[PATCH v4 08/10] powerpc/powernv: Add platform support for stop instruction

Ram Pai linuxram at us.ibm.com
Sat May 28 10:06:46 AEST 2016


On Tue, May 24, 2016 at 06:45:12PM +0530, Shreyas B. Prabhu wrote:
> 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.
> 
> Signed-off-by: Shreyas B. Prabhu <shreyas at linux.vnet.ibm.com>
> ---
> Changes in v4:
> ==============
>  - Added PSSCR layout to commit message
>  - Improved / Fixed comments
>  - Fixed whitespace error in paca.h
>  - Using MAX_POSSIBLE_STOP_STATE macro instead of hardcoding 0xF has 
>    max possible stop state
> 
> Changes in v3:
> ==============
>  - Instead of introducing new file idle_power_stop.S, P9 idle support
>    is added to idle_power_common.S using CPU_FTR sections.
>  - Fixed r4 reg clobbering in power_stop0
>  - Improved comments
> 
> Changes in v2:
> ==============
>  - Using CPU_FTR_ARCH_300 bit instead of CPU_FTR_STOP_INST
> 
>  arch/powerpc/include/asm/cpuidle.h        |   2 +
>  arch/powerpc/include/asm/kvm_book3s_asm.h |   2 +-
>  arch/powerpc/include/asm/machdep.h        |   1 +
>  arch/powerpc/include/asm/opal-api.h       |  11 ++-
>  arch/powerpc/include/asm/paca.h           |   2 +
>  arch/powerpc/include/asm/ppc-opcode.h     |   4 +
>  arch/powerpc/include/asm/processor.h      |   1 +
>  arch/powerpc/include/asm/reg.h            |  11 +++
>  arch/powerpc/kernel/asm-offsets.c         |   2 +
>  arch/powerpc/kernel/idle_power_common.S   | 149 +++++++++++++++++++++++++++---
>  arch/powerpc/platforms/powernv/idle.c     |  84 ++++++++++++++---
>  11 files changed, 239 insertions(+), 30 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/cpuidle.h b/arch/powerpc/include/asm/cpuidle.h
> index d2f99ca..3d7fc06 100644
> --- a/arch/powerpc/include/asm/cpuidle.h
> +++ b/arch/powerpc/include/asm/cpuidle.h
> @@ -13,6 +13,8 @@
>  #ifndef __ASSEMBLY__
>  extern u32 pnv_fastsleep_workaround_at_entry[];
>  extern u32 pnv_fastsleep_workaround_at_exit[];
> +
> +extern u64 pnv_first_deep_stop_state;
>  #endif
>  
>  #endif
> diff --git a/arch/powerpc/include/asm/kvm_book3s_asm.h b/arch/powerpc/include/asm/kvm_book3s_asm.h
> index 72b6225..d318d43 100644
> --- a/arch/powerpc/include/asm/kvm_book3s_asm.h
> +++ b/arch/powerpc/include/asm/kvm_book3s_asm.h
> @@ -162,7 +162,7 @@ struct kvmppc_book3s_shadow_vcpu {
>  
>  /* Values for kvm_state */
>  #define KVM_HWTHREAD_IN_KERNEL	0
> -#define KVM_HWTHREAD_IN_NAP	1
> +#define KVM_HWTHREAD_IN_IDLE	1
>  #define KVM_HWTHREAD_IN_KVM	2
>  
>  #endif /* __ASM_KVM_BOOK3S_ASM_H__ */
> diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
> index 6bdcd0d..ae3b155 100644
> --- a/arch/powerpc/include/asm/machdep.h
> +++ b/arch/powerpc/include/asm/machdep.h
> @@ -262,6 +262,7 @@ struct machdep_calls {
>  extern void e500_idle(void);
>  extern void power4_idle(void);
>  extern void power7_idle(void);
> +extern void power_stop0(void);
>  extern void ppc6xx_idle(void);
>  extern void book3e_idle(void);
>  
> diff --git a/arch/powerpc/include/asm/opal-api.h b/arch/powerpc/include/asm/opal-api.h
> index 9bb8ddf..7f3f8c6 100644
> --- a/arch/powerpc/include/asm/opal-api.h
> +++ b/arch/powerpc/include/asm/opal-api.h
> @@ -162,13 +162,20 @@
>  
>  /* Device tree flags */
>  
> -/* Flags set in power-mgmt nodes in device tree if
> - * respective idle states are supported in the platform.
> +/*
> + * Flags set in power-mgmt nodes in device tree describing
> + * idle states that are supported in the platform.
>   */
> +
> +#define OPAL_PM_TIMEBASE_STOP		0x00000002
> +#define OPAL_PM_LOSE_HYP_CONTEXT	0x00002000
> +#define OPAL_PM_LOSE_FULL_CONTEXT	0x00004000
>  #define OPAL_PM_NAP_ENABLED		0x00010000
>  #define OPAL_PM_SLEEP_ENABLED		0x00020000
>  #define OPAL_PM_WINKLE_ENABLED		0x00040000
>  #define OPAL_PM_SLEEP_ENABLED_ER1	0x00080000 /* with workaround */
> +#define OPAL_PM_STOP_INST_FAST		0x00100000
> +#define OPAL_PM_STOP_INST_DEEP		0x00200000
>  
>  /*
>   * OPAL_CONFIG_CPU_IDLE_STATE parameters
> diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h
> index 546540b..ae91b44 100644
> --- a/arch/powerpc/include/asm/paca.h
> +++ b/arch/powerpc/include/asm/paca.h
> @@ -171,6 +171,8 @@ struct paca_struct {
>  	/* Mask to denote subcore sibling threads */
>  	u8 subcore_sibling_mask;
>  #endif
> +	/* Template for PSSCR with EC, ESL, TR, PSLL, MTL fields set */
> +	u64 thread_psscr;
>  
>  #ifdef CONFIG_PPC_BOOK3S_64
>  	/* Exclusive emergency stack pointer for machine check exception. */
> diff --git a/arch/powerpc/include/asm/ppc-opcode.h b/arch/powerpc/include/asm/ppc-opcode.h
> index 1d035c1..6a8e43b 100644
> --- a/arch/powerpc/include/asm/ppc-opcode.h
> +++ b/arch/powerpc/include/asm/ppc-opcode.h
> @@ -199,6 +199,8 @@
>  #define PPC_INST_SLEEP			0x4c0003a4
>  #define PPC_INST_WINKLE			0x4c0003e4
>  
> +#define PPC_INST_STOP			0x4c0002e4
> +
>  /* A2 specific instructions */
>  #define PPC_INST_ERATWE			0x7c0001a6
>  #define PPC_INST_ERATRE			0x7c000166
> @@ -370,6 +372,8 @@
>  #define PPC_SLEEP		stringify_in_c(.long PPC_INST_SLEEP)
>  #define PPC_WINKLE		stringify_in_c(.long PPC_INST_WINKLE)
>  
> +#define PPC_STOP		stringify_in_c(.long PPC_INST_STOP)
> +
>  /* BHRB instructions */
>  #define PPC_CLRBHRB		stringify_in_c(.long PPC_INST_CLRBHRB)
>  #define PPC_MFBHRBE(r, n)	stringify_in_c(.long PPC_INST_BHRBE | \
> diff --git a/arch/powerpc/include/asm/processor.h b/arch/powerpc/include/asm/processor.h
> index 009fab1..7f92fc8 100644
> --- a/arch/powerpc/include/asm/processor.h
> +++ b/arch/powerpc/include/asm/processor.h
> @@ -457,6 +457,7 @@ extern int powersave_nap;	/* set if nap mode can be used in idle loop */
>  extern unsigned long power7_nap(int check_irq);
>  extern unsigned long power7_sleep(void);
>  extern unsigned long power7_winkle(void);
> +extern unsigned long power_stop(unsigned long state);
>  extern void flush_instruction_cache(void);
>  extern void hard_reset_now(void);
>  extern void poweroff_now(void);
> diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h
> index c1e82e9..ea971b6 100644
> --- a/arch/powerpc/include/asm/reg.h
> +++ b/arch/powerpc/include/asm/reg.h
> @@ -145,6 +145,16 @@
>  #define MSR_64BIT	0
>  #endif
>  
> +/* Power Management - PSSCR Fields */
> +#define PSSCR_RL_MASK		0x0000000F
> +#define PSSCR_MTL_MASK		0x000000F0
> +#define PSSCR_TR_MASK		0x00000300
> +#define PSSCR_PSLL_MASK		0x000F0000
> +#define PSSCR_EC		0x00100000
> +#define PSSCR_ESL		0x00200000
> +#define PSSCR_SD		0x00400000
> +
> +
>  /* Floating Point Status and Control Register (FPSCR) Fields */
>  #define FPSCR_FX	0x80000000	/* FPU exception summary */
>  #define FPSCR_FEX	0x40000000	/* FPU enabled exception summary */
> @@ -288,6 +298,7 @@
>  #define SPRN_PMICR	0x354   /* Power Management Idle Control Reg */
>  #define SPRN_PMSR	0x355   /* Power Management Status Reg */
>  #define SPRN_PMMAR	0x356	/* Power Management Memory Activity Register */
> +#define SPRN_PSSCR	0x357	/* Processor Stop Status and Control Register */
>  #define SPRN_PMCR	0x374	/* Power Management Control Register */
>  
>  /* HFSCR and FSCR bit numbers are the same */
> diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
> index 9ea0955..670d2a7 100644
> --- a/arch/powerpc/kernel/asm-offsets.c
> +++ b/arch/powerpc/kernel/asm-offsets.c
> @@ -779,6 +779,8 @@ int main(void)
>  			offsetof(struct paca_struct, thread_mask));
>  	DEFINE(PACA_SUBCORE_SIBLING_MASK,
>  			offsetof(struct paca_struct, subcore_sibling_mask));
> +	DEFINE(PACA_THREAD_PSSCR,
> +			offsetof(struct paca_struct, thread_psscr));
>  #endif
>  
>  	DEFINE(PPC_DBELL_SERVER, PPC_DBELL_SERVER);
> diff --git a/arch/powerpc/kernel/idle_power_common.S b/arch/powerpc/kernel/idle_power_common.S
> index 2f909a1..d5d706a 100644
> --- a/arch/powerpc/kernel/idle_power_common.S
> +++ b/arch/powerpc/kernel/idle_power_common.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 +38,7 @@
>  #define _AMOR	GPR9
>  #define _WORT	GPR10
>  #define _WORC	GPR11
> +#define _PTCR	GPR12
>  
>  /* Idle state entry routines */
>  
> @@ -50,6 +52,15 @@
>  	IDLE_INST;						\
>  	b	.
>  
> +/*
> + * rA - Requested stop state
> + * rB - Spare reg that can be used
> + */
> +#define PSSCR_REQUEST_STATE(rA, rB) 		\
> +	ld	rB, PACA_THREAD_PSSCR(r13);	\
> +	or	rB,rB,rA;			\
> +	mtspr	SPRN_PSSCR, rB;
> +
>  	.text
>  
>  /*
> @@ -61,8 +72,13 @@ 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)
> +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 +116,8 @@ 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 +178,7 @@ _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 +260,41 @@ 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 +345,21 @@ ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66);		\
>  
>  
>  /*
> + * Used for ppc_md.power_save which needs a function with no parameters
> + */
> +_GLOBAL(power_stop0)
> +	li	r3,0
> +	/* Fall through to power_stop */
> +/*
> + * r3 - requested stop state
> + */
> +_GLOBAL(power_stop)
> +	PSSCR_REQUEST_STATE(r3,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 +368,32 @@ 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)
> +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.
>  	 */
> @@ -324,7 +416,16 @@ _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)
> @@ -367,10 +468,10 @@ lwarx_loop2:
>  
>  	/*
>  	 * 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
> +	 * cr1 - eq if first thread to wakeup in subcore
> +	 * 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 */
> @@ -397,8 +498,11 @@ first_thread_in_subcore:
>  	bne	cr4,subcore_state_restored
>  
>  	/* Restore per-subcore state */
> +BEGIN_FTR_SECTION
>  	ld      r4,_SDR1(r1)
>  	mtspr   SPRN_SDR1,r4
> +END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
> +
>  	ld      r4,_RPR(r1)
>  	mtspr   SPRN_RPR,r4
>  	ld	r4,_AMOR(r1)
> @@ -414,19 +518,23 @@ 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 +547,16 @@ 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
> +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
> +
>  	ld	r4,_TSCR(r1)
>  	mtspr	SPRN_TSCR,r4
>  	ld	r4,_WORC(r1)
> @@ -464,6 +581,7 @@ common_exit:
>  	/* Restore per thread state */
>  	bl	__restore_cpu_power8
>  
> +BEGIN_MMU_FTR_SECTION
>  	/* Restore SLB  from PACA */
>  	ld	r8,PACA_SLBSHADOWPTR(r13)
>  
> @@ -477,6 +595,7 @@ common_exit:
>  	slbmte	r6,r5
>  1:	addi	r8,r8,16
>  	.endr
> +END_MMU_FTR_SECTION_IFCLR(MMU_FTR_RADIX)
>  
>  	ld	r4,_SPURR(r1)
>  	mtspr	SPRN_SPURR,r4
> diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
> index fbb09fb..8dc5936 100644
> --- a/arch/powerpc/platforms/powernv/idle.c
> +++ b/arch/powerpc/platforms/powernv/idle.c
> @@ -27,9 +27,11 @@
>  #include "powernv.h"
>  #include "subcore.h"
>  
> +#define MAX_POSSIBLE_STOP_STATE	0xF
> +
>  static u32 supported_cpuidle_states;
>  
> -int pnv_save_sprs_for_winkle(void)
> +int pnv_save_sprs_for_deep_states(void)
>  {
>  	int cpu;
>  	int rc;
> @@ -50,15 +52,19 @@ int pnv_save_sprs_for_winkle(void)
>  		uint64_t pir = get_hard_smp_processor_id(cpu);
>  		uint64_t hsprg0_val = (uint64_t)&paca[cpu];
>  
> -		/*
> -		 * HSPRG0 is used to store the cpu's pointer to paca. Hence last
> -		 * 3 bits are guaranteed to be 0. Program slw to restore HSPRG0
> -		 * with 63rd bit set, so that when a thread wakes up at 0x100 we
> -		 * can use this bit to distinguish between fastsleep and
> -		 * deep winkle.
> -		 */
> -		hsprg0_val |= 1;
> -
> +		if (!cpu_has_feature(CPU_FTR_ARCH_300)) {
> +			/*
> +			 * HSPRG0 is used to store the cpu's pointer to paca.
> +			 * Hence last 3 bits are guaranteed to be 0. Program
> +			 * slw to restore HSPRG0 with 63rd bit set, so that
> +			 * when a thread wakes up at 0x100 we can use this bit
> +			 * to distinguish between fastsleep and deep winkle.
> +			 * This is not necessary with stop/psscr since PLS
> +			 * field of psscr indicates which state we are waking
> +			 * up from.
> +			 */
> +			hsprg0_val |= 1;
> +		}
>  		rc = opal_slw_set_reg(pir, SPRN_HSPRG0, hsprg0_val);
>  		if (rc != 0)
>  			return rc;
> @@ -130,8 +136,8 @@ static void pnv_alloc_idle_core_states(void)
>  
>  	update_subcore_sibling_mask();
>  
> -	if (supported_cpuidle_states & OPAL_PM_WINKLE_ENABLED)
> -		pnv_save_sprs_for_winkle();
> +	if (supported_cpuidle_states & OPAL_PM_LOSE_FULL_CONTEXT)
> +		pnv_save_sprs_for_deep_states();
>  }
>  
>  u32 pnv_get_supported_cpuidle_states(void)
> @@ -230,11 +236,18 @@ static DEVICE_ATTR(fastsleep_workaround_applyonce, 0600,
>  			show_fastsleep_workaround_applyonce,
>  			store_fastsleep_workaround_applyonce);
>  
> +/*
> + * First deep stop state. Used to figure out when to save/restore
> + * hypervisor context.
> + */
> +u64 pnv_first_deep_stop_state;

maybe this has to be intialized to some correct default value?

It there a gaurantee that OPAL_PM_STOP_INST_FAST is set only when
CPU_FTR_ARCH_300 is supported?

if cpu_has_feature(CPU_FTR_ARCH_300) is not true, than
pnv_first_deep_stop_state will be not be initialized.  

And if supported_cpuidle_states
has OPAL_PM_STOP_INST_FAST flag set, than power_stop0 is called which
will blindly use pnv_first_deep_stop_state thinking it is initialized to
something sane.


RP




> +
>  static int __init pnv_init_idle_states(void)
>  {
>  	struct device_node *power_mgt;
>  	int dt_idle_states;
>  	u32 *flags;
> +	u64 *psscr_val = NULL;
>  	int i;
>  
>  	supported_cpuidle_states = 0;
> @@ -264,6 +277,32 @@ static int __init pnv_init_idle_states(void)
>  		goto out_free;
>  	}
>  
> +	if (cpu_has_feature(CPU_FTR_ARCH_300)) {
> +		psscr_val = kcalloc(dt_idle_states, sizeof(*psscr_val),
> +					GFP_KERNEL);
> +		if (!psscr_val)
> +			goto out_free;
> +		if (of_property_read_u64_array(power_mgt,
> +			"ibm,cpu-idle-state-psscr",
> +			psscr_val, dt_idle_states)) {
> +			pr_warn("cpuidle-powernv: missing ibm,cpu-idle-states-psscr in DT\n");
> +			goto out_free_psscr;
> +		}
> +
> +		/*
> +		 * Set pnv_first_deep_stop_state to the first stop level
> +		 * to cause hypervisor state loss
> +		 */
> +		pnv_first_deep_stop_state = MAX_POSSIBLE_STOP_STATE;
> +		for (i = 0; i < dt_idle_states; i++) {
> +			u64 psscr_rl = psscr_val[i] & PSSCR_RL_MASK;
> +
> +			if ((flags[i] & OPAL_PM_LOSE_FULL_CONTEXT) &&
> +			     (pnv_first_deep_stop_state > psscr_rl))
> +				pnv_first_deep_stop_state = psscr_rl;
> +		}
> +	}
> +
>  	for (i = 0; i < dt_idle_states; i++)
>  		supported_cpuidle_states |= flags[i];
>  
> @@ -286,8 +325,29 @@ static int __init pnv_init_idle_states(void)
>  
>  	pnv_alloc_idle_core_states();
>  
> +	if (supported_cpuidle_states & OPAL_PM_STOP_INST_FAST)
> +		for_each_possible_cpu(i) {
> +
> +			u64 psscr_init_val = PSSCR_ESL | PSSCR_EC |
> +					PSSCR_PSLL_MASK | PSSCR_TR_MASK |
> +					PSSCR_MTL_MASK;
> +
> +			paca[i].thread_psscr = psscr_init_val;
> +			/*
> +			 * Memory barrier to ensure that the writes to PACA
> +			 * goes through before ppc_md.power_save is updated
> +			 * below.
> +			 */
> +			mb();
> +		}
> +
>  	if (supported_cpuidle_states & OPAL_PM_NAP_ENABLED)
>  		ppc_md.power_save = power7_idle;
> +	else if (supported_cpuidle_states & OPAL_PM_STOP_INST_FAST)
> +		ppc_md.power_save = power_stop0;
> +
> +out_free_psscr:
> +	kfree(psscr_val);
>  out_free:
>  	kfree(flags);
>  out:
> -- 
> 2.4.11
> 
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev at lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev

-- 
Ram Pai



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