Messages in this thread Patch in this message | | | Date | Sat, 17 Feb 2018 03:42:10 -0800 | From | tip-bot for Baoquan He <> | Subject | [tip:x86/apic] x86/apic: Fix restoring boot IRQ mode in reboot and kexec/kdump |
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Commit-ID: 339b2ae0cd5d4a58f9efe06e4ee36adbeca59228 Gitweb: https://git.kernel.org/tip/339b2ae0cd5d4a58f9efe06e4ee36adbeca59228 Author: Baoquan He <bhe@redhat.com> AuthorDate: Wed, 14 Feb 2018 13:46:53 +0800 Committer: Ingo Molnar <mingo@kernel.org> CommitDate: Sat, 17 Feb 2018 11:47:45 +0100
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> --- arch/x86/kernel/crash.c | 3 ++- arch/x86/kernel/reboot.c | 3 ++- 2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index 10e74d4..1f66804 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 diff --git a/arch/x86/kernel/reboot.c b/arch/x86/kernel/reboot.c index 2126b9d..725624b 100644 --- a/arch/x86/kernel/reboot.c +++ b/arch/x86/kernel/reboot.c @@ -666,7 +666,7 @@ void native_machine_shutdown(void) * Even without the erratum, it still makes sense to quiet IO APIC * before disabling Local APIC. */ - disable_IO_APIC(); + clear_IO_APIC(); #endif #ifdef CONFIG_SMP @@ -680,6 +680,7 @@ void native_machine_shutdown(void) #endif lapic_shutdown(); + restore_boot_irq_mode(); #ifdef CONFIG_HPET_TIMER hpet_disable();
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