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x86, NMI: Allow NMI reason io port (0x61) to be processed on any CPU

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In original NMI handler, NMI reason io port (0x61) is only processed
on BSP.  This makes it impossible to hot-remove BSP.  To solve the
issue, a raw spinlock is used to allow the port to be processed on any
CPU.

Originally-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Don Zickus <dzickus@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1294348732-15030-6-git-send-email-dzickus@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Don Zickus 2011-01-06 16:18:51 -05:00 committed by Ingo Molnar
parent c410b83077
commit ab846f13f6
1 changed files with 10 additions and 6 deletions
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16
arch/x86/kernel/traps.c
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@ -84,6 +84,11 @@ EXPORT_SYMBOL_GPL(used_vectors);
static int ignore_nmis;
int unknown_nmi_panic;
/*
* Prevent NMI reason port (0x61) being accessed simultaneously, can
* only be used in NMI handler.
*/
static DEFINE_RAW_SPINLOCK(nmi_reason_lock);
static inline void conditional_sti(struct pt_regs *regs)
{
@ -392,7 +397,6 @@ unknown_nmi_error(unsigned char reason, struct pt_regs *regs)
static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
{
unsigned char reason = 0;
int cpu;
/*
* CPU-specific NMI must be processed before non-CPU-specific
@ -402,13 +406,12 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
if (notify_die(DIE_NMI, "nmi", regs, 0, 2, SIGINT) == NOTIFY_STOP)
return;
cpu = smp_processor_id();
/* Only the BSP gets external NMIs from the system. */
if (!cpu)
reason = get_nmi_reason();
/* Non-CPU-specific NMI: NMI sources can be processed on any CPU */
raw_spin_lock(&nmi_reason_lock);
reason = get_nmi_reason();
if (!(reason & NMI_REASON_MASK)) {
raw_spin_unlock(&nmi_reason_lock);
unknown_nmi_error(reason, regs);
return;
@ -426,6 +429,7 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs)
*/
reassert_nmi();
#endif
raw_spin_unlock(&nmi_reason_lock);
}
dotraplinkage notrace __kprobes void