The ISA specifies power save wakeup can cause a machine check interrupt.
The machine check handler currently has code to handle that for POWER8,
but POWER9 crashes when trying to execute the P8 style sleep
instructions.
So queue up the machine check, then call into the idle code to wake up
as the system reset interrupt does, rather than attempting to sleep
again without going through the main idle path.
Reviewed-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
---
arch/powerpc/include/asm/reg.h | 1 +
arch/powerpc/kernel/exceptions-64s.S | 69 ++++++++++++++++++------------------
2 files changed, 35 insertions(+), 35 deletions(-)
diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
index fc879fd6bdae..8bbdfacce970 100644
--- a/arch/powerpc/include/asm/reg.h
+++ b/arch/powerpc/include/asm/reg.h
@@ -656,6 +656,7 @@
#define SRR1_ISI_PROT 0x08000000 /* ISI: Other protection
fault */
#define SRR1_WAKEMASK 0x00380000 /* reason for wakeup */
#define SRR1_WAKEMASK_P8 0x003c0000 /* reason for wakeup on POWER8 and 9
*/
+#define SRR1_WAKEMCE_RESVD 0x003c0000 /* Unused/reserved value used by MCE
wakeup to indicate cause to idle wakeup handler */
#define SRR1_WAKESYSERR 0x00300000 /* System error */
#define SRR1_WAKEEE 0x00200000 /* External interrupt */
#define SRR1_WAKEHVI 0x00240000 /* Hypervisor Virtualization
Interrupt (P9) */
diff --git a/arch/powerpc/kernel/exceptions-64s.S
b/arch/powerpc/kernel/exceptions-64s.S
index e390fcd04bcb..5779d2d6a192 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -306,6 +306,33 @@ EXC_COMMON_BEGIN(machine_check_common)
/* restore original r1. */ \
ld r1,GPR1(r1)
+#ifdef CONFIG_PPC_P7_NAP
+EXC_COMMON_BEGIN(machine_check_idle_common)
+ bl machine_check_queue_event
+ /*
+ * Queue the machine check, then reload SRR1 and use it to set
+ * CR3 according to pnv_powersave_wakeup convention.
+ */
+ ld r12,_MSR(r1)
+ rlwinm r11,r12,47-31,30,31
+ cmpwi cr3,r11,2
+
+ /*
+ * Now put SRR1_WAKEMCE_RESVD into SRR1, allows it to follow the
+ * system reset wakeup code.
+ */
+ oris r12,r12,SRR1_WAKEMCE_RESVD@h
+ mtspr SPRN_SRR1,r12
+ std r12,_MSR(r1)
+
+ /*
+ * Decrement MCE nesting after finishing with the stack.
+ */
+ lhz r11,PACA_IN_MCE(r13)
+ subi r11,r11,1
+ sth r11,PACA_IN_MCE(r13)
+ b pnv_powersave_wakeup
+#endif
/*
* Handle machine check early in real mode. We come here with
* ME=1, MMU (IR=0 and DR=0) off and using MC emergency stack.
@@ -318,6 +345,7 @@ EXC_COMMON_BEGIN(machine_check_handle_early)
bl machine_check_early
std r3,RESULT(r1) /* Save result */
ld r12,_MSR(r1)
+
#ifdef CONFIG_PPC_P7_NAP
/*
* Check if thread was in power saving mode. We come here when any
@@ -328,43 +356,14 @@ EXC_COMMON_BEGIN(machine_check_handle_early)
*
* Go back to nap/sleep/winkle mode again if (b) is true.
*/
- rlwinm. r11,r12,47-31,30,31 /* Was it in power saving mode? */
- beq 4f /* No, it wasn't */
- /* Thread was in power saving mode. Go back to nap again. */
- cmpwi r11,2
- blt 3f
- /* Supervisor/Hypervisor state loss */
- li r0,1
- stb r0,PACA_NAPSTATELOST(r13)
-3: bl machine_check_queue_event
- MACHINE_CHECK_HANDLER_WINDUP
- GET_PACA(r13)
- ld r1,PACAR1(r13)
- /*
- * Check what idle state this CPU was in and go back to same mode
- * again.
- */
- lbz r3,PACA_THREAD_IDLE_STATE(r13)
- cmpwi r3,PNV_THREAD_NAP
- bgt 10f
- IDLE_STATE_ENTER_SEQ_NORET(PPC_NAP)
- /* No return */
-10:
- cmpwi r3,PNV_THREAD_SLEEP
- bgt 2f
- IDLE_STATE_ENTER_SEQ_NORET(PPC_SLEEP)
- /* No return */
-
-2:
- /*
- * Go back to winkle. Please note that this thread was woken up in
- * machine check from winkle and have not restored the per-subcore
- * state.
- */
- IDLE_STATE_ENTER_SEQ_NORET(PPC_WINKLE)
- /* No return */
+ BEGIN_FTR_SECTION
+ rlwinm. r11,r12,47-31,30,31
+ beq- 4f
+ BRANCH_TO_COMMON(r10, machine_check_idle_common)
4:
+ END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
#endif
+
/*
* Check if we are coming from hypervisor userspace. If yes then we
* continue in host kernel in V mode to deliver the MC event.
--
2.11.0
