Messages in this thread Patch in this message | | | From | Don Zickus <> | Subject | [PATCH 4/5] x86, NMI: Allow NMI reason io port (0x61) to be processed on any CPU | Date | Fri, 15 Oct 2010 22:22:17 -0400 |
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From: Huang Ying <ying.huang@intel.com>
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 make the port can be processed on any CPU.
Signed-off-by: Huang Ying <ying.huang@intel.com> Signed-off-by: Don Zickus <dzickus@redhat.com> --- arch/x86/kernel/traps.c | 45 +++++++++++++++++++++++++-------------------- 1 files changed, 25 insertions(+), 20 deletions(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index d8acab3..accb2f4 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -83,6 +83,12 @@ EXPORT_SYMBOL_GPL(used_vectors); static int ignore_nmis; +/* + * 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) { if (regs->flags & X86_EFLAGS_IF) @@ -383,7 +389,6 @@ 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 @@ -400,28 +405,28 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs) return; /* Non-CPU-specific NMI: NMI sources can be processed on any CPU */ - cpu = smp_processor_id(); - /* Only the BSP gets external NMIs from the system. */ - if (!cpu) { - reason = get_nmi_reason(); - if (reason & NMI_REASON_MASK) { - if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) - == NOTIFY_STOP) - return; - if (reason & NMI_REASON_SERR) - pci_serr_error(reason, regs); - else if (reason & NMI_REASON_IOCHK) - io_check_error(reason, regs); + raw_spin_lock(&nmi_reason_lock); + reason = get_nmi_reason(); + if (reason & NMI_REASON_MASK) { + if (notify_die(DIE_NMI, "nmi", regs, reason, 2, SIGINT) + == NOTIFY_STOP) + goto unlock_return; + if (reason & NMI_REASON_SERR) + pci_serr_error(reason, regs); + else if (reason & NMI_REASON_IOCHK) + io_check_error(reason, regs); #ifdef CONFIG_X86_32 - /* - * Reassert NMI in case it became active - * meanwhile as it's edge-triggered: - */ - reassert_nmi(); + /* + * Reassert NMI in case it became active + * meanwhile as it's edge-triggered: + */ + reassert_nmi(); #endif - return; - } +unlock_return: + raw_spin_unlock(&nmi_reason_lock); + return; } + raw_spin_unlock(&nmi_reason_lock); if (notify_die(DIE_NMI, "nmi", regs, 0, 2, SIGINT) == NOTIFY_STOP) return; -- 1.7.2.3
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