Commit fba4f472 authored Apr 19, 2017 by Tiantian Feng Committed by Ingo Molnar Apr 20, 2017

x86/reboot: Turn off KVM when halting a CPU



A CPU in VMX root mode will ignore INIT signals and will fail to bring
up the APs after reboot.  Therefore, on a panic we disable VMX on all
CPUs before rebooting or triggering kdump.

Do this when halting the machine as well, in case a firmware-level reboot
does not perform a cold reset for all processors.  Without doing this,
rebooting the host may hang.

Signed-off-by: Tiantian Feng <fengtiantian@huawei.com>
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
[ Rewritten commit message. ]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm@vger.kernel.org
Link: http://lkml.kernel.org/r/20170419161839.30550-1-pbonzini@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent d594aa02

arch/x86/kernel/smp.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -33,6 +33,7 @@
		#include <asm/mce.h>
		#include <asm/trace/irq_vectors.h>
		#include <asm/kexec.h>
		#include <asm/virtext.h>

		/*
		* Some notes on x86 processor bugs affecting SMP operation:
		@@ -162,6 +163,7 @@ static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs)
		if (raw_smp_processor_id() == atomic_read(&stopping_cpu))
		return NMI_HANDLED;

		cpu_emergency_vmxoff();
		stop_this_cpu(NULL);

		return NMI_HANDLED;
		@@ -174,6 +176,7 @@ static int smp_stop_nmi_callback(unsigned int val, struct pt_regs *regs)
		asmlinkage __visible void smp_reboot_interrupt(void)
		{
		ipi_entering_ack_irq();
		cpu_emergency_vmxoff();
		stop_this_cpu(NULL);
		irq_exit();
		}

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