diff options
| author | Baoquan He <bhe@redhat.com> | 2018-02-14 13:46:56 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-05-30 07:50:50 +0200 |
| commit | 1e6b708a1dc617478a6dede5ecd38e055f3b1e35 (patch) | |
| tree | 3f07c838c7a8c529018ec65cb3d220abd7f63e83 | |
| parent | 996c5d9d9c625a29544c83bf94ffe107d2cd724f (diff) | |
x86/apic: Set up through-local-APIC mode on the boot CPU if 'noapic' specified
[ Upstream commit bee3204ec3c49f6f53add9c3962c9012a5c036fa ]
Currently the kdump kernel becomes very slow if 'noapic' is specified.
Normal kernel doesn't have this bug.
Kernel parameter 'noapic' is used to disable IO-APIC in system for
testing or special purpose. Here the root cause is that in kdump
kernel LAPIC is disabled since commit:
522e664644 ("x86/apic: Disable I/O APIC before shutdown of the local APIC")
In this case we need set up through-local-APIC on boot CPU in
setup_local_APIC().
In normal kernel the legacy irq mode is enabled by the BIOS. If
it is virtual wire mode, the local-APIC has been enabled and set as
through-local-APIC.
Though we fixed the regression introduced by commit 522e664644,
to further improve robustness set up the through-local-APIC mode
explicitly, do not rely on the default boot IRQ mode.
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: uobergfe@redhat.com
Link: http://lkml.kernel.org/r/20180214054656.3780-7-bhe@redhat.com
[ Rewrote the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kernel/apic/apic.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index c6583efdbdaf..76cf21f887bd 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1403,7 +1403,7 @@ void setup_local_APIC(void) * TODO: set up through-local-APIC from through-I/O-APIC? --macro */ value = apic_read(APIC_LVT0) & APIC_LVT_MASKED; - if (!cpu && (pic_mode || !value)) { + if (!cpu && (pic_mode || !value || skip_ioapic_setup)) { value = APIC_DM_EXTINT; apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n", cpu); } else { |