Messages in this thread | | | From | Akshay Adiga <> | Subject | Re: [PATCH] powerpc/powernv: Clear LPCR[PECE1] via stop-api only for deep state offline | Date | Tue, 19 Sep 2017 20:02:43 +0530 |
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Hi Michael,
Any comments on this patch ?
On 09/06/2017 02:32 PM, pavrampu wrote: > On 2017-08-31 17:17, Gautham R. Shenoy wrote: > > From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> > > > > commit 24be85a23d1f ("powerpc/powernv: Clear PECE1 in LPCR via > > stop-api only on Hotplug") clears the PECE1 bit of the LPCR via > > stop-api during CPU-Hotplug to prevent wakeup due to a decrementer on > > an offlined CPU which is in a deep stop state. > > > > In the case where the stop-api support is found to be lacking, the > > commit 785a12afdb4a ("powerpc/powernv/idle: Disable LOSE_FULL_CONTEXT > > states when stop-api fails") disables deep states that lose hypervisor > > context. Thus in this case, the offlined CPU will be put to some > > shallow idle state. > > > > However, we currently unconditionally clear the PECE1 in LPCR via > > stop-api during CPU-Hotplug even when deep states are disabled due to > > stop-api failure. > > > > Fix this by clearing PECE1 of LPCR via stop-api during CPU-Hotplug > > *only* when the offlined CPU will be put to a deep state that loses > > hypervisor context. > > > > Fixes: commit 24be85a23d1f ("powerpc/powernv: Clear PECE1 in LPCR via > > stop-api only on Hotplug") > > > > Reported-by: Pavithra Prakash <pavirampu@linux.vnet.ibm.com> > > Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> > > Tested-by: Pavithra Prakash <pavrampu@linux.vnet.ibm.com> > > > --- > > arch/powerpc/platforms/powernv/idle.c | 8 +++++++- > > 1 file changed, 7 insertions(+), 1 deletion(-) > > > > diff --git a/arch/powerpc/platforms/powernv/idle.c > > b/arch/powerpc/platforms/powernv/idle.c > > index 9f59041..23f8fba 100644 > > --- a/arch/powerpc/platforms/powernv/idle.c > > +++ b/arch/powerpc/platforms/powernv/idle.c > > @@ -393,7 +393,13 @@ static void pnv_program_cpu_hotplug_lpcr(unsigned > > int cpu, u64 lpcr_val) > > u64 pir = get_hard_smp_processor_id(cpu); > > > > mtspr(SPRN_LPCR, lpcr_val); > > - opal_slw_set_reg(pir, SPRN_LPCR, lpcr_val); > > + > > + /* > > + * Program the LPCR via stop-api only for deepest stop state > > + * can lose hypervisor context. > > + */ > > + if (supported_cpuidle_states & OPAL_PM_LOSE_FULL_CONTEXT) > > + opal_slw_set_reg(pir, SPRN_LPCR, lpcr_val); > > } > > > > /*
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