* Nicholas Piggin <npig...@gmail.com> [2017-11-18 00:08:05]:
> Implement a new function to invoke stop, power9_offline_stop, which is
> like power9_idle_stop but used by the cpu hotplug code.
>
> Move KVM secondary state manipulation code to the offline case.
>
> Signed-off-by: Nicholas Piggin <npig...@gmail.com>
Reviewed-by: Vaidyanathan Srinivasan <sva...@linux.vnet.ibm.com>
> ---
> arch/powerpc/include/asm/processor.h | 1 +
> arch/powerpc/kernel/idle_book3s.S | 24 ++++++++++++++++++------
> arch/powerpc/platforms/powernv/idle.c | 2 +-
> 3 files changed, 20 insertions(+), 7 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/processor.h
> b/arch/powerpc/include/asm/processor.h
> index bdab3b74eb98..0ebdb58460ce 100644
> --- a/arch/powerpc/include/asm/processor.h
> +++ b/arch/powerpc/include/asm/processor.h
> @@ -500,6 +500,7 @@ extern int powersave_nap; /* set if nap mode can be used
> in idle loop */
> extern unsigned long power7_idle_insn(unsigned long type); /*
> PNV_THREAD_NAP/etc*/
> extern void power7_idle_type(unsigned long type);
> extern unsigned long power9_idle_stop(unsigned long psscr_val);
> +extern unsigned long power9_offline_stop(unsigned long psscr_val);
> extern void power9_idle_type(unsigned long stop_psscr_val,
> unsigned long stop_psscr_mask);
>
> diff --git a/arch/powerpc/kernel/idle_book3s.S
> b/arch/powerpc/kernel/idle_book3s.S
> index 01e1c1997893..2f8364e7b489 100644
> --- a/arch/powerpc/kernel/idle_book3s.S
> +++ b/arch/powerpc/kernel/idle_book3s.S
> @@ -325,12 +325,6 @@ enter_winkle:
> * r3 - PSSCR value corresponding to the requested stop state.
> */
> power_enter_stop:
> -#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
> - /* Tell KVM we're entering idle */
> - li r4,KVM_HWTHREAD_IN_IDLE
> - /* DO THIS IN REAL MODE! See comment above. */
> - stb r4,HSTATE_HWTHREAD_STATE(r13)
> -#endif
> /*
> * Check if we are executing the lite variant with ESL=EC=0
> */
> @@ -435,6 +429,24 @@ _GLOBAL(power9_idle_stop)
> b pnv_powersave_common
> /* No return */
>
> +/*
> + * Entered with MSR[EE]=0 and no soft-masked interrupts pending.
> + * r3 contains desired PSSCR register value.
> + */
> +_GLOBAL(power9_offline_stop)
> + std r3, PACA_REQ_PSSCR(r13)
> + mtspr SPRN_PSSCR,r3
> +#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
> + /* Tell KVM we're entering idle */
> + li r4,KVM_HWTHREAD_IN_IDLE
> + /* DO THIS IN REAL MODE! See comment above. */
> + stb r4,HSTATE_HWTHREAD_STATE(r13)
> +#endif
> + LOAD_REG_ADDR(r4,power_enter_stop)
> + b pnv_powersave_common
> + /* No return */
> +
Good optimization. This code is needed only when an offline thread is
wokenup at 0x100 to get into guest. Can be skipped in idle wakeup
case.
> +
> /*
> * 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
> diff --git a/arch/powerpc/platforms/powernv/idle.c
> b/arch/powerpc/platforms/powernv/idle.c
> index 443d5ca71995..a921d5428d76 100644
> --- a/arch/powerpc/platforms/powernv/idle.c
> +++ b/arch/powerpc/platforms/powernv/idle.c
> @@ -434,7 +434,7 @@ unsigned long pnv_cpu_offline(unsigned int cpu)
> psscr = mfspr(SPRN_PSSCR);
> psscr = (psscr & ~pnv_deepest_stop_psscr_mask) |
> pnv_deepest_stop_psscr_val;
> - srr1 = power9_idle_stop(psscr);
> + srr1 = power9_offline_stop(psscr);
>
> } else if ((idle_states & OPAL_PM_WINKLE_ENABLED) &&
> (idle_states & OPAL_PM_LOSE_FULL_CONTEXT)) {
> --
> 2.15.0
>
