powerpc/booke64: Use GSRR registers in Guest Doorbell interrupts

Guest Doorbell interrupts use guest save and restore registers. Add a new
Guest Doorbell exception type to accommodate GSRR0/1 SPRs usage in exception
prolog and fix the exception handler.

Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 19 insertions, 2 deletions

diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
index 0243b1b29031..0f58a95fd216 100644
--- a/arch/powerpc/kernel/exceptions-64e.S
+++ b/arch/powerpc/kernel/exceptions-64e.S
@@ -59,6 +59,10 @@
 #define SPRN_GEN_SRR0   SPRN_SRR0
 #define SPRN_GEN_SRR1   SPRN_SRR1
 
+#define GDBELL_SET_KSTACK       GEN_SET_KSTACK
+#define SPRN_GDBELL_SRR0        SPRN_GSRR0
+#define SPRN_GDBELL_SRR1        SPRN_GSRR1
+
 #define CRIT_SET_KSTACK                                                     \
         ld      r1,PACA_CRIT_STACK(r13);                                    \
         subi    r1,r1,SPECIAL_EXC_FRAME_SIZE;
@@ -89,10 +93,13 @@
 #define MC_EXCEPTION_PROLOG(n, addition)                                    \
         EXCEPTION_PROLOG(n, MC, addition##_MC(n))
 
+#define GDBELL_EXCEPTION_PROLOG(n, addition)                                \
+        EXCEPTION_PROLOG(n, GDBELL, addition##_GDBELL(n))
 
 /* Variants of the "addition" argument for the prolog
  */
 #define PROLOG_ADDITION_NONE_GEN(n)
+#define PROLOG_ADDITION_NONE_GDBELL(n)
 #define PROLOG_ADDITION_NONE_CRIT(n)
 #define PROLOG_ADDITION_NONE_DBG(n)
 #define PROLOG_ADDITION_NONE_MC(n)
@@ -543,8 +550,18 @@ kernel_dbg_exc:
 //      b       ret_from_crit_except
         b       .
 
-/* Guest Doorbell */
-        MASKABLE_EXCEPTION(0x2c0, guest_doorbell, .unknown_exception, ACK_NONE)
+/*
+ *      Guest doorbell interrupt
+ *      This general exception use GSRRx save/restore registers
+ */
+        START_EXCEPTION(guest_doorbell);
+        GDBELL_EXCEPTION_PROLOG(0x2c0, PROLOG_ADDITION_NONE)
+        EXCEPTION_COMMON(0x2c0, PACA_EXGEN, INTS_KEEP)
+        addi    r3,r1,STACK_FRAME_OVERHEAD
+        bl      .save_nvgprs
+        INTS_RESTORE_HARD
+        bl      .unknown_exception
+        b       .ret_from_except
 
 /* Guest Doorbell critical Interrupt */
         START_EXCEPTION(guest_doorbell_crit);