[RFC,22/43] KVM: PPC: Book3S HV P9: Optimise timebase reads

Message ID	20210622105736.633352-23-npiggin@gmail.com
State	New
Headers	show Return-Path: <kvm-ppc-owner@vger.kernel.org> From: Nicholas Piggin <npiggin@gmail.com> To: kvm-ppc@vger.kernel.org Cc: Nicholas Piggin <npiggin@gmail.com>, linuxppc-dev@lists.ozlabs.org Subject: [RFC PATCH 22/43] KVM: PPC: Book3S HV P9: Optimise timebase reads Date: Tue, 22 Jun 2021 20:57:15 +1000 Message-Id: <20210622105736.633352-23-npiggin@gmail.com> In-Reply-To: <20210622105736.633352-1-npiggin@gmail.com> References: <20210622105736.633352-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk
Series	KVM: PPC: Book3S HV P9: entry/exit optimisations round 1 \| expand [RFC,00/43] KVM: PPC: Book3S HV P9: entry/exit optimisations round 1 [RFC,01/43] powerpc/64s: Remove WORT SPR from POWER9/10 [RFC,02/43] KMV: PPC: Book3S HV P9: Use set_dec to set decrementer to host [RFC,03/43] KVM: PPC: Book3S HV P9: Use host timer accounting to avoid decrementer read [RFC,04/43] KVM: PPC: Book3S HV P9: Use large decrementer for HDEC [RFC,05/43] KVM: PPC: Book3S HV P9: Reduce mftb per guest entry/exit [RFC,06/43] powerpc/time: add API for KVM to re-arm the host timer/decrementer [RFC,07/43] KVM: PPC: Book3S HV: POWER10 enable HAIL when running radix guests [RFC,08/43] powerpc/64s: Keep AMOR SPR a constant ~0 at runtime [RFC,09/43] KVM: PPC: Book3S HV: Don't always save PMU for guest capable of nesting [RFC,10/43] powerpc/64s: Always set PMU control registers to frozen/disabled when not in use [RFC,11/43] KVM: PPC: Book3S HV P9: Implement PMU save/restore in C [RFC,12/43] KVM: PPC: Book3S HV P9: Factor out yield_count increment [RFC,13/43] KVM: PPC: Book3S HV P9: Factor PMU save/load into context switch functions [RFC,14/43] KVM: PPC: Book3S HV P9: Demand fault PMU SPRs when marked not inuse [RFC,15/43] KVM: PPC: Book3S HV: CTRL SPR does not require read-modify-write [RFC,16/43] KVM: PPC: Book3S HV P9: Move SPRG restore to restore_p9_host_os_sprs [RFC,17/43] KVM: PPC: Book3S HV P9: Reduce mtmsrd instructions required to save host SPRs [RFC,18/43] KVM: PPC: Book3S HV P9: Improve mtmsrd scheduling by delaying MSR[EE] disable [RFC,19/43] KVM: PPC: Book3S HV P9: Add kvmppc_stop_thread to match kvmppc_start_thread [RFC,20/43] KVM: PPC: Book3S HV: Change dec_expires to be relative to guest timebase [RFC,21/43] KVM: PPC: Book3S HV P9: Move TB updates [RFC,22/43] KVM: PPC: Book3S HV P9: Optimise timebase reads [RFC,23/43] KVM: PPC: Book3S HV P9: Avoid SPR scoreboard stalls [RFC,24/43] KVM: PPC: Book3S HV P9: Only execute mtSPR if the value changed [RFC,25/43] KVM: PPC: Book3S HV P9: Juggle SPR switching around [RFC,26/43] KVM: PPC: Book3S HV P9: Move vcpu register save/restore into functions [RFC,27/43] KVM: PPC: Book3S HV P9: Move host OS save/restore functions to built-in [RFC,28/43] KVM: PPC: Book3S HV P9: Move nested guest entry into its own function [RFC,29/43] KVM: PPC: Book3S HV P9: Move remaining SPR and MSR access into low level entry [RFC,30/43] KVM: PPC: Book3S HV P9: Implement TM fastpath for guest entry/exit [RFC,31/43] KVM: PPC: Book3S HV P9: Switch PMU to guest as late as possible [RFC,32/43] KVM: PPC: Book3S HV P9: Restrict DSISR canary workaround to processors that require it [RFC,33/43] KVM: PPC: Book3S HV P9: More SPR speed improvements [RFC,34/43] KVM: PPC: Book3S HV P9: Demand fault EBB facility registers [RFC,35/43] KVM: PPC: Book3S HV P9: Demand fault TM facility registers [RFC,36/43] KVM: PPC: Book3S HV P9: Use Linux SPR save/restore to manage some host SPRs [RFC,37/43] KVM: PPC: Book3S HV P9: Comment and fix MMU context switching code [RFC,38/43] KVM: PPC: Book3S HV P9: Test dawr_enabled() before saving host DAWR SPRs [RFC,39/43] KVM: PPC: Book3S HV P9: Don't restore PSSCR if not needed [RFC,40/43] KVM: PPC: Book3S HV P9: Avoid tlbsync sequence on radix guest exit [RFC,41/43] KVM: PPC: Book3S HV Nested: Avoid extra mftb() in nested entry [RFC,42/43] KVM: PPC: Book3S HV P9: Improve mfmsr performance on entry [RFC,43/43] KVM: PPC: Book3S HV P9: Optimise hash guest SLB saving

diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h index eaf3a562bf1e..f8a0ed90b853 100644 --- a/arch/powerpc/include/asm/kvm_book3s_64.h +++ b/arch/powerpc/include/asm/kvm_book3s_64.h @@ -153,7 +153,7 @@ static inline bool kvmhv_vcpu_is_radix(struct kvm_vcpu *vcpu) return radix; } -int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpcr); +int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpcr, u64 *tb); #define KVM_DEFAULT_HPT_ORDER 24 /* 16MB HPT by default */ #endif diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 218dacd78e25..99b19f4e7ed7 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -275,22 +275,22 @@ static void kvmppc_fast_vcpu_kick_hv(struct kvm_vcpu *vcpu) * they should never fail.) */ -static void kvmppc_core_start_stolen(struct kvmppc_vcore *vc) +static void kvmppc_core_start_stolen(struct kvmppc_vcore *vc, u64 tb) { unsigned long flags; spin_lock_irqsave(&vc->stoltb_lock, flags); - vc->preempt_tb = mftb(); + vc->preempt_tb = tb; spin_unlock_irqrestore(&vc->stoltb_lock, flags); } -static void kvmppc_core_end_stolen(struct kvmppc_vcore *vc) +static void kvmppc_core_end_stolen(struct kvmppc_vcore *vc, u64 tb) { unsigned long flags; spin_lock_irqsave(&vc->stoltb_lock, flags); if (vc->preempt_tb != TB_NIL) { - vc->stolen_tb += mftb() - vc->preempt_tb; + vc->stolen_tb += tb - vc->preempt_tb; vc->preempt_tb = TB_NIL; } spin_unlock_irqrestore(&vc->stoltb_lock, flags); @@ -300,6 +300,7 @@ static void kvmppc_core_vcpu_load_hv(struct kvm_vcpu *vcpu, int cpu) { struct kvmppc_vcore *vc = vcpu->arch.vcore; unsigned long flags; + u64 now = mftb(); /* * We can test vc->runner without taking the vcore lock, @@ -308,12 +309,12 @@ static void kvmppc_core_vcpu_load_hv(struct kvm_vcpu *vcpu, int cpu) * ever sets it to NULL. */ if (vc->runner == vcpu && vc->vcore_state >= VCORE_SLEEPING) - kvmppc_core_end_stolen(vc); + kvmppc_core_end_stolen(vc, now); spin_lock_irqsave(&vcpu->arch.tbacct_lock, flags); if (vcpu->arch.state == KVMPPC_VCPU_BUSY_IN_HOST && vcpu->arch.busy_preempt != TB_NIL) { - vcpu->arch.busy_stolen += mftb() - vcpu->arch.busy_preempt; + vcpu->arch.busy_stolen += now - vcpu->arch.busy_preempt; vcpu->arch.busy_preempt = TB_NIL; } spin_unlock_irqrestore(&vcpu->arch.tbacct_lock, flags); @@ -323,13 +324,14 @@ static void kvmppc_core_vcpu_put_hv(struct kvm_vcpu *vcpu) { struct kvmppc_vcore *vc = vcpu->arch.vcore; unsigned long flags; + u64 now = mftb(); if (vc->runner == vcpu && vc->vcore_state >= VCORE_SLEEPING) - kvmppc_core_start_stolen(vc); + kvmppc_core_start_stolen(vc, now); spin_lock_irqsave(&vcpu->arch.tbacct_lock, flags); if (vcpu->arch.state == KVMPPC_VCPU_BUSY_IN_HOST) - vcpu->arch.busy_preempt = mftb(); + vcpu->arch.busy_preempt = now; spin_unlock_irqrestore(&vcpu->arch.tbacct_lock, flags); } @@ -684,7 +686,7 @@ static u64 vcore_stolen_time(struct kvmppc_vcore *vc, u64 now) } static void kvmppc_create_dtl_entry(struct kvm_vcpu *vcpu, - struct kvmppc_vcore *vc) + struct kvmppc_vcore *vc, u64 tb) { struct dtl_entry *dt; struct lppaca *vpa; @@ -695,7 +697,7 @@ static void kvmppc_create_dtl_entry(struct kvm_vcpu *vcpu, dt = vcpu->arch.dtl_ptr; vpa = vcpu->arch.vpa.pinned_addr; - now = mftb(); + now = tb; core_stolen = vcore_stolen_time(vc, now); stolen = core_stolen - vcpu->arch.stolen_logged; vcpu->arch.stolen_logged = core_stolen; @@ -2792,14 +2794,14 @@ static void kvmppc_set_timer(struct kvm_vcpu *vcpu) extern int __kvmppc_vcore_entry(void); static void kvmppc_remove_runnable(struct kvmppc_vcore *vc, - struct kvm_vcpu *vcpu) + struct kvm_vcpu *vcpu, u64 tb) { u64 now; if (vcpu->arch.state != KVMPPC_VCPU_RUNNABLE) return; spin_lock_irq(&vcpu->arch.tbacct_lock); - now = mftb(); + now = tb; vcpu->arch.busy_stolen += vcore_stolen_time(vc, now) - vcpu->arch.stolen_logged; vcpu->arch.busy_preempt = now; @@ -3050,14 +3052,14 @@ static void kvmppc_vcore_preempt(struct kvmppc_vcore *vc) } /* Start accumulating stolen time */ - kvmppc_core_start_stolen(vc); + kvmppc_core_start_stolen(vc, mftb()); } static void kvmppc_vcore_end_preempt(struct kvmppc_vcore *vc) { struct preempted_vcore_list *lp; - kvmppc_core_end_stolen(vc); + kvmppc_core_end_stolen(vc, mftb()); if (!list_empty(&vc->preempt_list)) { lp = &per_cpu(preempted_vcores, vc->pcpu); spin_lock(&lp->lock); @@ -3184,7 +3186,7 @@ static void prepare_threads(struct kvmppc_vcore *vc) vcpu->arch.ret = RESUME_GUEST; else continue; - kvmppc_remove_runnable(vc, vcpu); + kvmppc_remove_runnable(vc, vcpu, mftb()); wake_up(&vcpu->arch.cpu_run); } } @@ -3203,7 +3205,7 @@ static void collect_piggybacks(struct core_info *cip, int target_threads) list_del_init(&pvc->preempt_list); if (pvc->runner == NULL) { pvc->vcore_state = VCORE_INACTIVE; - kvmppc_core_end_stolen(pvc); + kvmppc_core_end_stolen(pvc, mftb()); } spin_unlock(&pvc->lock); continue; @@ -3212,7 +3214,7 @@ static void collect_piggybacks(struct core_info *cip, int target_threads) spin_unlock(&pvc->lock); continue; } - kvmppc_core_end_stolen(pvc); + kvmppc_core_end_stolen(pvc, mftb()); pvc->vcore_state = VCORE_PIGGYBACK; if (cip->total_threads >= target_threads) break; @@ -3279,7 +3281,7 @@ static void post_guest_process(struct kvmppc_vcore *vc, bool is_master) else ++still_running; } else { - kvmppc_remove_runnable(vc, vcpu); + kvmppc_remove_runnable(vc, vcpu, mftb()); wake_up(&vcpu->arch.cpu_run); } } @@ -3288,7 +3290,7 @@ static void post_guest_process(struct kvmppc_vcore *vc, bool is_master) kvmppc_vcore_preempt(vc); } else if (vc->runner) { vc->vcore_state = VCORE_PREEMPT; - kvmppc_core_start_stolen(vc); + kvmppc_core_start_stolen(vc, mftb()); } else { vc->vcore_state = VCORE_INACTIVE; } @@ -3419,7 +3421,7 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) ((vc->num_threads > threads_per_subcore) || !on_primary_thread())) { for_each_runnable_thread(i, vcpu, vc) { vcpu->arch.ret = -EBUSY; - kvmppc_remove_runnable(vc, vcpu); + kvmppc_remove_runnable(vc, vcpu, mftb()); wake_up(&vcpu->arch.cpu_run); } goto out; @@ -3551,7 +3553,7 @@ static noinline void kvmppc_run_core(struct kvmppc_vcore *vc) pvc->pcpu = pcpu + thr; for_each_runnable_thread(i, vcpu, pvc) { kvmppc_start_thread(vcpu, pvc); - kvmppc_create_dtl_entry(vcpu, pvc); + kvmppc_create_dtl_entry(vcpu, pvc, mftb()); trace_kvm_guest_enter(vcpu); if (!vcpu->arch.ptid) thr0_done = true; @@ -3998,20 +4000,17 @@ static void vcpu_vpa_increment_dispatch(struct kvm_vcpu *vcpu) * Guest entry for POWER9 and later CPUs. */ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, - unsigned long lpcr) + unsigned long lpcr, u64 *tb) { struct kvmppc_vcore *vc = vcpu->arch.vcore; struct p9_host_os_sprs host_os_sprs; s64 dec; - u64 tb, next_timer; + u64 next_timer; unsigned long msr; int trap; - WARN_ON_ONCE(vcpu->arch.ceded); - - tb = mftb(); next_timer = timer_get_next_tb(); - if (tb >= next_timer) + if (*tb >= next_timer) return BOOK3S_INTERRUPT_HV_DECREMENTER; if (next_timer < time_limit) time_limit = next_timer; @@ -4106,7 +4105,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, * * XXX: Another day's problem. */ - mtspr(SPRN_DEC, kvmppc_dec_expires_host_tb(vcpu) - tb); + mtspr(SPRN_DEC, kvmppc_dec_expires_host_tb(vcpu) - *tb); mtspr(SPRN_DAR, vcpu->arch.shregs.dar); mtspr(SPRN_DSISR, vcpu->arch.shregs.dsisr); @@ -4122,8 +4121,8 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, dec = mfspr(SPRN_DEC); if (!(lpcr & LPCR_LD)) /* Sign extend if not using large decrementer */ dec = (s32) dec; - tb = mftb(); - vcpu->arch.dec_expires = dec + (tb + vc->tb_offset); + *tb = mftb(); + vcpu->arch.dec_expires = dec + (*tb + vc->tb_offset); /* H_CEDE has to be handled now, not later */ if (trap == BOOK3S_INTERRUPT_SYSCALL && !vcpu->arch.nested && @@ -4135,7 +4134,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, } else { kvmppc_xive_push_vcpu(vcpu); - trap = kvmhv_vcpu_entry_p9(vcpu, time_limit, lpcr); + trap = kvmhv_vcpu_entry_p9(vcpu, time_limit, lpcr, tb); if (trap == BOOK3S_INTERRUPT_SYSCALL && !vcpu->arch.nested && !(vcpu->arch.shregs.msr & MSR_PR)) { unsigned long req = kvmppc_get_gpr(vcpu, 3); @@ -4166,6 +4165,8 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, store_spr_state(vcpu); + timer_rearm_host_dec(*tb); + restore_p9_host_os_sprs(vcpu, &host_os_sprs); store_fp_state(&vcpu->arch.fp); @@ -4185,8 +4186,6 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, vc->entry_exit_map = 0x101; vc->in_guest = 0; - timer_rearm_host_dec(tb); - kvmppc_subcore_exit_guest(); return trap; @@ -4428,7 +4427,7 @@ static int kvmppc_run_vcpu(struct kvm_vcpu *vcpu) if ((vc->vcore_state == VCORE_PIGGYBACK || vc->vcore_state == VCORE_RUNNING) && !VCORE_IS_EXITING(vc)) { - kvmppc_create_dtl_entry(vcpu, vc); + kvmppc_create_dtl_entry(vcpu, vc, mftb()); kvmppc_start_thread(vcpu, vc); trace_kvm_guest_enter(vcpu); } else if (vc->vcore_state == VCORE_SLEEPING) { @@ -4463,7 +4462,7 @@ static int kvmppc_run_vcpu(struct kvm_vcpu *vcpu) for_each_runnable_thread(i, v, vc) { kvmppc_core_prepare_to_enter(v); if (signal_pending(v->arch.run_task)) { - kvmppc_remove_runnable(vc, v); + kvmppc_remove_runnable(vc, v, mftb()); v->stat.signal_exits++; v->run->exit_reason = KVM_EXIT_INTR; v->arch.ret = -EINTR; @@ -4504,7 +4503,7 @@ static int kvmppc_run_vcpu(struct kvm_vcpu *vcpu) kvmppc_vcore_end_preempt(vc); if (vcpu->arch.state == KVMPPC_VCPU_RUNNABLE) { - kvmppc_remove_runnable(vc, vcpu); + kvmppc_remove_runnable(vc, vcpu, mftb()); vcpu->stat.signal_exits++; run->exit_reason = KVM_EXIT_INTR; vcpu->arch.ret = -EINTR; @@ -4532,6 +4531,7 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit, struct kvm *kvm = vcpu->kvm; struct kvm_nested_guest *nested = vcpu->arch.nested; unsigned long flags; + u64 tb; trace_kvmppc_run_vcpu_enter(vcpu); @@ -4542,7 +4542,6 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit, vc = vcpu->arch.vcore; vcpu->arch.ceded = 0; vcpu->arch.run_task = current; - vcpu->arch.stolen_logged = vcore_stolen_time(vc, mftb()); vcpu->arch.state = KVMPPC_VCPU_RUNNABLE; vcpu->arch.busy_preempt = TB_NIL; vcpu->arch.last_inst = KVM_INST_FETCH_FAILED; @@ -4567,7 +4566,6 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit, kvmppc_update_vpas(vcpu); init_vcore_to_run(vc); - vc->preempt_tb = TB_NIL; preempt_disable(); pcpu = smp_processor_id(); @@ -4577,6 +4575,7 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit, /* flags save not required, but irq_pmu has no disable/enable API */ powerpc_local_irq_pmu_save(flags); + if (signal_pending(current)) goto sigpend; if (need_resched() || !kvm->arch.mmu_ready) @@ -4599,12 +4598,17 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit, goto out; } + tb = mftb(); + + vcpu->arch.stolen_logged = vcore_stolen_time(vc, tb); + vc->preempt_tb = TB_NIL; + kvmppc_clear_host_core(pcpu); local_paca->kvm_hstate.napping = 0; local_paca->kvm_hstate.kvm_split_mode = NULL; kvmppc_start_thread(vcpu, vc); - kvmppc_create_dtl_entry(vcpu, vc); + kvmppc_create_dtl_entry(vcpu, vc, tb); trace_kvm_guest_enter(vcpu); vc->vcore_state = VCORE_RUNNING; @@ -4619,7 +4623,7 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit, /* Tell lockdep that we're about to enable interrupts */ trace_hardirqs_on(); - trap = kvmhv_p9_guest_entry(vcpu, time_limit, lpcr); + trap = kvmhv_p9_guest_entry(vcpu, time_limit, lpcr, &tb); vcpu->arch.trap = trap; trace_hardirqs_off(); @@ -4648,7 +4652,7 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit, * by L2 and the L1 decrementer is provided in hdec_expires */ if (kvmppc_core_pending_dec(vcpu) && - ((get_tb() < kvmppc_dec_expires_host_tb(vcpu)) || + ((tb < kvmppc_dec_expires_host_tb(vcpu)) || (trap == BOOK3S_INTERRUPT_SYSCALL && kvmppc_get_gpr(vcpu, 3) == H_ENTER_NESTED))) kvmppc_core_dequeue_dec(vcpu); @@ -4684,7 +4688,7 @@ int kvmhv_run_single_vcpu(struct kvm_vcpu *vcpu, u64 time_limit, trace_kvmppc_run_core(vc, 1); done: - kvmppc_remove_runnable(vc, vcpu); + kvmppc_remove_runnable(vc, vcpu, tb); trace_kvmppc_run_vcpu_exit(vcpu); return vcpu->arch.ret; diff --git a/arch/powerpc/kvm/book3s_hv_p9_entry.c b/arch/powerpc/kvm/book3s_hv_p9_entry.c index 44ee805875ba..237ea1ef1eab 100644 --- a/arch/powerpc/kvm/book3s_hv_p9_entry.c +++ b/arch/powerpc/kvm/book3s_hv_p9_entry.c @@ -183,13 +183,13 @@ static void save_clear_guest_mmu(struct kvm *kvm, struct kvm_vcpu *vcpu) } } -int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpcr) +int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpcr, u64 *tb) { struct kvm *kvm = vcpu->kvm; struct kvm_nested_guest *nested = vcpu->arch.nested; struct kvmppc_vcore *vc = vcpu->arch.vcore; s64 hdec, dec; - u64 tb, purr, spurr; + u64 purr, spurr; u64 *exsave; bool ri_set; int trap; @@ -203,8 +203,7 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc unsigned long host_dawr1; unsigned long host_dawrx1; - tb = mftb(); - hdec = time_limit - tb; + hdec = time_limit - *tb; if (hdec < 0) return BOOK3S_INTERRUPT_HV_DECREMENTER; @@ -230,11 +229,13 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc } if (vc->tb_offset) { - u64 new_tb = tb + vc->tb_offset; + u64 new_tb = *tb + vc->tb_offset; mtspr(SPRN_TBU40, new_tb); - tb = mftb(); - if ((tb & 0xffffff) < (new_tb & 0xffffff)) - mtspr(SPRN_TBU40, new_tb + 0x1000000); + if ((mftb() & 0xffffff) < (new_tb & 0xffffff)) { + new_tb += 0x1000000; + mtspr(SPRN_TBU40, new_tb); + } + *tb = new_tb; vc->tb_offset_applied = vc->tb_offset; } @@ -317,7 +318,7 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc */ mtspr(SPRN_HDEC, hdec); - mtspr(SPRN_DEC, vcpu->arch.dec_expires - tb); + mtspr(SPRN_DEC, vcpu->arch.dec_expires - *tb); mtspr(SPRN_DAR, vcpu->arch.shregs.dar); mtspr(SPRN_DSISR, vcpu->arch.shregs.dsisr); @@ -451,15 +452,17 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc dec = mfspr(SPRN_DEC); if (!(lpcr & LPCR_LD)) /* Sign extend if not using large decrementer */ dec = (s32) dec; - tb = mftb(); - vcpu->arch.dec_expires = dec + tb; + *tb = mftb(); + vcpu->arch.dec_expires = dec + *tb; if (vc->tb_offset_applied) { - u64 new_tb = tb - vc->tb_offset_applied; + u64 new_tb = *tb - vc->tb_offset_applied; mtspr(SPRN_TBU40, new_tb); - tb = mftb(); - if ((tb & 0xffffff) < (new_tb & 0xffffff)) - mtspr(SPRN_TBU40, new_tb + 0x1000000); + if ((mftb() & 0xffffff) < (new_tb & 0xffffff)) { + new_tb += 0x1000000; + mtspr(SPRN_TBU40, new_tb); + } + *tb = new_tb; vc->tb_offset_applied = 0; }

[RFC,22/43] KVM: PPC: Book3S HV P9: Optimise timebase reads

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Patch