powerpc: Add NAP mode support on Power7 in HV mode
Wakeup comes from the system reset handler with a potential loss of
the non-hypervisor CPU state. We save the non-volatile state on the
stack and a pointer to it in the PACA, which the system reset handler
uses to restore things
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index e513c1d..ad06333 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -37,7 +37,35 @@
.globl __start_interrupts
__start_interrupts:
- STD_EXCEPTION_PSERIES(0x100, 0x100, system_reset)
+ .globl system_reset_pSeries;
+system_reset_pSeries:
+ HMT_MEDIUM;
+ DO_KVM 0x100;
+ SET_SCRATCH0(r13)
+#ifdef CONFIG_PPC_P7_NAP
+BEGIN_FTR_SECTION
+ /* Running native on arch 2.06 or later, check if we are
+ * waking up from nap. We only handle no state loss and
+ * supervisor state loss. We do -not- handle hypervisor
+ * state loss at this time.
+ */
+ mfspr r13,SPRN_SRR1
+ rlwinm r13,r13,47-31,30,31
+ cmpwi cr0,r13,1
+ bne 1f
+ b .power7_wakeup_noloss
+1: cmpwi cr0,r13,2
+ bne 1f
+ b .power7_wakeup_loss
+ /* Total loss of HV state is fatal, we could try to use the
+ * PIR to locate a PACA, then use an emergency stack etc...
+ * but for now, let's just stay stuck here
+ */
+1: cmpwi cr0,r13,3
+ beq .
+END_FTR_SECTION_IFSET(CPU_FTR_HVMODE_206)
+#endif /* CONFIG_PPC_P7_NAP */
+ EXCEPTION_PROLOG_PSERIES(PACA_EXGEN, system_reset_common, EXC_STD)
. = 0x200
_machine_check_pSeries: