diff options
| author | Nicholas Piggin <npiggin@gmail.com> | 2017-06-13 23:05:51 +1000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2017-06-19 19:46:29 +1000 |
| commit | 9d29250136f60438fc0839871bae0a0e9cbbd47e (patch) | |
| tree | 3bda3145c64871a268c69e1ccb8b354e92e52c8b /arch/powerpc/kvm | |
| parent | b51351e264009e890936af83b8d800b32034273d (diff) | |
| download | linux-stable-9d29250136f60438fc0839871bae0a0e9cbbd47e.tar.gz linux-stable-9d29250136f60438fc0839871bae0a0e9cbbd47e.tar.bz2 linux-stable-9d29250136f60438fc0839871bae0a0e9cbbd47e.zip | |
powerpc/64s/idle: Avoid SRR usage in idle sleep/wake paths
Idle code now always runs at the 0xc... effective address whether
in real or virtual mode. This means rfid can be ditched, along
with a lot of SRR manipulations.
In the wakeup path, carry SRR1 around in r12. Use mtmsrd to change
MSR states as required.
This also balances the return prediction for the idle call, by
doing blr rather than rfid to return to the idle caller.
On POWER9, 2-process context switch on different cores, with snooze
disabled, increases performance by 2%.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Incorporate v2 fixes from Nick]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/kvm')
| -rw-r--r-- | arch/powerpc/kvm/book3s_hv_rmhandlers.S | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index bdb3f76ceb6b..ecb69c4ee943 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -329,15 +329,21 @@ kvm_novcpu_exit: * We come in here when wakened from nap mode. * Relocation is off and most register values are lost. * r13 points to the PACA. + * r3 contains the SRR1 wakeup value, SRR1 is trashed. */ .globl kvm_start_guest kvm_start_guest: - /* Set runlatch bit the minute you wake up from nap */ mfspr r0, SPRN_CTRLF ori r0, r0, 1 mtspr SPRN_CTRLT, r0 + /* + * Could avoid this and pass it through in r3. For now, + * code expects it to be in SRR1. + */ + mtspr SPRN_SRR1,r3 + ld r2,PACATOC(r13) li r0,KVM_HWTHREAD_IN_KVM @@ -456,13 +462,15 @@ kvm_no_guest: /* * We jump to pnv_wakeup_loss, which will return to the caller * of power7_nap in the powernv cpu offline loop. The value we - * put in r3 becomes the return value for power7_nap. + * put in r3 becomes the return value for power7_nap. pnv_wakeup_loss + * requires SRR1 in r12. */ li r3, LPCR_PECE0 mfspr r4, SPRN_LPCR rlwimi r4, r3, 0, LPCR_PECE0 | LPCR_PECE1 mtspr SPRN_LPCR, r4 li r3, 0 + mfspr r12,SPRN_SRR1 b pnv_wakeup_loss 53: HMT_LOW |