From 5d298baa41883fc421acfd932799c0f4177249ae Mon Sep 17 00:00:00 2001 From: "Gautham R. Shenoy" Date: Thu, 31 Aug 2017 17:17:41 +0530 Subject: [PATCH] powerpc/powernv: Clear LPCR[PECE1] via stop-api only for deep state offline 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: 24be85a23d1f ("powerpc/powernv: Clear PECE1 in LPCR via stop-api only on Hotplug") Reported-by: Pavithra Prakash Signed-off-by: Gautham R. Shenoy Reviewed-by: Nicholas Piggin Tested-by: Pavithra Prakash Signed-off-by: Michael Ellerman --- 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 9f59041a172b..443d5ca71995 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 if the 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); } /* -- 2.20.1