2 files changed, 21 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/apic.c b/arch/x86_64/kernel/apic.c
index e5b14c57eaa0..d54620147e8e 100644
--- a/arch/x86_64/kernel/apic.c
+++ b/arch/x86_64/kernel/apic.c
@@ -342,6 +342,7 @@ void __init init_bsp_APIC(void)
 void __cpuinit setup_local_APIC (void)
 {
         unsigned int value, maxlvt;
+        int i, j;
 
         value = apic_read(APIC_LVR);
 
@@ -371,6 +372,25 @@ void __cpuinit setup_local_APIC (void)
         apic_write(APIC_TASKPRI, value);
 
         /*
+         * After a crash, we no longer service the interrupts and a pending
+         * interrupt from previous kernel might still have ISR bit set.
+         *
+         * Most probably by now CPU has serviced that pending interrupt and
+         * it might not have done the ack_APIC_irq() because it thought,
+         * interrupt came from i8259 as ExtInt. LAPIC did not get EOI so it
+         * does not clear the ISR bit and cpu thinks it has already serivced
+         * the interrupt. Hence a vector might get locked. It was noticed
+         * for timer irq (vector 0x31). Issue an extra EOI to clear ISR.
+         */
+        for (i = APIC_ISR_NR - 1; i >= 0; i--) {
+                value = apic_read(APIC_ISR + i*0x10);
+                for (j = 31; j >= 0; j--) {
+                        if (value & (1<<j))
+                                ack_APIC_irq();
+                }
+        }
+
+        /*
          * Now that we are all set up, enable the APIC
          */
         value = apic_read(APIC_SPIV);
diff --git a/include/asm-x86_64/apicdef.h b/include/asm-x86_64/apicdef.h
index decaa2d540e8..5a48e9bcf218 100644
--- a/include/asm-x86_64/apicdef.h
+++ b/include/asm-x86_64/apicdef.h
@@ -39,6 +39,7 @@
 #define                 APIC_SPIV_FOCUS_DISABLED        (1<<9)
 #define                 APIC_SPIV_APIC_ENABLED          (1<<8)
 #define         APIC_ISR        0x100
+#define         APIC_ISR_NR     0x8     /* Number of 32 bit ISR registers. */
 #define         APIC_TMR        0x180
 #define         APIC_IRR        0x200
 #define         APIC_ESR        0x280