powerpc: Add code to handle soft-disabled doorbells on server

This patch adds the logic to properly handle doorbells that come in when
interrupts have been soft disabled and to replay them when interrupts
are re-enabled:

- masked_##_H##interrupt is modified to leave interrupts enabled when a
  doorbell has come in since doorbells are edge sensitive and as such
  won't be automatically re-raised.

- __check_irq_replay now tests if a doorbell happened on book3s, and
  returns either 0xe80 or 0xa00 depending on whether we are the
  hypervisor or not.

- restore_check_irq_replay now tests for the two possible server
  doorbell vector numbers to replay.

- __replay_interrupt also adds tests for the two server doorbell vector
  numbers, and is modified to use a compare instruction rather than an
  andi. on the single bit difference between 0x500 and 0x900.

The last two use a CPU feature section to avoid needlessly testing
against the hypervisor vector if it is not the hypervisor, and vice
versa.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 11 insertions, 2 deletions

diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index b310a0573625..73c1f083ba21 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -836,13 +836,22 @@ restore_check_irq_replay:
         addi    r3,r1,STACK_FRAME_OVERHEAD;
         bl      .timer_interrupt
         b       .ret_from_except
+#ifdef CONFIG_PPC_DOORBELL
+1:
 #ifdef CONFIG_PPC_BOOK3E
-1:      cmpwi   cr0,r3,0x280
+        cmpwi   cr0,r3,0x280
+#else
+        BEGIN_FTR_SECTION
+                cmpwi   cr0,r3,0xe80
+        FTR_SECTION_ELSE
+                cmpwi   cr0,r3,0xa00
+        ALT_FTR_SECTION_END_IFSET(CPU_FTR_HVMODE)
+#endif /* CONFIG_PPC_BOOK3E */
         bne     1f
         addi    r3,r1,STACK_FRAME_OVERHEAD;
         bl      .doorbell_exception
         b       .ret_from_except
-#endif /* CONFIG_PPC_BOOK3E */
+#endif /* CONFIG_PPC_DOORBELL */
 1:      b       .ret_from_except /* What else to do here ? */
  
 unrecov_restore: