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[115.64.153.41]) by smtp.gmail.com with ESMTPSA id 130sm15557223pfz.77.2021.10.04.09.02.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 Oct 2021 09:02:17 -0700 (PDT) From: Nicholas Piggin To: kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Cc: Nicholas Piggin Subject: [PATCH v3 31/52] KVM: PPC: Book3S HV P9: Move remaining SPR and MSR access into low level entry Date: Tue, 5 Oct 2021 02:00:28 +1000 Message-Id: <20211004160049.1338837-32-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20211004160049.1338837-1-npiggin@gmail.com> References: <20211004160049.1338837-1-npiggin@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org Move register saving and loading from kvmhv_p9_guest_entry() into the HV and nested entry handlers. Accesses are scheduled to reduce mtSPR / mfSPR interleaving which reduces SPR scoreboard stalls. Signed-off-by: Nicholas Piggin --- arch/powerpc/kvm/book3s_hv.c | 79 ++++++++++------------ arch/powerpc/kvm/book3s_hv_p9_entry.c | 96 ++++++++++++++++++++------- 2 files changed, 109 insertions(+), 66 deletions(-) diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index a57727463980..db42eeb27c15 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3814,9 +3814,15 @@ static int kvmhv_vcpu_entry_p9_nested(struct kvm_vcpu *vcpu, u64 time_limit, uns { struct kvmppc_vcore *vc = vcpu->arch.vcore; unsigned long host_psscr; + unsigned long msr; struct hv_guest_state hvregs; - int trap; + struct p9_host_os_sprs host_os_sprs; s64 dec; + int trap; + + switch_pmu_to_guest(vcpu, &host_os_sprs); + + save_p9_host_os_sprs(&host_os_sprs); /* * We need to save and restore the guest visible part of the @@ -3825,6 +3831,27 @@ static int kvmhv_vcpu_entry_p9_nested(struct kvm_vcpu *vcpu, u64 time_limit, uns * this is done in kvmhv_vcpu_entry_p9() below otherwise. */ host_psscr = mfspr(SPRN_PSSCR_PR); + + hard_irq_disable(); + if (lazy_irq_pending()) + return 0; + + /* MSR bits may have been cleared by context switch */ + msr = 0; + if (IS_ENABLED(CONFIG_PPC_FPU)) + msr |= MSR_FP; + if (cpu_has_feature(CPU_FTR_ALTIVEC)) + msr |= MSR_VEC; + if (cpu_has_feature(CPU_FTR_VSX)) + msr |= MSR_VSX; + if (cpu_has_feature(CPU_FTR_TM) || + cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) + msr |= MSR_TM; + msr = msr_check_and_set(msr); + + if (unlikely(load_vcpu_state(vcpu, &host_os_sprs))) + msr = mfmsr(); /* TM restore can update msr */ + mtspr(SPRN_PSSCR_PR, vcpu->arch.psscr); kvmhv_save_hv_regs(vcpu, &hvregs); hvregs.lpcr = lpcr; @@ -3866,12 +3893,20 @@ static int kvmhv_vcpu_entry_p9_nested(struct kvm_vcpu *vcpu, u64 time_limit, uns vcpu->arch.psscr = mfspr(SPRN_PSSCR_PR); mtspr(SPRN_PSSCR_PR, host_psscr); + store_vcpu_state(vcpu); + 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); + timer_rearm_host_dec(*tb); + + restore_p9_host_os_sprs(vcpu, &host_os_sprs); + + switch_pmu_to_host(vcpu, &host_os_sprs); + return trap; } @@ -3882,9 +3917,7 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpcr, u64 *tb) { struct kvmppc_vcore *vc = vcpu->arch.vcore; - struct p9_host_os_sprs host_os_sprs; u64 next_timer; - unsigned long msr; int trap; next_timer = timer_get_next_tb(); @@ -3895,33 +3928,6 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, vcpu->arch.ceded = 0; - save_p9_host_os_sprs(&host_os_sprs); - - /* - * This could be combined with MSR[RI] clearing, but that expands - * the unrecoverable window. It would be better to cover unrecoverable - * with KVM bad interrupt handling rather than use MSR[RI] at all. - * - * Much more difficult and less worthwhile to combine with IR/DR - * disable. - */ - hard_irq_disable(); - if (lazy_irq_pending()) - return 0; - - /* MSR bits may have been cleared by context switch */ - msr = 0; - if (IS_ENABLED(CONFIG_PPC_FPU)) - msr |= MSR_FP; - if (cpu_has_feature(CPU_FTR_ALTIVEC)) - msr |= MSR_VEC; - if (cpu_has_feature(CPU_FTR_VSX)) - msr |= MSR_VSX; - if (cpu_has_feature(CPU_FTR_TM) || - cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) - msr |= MSR_TM; - msr = msr_check_and_set(msr); - kvmppc_subcore_enter_guest(); vc->entry_exit_map = 1; @@ -3929,11 +3935,6 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, vcpu_vpa_increment_dispatch(vcpu); - if (unlikely(load_vcpu_state(vcpu, &host_os_sprs))) - msr = mfmsr(); /* MSR may have been updated */ - - switch_pmu_to_guest(vcpu, &host_os_sprs); - if (kvmhv_on_pseries()) { trap = kvmhv_vcpu_entry_p9_nested(vcpu, time_limit, lpcr, tb); @@ -3976,16 +3977,8 @@ static int kvmhv_p9_guest_entry(struct kvm_vcpu *vcpu, u64 time_limit, vcpu->arch.slb_max = 0; } - switch_pmu_to_host(vcpu, &host_os_sprs); - - store_vcpu_state(vcpu); - vcpu_vpa_increment_dispatch(vcpu); - timer_rearm_host_dec(*tb); - - restore_p9_host_os_sprs(vcpu, &host_os_sprs); - vc->entry_exit_map = 0x101; vc->in_guest = 0; diff --git a/arch/powerpc/kvm/book3s_hv_p9_entry.c b/arch/powerpc/kvm/book3s_hv_p9_entry.c index 784ff5429ebc..fa080533bd8d 100644 --- a/arch/powerpc/kvm/book3s_hv_p9_entry.c +++ b/arch/powerpc/kvm/book3s_hv_p9_entry.c @@ -538,6 +538,7 @@ 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, u64 *tb) { + struct p9_host_os_sprs host_os_sprs; struct kvm *kvm = vcpu->kvm; struct kvm_nested_guest *nested = vcpu->arch.nested; struct kvmppc_vcore *vc = vcpu->arch.vcore; @@ -567,9 +568,6 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc vcpu->arch.ceded = 0; - /* Could avoid mfmsr by passing around, but probably no big deal */ - msr = mfmsr(); - host_hfscr = mfspr(SPRN_HFSCR); host_ciabr = mfspr(SPRN_CIABR); host_dawr0 = mfspr(SPRN_DAWR0); @@ -584,6 +582,41 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc local_paca->kvm_hstate.host_purr = mfspr(SPRN_PURR); local_paca->kvm_hstate.host_spurr = mfspr(SPRN_SPURR); + switch_pmu_to_guest(vcpu, &host_os_sprs); + + save_p9_host_os_sprs(&host_os_sprs); + + /* + * This could be combined with MSR[RI] clearing, but that expands + * the unrecoverable window. It would be better to cover unrecoverable + * with KVM bad interrupt handling rather than use MSR[RI] at all. + * + * Much more difficult and less worthwhile to combine with IR/DR + * disable. + */ + hard_irq_disable(); + if (lazy_irq_pending()) { + trap = 0; + goto out; + } + + /* MSR bits may have been cleared by context switch */ + msr = 0; + if (IS_ENABLED(CONFIG_PPC_FPU)) + msr |= MSR_FP; + if (cpu_has_feature(CPU_FTR_ALTIVEC)) + msr |= MSR_VEC; + if (cpu_has_feature(CPU_FTR_VSX)) + msr |= MSR_VSX; + if (cpu_has_feature(CPU_FTR_TM) || + cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) + msr |= MSR_TM; + msr = msr_check_and_set(msr); + /* Save MSR for restore. This is after hard disable, so EE is clear. */ + + if (unlikely(load_vcpu_state(vcpu, &host_os_sprs))) + msr = mfmsr(); /* MSR may have been updated */ + if (vc->tb_offset) { u64 new_tb = *tb + vc->tb_offset; mtspr(SPRN_TBU40, new_tb); @@ -642,6 +675,14 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc mtspr(SPRN_SPRG2, vcpu->arch.shregs.sprg2); mtspr(SPRN_SPRG3, vcpu->arch.shregs.sprg3); + /* + * It might be preferable to load_vcpu_state here, in order to get the + * GPR/FP register loads executing in parallel with the previous mtSPR + * instructions, but for now that can't be done because the TM handling + * in load_vcpu_state can change some SPRs and vcpu state (nip, msr). + * But TM could be split out if this would be a significant benefit. + */ + local_paca->kvm_hstate.in_guest = KVM_GUEST_MODE_HV_P9; /* @@ -819,6 +860,20 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc vc->dpdes = mfspr(SPRN_DPDES); vc->vtb = mfspr(SPRN_VTB); + save_clear_guest_mmu(kvm, vcpu); + switch_mmu_to_host(kvm, host_pidr); + + /* + * If we are in real mode, only switch MMU on after the MMU is + * switched to host, to avoid the P9_RADIX_PREFETCH_BUG. + */ + if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) && + vcpu->arch.shregs.msr & MSR_TS_MASK) + msr |= MSR_TS_S; + __mtmsrd(msr, 0); + + store_vcpu_state(vcpu); + dec = mfspr(SPRN_DEC); if (!(lpcr & LPCR_LD)) /* Sign extend if not using large decrementer */ dec = (s32) dec; @@ -851,6 +906,19 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc mtspr(SPRN_DAWRX1, host_dawrx1); } + mtspr(SPRN_DPDES, 0); + if (vc->pcr) + mtspr(SPRN_PCR, PCR_MASK); + + /* HDEC must be at least as large as DEC, so decrementer_max fits */ + mtspr(SPRN_HDEC, decrementer_max); + + timer_rearm_host_dec(*tb); + + restore_p9_host_os_sprs(vcpu, &host_os_sprs); + + local_paca->kvm_hstate.in_guest = KVM_GUEST_MODE_NONE; + if (kvm_is_radix(kvm)) { /* * Since this is radix, do a eieio; tlbsync; ptesync sequence @@ -867,26 +935,8 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc if (cpu_has_feature(CPU_FTR_ARCH_31)) asm volatile(PPC_CP_ABORT); - mtspr(SPRN_DPDES, 0); - if (vc->pcr) - mtspr(SPRN_PCR, PCR_MASK); - - /* HDEC must be at least as large as DEC, so decrementer_max fits */ - mtspr(SPRN_HDEC, decrementer_max); - - save_clear_guest_mmu(kvm, vcpu); - switch_mmu_to_host(kvm, host_pidr); - local_paca->kvm_hstate.in_guest = KVM_GUEST_MODE_NONE; - - /* - * If we are in real mode, only switch MMU on after the MMU is - * switched to host, to avoid the P9_RADIX_PREFETCH_BUG. - */ - if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) && - vcpu->arch.shregs.msr & MSR_TS_MASK) - msr |= MSR_TS_S; - - __mtmsrd(msr, 0); +out: + switch_pmu_to_host(vcpu, &host_os_sprs); end_timing(vcpu);