Hi Eric, On Wed, 2023-12-13 at 10:39 -0600, Eric W. Biederman wrote: > > James Gowans <jgowans@xxxxxxxxxx> writes: > > > 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_cpus()") > > 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 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 6f389a8f1dd2 ("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 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 is no longer valid.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 = 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. > > From the 10,000 foot perspective: > Acked-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Thanks for the ACK! What's the next step to get this into the kexec tree? JG > > > Eric > > > Fixes: 6735150b6997 ("KVM: Use syscore_ops instead of reboot_notifier to hook restart/shutdown") > > > > Signed-off-by: James Gowans <jgowans@xxxxxxxxxx> > > Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx> > > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > > Cc: Sean Christopherson <seanjc@xxxxxxxxxx> > > Cc: Marc Zyngier <maz@xxxxxxxxxx> > > Cc: Arnd Bergmann <arnd@xxxxxxxx> > > Cc: Tony Luck <tony.luck@xxxxxxxxx> > > Cc: Borislav Petkov <bp@xxxxxxxxx> > > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > > Cc: Chen-Yu Tsai <wens@xxxxxxxx> > > Cc: Jernej Skrabec <jernej.skrabec@xxxxxxxxx> > > Cc: Samuel Holland <samuel@xxxxxxxxxxxx> > > Cc: Pavel Machek <pavel@xxxxxx> > > Cc: Sebastian Reichel <sre@xxxxxxxxxx> > > Cc: Orson Zhai <orsonzhai@xxxxxxxxx> > > Cc: Alexander Graf <graf@xxxxxxxxx> > > Cc: Jan H. Schoenherr <jschoenh@xxxxxxxxx> > > --- > > 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 = true; > > kernel_restart_prepare("kexec reboot"); > > migrate_to_reboot_cpu(); > > + syscore_shutdown(); > > > > /* > > * migrate_to_reboot_cpu() disables CPU hotplug assuming that _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec