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James Gowans 7bb943806f kexec: do syscore_shutdown() in kernel_kexec 
syscore_shutdown() runs driver and module callbacks to get the system into
a state where it can be correctly shut down.  In commit 6f389a8f1d ("PM
/ reboot: call syscore_shutdown() after disable_nonboot_cpus()")
syscore_shutdown() was removed from kernel_restart_prepare() and hence got
(incorrectly?) removed from the kexec flow.  This was innocuous until
commit 6735150b69 ("KVM: Use syscore_ops instead of reboot_notifier to
hook 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 6f389a8f1d ("PM / reboot: call
syscore_shutdown() 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 6f389a8f1d
("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no longer valid.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 = spu_shutdown,
arch/x86/kernel/cpu/mce/core.c	        .shutdown = mce_syscore_shutdown,
arch/x86/kernel/i8259.c                 .shutdown = i8259A_shutdown,
drivers/irqchip/irq-i8259.c	        .shutdown = i8259A_shutdown,
drivers/irqchip/irq-sun6i-r.c	        .shutdown = sun6i_r_intc_shutdown,
drivers/leds/trigger/ledtrig-cpu.c	.shutdown = ledtrig_cpu_syscore_shutdown,
drivers/power/reset/sc27xx-poweroff.c	.shutdown = sc27xx_poweroff_shutdown,
kernel/irq/generic-chip.c	        .shutdown = irq_gc_shutdown,
virt/kvm/kvm_main.c	                .shutdown = kvm_shutdown,

This has been tested by doing a kexec on x86_64 and aarch64.

Link: https://lkml.kernel.org/r/20231213064004.2419447-1-jgowans@amazon.com
Fixes: 6735150b69 ("KVM: Use syscore_ops instead of reboot_notifier to hook restart/shutdown")
Signed-off-by: James Gowans <jgowans@amazon.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
Cc: Samuel Holland <samuel@sholland.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Sebastian Reichel <sre@kernel.org>
Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: Alexander Graf <graf@amazon.de>
Cc: Jan H. Schoenherr <jschoenh@amazon.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-01-12 15:20:47 -08:00
arch EFI updates for v6.8 2024-01-09 17:11:27 -08:00
block Many singleton patches against the MM code. The patch series which 2024-01-09 11:18:47 -08:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This push fixes a regression in ahash and hides the Kconfig sub-options for the jitter RNG. 2023-11-09 17:04:58 -08:00
Documentation linux_kselftest-kunit-6.8-rc1 2024-01-09 17:16:58 -08:00
drivers linux_kselftest-kunit-6.8-rc1 2024-01-09 17:16:58 -08:00
fs fs/proc/task_mmu: move mmu notification mechanism inside mm lock 2024-01-12 15:20:46 -08:00
include linux_kselftest-kunit-6.8-rc1 2024-01-09 17:16:58 -08:00
init init/Kconfig: move more items into the EXPERT menu 2023-12-20 15:02:58 -08:00
io_uring Many singleton patches against the MM code. The patch series which 2024-01-09 11:18:47 -08:00
ipc Many singleton patches against the MM code. The patch series which are 2023-11-02 19:38:47 -10:00
kernel kexec: do syscore_shutdown() in kernel_kexec 2024-01-12 15:20:47 -08:00
lib lib/Kconfig.debug: disable CONFIG_DEBUG_INFO_BTF for Hexagon 2024-01-12 15:20:45 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm kasan: avoid resetting aux_lock 2024-01-12 15:20:45 -08:00
net lsm/stable-6.8 PR 20240105 2024-01-09 12:57:46 -08:00
rust Kbuild updates for v6.7 2023-11-04 08:07:19 -10:00
samples Many singleton patches against the MM code. The patch series which 2024-01-09 11:18:47 -08:00
scripts scripts/decode_stacktrace.sh: optionally use LLVM utilities 2024-01-12 15:20:46 -08:00
security integrity-v6.8 2024-01-09 13:24:06 -08:00
sound linux_kselftest-kunit-6.8-rc1 2024-01-09 17:16:58 -08:00
tools linux_kselftest-next-6.8-rc1 2024-01-09 17:28:41 -08:00
usr usr/Kconfig: fix typos of "its" 2023-12-20 15:02:58 -08:00
virt vfs-6.8.misc 2024-01-08 10:26:08 -08:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: generate kernel.spec in rpmbuild/SPECS/ 2023-10-03 20:49:09 +09:00
.mailmap mailmap: update entry for Manivannan Sadhasivam 2024-01-12 15:20:46 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS Quite a lot of kexec work this time around. Many singleton patches in 2024-01-09 11:46:20 -08:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS mm: zswap: switch maintainers to recently active developers and reviewers 2024-01-12 15:20:46 -08:00
Makefile Quite a lot of kexec work this time around. Many singleton patches in 2024-01-09 11:46:20 -08:00
README

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.