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authorBaoquan He <bhe@redhat.com>2018-02-14 08:46:53 +0300
committerIngo Molnar <mingo@kernel.org>2018-02-17 13:47:45 +0300
commit339b2ae0cd5d4a58f9efe06e4ee36adbeca59228 (patch)
treec629f2ed6224a140624e3a7cfef0790064b6efd2 /arch/x86/kernel/crash.c
parent3c9e76dbea004b2c7c3ce872022ceaf5ff0dae79 (diff)
downloadlinux-339b2ae0cd5d4a58f9efe06e4ee36adbeca59228.tar.xz
x86/apic: Fix restoring boot IRQ mode in reboot and kexec/kdump
This is a regression fix. Before, to fix erratum AVR31, the following commit: 522e66464467 ("x86/apic: Disable I/O APIC before shutdown of the local APIC") ... moved the lapic_shutdown() call to after disable_IO_APIC() in the reboot and kexec/kdump code paths. This introduced the following regression: disable_IO_APIC() not only clears the IO-APIC, but it also restores boot IRQ mode by setting the LAPIC/APIC/IMCR, calling lapic_shutdown() after disable_IO_APIC() will disable LAPIC and ruin the possible virtual wire mode setting which the code has been trying to do all along. The consequence is that a KVM guest kernel always prints the warning below during kexec/kdump as the kernel boots up: [ 0.001000] WARNING: CPU: 0 PID: 0 at arch/x86/kernel/apic/apic.c:1467 setup_local_APIC+0x228/0x330 [ ........] [ 0.001000] Call Trace: [ 0.001000] apic_bsp_setup+0x56/0x74 [ 0.001000] x86_late_time_init+0x11/0x16 [ 0.001000] start_kernel+0x3c9/0x486 [ 0.001000] secondary_startup_64+0xa5/0xb0 [ ........] [ 0.001000] masked ExtINT on CPU#0 To fix this, just call clear_IO_APIC() to stop the IO-APIC where disable_IO_APIC() was called, and call restore_boot_irq_mode() to restore boot IRQ mode before a reboot or a kexec/kdump jump. Signed-off-by: Baoquan He <bhe@redhat.com> Reviewed-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: douly.fnst@cn.fujitsu.com Cc: joro@8bytes.org Cc: prarit@redhat.com Cc: stable@vger.kernel.org Cc: uobergfe@redhat.com Fixes: commit 522e66464467 ("x86/apic: Disable I/O APIC before shutdown of the local APIC") Link: http://lkml.kernel.org/r/20180214054656.3780-4-bhe@redhat.com [ Rewrote the changelog. ] Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/crash.c')
-rw-r--r--arch/x86/kernel/crash.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 10e74d4778a1..1f6680427ff0 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -199,9 +199,10 @@ void native_machine_crash_shutdown(struct pt_regs *regs)
#ifdef CONFIG_X86_IO_APIC
/* Prevent crash_kexec() from deadlocking on ioapic_lock. */
ioapic_zap_locks();
- disable_IO_APIC();
+ clear_IO_APIC();
#endif
lapic_shutdown();
+ restore_boot_irq_mode();
#ifdef CONFIG_HPET_TIMER
hpet_disable();
#endif