POWER9 replaces the various power-saving mode instructions on POWER8 (doze, nap, sleep and rvwinkle) with a single "stop" instruction, plus a register, PSSCR, which controls the depth of the power-saving mode. This replaces the use of the nap instruction when threads are idle during guest execution with the stop instruction, and adds code to set PSSCR to a value which will allow an SMT mode switch while the thread is idle (given that the core as a whole won't be idle in these cases). Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx> --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 29 ++++++++++++++++++----------- 1 file changed, 18 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index acae5c3..e9eaff4 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -501,17 +501,9 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) cmpwi r0, 0 beq 57f li r3, (LPCR_PECEDH | LPCR_PECE0) >> 4 - mfspr r4, SPRN_LPCR - rlwimi r4, r3, 4, (LPCR_PECEDP | LPCR_PECEDH | LPCR_PECE0 | LPCR_PECE1) - mtspr SPRN_LPCR, r4 - isync - std r0, HSTATE_SCRATCH0(r13) - ptesync - ld r0, HSTATE_SCRATCH0(r13) -1: cmpd r0, r0 - bne 1b - nap - b . + mfspr r5, SPRN_LPCR + rlwimi r5, r3, 4, (LPCR_PECEDP | LPCR_PECEDH | LPCR_PECE0 | LPCR_PECE1) + b kvm_nap_sequence 57: li r0, 0 stbx r0, r3, r4 @@ -2256,6 +2248,17 @@ BEGIN_FTR_SECTION ori r5, r5, LPCR_PECEDH rlwimi r5, r3, 0, LPCR_PECEDP END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) + +kvm_nap_sequence: /* desired LPCR value in r5 */ +BEGIN_FTR_SECTION + /* + * PSSCR bits: exit criterion = 1 (wakeup based on LPCR at sreset) + * enable state loss = 1 (allow SMT mode switch) + * requested level = 0 (just stop dispatching) + */ + lis r3, (PSSCR_EC | PSSCR_ESL)@h + mtspr SPRN_PSSCR, r3 +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300) mtspr SPRN_LPCR,r5 isync li r0, 0 @@ -2264,7 +2267,11 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) ld r0, HSTATE_SCRATCH0(r13) 1: cmpd r0, r0 bne 1b +BEGIN_FTR_SECTION nap +FTR_SECTION_ELSE + PPC_STOP +ALT_FTR_SECTION_END_IFCLR(CPU_FTR_ARCH_300) b . 33: mr r4, r3 -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
