linux/arch/x86
Kerstin Jonsson 8c3ba8d049 x86, apic: ack all pending irqs when crashed/on kexec
When the SMP kernel decides to crash_kexec() the local APICs may have
pending interrupts in their vector tables.

The setup routine for the local APIC has a deficient mechanism for
clearing these interrupts, it only handles interrupts that has already
been dispatched to the local core for servicing (the ISR register) safely,
it doesn't consider lower prioritized queued interrupts stored in the IRR
register.

If you have more than one pending interrupt within the same 32 bit word in
the LAPIC vector table registers you may find yourself entering the IO
APIC setup with pending interrupts left in the LAPIC.  This is a situation
for wich the IO APIC setup is not prepared.  Depending of what/which
interrupt vector/vectors are stuck in the APIC tables your system may show
various degrees of malfunctioning.  That was the reason why the
check_timer() failed in our system, the timer interrupts was blocked by
pending interrupts from the old kernel when routed trough the IO APIC.

Additional comment from Jiri Bohac:
==============
If this should go into stable release,
I'd add some kind of limit on the number of iterations, just to be safe from
hard to debug lock-ups:

+if (loops++  > MAX_LOOPS) {
+        printk("LAPIC pending clean-up")
+        break;
+}
 while (queued);

with MAX_LOOPS something like 1E9 this would leave plenty of time for the
pending IRQs to be cleared and would and still cause at most a second of delay
if the loop were to lock-up for whatever reason.

[trenn@suse.de:

V2: Use tsc if avail to bail out after 1 sec due to possible virtual
    apic_read calls which may take rather long (suggested by: Avi Kivity
    <avi@redhat.com>) If no tsc is available bail out quickly after
    cpu_khz, if we broke out too early and still have irqs pending (which
    should never happen?) we still get a WARN_ON...

V3: - Fixed indentation -> checkpatch clean
    - max_loops must be signed

V4: - Fix typo, mixed up tsc and ntsc in first rdtscll() call

V5: Adjust WARN_ON() condition to also catch error in cpu_has_tsc case]

Cc: <jbohac@novell.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Kerstin Jonsson <kerstin.jonsson@ericsson.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
Tested-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
LKML-Reference: <201005241913.o4OJDGWM010865@imap1.linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2010-05-24 13:31:35 -07:00
..
boot Merge branch 'x86-setup-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-02-28 10:43:53 -08:00
configs
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 2010-05-03 11:28:58 +08:00
ia32 x86: correctly wire up the newuname system call 2010-04-20 09:17:21 -07:00
include/asm Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2010-05-21 18:58:52 -07:00
kernel x86, apic: ack all pending irqs when crashed/on kexec 2010-05-24 13:31:35 -07:00
kvm Merge branch 'kvm-updates/2.6.35' of git://git.kernel.org/pub/scm/virt/kvm/kvm 2010-05-21 17:16:21 -07:00
lguest lguest: stop using KVM hypercall mechanism 2010-04-14 21:43:56 +09:30
lib Merge branch 'x86-atomic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-05-18 08:40:05 -07:00
math-emu x86, fpu: Unbreak FPU emulation 2010-05-10 13:37:16 -07:00
mm Merge branch 'drm-for-2.6.35' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6 2010-05-21 11:14:52 -07:00
oprofile Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-05-18 08:19:03 -07:00
pci Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2010-05-21 18:58:52 -07:00
power Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip 2010-04-07 11:02:23 -07:00
tools x86: Remove trailing spaces in messages 2010-02-07 17:47:51 +01:00
vdso include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
video
xen Merge branch 'timers-for-linus-cleanups' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-05-19 17:10:06 -07:00
Kbuild
Kconfig Merge branch 'linux-next' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6 2010-05-21 18:58:52 -07:00
Kconfig.cpu Merge branch 'x86-fpu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-05-18 08:58:16 -07:00
Kconfig.debug Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2010-05-18 08:40:21 -07:00
Makefile x86: Use .cfi_sections for assembly code 2010-05-13 22:15:18 -07:00
Makefile_32.cpu Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-12-08 13:38:11 -08:00