[PATCH] x86_64: Standardize i386/x86_64 handling of NMI_VECTOR

x86_64 and i386 behave inconsistently when sending an IPI on vector 2
(NMI_VECTOR).  Make both behave the same, so IPI 2 is sent as NMI.

The crash code was abusing send_IPI_allbutself() by passing a code
instead of a vector, it only worked because crash knew about the
internal code of send_IPI_allbutself().  Change crash to use NMI_VECTOR
instead, and remove the comment about how crash was abusing the function.

This patch is a pre-requisite for fixing the problem where sending an
IPI as NMI would reboot some Dell Xeon systems.  I cannot fix that
problem while crash continus to abuse send_IPI_allbutself().

It also removes the inconsistency between i386 and x86_64 for
NMI_VECTOR.  That will simplify all the RAS code that needs to bring
all the cpus to a clean stop, even when one or more cpus are spinning
disabled.

Signed-off-by: Keith Owens <kaos@sgi.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

2 files changed, 12 insertions, 7 deletions

diff --git a/arch/i386/kernel/crash.c b/arch/i386/kernel/crash.c
index 21dc1bbb8067..0c88d3ec8c18 100644
--- a/arch/i386/kernel/crash.c
+++ b/arch/i386/kernel/crash.c
@@ -120,14 +120,9 @@ static int crash_nmi_callback(struct pt_regs *regs, int cpu)
         return 1;
 }
 
-/*
- * By using the NMI code instead of a vector we just sneak thru the
- * word generator coming out with just what we want.  AND it does
- * not matter if clustered_apic_mode is set or not.
- */
 static void smp_send_nmi_allbutself(void)
 {
-        send_IPI_allbutself(APIC_DM_NMI);
+        send_IPI_allbutself(NMI_VECTOR);
 }
 
 static void nmi_shootdown_cpus(void)
diff --git a/arch/i386/kernel/smp.c b/arch/i386/kernel/smp.c
index d134e9643a58..c10789d7a9d3 100644
--- a/arch/i386/kernel/smp.c
+++ b/arch/i386/kernel/smp.c
@@ -114,7 +114,17 @@ DEFINE_PER_CPU(struct tlb_state, cpu_tlbstate) ____cacheline_aligned = { &init_m
 
 static inline int __prepare_ICR (unsigned int shortcut, int vector)
 {
-        return APIC_DM_FIXED | shortcut | vector | APIC_DEST_LOGICAL;
+        unsigned int icr = shortcut | APIC_DEST_LOGICAL;
+
+        switch (vector) {
+        default:
+                icr |= APIC_DM_FIXED | vector;
+                break;
+        case NMI_VECTOR:
+                icr |= APIC_DM_NMI;
+                break;
+        }
+        return icr;
 }
 
 static inline int __prepare_ICR2 (unsigned int mask)