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author | Nicholas Piggin <npiggin@gmail.com> | 2019-04-12 17:30:52 +0300 |
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committer | Michael Ellerman <mpe@ellerman.id.au> | 2019-04-30 15:37:48 +0300 |
commit | 10d91611f426d4bafd2a83d966c36da811b2f7ad (patch) | |
tree | e455d47497c64533f4537290dae97baae10d0340 /arch/powerpc/kernel/asm-offsets.c | |
parent | c1fe190c06723322f2dfac31d3b982c581e434ef (diff) | |
download | linux-10d91611f426d4bafd2a83d966c36da811b2f7ad.tar.xz |
powerpc/64s: Reimplement book3s idle code in C
Reimplement Book3S idle code in C, moving POWER7/8/9 implementation
speific HV idle code to the powernv platform code.
Book3S assembly stubs are kept in common code and used only to save
the stack frame and non-volatile GPRs before executing architected
idle instructions, and restoring the stack and reloading GPRs then
returning to C after waking from idle.
The complex logic dealing with threads and subcores, locking, SPRs,
HMIs, timebase resync, etc., is all done in C which makes it more
maintainable.
This is not a strict translation to C code, there are some
significant differences:
- Idle wakeup no longer uses the ->cpu_restore call to reinit SPRs,
but saves and restores them itself.
- The optimisation where EC=ESL=0 idle modes did not have to save GPRs
or change MSR is restored, because it's now simple to do. ESL=1
sleeps that do not lose GPRs can use this optimization too.
- KVM secondary entry and cede is now more of a call/return style
rather than branchy. nap_state_lost is not required because KVM
always returns via NVGPR restoring path.
- KVM secondary wakeup from offline sequence is moved entirely into
the offline wakeup, which avoids a hwsync in the normal idle wakeup
path.
Performance measured with context switch ping-pong on different
threads or cores, is possibly improved a small amount, 1-3% depending
on stop state and core vs thread test for shallow states. Deep states
it's in the noise compared with other latencies.
KVM improvements:
- Idle sleepers now always return to caller rather than branch out
to KVM first.
- This allows optimisations like very fast return to caller when no
state has been lost.
- KVM no longer requires nap_state_lost because it controls NVGPR
save/restore itself on the way in and out.
- The heavy idle wakeup KVM request check can be moved out of the
normal host idle code and into the not-performance-critical offline
code.
- KVM nap code now returns from where it is called, which makes the
flow a bit easier to follow.
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Squash the KVM changes in]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kernel/asm-offsets.c')
-rw-r--r-- | arch/powerpc/kernel/asm-offsets.c | 18 |
1 files changed, 0 insertions, 18 deletions
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 86a61e5f8285..83ad99f9f05d 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -268,7 +268,6 @@ int main(void) OFFSET(ACCOUNT_USER_TIME, paca_struct, accounting.utime); OFFSET(ACCOUNT_SYSTEM_TIME, paca_struct, accounting.stime); OFFSET(PACA_TRAP_SAVE, paca_struct, trap_save); - OFFSET(PACA_NAPSTATELOST, paca_struct, nap_state_lost); OFFSET(PACA_SPRG_VDSO, paca_struct, sprg_vdso); #else /* CONFIG_PPC64 */ #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE @@ -766,23 +765,6 @@ int main(void) OFFSET(VCPU_TIMING_LAST_ENTER_TBL, kvm_vcpu, arch.timing_last_enter.tv32.tbl); #endif -#ifdef CONFIG_PPC_POWERNV - OFFSET(PACA_CORE_IDLE_STATE_PTR, paca_struct, core_idle_state_ptr); - OFFSET(PACA_THREAD_IDLE_STATE, paca_struct, thread_idle_state); - OFFSET(PACA_THREAD_MASK, paca_struct, thread_mask); - OFFSET(PACA_SUBCORE_SIBLING_MASK, paca_struct, subcore_sibling_mask); - OFFSET(PACA_REQ_PSSCR, paca_struct, requested_psscr); - OFFSET(PACA_DONT_STOP, paca_struct, dont_stop); -#define STOP_SPR(x, f) OFFSET(x, paca_struct, stop_sprs.f) - STOP_SPR(STOP_PID, pid); - STOP_SPR(STOP_LDBAR, ldbar); - STOP_SPR(STOP_FSCR, fscr); - STOP_SPR(STOP_HFSCR, hfscr); - STOP_SPR(STOP_MMCR1, mmcr1); - STOP_SPR(STOP_MMCR2, mmcr2); - STOP_SPR(STOP_MMCRA, mmcra); -#endif - DEFINE(PPC_DBELL_SERVER, PPC_DBELL_SERVER); DEFINE(PPC_DBELL_MSGTYPE, PPC_DBELL_MSGTYPE); |