powerpc/powernv: Add platform support for stop instruction

POWER ISA v3 defines a new idle processor core mechanism. In summary,
 a) new instruction named stop is added. This instruction replaces
	instructions like nap, sleep, rvwinkle.
 b) new per thread SPR named Processor Stop Status and Control Register
	(PSSCR) is added which controls the behavior of stop instruction.

PSSCR layout:
----------------------------------------------------------
| PLS | /// | SD | ESL | EC | PSLL | /// | TR | MTL | RL |
----------------------------------------------------------
0      4     41   42    43   44     48    54   56    60

PSSCR key fields:
	Bits 0:3  - Power-Saving Level Status. This field indicates the lowest
	power-saving state the thread entered since stop instruction was last
	executed.

	Bit 42 - Enable State Loss
	0 - No state is lost irrespective of other fields
	1 - Allows state loss

	Bits 44:47 - Power-Saving Level Limit
	This limits the power-saving level that can be entered into.

	Bits 60:63 - Requested Level
	Used to specify which power-saving level must be entered on executing
	stop instruction

This patch adds support for stop instruction and PSSCR handling.

Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 159 insertions, 34 deletions

diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S
index 2f909a1..1f564eb 100644
--- a/arch/powerpc/kernel/idle_book3s.S
+++ b/arch/powerpc/kernel/idle_book3s.S
@@ -1,6 +1,6 @@
 /*
- *  This file contains idle entry/exit functions for POWER7 and
- *  POWER8 CPUs.
+ *  This file contains idle entry/exit functions for POWER7,
+ *  POWER8 and POWER9 CPUs.
  *
  *  This program is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU General Public License
@@ -21,6 +21,7 @@
 #include <asm/opal.h>
 #include <asm/cpuidle.h>
 #include <asm/book3s/64/mmu-hash.h>
+#include <asm/mmu.h>
 
 #undef DEBUG
 
@@ -37,6 +38,11 @@
 #define _AMOR	GPR9
 #define _WORT	GPR10
 #define _WORC	GPR11
+#define _PTCR	GPR12
+
+#define PSSCR_HV_TEMPLATE	PSSCR_ESL | PSSCR_EC | \
+				PSSCR_PSLL_MASK | PSSCR_TR_MASK | \
+				PSSCR_MTL_MASK
 
 /* Idle state entry routines */
 
@@ -61,8 +67,17 @@ save_sprs_to_stack:
 	 * Note all register i.e per-core, per-subcore or per-thread is saved
 	 * here since any thread in the core might wake up first
 	 */
+BEGIN_FTR_SECTION
+	mfspr	r3,SPRN_PTCR
+	std	r3,_PTCR(r1)
+	/*
+	 * Note - SDR1 is dropped in Power ISA v3. Hence not restoring
+	 * SDR1 here
+	 */
+FTR_SECTION_ELSE
 	mfspr	r3,SPRN_SDR1
 	std	r3,_SDR1(r1)
+ALT_FTR_SECTION_END_IFSET(CPU_FTR_ARCH_300)
 	mfspr	r3,SPRN_RPR
 	std	r3,_RPR(r1)
 	mfspr	r3,SPRN_SPURR
@@ -100,7 +115,8 @@ core_idle_lock_held:
 
 /*
  * Pass requested state in r3:
- *	r3 - PNV_THREAD_NAP/SLEEP/WINKLE
+ *	r3 - PNV_THREAD_NAP/SLEEP/WINKLE in POWER8
+ *	   - Requested STOP state in POWER9
  *
  * To check IRQ_HAPPENED in r4
  * 	0 - don't check
@@ -161,7 +177,7 @@ _GLOBAL(pnv_powersave_common)
 
 #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
 	/* Tell KVM we're entering idle */
-	li	r4,KVM_HWTHREAD_IN_NAP
+	li	r4,KVM_HWTHREAD_IN_IDLE
 	stb	r4,HSTATE_HWTHREAD_STATE(r13)
 #endif
 
@@ -243,6 +259,41 @@ enter_winkle:
 
 	IDLE_STATE_ENTER_SEQ(PPC_WINKLE)
 
+/*
+ * r3 - requested stop state
+ */
+power_enter_stop:
+/*
+ * Check if the requested state is a deep idle state.
+ */
+	LOAD_REG_ADDRBASE(r5,pnv_first_deep_stop_state)
+	ld	r4,ADDROFF(pnv_first_deep_stop_state)(r5)
+	cmpd	r3,r4
+	bge	2f
+	IDLE_STATE_ENTER_SEQ(PPC_STOP)
+2:
+/*
+ * Entering deep idle state.
+ * Clear thread bit in PACA_CORE_IDLE_STATE, save SPRs to
+ * stack and enter stop
+ */
+	lbz     r7,PACA_THREAD_MASK(r13)
+	ld      r14,PACA_CORE_IDLE_STATE_PTR(r13)
+
+lwarx_loop_stop:
+	lwarx   r15,0,r14
+	andi.   r9,r15,PNV_CORE_IDLE_LOCK_BIT
+	bnel    core_idle_lock_held
+	andc    r15,r15,r7                      /* Clear thread bit */
+
+	stwcx.  r15,0,r14
+	bne-    lwarx_loop_stop
+	isync
+
+	bl	save_sprs_to_stack
+
+	IDLE_STATE_ENTER_SEQ(PPC_STOP)
+
 _GLOBAL(power7_idle)
 	/* Now check if user or arch enabled NAP mode */
 	LOAD_REG_ADDRBASE(r3,powersave_nap)
@@ -293,6 +344,17 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66);		\
 
 
 /*
+ * r3 - requested stop state
+ */
+_GLOBAL(power9_idle_stop)
+	LOAD_REG_IMMEDIATE(r4, PSSCR_HV_TEMPLATE)
+	or	r4,r4,r3
+	mtspr	SPRN_PSSCR, r4
+	li	r4, 1
+	LOAD_REG_ADDR(r5,power_enter_stop)
+	b	pnv_powersave_common
+	/* No return */
+/*
  * Called from reset vector. Check whether we have woken up with
  * hypervisor state loss. If yes, restore hypervisor state and return
  * back to reset vector.
@@ -301,7 +363,33 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66);		\
  * cr3 - set to gt if waking up with partial/complete hypervisor state loss
  */
 _GLOBAL(pnv_restore_hyp_resource)
+	ld	r2,PACATOC(r13);
+BEGIN_FTR_SECTION
+	/*
+	 * POWER ISA 3. Use PSSCR to determine if we
+	 * are waking up from deep idle state
+	 */
+	LOAD_REG_ADDRBASE(r5,pnv_first_deep_stop_state)
+	ld	r4,ADDROFF(pnv_first_deep_stop_state)(r5)
+
+	mfspr	r5,SPRN_PSSCR
 	/*
+	 * 0-3 bits correspond to Power-Saving Level Status
+	 * which indicates the idle state we are waking up from
+	 */
+	rldicl  r5,r5,4,60
+	cmpd	cr4,r5,r4
+	bge	cr4,pnv_wakeup_tb_loss
+	/*
+	 * Waking up without hypervisor state loss. Return to
+	 * reset vector
+	 */
+	blr
+
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
+
+	/*
+	 * POWER ISA 2.07 or less.
 	 * Check if last bit of HSPGR0 is set. This indicates whether we are
 	 * waking up from winkle.
 	 */
@@ -324,9 +412,17 @@ _GLOBAL(pnv_restore_hyp_resource)
 	blr	/* Return back to System Reset vector from where
 		   pnv_restore_hyp_resource was invoked */
 
-
+/*
+ * Called if waking up from idle state which can cause either partial or
+ * complete hyp state loss.
+ * In POWER8, called if waking up from fastsleep or winkle
+ * In POWER9, called if waking up from stop state >= pnv_first_deep_stop_state
+ *
+ * r13 - PACA
+ * cr3 - gt if waking up with partial/complete hypervisor state loss
+ * cr4 - eq if waking up from complete hypervisor state loss.
+ */
 _GLOBAL(pnv_wakeup_tb_loss)
-	ld	r2,PACATOC(r13);
 	ld	r1,PACAR1(r13)
 	/*
 	 * Before entering any idle state, the NVGPRs are saved in the stack
@@ -361,35 +457,35 @@ lwarx_loop2:
 	bnel	core_idle_lock_held
 
 	cmpwi	cr2,r15,0
-	lbz	r4,PACA_SUBCORE_SIBLING_MASK(r13)
-	and	r4,r4,r15
-	cmpwi	cr1,r4,0	/* Check if first in subcore */
 
 	/*
 	 * At this stage
-	 * cr1 - 0b0100 if first thread to wakeup in subcore
-	 * cr2 - 0b0100 if first thread to wakeup in core
-	 * cr3-  0b0010 if waking up from sleep or winkle
-	 * cr4 - 0b0100 if waking up from winkle
+	 * cr2 - eq if first thread to wakeup in core
+	 * cr3-  gt if waking up with partial/complete hypervisor state loss
+	 * cr4 - eq if waking up from complete hypervisor state loss.
 	 */
 
-	or	r15,r15,r7		/* Set thread bit */
-
-	beq	cr1,first_thread_in_subcore
-
-	/* Not first thread in subcore to wake up */
-	stwcx.	r15,0,r14
-	bne-	lwarx_loop2
-	isync
-	b	common_exit
-
-first_thread_in_subcore:
-	/* First thread in subcore to wakeup */
 	ori	r15,r15,PNV_CORE_IDLE_LOCK_BIT
 	stwcx.	r15,0,r14
 	bne-	lwarx_loop2
 	isync
 
+BEGIN_FTR_SECTION
+	lbz	r4,PACA_SUBCORE_SIBLING_MASK(r13)
+	and	r4,r4,r15
+	cmpwi	r4,0	/* Check if first in subcore */
+
+	or	r15,r15,r7		/* Set thread bit */
+	beq	first_thread_in_subcore
+END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
+
+	or	r15,r15,r7		/* Set thread bit */
+	beq	cr2,first_thread_in_core
+
+	/* Not first thread in core or subcore to wake up */
+	b	clear_lock
+
+first_thread_in_subcore:
 	/*
 	 * If waking up from sleep, subcore state is not lost. Hence
 	 * skip subcore state restore
@@ -399,6 +495,7 @@ first_thread_in_subcore:
 	/* Restore per-subcore state */
 	ld      r4,_SDR1(r1)
 	mtspr   SPRN_SDR1,r4
+
 	ld      r4,_RPR(r1)
 	mtspr   SPRN_RPR,r4
 	ld	r4,_AMOR(r1)
@@ -414,19 +511,23 @@ subcore_state_restored:
 first_thread_in_core:
 
 	/*
-	 * First thread in the core waking up from fastsleep. It needs to
+	 * First thread in the core waking up from any state which can cause
+	 * partial or complete hypervisor state loss. It needs to
 	 * call the fastsleep workaround code if the platform requires it.
 	 * Call it unconditionally here. The below branch instruction will
-	 * be patched out when the idle states are discovered if platform
-	 * does not require workaround.
+	 * be patched out if the platform does not have fastsleep or does not
+	 * require the workaround. Patching will be performed during the
+	 * discovery of idle-states.
 	 */
 .global pnv_fastsleep_workaround_at_exit
 pnv_fastsleep_workaround_at_exit:
 	b	fastsleep_workaround_at_exit
 
 timebase_resync:
-	/* Do timebase resync if we are waking up from sleep. Use cr3 value
-	 * set in exceptions-64s.S */
+	/*
+	 * Use cr3 which indicates that we are waking up with atleast partial
+	 * hypervisor state loss to determine if TIMEBASE RESYNC is needed.
+	 */
 	ble	cr3,clear_lock
 	/* Time base re-sync */
 	li	r0,OPAL_RESYNC_TIMEBASE
@@ -439,7 +540,18 @@ timebase_resync:
 	 */
 	bne	cr4,clear_lock
 
-	/* Restore per core state */
+	/*
+	 * First thread in the core to wake up and its waking up with
+	 * complete hypervisor state loss. Restore per core hypervisor
+	 * state.
+	 */
+BEGIN_FTR_SECTION
+	ld	r4,_PTCR(r1)
+	mtspr	SPRN_PTCR,r4
+	ld	r4,_RPR(r1)
+	mtspr	SPRN_RPR,r4
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
+
 	ld	r4,_TSCR(r1)
 	mtspr	SPRN_TSCR,r4
 	ld	r4,_WORC(r1)
@@ -461,9 +573,9 @@ common_exit:
 
 	/* Waking up from winkle */
 
-	/* Restore per thread state */
-	bl	__restore_cpu_power8
-
+BEGIN_MMU_FTR_SECTION
+	b	no_segments
+END_MMU_FTR_SECTION_IFSET(MMU_FTR_RADIX)
 	/* Restore SLB  from PACA */
 	ld	r8,PACA_SLBSHADOWPTR(r13)
 
@@ -477,6 +589,9 @@ common_exit:
 	slbmte	r6,r5
 1:	addi	r8,r8,16
 	.endr
+no_segments:
+
+	/* Restore per thread state */
 
 	ld	r4,_SPURR(r1)
 	mtspr	SPRN_SPURR,r4
@@ -487,6 +602,16 @@ common_exit:
 	ld	r4,_WORT(r1)
 	mtspr	SPRN_WORT,r4
 
+	/* Call cur_cpu_spec->cpu_restore() */
+	LOAD_REG_ADDR(r4, cur_cpu_spec)
+	ld	r4,0(r4)
+	ld	r12,CPU_SPEC_RESTORE(r4)
+#ifdef PPC64_ELF_ABI_v1
+	ld	r12,0(r12)
+#endif
+	mtctr	r12
+	bctrl
+
 hypervisor_state_restored:
 
 	mtspr	SPRN_SRR1,r16