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Date: Wed, 28 May 2014 10:09:31 +0530 From: Preeti U Murthy <preeti@...ux.vnet.ibm.com> To: benh@...nel.crashing.org, linux-kernel@...r.kernel.org, svaidyan@...ibm.com, paulus@...ba.org, srivatsa.bhat@...ux.vnet.ibm.com, linuxppc-dev@...ts.ozlabs.org Subject: [PATCH 5/6] KVM: PPC: Book3S HV: Put KVM standby hwthreads to fast-sleep instead of nap From: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com> Now that the support for fast sleep idle state is present, allow the KVM standby threads to go to fast sleep if the platform supports it.This will fetch us maximum power savings if an entire core is idle. Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@...ux.vnet.ibm.com> [ Changelog added by <preeti@...ux.vnet.ibm.com> ] Signed-off-by: Preeti U Murthy <preeti@...ux.vnet.ibm.com> --- arch/powerpc/kvm/book3s_hv_rmhandlers.S | 73 ++++++++++++++++++++++++++++--- 1 file changed, 65 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S index 43aa806..69244cc 100644 --- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S +++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S @@ -207,7 +207,7 @@ kvmppc_primary_no_guest: li r3, 1 stb r3, HSTATE_HWTHREAD_REQ(r13) - b kvm_do_nap + b kvm_do_idle kvm_novcpu_wakeup: ld r1, HSTATE_HOST_R1(r13) @@ -247,7 +247,7 @@ kvm_novcpu_exit: b hdec_soon /* - * We come in here when wakened from nap mode. + * We come in here when wakened from nap or fast-sleep mode. * Relocation is off and most register values are lost. * r13 points to the PACA. */ @@ -303,7 +303,7 @@ kvm_start_guest: bl kvmppc_hv_entry - /* Back from the guest, go back to nap */ + /* Back from the guest, go back to nap or fastsleep */ /* Clear our vcpu pointer so we don't come back in early */ li r0, 0 std r0, HSTATE_KVM_VCPU(r13) @@ -314,7 +314,7 @@ kvm_start_guest: */ lwsync - /* increment the nap count and then go to nap mode */ + /* increment the nap count and then go to nap or fast-sleep mode */ ld r4, HSTATE_KVM_VCORE(r13) addi r4, r4, VCORE_NAP_COUNT 51: lwarx r3, 0, r4 @@ -325,6 +325,24 @@ kvm_start_guest: kvm_no_guest: li r0, KVM_HWTHREAD_IN_NAP stb r0, HSTATE_HWTHREAD_STATE(r13) + +kvm_do_idle: + /* + * if (supported_cpuidle_states & IDLE_USE_SLEEP) + * kvm_do_fastsleep(); + * else + * kvm_do_nap(); + */ + LOAD_REG_ADDRBASE(r3,supported_cpuidle_states) + lwz r4,ADDROFF(supported_cpuidle_states)(r3) + /* + * andi. r4,r4,IDLE_USE_SLEEP. Replacing IDLE_USE_SLEEP + * with the immediate value since it is a 32 bit instruction + * and the operand needs to fit into this. + */ + andi. r4,r4,2 + bne kvm_do_fastsleep + kvm_do_nap: /* Clear the runlatch bit before napping */ mfspr r2, SPRN_CTRLF @@ -339,6 +357,18 @@ kvm_do_nap: IDLE_STATE_ENTER_SEQ_HV(PPC_NAP) /* No return */ +kvm_do_fastsleep: + li r3, LPCR_PECE0 + mfspr r4, SPRN_LPCR + /* Don't set LPCR_PECE1 since we want to wakeup only on an external + * interrupt, and not on a decrementer interrupt. + */ + rlwimi r4, r3, 0, LPCR_PECE0 + mtspr SPRN_LPCR, r4 + isync + IDLE_STATE_ENTER_SEQ_HV(PPC_SLEEP) + /* No return */ + /****************************************************************************** * * @@ -2016,8 +2046,8 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_206) bl kvmppc_save_fp /* - * Take a nap until a decrementer or external or doobell interrupt - * occurs, with PECE1, PECE0 and PECEDP set in LPCR. Also clear the + * Go to fastsleep until an external or doobell interrupt + * occurs, with PECE0 and PECEDP set in LPCR. Also clear the * runlatch bit before napping. */ mfspr r2, SPRN_CTRLF @@ -2026,6 +2056,22 @@ END_FTR_SECTION_IFCLR(CPU_FTR_ARCH_206) li r0,1 stb r0,HSTATE_HWTHREAD_REQ(r13) + /* + * if (supported_cpuidle_states & IDLE_USE_SLEEP) + * PPC_SLEEP; + * else + * PPC_NAP; + */ + LOAD_REG_ADDRBASE(r3,supported_cpuidle_states) + lwz r4,ADDROFF(supported_cpuidle_states)(r3) + /* + * andi. r4,r4,IDLE_USE_SLEEP. Replacing IDLE_USE_SLEEP + * with the immediate value since it is a 32 bit instruction + * and the operand needs to fit into this. + */ + andi. r4,r4,2 + bne 35f + mfspr r5,SPRN_LPCR ori r5,r5,LPCR_PECE0 | LPCR_PECE1 BEGIN_FTR_SECTION @@ -2037,6 +2083,17 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) IDLE_STATE_ENTER_SEQ_HV(PPC_NAP) /* No return */ +35: mfspr r5,SPRN_LPCR + ori r5,r5,LPCR_PECE0 +BEGIN_FTR_SECTION + oris r5,r5,LPCR_PECEDP@h +END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S) + mtspr SPRN_LPCR,r5 + isync + li r0, 0 + IDLE_STATE_ENTER_SEQ_HV(PPC_SLEEP) + /* No return */ + 33: mr r4, r3 li r3, 0 li r12, 0 @@ -2046,7 +2103,7 @@ kvm_end_cede: /* get vcpu pointer */ ld r4, HSTATE_KVM_VCPU(r13) - /* Woken by external or decrementer interrupt */ + /* Woken by external */ ld r1, HSTATE_HOST_R1(r13) /* load up FP state */ @@ -2129,7 +2186,7 @@ machine_check_realmode: b fast_interrupt_c_return /* - * Check the reason we woke from nap, and take appropriate action. + * Check the reason we woke from nap or fastsleep, and take appropriate action. * Returns: * 0 if nothing needs to be done * 1 if something happened that needs to be handled by the host -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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