From: Paul Mackerras <paulus@ozlabs.org>
To: kvm-ppc@vger.kernel.org, kvm@vger.kernel.org, linuxppc-dev@ozlabs.org
Subject: [PATCH v2 08/11] KVM: PPC: Book3S HV: Use stop instruction rather than nap on POWER9
Date: Wed, 23 Nov 2016 11:32:02 +1100 [thread overview]
Message-ID: <1479861125-21394-9-git-send-email-paulus@ozlabs.org> (raw)
In-Reply-To: <1479861125-21394-1-git-send-email-paulus@ozlabs.org>
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@ozlabs.org>
---
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 33 ++++++++++++++++++++++-----------
1 file changed, 22 insertions(+), 11 deletions(-)
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 598d828..9338a81 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 +2248,21 @@ 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
+ /* Set LPCR_PECE_HVEE bit to enable wakeup by HV interrupts */
+ li r4, LPCR_PECE_HVEE@higher
+ sldi r4, r4, 32
+ or r5, r5, r4
+END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
mtspr SPRN_LPCR,r5
isync
li r0, 0
@@ -2264,7 +2271,11 @@ 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
next prev parent reply other threads:[~2016-11-23 0:32 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-23 0:31 [PATCH 00/11] KVM: PPC: Book3S HV: Support KVM guests on POWER9 Paul Mackerras
2016-11-23 0:31 ` [PATCH v2 01/11] KVM: PPC: Book3S HV: Adapt to new HPTE format " Paul Mackerras
2016-11-23 0:31 ` [PATCH v2 02/11] KVM: PPC: Book3S HV: Set partition table rather than SDR1 " Paul Mackerras
2016-11-23 0:31 ` [PATCH v2 03/11] KVM: PPC: Book3S HV: Adjust host/guest context switch for POWER9 Paul Mackerras
2016-11-23 0:31 ` [PATCH v2 04/11] KVM: PPC: Book3S HV: Add new POWER9 guest-accessible SPRs Paul Mackerras
2016-11-23 0:31 ` [PATCH v2 05/11] KVM: PPC: Book3S HV: Adapt TLB invalidations to work on POWER9 Paul Mackerras
2016-11-23 0:32 ` [PATCH v2 06/11] KVM: PPC: Book3S HV: Use msgsnd for IPIs to other cores " Paul Mackerras
2016-11-23 0:32 ` [PATCH v2 07/11] KVM: PPC: Book3S HV: Use OPAL XICS emulation " Paul Mackerras
2016-11-23 0:32 ` Paul Mackerras [this message]
2016-11-23 0:32 ` [PATCH v2 09/11] KVM: PPC: Book3S HV: Enable hypervisor virtualization interrupts while in guest Paul Mackerras
2016-11-23 0:32 ` [PATCH v2 10/11] KVM: PPC: Book3S HV: Treat POWER9 CPU threads as independent subcores Paul Mackerras
2016-11-23 0:32 ` [PATCH v2 11/11] KVM: PPC: Book3S HV: Update kvmppc_set_arch_compat() for ISA v3.00 Paul Mackerras
2016-11-23 6:26 ` kbuild test robot
2016-11-23 23:03 ` [PATCH 00/11] KVM: PPC: Book3S HV: Support KVM guests on POWER9 Paul Mackerras
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