From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [103.22.144.67]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3tKqP32dz0zDvt1 for ; Fri, 18 Nov 2016 18:28:55 +1100 (AEDT) From: Paul Mackerras To: kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linuxppc-dev@ozlabs.org Subject: [PATCH 12/13] KVM: PPC: Book3S HV: Use stop instruction rather than nap on POWER9 Date: Fri, 18 Nov 2016 18:28:41 +1100 Message-Id: <1479454122-26994-13-git-send-email-paulus@ozlabs.org> In-Reply-To: <1479454122-26994-1-git-send-email-paulus@ozlabs.org> References: <1479454122-26994-1-git-send-email-paulus@ozlabs.org> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 --- 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