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>

1 files changed, 29 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index e513c1d35b2a..ad06333631ac 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: