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powernv/cpuidle: Redesign idle states management

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Deep idle states like sleep and winkle are per core idle states. A core
enters these states only when all the threads enter either the
particular idle state or a deeper one. There are tasks like fastsleep
hardware bug workaround and hypervisor core state save which have to be
done only by the last thread of the core entering deep idle state and
similarly tasks like timebase resync, hypervisor core register restore
that have to be done only by the first thread waking up from these
state.

The current idle state management does not have a way to distinguish the
first/last thread of the core waking/entering idle states. Tasks like
timebase resync are done for all the threads. This is not only is
suboptimal, but can cause functionality issues when subcores and kvm is
involved.

This patch adds the necessary infrastructure to track idle states of
threads in a per-core structure. It uses this info to perform tasks like
fastsleep workaround and timebase resync only once per core.

Signed-off-by: Shreyas B. Prabhu <shreyas@linux.vnet.ibm.com>
Originally-by: Preeti U. Murthy <preeti@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: linux-pm@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Shreyas B. Prabhu
2014-12-10 00:26:52 +05:30
committed by Michael Ellerman
parent 8eb8ac89a3
commit 7cba160ad7
11 changed files with 297 additions and 59 deletions
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24
arch/powerpc/kernel/exceptions-64s.S
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@@ -15,6 +15,7 @@
#include <asm/hw_irq.h>
#include <asm/exception-64s.h>
#include <asm/ptrace.h>
#include <asm/cpuidle.h>
/*
* We layout physical memory as follows:
@@ -109,15 +110,19 @@ BEGIN_FTR_SECTION
rlwinm. r13,r13,47-31,30,31
beq 9f
/* waking up from powersave (nap) state */
cmpwi cr1,r13,2
/* Total loss of HV state is fatal, we could try to use the
* PIR to locate a PACA, then use an emergency stack etc...
* OPAL v3 based powernv platforms have new idle states
* which fall in this catagory.
*/
bgt cr1,8f
cmpwi cr3,r13,2
GET_PACA(r13)
lbz r0,PACA_THREAD_IDLE_STATE(r13)
cmpwi cr2,r0,PNV_THREAD_NAP
bgt cr2,8f /* Either sleep or Winkle */
/* Waking up from nap should not cause hypervisor state loss */
bgt cr3,.
/* Waking up from nap */
li r0,PNV_THREAD_RUNNING
stb r0,PACA_THREAD_IDLE_STATE(r13) /* Clear thread state */
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
li r0,KVM_HWTHREAD_IN_KERNEL
@@ -133,7 +138,7 @@ BEGIN_FTR_SECTION
/* Return SRR1 from power7_nap() */
mfspr r3,SPRN_SRR1
beq cr1,2f
beq cr3,2f
b power7_wakeup_noloss
2: b power7_wakeup_loss
@@ -1382,6 +1387,7 @@ machine_check_handle_early:
MACHINE_CHECK_HANDLER_WINDUP
GET_PACA(r13)
ld r1,PACAR1(r13)
li r3,PNV_THREAD_NAP
b power7_enter_nap_mode
4:
#endif