EX19D031UWC004.ant.amazon.com (10.13.139.246) To EX19D014EUC004.ant.amazon.com (10.252.51.182) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" syscore_shutdown() runs driver and module callbacks to get the system into a state where it can be correctly shut down. In commit 6f389a8f1dd2 ("PM / reboot: call syscore_shutdown() after disable_nonboot_c= pus()") syscore_shutdown() was removed from kernel_restart_prepare() and hence got (incorrectly?) removed from the kexec flow. This was innocuous until commit 6735150b6997 ("KVM: Use syscore_ops instead of reboot_notifier to ho= ok restart/shutdown") changed the way that KVM registered its shutdown callbacks, switching from reboot notifiers to syscore_ops.shutdown. As syscore_shutdown() is missing from kexec, KVM's shutdown hook is not run and virtualisation is left enabled on the boot CPU which results in triple faults when switching to the new kernel on Intel x86 VT-x with VMXE enabled. Fix this by adding syscore_shutdown() to the kexec sequence. In terms of where to add it, it is being added after migrating the kexec task to the boot CPU, but before APs are shut down. It is not totally clear if this is the best place: in commit 6f389a8f1dd2 ("PM / reboot: call syscore_shutd= own() after disable_nonboot_cpus()") it is stated that "syscore_ops operations should be carried with one CPU on-line and interrupts disabled." APs are only offlined later in machine_shutdown(), so this syscore_shutdown() is being run while APs are still online. This seems to be the correct place as it matches where syscore_shutdown() is run in the reboot and halt flows - they also run it before APs are shut down. The assumption is that the commit message in commit 6f389a8f1dd2 ("PM / reboot: call syscore_shutdown() after disable= _nonboot_cpus()") is no longer valid. KVM has been discussed here as it is what broke loudly by not having syscore_shutdown() in kexec, but this change impacts more than just KVM; all drivers/modules which register a syscore_ops.shutdown callback will now be invoked in the kexec flow. Looking at some of them like x86 MCE it is probably more correct to also shut these down during kexec. Maintainers of all drivers which use syscore_ops.shutdown are added on CC for visibility. They are: arch/powerpc/platforms/cell/spu_base.c .shutdown =3D spu_shutdown, arch/x86/kernel/cpu/mce/core.c .shutdown =3D mce_syscore_shutdown, arch/x86/kernel/i8259.c .shutdown =3D i8259A_shutdown, drivers/irqchip/irq-i8259.c .shutdown =3D i8259A_shutdown, drivers/irqchip/irq-sun6i-r.c .shutdown =3D sun6i_r_intc_shutdown, drivers/leds/trigger/ledtrig-cpu.c .shutdown =3D ledtrig_cpu_syscore_shutdo= wn, drivers/power/reset/sc27xx-poweroff.c .shutdown =3D sc27xx_poweroff_shutdow= n, kernel/irq/generic-chip.c .shutdown =3D irq_gc_shutdown, virt/kvm/kvm_main.c .shutdown =3D kvm_shutdown, This has been tested by doing a kexec on x86_64 and aarch64. Fixes: 6735150b6997 ("KVM: Use syscore_ops instead of reboot_notifier to ho= ok restart/shutdown") Signed-off-by: James Gowans Cc: Eric Biederman Cc: Paolo Bonzini Cc: Sean Christopherson Cc: Marc Zyngier Cc: Arnd Bergmann Cc: Tony Luck Cc: Borislav Petkov Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Chen-Yu Tsai Cc: Jernej Skrabec Cc: Samuel Holland Cc: Pavel Machek Cc: Sebastian Reichel Cc: Orson Zhai Cc: Alexander Graf Cc: Jan H. Schoenherr Acked-by: "Eric W. Biederman" --- kernel/kexec_core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index be5642a4ec49..b926c4db8a91 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -1254,6 +1254,7 @@ int kernel_kexec(void) kexec_in_progress =3D true; kernel_restart_prepare("kexec reboot"); migrate_to_reboot_cpu(); + syscore_shutdown(); =20 /* * migrate_to_reboot_cpu() disables CPU hotplug assuming that --=20 2.34.1