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a67cc594df
linux/arch/powerpc/kernel/idle_book3s.S
Michael Ellerman a67cc594df Revert "powerpc/64s/idle: POWER9 ESL=0 stop avoid save/restore overhead" 
As described in that commit:

  When stop is executed with EC=ESL=0, it appears to execute like a
  normal instruction (resuming from NIP when woken by interrupt). So
  all the save/restore handling can be avoided completely.

This is true, except in the case of an NMI interrupt (sreset or
machine check) interrupting the instruction. In that case, the NMI
gets an "interrupt occurred while the processor was in power-saving
mode" indication. The power-save wakeup code uses that bit to decide
whether to restore some registers (e.g., LR). Because these are no
longer saved, this causes random register corruption.

It may be possible to restore this optimisation by detecting the case
of no register loss on the wakeup side, and avoid restoring in that
case, but that's not a minor fix because the wakeup code itself uses
some registers that would be live (e.g., LR).

Fixes: b9ee31e100 ("powerpc/64s/idle: POWER9 ESL=0 stop avoid save/restore overhead")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2018-04-05 16:06:25 +10:00

1001 lines
26 KiB
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/*
* 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
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/threads.h>
#include <asm/processor.h>
#include <asm/page.h>
#include <asm/cputable.h>
#include <asm/thread_info.h>
#include <asm/ppc_asm.h>
#include <asm/asm-offsets.h>
#include <asm/ppc-opcode.h>
#include <asm/hw_irq.h>
#include <asm/kvm_book3s_asm.h>
#include <asm/opal.h>
#include <asm/cpuidle.h>
#include <asm/exception-64s.h>
#include <asm/book3s/64/mmu-hash.h>
#include <asm/mmu.h>
#undef DEBUG
/*
* Use unused space in the interrupt stack to save and restore
* registers for winkle support.
*/
#define _MMCR0 GPR0
#define _SDR1 GPR3
#define _PTCR GPR3
#define _RPR GPR4
#define _SPURR GPR5
#define _PURR GPR6
#define _TSCR GPR7
#define _DSCR GPR8
#define _AMOR GPR9
#define _WORT GPR10
#define _WORC GPR11
#define _LPCR GPR12
#define PSSCR_EC_ESL_MASK_SHIFTED (PSSCR_EC | PSSCR_ESL) >> 16
.text
/*
* Used by threads before entering deep idle states. Saves SPRs
* in interrupt stack frame
*/
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
/*
* Note - SDR1 is dropped in Power ISA v3. Hence not restoring
* SDR1 here
*/
mfspr r3,SPRN_PTCR
std r3,_PTCR(r1)
mfspr r3,SPRN_LPCR
std r3,_LPCR(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
std r3,_SPURR(r1)
mfspr r3,SPRN_PURR
std r3,_PURR(r1)
mfspr r3,SPRN_TSCR
std r3,_TSCR(r1)
mfspr r3,SPRN_DSCR
std r3,_DSCR(r1)
mfspr r3,SPRN_AMOR
std r3,_AMOR(r1)
mfspr r3,SPRN_WORT
std r3,_WORT(r1)
mfspr r3,SPRN_WORC
std r3,_WORC(r1)
/*
* On POWER9, there are idle states such as stop4, invoked via cpuidle,
* that lose hypervisor resources. In such cases, we need to save
* additional SPRs before entering those idle states so that they can
* be restored to their older values on wakeup from the idle state.
*
* On POWER8, the only such deep idle state is winkle which is used
* only in the context of CPU-Hotplug, where these additional SPRs are
* reinitiazed to a sane value. Hence there is no need to save/restore
* these SPRs.
*/
BEGIN_FTR_SECTION
blr
END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_300)
power9_save_additional_sprs:
mfspr r3, SPRN_PID
mfspr r4, SPRN_LDBAR
std r3, STOP_PID(r13)
std r4, STOP_LDBAR(r13)
mfspr r3, SPRN_FSCR
mfspr r4, SPRN_HFSCR
std r3, STOP_FSCR(r13)
std r4, STOP_HFSCR(r13)
mfspr r3, SPRN_MMCRA
mfspr r4, SPRN_MMCR0
std r3, STOP_MMCRA(r13)
std r4, _MMCR0(r1)
mfspr r3, SPRN_MMCR1
mfspr r4, SPRN_MMCR2
std r3, STOP_MMCR1(r13)
std r4, STOP_MMCR2(r13)
blr
power9_restore_additional_sprs:
ld r3,_LPCR(r1)
ld r4, STOP_PID(r13)
mtspr SPRN_LPCR,r3
mtspr SPRN_PID, r4
ld r3, STOP_LDBAR(r13)
ld r4, STOP_FSCR(r13)
mtspr SPRN_LDBAR, r3
mtspr SPRN_FSCR, r4
ld r3, STOP_HFSCR(r13)
ld r4, STOP_MMCRA(r13)
mtspr SPRN_HFSCR, r3
mtspr SPRN_MMCRA, r4
ld r3, _MMCR0(r1)
ld r4, STOP_MMCR1(r13)
mtspr SPRN_MMCR0, r3
mtspr SPRN_MMCR1, r4
ld r3, STOP_MMCR2(r13)
mtspr SPRN_MMCR2, r3
blr
/*
* Used by threads when the lock bit of core_idle_state is set.
* Threads will spin in HMT_LOW until the lock bit is cleared.
* r14 - pointer to core_idle_state
* r15 - used to load contents of core_idle_state
* r9 - used as a temporary variable
*/
core_idle_lock_held:
HMT_LOW
3: lwz r15,0(r14)
andis. r15,r15,PNV_CORE_IDLE_LOCK_BIT@h
bne 3b
HMT_MEDIUM
lwarx r15,0,r14
andis. r9,r15,PNV_CORE_IDLE_LOCK_BIT@h
bne- core_idle_lock_held
blr
/*
* Pass requested state in r3:
* r3 - PNV_THREAD_NAP/SLEEP/WINKLE in POWER8
* - Requested PSSCR value in POWER9
*
* Address of idle handler to branch to in realmode in r4
*/
pnv_powersave_common:
/* Use r3 to pass state nap/sleep/winkle */
/* NAP is a state loss, we create a regs frame on the
* stack, fill it up with the state we care about and
* stick a pointer to it in PACAR1. We really only
* need to save PC, some CR bits and the NV GPRs,
* but for now an interrupt frame will do.
*/
mtctr r4
mflr r0
std r0,16(r1)
stdu r1,-INT_FRAME_SIZE(r1)
std r0,_LINK(r1)
std r0,_NIP(r1)
/* We haven't lost state ... yet */
li r0,0
stb r0,PACA_NAPSTATELOST(r13)
/* Continue saving state */
SAVE_GPR(2, r1)
SAVE_NVGPRS(r1)
mfcr r5
std r5,_CCR(r1)
std r1,PACAR1(r13)
BEGIN_FTR_SECTION
/*
* POWER9 does not require real mode to stop, and presently does not
* set hwthread_state for KVM (threads don't share MMU context), so
* we can remain in virtual mode for this.
*/
bctr
END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
/*
* POWER8
* Go to real mode to do the nap, as required by the architecture.
* Also, we need to be in real mode before setting hwthread_state,
* because as soon as we do that, another thread can switch
* the MMU context to the guest.
*/
LOAD_REG_IMMEDIATE(r7, MSR_IDLE)
mtmsrd r7,0
bctr
/*
* This is the sequence required to execute idle instructions, as
* specified in ISA v2.07 (and earlier). MSR[IR] and MSR[DR] must be 0.
*/
#define IDLE_STATE_ENTER_SEQ_NORET(IDLE_INST) \
/* Magic NAP/SLEEP/WINKLE mode enter sequence */ \
std r0,0(r1); \
ptesync; \
ld r0,0(r1); \
236: cmpd cr0,r0,r0; \
bne 236b; \
IDLE_INST;
.globl pnv_enter_arch207_idle_mode
pnv_enter_arch207_idle_mode:
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
/* Tell KVM we're entering idle */
li r4,KVM_HWTHREAD_IN_IDLE
/******************************************************/
/* N O T E W E L L ! ! ! N O T E W E L L */
/* The following store to HSTATE_HWTHREAD_STATE(r13) */
/* MUST occur in real mode, i.e. with the MMU off, */
/* and the MMU must stay off until we clear this flag */
/* and test HSTATE_HWTHREAD_REQ(r13) in */
/* pnv_powersave_wakeup in this file. */
/* The reason is that another thread can switch the */
/* MMU to a guest context whenever this flag is set */
/* to KVM_HWTHREAD_IN_IDLE, and if the MMU was on, */
/* that would potentially cause this thread to start */
/* executing instructions from guest memory in */
/* hypervisor mode, leading to a host crash or data */
/* corruption, or worse. */
/******************************************************/
stb r4,HSTATE_HWTHREAD_STATE(r13)
#endif
stb r3,PACA_THREAD_IDLE_STATE(r13)
cmpwi cr3,r3,PNV_THREAD_SLEEP
bge cr3,2f
IDLE_STATE_ENTER_SEQ_NORET(PPC_NAP)
/* No return */
2:
/* Sleep or winkle */
lbz r7,PACA_THREAD_MASK(r13)
ld r14,PACA_CORE_IDLE_STATE_PTR(r13)
li r5,0
beq cr3,3f
lis r5,PNV_CORE_IDLE_WINKLE_COUNT@h
3:
lwarx_loop1:
lwarx r15,0,r14
andis. r9,r15,PNV_CORE_IDLE_LOCK_BIT@h
bnel- core_idle_lock_held
add r15,r15,r5 /* Add if winkle */
andc r15,r15,r7 /* Clear thread bit */
andi. r9,r15,PNV_CORE_IDLE_THREAD_BITS
/*
* If cr0 = 0, then current thread is the last thread of the core entering
* sleep. Last thread needs to execute the hardware bug workaround code if
* required by the platform.
* Make the workaround call unconditionally here. The below branch call is
* patched out when the idle states are discovered if the platform does not
* require it.
*/
.global pnv_fastsleep_workaround_at_entry
pnv_fastsleep_workaround_at_entry:
beq fastsleep_workaround_at_entry
stwcx. r15,0,r14
bne- lwarx_loop1
isync
common_enter: /* common code for all the threads entering sleep or winkle */
bgt cr3,enter_winkle
IDLE_STATE_ENTER_SEQ_NORET(PPC_SLEEP)
fastsleep_workaround_at_entry:
oris r15,r15,PNV_CORE_IDLE_LOCK_BIT@h
stwcx. r15,0,r14
bne- lwarx_loop1
isync
/* Fast sleep workaround */
li r3,1
li r4,1
bl opal_config_cpu_idle_state
/* Unlock */
xoris r15,r15,PNV_CORE_IDLE_LOCK_BIT@h
lwsync
stw r15,0(r14)
b common_enter
enter_winkle:
bl save_sprs_to_stack
IDLE_STATE_ENTER_SEQ_NORET(PPC_WINKLE)
/*
* r3 - PSSCR value corresponding to the requested stop state.
*/
power_enter_stop:
/*
* Check if we are executing the lite variant with ESL=EC=0
*/
andis. r4,r3,PSSCR_EC_ESL_MASK_SHIFTED
clrldi r3,r3,60 /* r3 = Bits[60:63] = Requested Level (RL) */
bne .Lhandle_esl_ec_set
PPC_STOP
li r3,0 /* Since we didn't lose state, return 0 */
std r3, PACA_REQ_PSSCR(r13)
/*
* pnv_wakeup_noloss() expects r12 to contain the SRR1 value so
* it can determine if the wakeup reason is an HMI in
* CHECK_HMI_INTERRUPT.
*
* However, when we wakeup with ESL=0, SRR1 will not contain the wakeup
* reason, so there is no point setting r12 to SRR1.
*
* Further, we clear r12 here, so that we don't accidentally enter the
* HMI in pnv_wakeup_noloss() if the value of r12[42:45] == WAKE_HMI.
*/
li r12, 0
b pnv_wakeup_noloss
.Lhandle_esl_ec_set:
BEGIN_FTR_SECTION
/*
* POWER9 DD2.0 or earlier can incorrectly set PMAO when waking up after
* a state-loss idle. Saving and restoring MMCR0 over idle is a
* workaround.
*/
mfspr r4,SPRN_MMCR0
std r4,_MMCR0(r1)
END_FTR_SECTION_IFCLR(CPU_FTR_POWER9_DD2_1)
/*
* 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 .Lhandle_deep_stop
PPC_STOP /* Does not return (system reset interrupt) */
.Lhandle_deep_stop:
/*
* 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
andis. r9,r15,PNV_CORE_IDLE_LOCK_BIT@h
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
PPC_STOP /* Does not return (system reset interrupt) */
/*
* Entered with MSR[EE]=0 and no soft-masked interrupts pending.
* r3 contains desired idle state (PNV_THREAD_NAP/SLEEP/WINKLE).
*/
_GLOBAL(power7_idle_insn)
/* Now check if user or arch enabled NAP mode */
LOAD_REG_ADDR(r4, pnv_enter_arch207_idle_mode)
b pnv_powersave_common
#define CHECK_HMI_INTERRUPT \
BEGIN_FTR_SECTION_NESTED(66); \
rlwinm r0,r12,45-31,0xf; /* extract wake reason field (P8) */ \
FTR_SECTION_ELSE_NESTED(66); \
rlwinm r0,r12,45-31,0xe; /* P7 wake reason field is 3 bits */ \
ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_ARCH_207S, 66); \
cmpwi r0,0xa; /* Hypervisor maintenance ? */ \
bne+ 20f; \
/* Invoke opal call to handle hmi */ \
ld r2,PACATOC(r13); \
ld r1,PACAR1(r13); \
std r3,ORIG_GPR3(r1); /* Save original r3 */ \
li r3,0; /* NULL argument */ \
bl hmi_exception_realmode; \
nop; \
ld r3,ORIG_GPR3(r1); /* Restore original r3 */ \
20: nop;
/*
* Entered with MSR[EE]=0 and no soft-masked interrupts pending.
* r3 contains desired PSSCR register value.
*
* Offline (CPU unplug) case also must notify KVM that the CPU is
* idle.
*/
_GLOBAL(power9_offline_stop)
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
/*
* Tell KVM we're entering idle.
* This does not have to be done in real mode because the P9 MMU
* is independent per-thread. Some steppings share radix/hash mode
* between threads, but in that case KVM has a barrier sync in real
* mode before and after switching between radix and hash.
*/
li r4,KVM_HWTHREAD_IN_IDLE
stb r4,HSTATE_HWTHREAD_STATE(r13)
#endif
/* fall through */
_GLOBAL(power9_idle_stop)
std r3, PACA_REQ_PSSCR(r13)
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
BEGIN_FTR_SECTION
sync
lwz r5, PACA_DONT_STOP(r13)
cmpwi r5, 0
bne 1f
END_FTR_SECTION_IFSET(CPU_FTR_P9_TM_XER_SO_BUG)
#endif
mtspr SPRN_PSSCR,r3
LOAD_REG_ADDR(r4,power_enter_stop)
b pnv_powersave_common
/* No return */
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
1:
/*
* We get here when TM / thread reconfiguration bug workaround
* code wants to get the CPU into SMT4 mode, and therefore
* we are being asked not to stop.
*/
li r3, 0
std r3, PACA_REQ_PSSCR(r13)
blr /* return 0 for wakeup cause / SRR1 value */
#endif
/*
* On waking up from stop 0,1,2 with ESL=1 on POWER9 DD1,
* HSPRG0 will be set to the HSPRG0 value of one of the
* threads in this core. Thus the value we have in r13
* may not be this thread's paca pointer.
*
* Fortunately, the TIR remains invariant. Since this thread's
* paca pointer is recorded in all its sibling's paca, we can
* correctly recover this thread's paca pointer if we
* know the index of this thread in the core.
*
* This index can be obtained from the TIR.
*
* i.e, thread's position in the core = TIR.
* If this value is i, then this thread's paca is
* paca->thread_sibling_pacas[i].
*/
power9_dd1_recover_paca:
mfspr r4, SPRN_TIR
/*
* Since each entry in thread_sibling_pacas is 8 bytes
* we need to left-shift by 3 bits. Thus r4 = i * 8
*/
sldi r4, r4, 3
/* Get &paca->thread_sibling_pacas[0] in r5 */
ld r5, PACA_SIBLING_PACA_PTRS(r13)
/* Load paca->thread_sibling_pacas[i] into r13 */
ldx r13, r4, r5
SET_PACA(r13)
/*
* Indicate that we have lost NVGPR state
* which needs to be restored from the stack.
*/
li r3, 1
stb r3,PACA_NAPSTATELOST(r13)
blr
/*
* Called from machine check handler for powersave wakeups.
* Low level machine check processing has already been done. Now just
* go through the wake up path to get everything in order.
*
* r3 - The original SRR1 value.
* Original SRR[01] have been clobbered.
* MSR_RI is clear.
*/
.global pnv_powersave_wakeup_mce
pnv_powersave_wakeup_mce:
/* Set cr3 for pnv_powersave_wakeup */
rlwinm r11,r3,47-31,30,31
cmpwi cr3,r11,2
/*
* Now put the original SRR1 with SRR1_WAKEMCE_RESVD as the wake
* reason into r12, which allows reuse of the system reset wakeup
* code without being mistaken for another type of wakeup.
*/
oris r12,r3,SRR1_WAKEMCE_RESVD@h
b pnv_powersave_wakeup
/*
* Called from reset vector for powersave wakeups.
* cr3 - set to gt if waking up with partial/complete hypervisor state loss
* r12 - SRR1
*/
.global pnv_powersave_wakeup
pnv_powersave_wakeup:
ld r2, PACATOC(r13)
BEGIN_FTR_SECTION
BEGIN_FTR_SECTION_NESTED(70)
bl power9_dd1_recover_paca
END_FTR_SECTION_NESTED_IFSET(CPU_FTR_POWER9_DD1, 70)
bl pnv_restore_hyp_resource_arch300
FTR_SECTION_ELSE
bl pnv_restore_hyp_resource_arch207
ALT_FTR_SECTION_END_IFSET(CPU_FTR_ARCH_300)
li r0,PNV_THREAD_RUNNING
stb r0,PACA_THREAD_IDLE_STATE(r13) /* Clear thread state */
mr r3,r12
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
lbz r0,HSTATE_HWTHREAD_STATE(r13)
cmpwi r0,KVM_HWTHREAD_IN_KERNEL
beq 1f
li r0,KVM_HWTHREAD_IN_KERNEL
stb r0,HSTATE_HWTHREAD_STATE(r13)
/* Order setting hwthread_state vs. testing hwthread_req */
sync
lbz r0,HSTATE_HWTHREAD_REQ(r13)
cmpwi r0,0
beq 1f
b kvm_start_guest
1:
#endif
/* Return SRR1 from power7_nap() */
blt cr3,pnv_wakeup_noloss
b pnv_wakeup_loss
/*
* Check whether we have woken up with hypervisor state loss.
* If yes, restore hypervisor state and return back to link.
*
* cr3 - set to gt if waking up with partial/complete hypervisor state loss
*/
pnv_restore_hyp_resource_arch300:
/*
* Workaround for POWER9, if we lost resources, the ERAT
* might have been mixed up and needs flushing. We also need
* to reload MMCR0 (see comment above). We also need to set
* then clear bit 60 in MMCRA to ensure the PMU starts running.
*/
blt cr3,1f
BEGIN_FTR_SECTION
PPC_INVALIDATE_ERAT
ld r1,PACAR1(r13)
ld r4,_MMCR0(r1)
mtspr SPRN_MMCR0,r4
END_FTR_SECTION_IFCLR(CPU_FTR_POWER9_DD2_1)
mfspr r4,SPRN_MMCRA
ori r4,r4,(1 << (63-60))
mtspr SPRN_MMCRA,r4
xori r4,r4,(1 << (63-60))
mtspr SPRN_MMCRA,r4
1:
/*
* 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)
BEGIN_FTR_SECTION_NESTED(71)
/*
* Assume that we are waking up from the state
* same as the Requested Level (RL) in the PSSCR
* which are Bits 60-63
*/
ld r5,PACA_REQ_PSSCR(r13)
rldicl r5,r5,0,60
FTR_SECTION_ELSE_NESTED(71)
/*
* 0-3 bits correspond to Power-Saving Level Status
* which indicates the idle state we are waking up from
*/
mfspr r5, SPRN_PSSCR
rldicl r5,r5,4,60
ALT_FTR_SECTION_END_NESTED_IFSET(CPU_FTR_POWER9_DD1, 71)
li r0, 0 /* clear requested_psscr to say we're awake */
std r0, PACA_REQ_PSSCR(r13)
cmpd cr4,r5,r4
bge cr4,pnv_wakeup_tb_loss /* returns to caller */
blr /* Waking up without hypervisor state loss. */
/* Same calling convention as arch300 */
pnv_restore_hyp_resource_arch207:
/*
* POWER ISA 2.07 or less.
* Check if we slept with sleep or winkle.
*/
lbz r4,PACA_THREAD_IDLE_STATE(r13)
cmpwi cr2,r4,PNV_THREAD_NAP
bgt cr2,pnv_wakeup_tb_loss /* Either sleep or Winkle */
/*
* We fall through here if PACA_THREAD_IDLE_STATE shows we are waking
* up from nap. At this stage CR3 shouldn't contains 'gt' since that
* indicates we are waking with hypervisor state loss from nap.
*/
bgt cr3,.
blr /* Waking up without hypervisor state loss */
/*
* 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
*
* If ISA300:
* cr4 - gt or eq if waking up from complete hypervisor state loss.
*
* If ISA207:
* r4 - PACA_THREAD_IDLE_STATE
*/
pnv_wakeup_tb_loss:
ld r1,PACAR1(r13)
/*
* Before entering any idle state, the NVGPRs are saved in the stack.
* If there was a state loss, or PACA_NAPSTATELOST was set, then the
* NVGPRs are restored. If we are here, it is likely that state is lost,
* but not guaranteed -- neither ISA207 nor ISA300 tests to reach
* here are the same as the test to restore NVGPRS:
* PACA_THREAD_IDLE_STATE test for ISA207, PSSCR test for ISA300,
* and SRR1 test for restoring NVGPRs.
*
* We are about to clobber NVGPRs now, so set NAPSTATELOST to
* guarantee they will always be restored. This might be tightened
* with careful reading of specs (particularly for ISA300) but this
* is already a slow wakeup path and it's simpler to be safe.
*/
li r0,1
stb r0,PACA_NAPSTATELOST(r13)
/*
*
* Save SRR1 and LR in NVGPRs as they might be clobbered in
* opal_call() (called in CHECK_HMI_INTERRUPT). SRR1 is required
* to determine the wakeup reason if we branch to kvm_start_guest. LR
* is required to return back to reset vector after hypervisor state
* restore is complete.
*/
mr r19,r12
mr r18,r4
mflr r17
BEGIN_FTR_SECTION
CHECK_HMI_INTERRUPT
END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
ld r14,PACA_CORE_IDLE_STATE_PTR(r13)
lbz r7,PACA_THREAD_MASK(r13)
/*
* Take the core lock to synchronize against other threads.
*
* Lock bit is set in one of the 2 cases-
* a. In the sleep/winkle enter path, the last thread is executing
* fastsleep workaround code.
* b. In the wake up path, another thread is executing fastsleep
* workaround undo code or resyncing timebase or restoring context
* In either case loop until the lock bit is cleared.
*/
1:
lwarx r15,0,r14
andis. r9,r15,PNV_CORE_IDLE_LOCK_BIT@h
bnel- core_idle_lock_held
oris r15,r15,PNV_CORE_IDLE_LOCK_BIT@h
stwcx. r15,0,r14
bne- 1b
isync
andi. r9,r15,PNV_CORE_IDLE_THREAD_BITS
cmpwi cr2,r9,0
/*
* At this stage
* cr2 - eq if first thread to wakeup in core
* cr3- gt if waking up with partial/complete hypervisor state loss
* ISA300:
* cr4 - gt or eq if waking up from complete hypervisor state loss.
*/
BEGIN_FTR_SECTION
/*
* Were we in winkle?
* If yes, check if all threads were in winkle, decrement our
* winkle count, set all thread winkle bits if all were in winkle.
* Check if our thread has a winkle bit set, and set cr4 accordingly
* (to match ISA300, above). Pseudo-code for core idle state
* transitions for ISA207 is as follows (everything happens atomically
* due to store conditional and/or lock bit):
*
* nap_idle() { }
* nap_wake() { }
*
* sleep_idle()
* {
* core_idle_state &= ~thread_in_core
* }
*
* sleep_wake()
* {
* bool first_in_core, first_in_subcore;
*
* first_in_core = (core_idle_state & IDLE_THREAD_BITS) == 0;
* first_in_subcore = (core_idle_state & SUBCORE_SIBLING_MASK) == 0;
*
* core_idle_state |= thread_in_core;
* }
*
* winkle_idle()
* {
* core_idle_state &= ~thread_in_core;
* core_idle_state += 1 << WINKLE_COUNT_SHIFT;
* }
*
* winkle_wake()
* {
* bool first_in_core, first_in_subcore, winkle_state_lost;
*
* first_in_core = (core_idle_state & IDLE_THREAD_BITS) == 0;
* first_in_subcore = (core_idle_state & SUBCORE_SIBLING_MASK) == 0;
*
* core_idle_state |= thread_in_core;
*
* if ((core_idle_state & WINKLE_MASK) == (8 << WINKLE_COUNT_SIHFT))
* core_idle_state |= THREAD_WINKLE_BITS;
* core_idle_state -= 1 << WINKLE_COUNT_SHIFT;
*
* winkle_state_lost = core_idle_state &
* (thread_in_core << WINKLE_THREAD_SHIFT);
* core_idle_state &= ~(thread_in_core << WINKLE_THREAD_SHIFT);
* }
*
*/
cmpwi r18,PNV_THREAD_WINKLE
bne 2f
andis. r9,r15,PNV_CORE_IDLE_WINKLE_COUNT_ALL_BIT@h
subis r15,r15,PNV_CORE_IDLE_WINKLE_COUNT@h
beq 2f
ori r15,r15,PNV_CORE_IDLE_THREAD_WINKLE_BITS /* all were winkle */
2:
/* Shift thread bit to winkle mask, then test if this thread is set,
* and remove it from the winkle bits */
slwi r8,r7,8
and r8,r8,r15
andc r15,r15,r8
cmpwi cr4,r8,1 /* cr4 will be gt if our bit is set, lt if not */
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
*/
blt cr4,subcore_state_restored
/* Restore per-subcore state */
ld r4,_SDR1(r1)
mtspr SPRN_SDR1,r4
ld r4,_RPR(r1)
mtspr SPRN_RPR,r4
ld r4,_AMOR(r1)
mtspr SPRN_AMOR,r4
subcore_state_restored:
/*
* Check if the thread is also the first thread in the core. If not,
* skip to clear_lock.
*/
bne cr2,clear_lock
first_thread_in_core:
/*
* 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 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:
/*
* Use cr3 which indicates that we are waking up with atleast partial
* hypervisor state loss to determine if TIMEBASE RESYNC is needed.
*/
ble cr3,.Ltb_resynced
/* Time base re-sync */
bl opal_resync_timebase;
/*
* If waking up from sleep (POWER8), per core state
* is not lost, skip to clear_lock.
*/
.Ltb_resynced:
blt cr4,clear_lock
/*
* 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)
mtspr SPRN_WORC,r4
clear_lock:
xoris r15,r15,PNV_CORE_IDLE_LOCK_BIT@h
lwsync
stw r15,0(r14)
common_exit:
/*
* Common to all threads.
*
* If waking up from sleep, hypervisor state is not lost. Hence
* skip hypervisor state restore.
*/
blt cr4,hypervisor_state_restored
/* Waking up from winkle */
BEGIN_MMU_FTR_SECTION
b no_segments
END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX)
/* Restore SLB from PACA */
ld r8,PACA_SLBSHADOWPTR(r13)
.rept SLB_NUM_BOLTED
li r3, SLBSHADOW_SAVEAREA
LDX_BE r5, r8, r3
addi r3, r3, 8
LDX_BE r6, r8, r3
andis. r7,r5,SLB_ESID_V@h
beq 1f
slbmte r6,r5
1: addi r8,r8,16
.endr
no_segments:
/* Restore per thread state */
ld r4,_SPURR(r1)
mtspr SPRN_SPURR,r4
ld r4,_PURR(r1)
mtspr SPRN_PURR,r4
ld r4,_DSCR(r1)
mtspr SPRN_DSCR,r4
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
/*
* On POWER9, we can come here on wakeup from a cpuidle stop state.
* Hence restore the additional SPRs to the saved value.
*
* On POWER8, we come here only on winkle. Since winkle is used
* only in the case of CPU-Hotplug, we don't need to restore
* the additional SPRs.
*/
BEGIN_FTR_SECTION
bl power9_restore_additional_sprs
END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
hypervisor_state_restored:
mr r12,r19
mtlr r17
blr /* return to pnv_powersave_wakeup */
fastsleep_workaround_at_exit:
li r3,1
li r4,0
bl opal_config_cpu_idle_state
b timebase_resync
/*
* R3 here contains the value that will be returned to the caller
* of power7_nap.
* R12 contains SRR1 for CHECK_HMI_INTERRUPT.
*/
.global pnv_wakeup_loss
pnv_wakeup_loss:
ld r1,PACAR1(r13)
BEGIN_FTR_SECTION
CHECK_HMI_INTERRUPT
END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
REST_NVGPRS(r1)
REST_GPR(2, r1)
ld r4,PACAKMSR(r13)
ld r5,_LINK(r1)
ld r6,_CCR(r1)
addi r1,r1,INT_FRAME_SIZE
mtlr r5
mtcr r6
mtmsrd r4
blr
/*
* R3 here contains the value that will be returned to the caller
* of power7_nap.
* R12 contains SRR1 for CHECK_HMI_INTERRUPT.
*/
pnv_wakeup_noloss:
lbz r0,PACA_NAPSTATELOST(r13)
cmpwi r0,0
bne pnv_wakeup_loss
ld r1,PACAR1(r13)
BEGIN_FTR_SECTION
CHECK_HMI_INTERRUPT
END_FTR_SECTION_IFSET(CPU_FTR_HVMODE)
ld r4,PACAKMSR(r13)
ld r5,_NIP(r1)
ld r6,_CCR(r1)
addi r1,r1,INT_FRAME_SIZE
mtlr r5
mtcr r6
mtmsrd r4
blr
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