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[60.242.147.73]) by smtp.gmail.com with ESMTPSA id l6sm5623621pgh.34.2021.06.22.03.59.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 22 Jun 2021 03:59:18 -0700 (PDT) From: Nicholas Piggin To: kvm-ppc@vger.kernel.org Subject: [RFC PATCH 34/43] KVM: PPC: Book3S HV P9: Demand fault EBB facility registers Date: Tue, 22 Jun 2021 20:57:27 +1000 Message-Id: <20210622105736.633352-35-npiggin@gmail.com> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20210622105736.633352-1-npiggin@gmail.com> References: <20210622105736.633352-1-npiggin@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, Nicholas Piggin Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Use HFSCR facility disabling to implement demand faulting for EBB, with a hysteresis counter similar to the load_fp etc counters in context switching that implement the equivalent demand faulting for userspace facilities. This speeds up guest entry/exit by avoiding the register save/restore when a guest is not frequently using them. When a guest does use them often, there will be some additional demand fault overhead, but these are not commonly used facilities. Signed-off-by: Nicholas Piggin --- arch/powerpc/include/asm/kvm_host.h | 1 + arch/powerpc/kvm/book3s_hv.c | 11 +++++++++++ arch/powerpc/kvm/book3s_hv_nested.c | 3 ++- arch/powerpc/kvm/book3s_hv_p9_entry.c | 26 ++++++++++++++++++++------ 4 files changed, 34 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 118b388ea887..bee95106c1f2 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -585,6 +585,7 @@ struct kvm_vcpu_arch { ulong cfar; ulong ppr; u32 pspb; + u8 load_ebb; ulong fscr; ulong shadow_fscr; ulong ebbhr; diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index ae528eb37792..99e9da078e7d 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1366,6 +1366,13 @@ static int kvmppc_pmu_unavailable(struct kvm_vcpu *vcpu) return RESUME_GUEST; } +static int kvmppc_ebb_unavailable(struct kvm_vcpu *vcpu) +{ + vcpu->arch.hfscr |= HFSCR_EBB; + + return RESUME_GUEST; +} + static int kvmppc_handle_exit_hv(struct kvm_vcpu *vcpu, struct task_struct *tsk) { @@ -1645,6 +1652,8 @@ XXX benchmark guest exits r = kvmppc_emulate_doorbell_instr(vcpu); if (cause == FSCR_PM_LG) r = kvmppc_pmu_unavailable(vcpu); + if (cause == FSCR_EBB_LG) + r = kvmppc_ebb_unavailable(vcpu); } if (r == EMULATE_FAIL) { kvmppc_core_queue_program(vcpu, SRR1_PROGILL); @@ -1764,6 +1773,8 @@ static int kvmppc_handle_nested_exit(struct kvm_vcpu *vcpu) r = EMULATE_FAIL; if (cause == FSCR_PM_LG && (vcpu->arch.nested_hfscr & HFSCR_PM)) r = kvmppc_pmu_unavailable(vcpu); + if (cause == FSCR_EBB_LG && (vcpu->arch.nested_hfscr & HFSCR_EBB)) + r = kvmppc_ebb_unavailable(vcpu); if (r == EMULATE_FAIL) r = RESUME_HOST; diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c index 024b0ce5b702..ee8668f056f9 100644 --- a/arch/powerpc/kvm/book3s_hv_nested.c +++ b/arch/powerpc/kvm/book3s_hv_nested.c @@ -168,7 +168,8 @@ static void sanitise_hv_regs(struct kvm_vcpu *vcpu, struct hv_guest_state *hr) * but preserve the interrupt cause field and facilities that might * be disabled for demand faulting in the L1. */ - hr->hfscr &= (HFSCR_INTR_CAUSE | HFSCR_PM | vcpu->arch.hfscr); + hr->hfscr &= (HFSCR_INTR_CAUSE | HFSCR_PM | HFSCR_EBB | + vcpu->arch.hfscr); /* Don't let data address watchpoint match in hypervisor state */ hr->dawrx0 &= ~DAWRX_HYP; diff --git a/arch/powerpc/kvm/book3s_hv_p9_entry.c b/arch/powerpc/kvm/book3s_hv_p9_entry.c index 4d1a2d1ff4c1..cf41261daa97 100644 --- a/arch/powerpc/kvm/book3s_hv_p9_entry.c +++ b/arch/powerpc/kvm/book3s_hv_p9_entry.c @@ -218,9 +218,12 @@ static void load_spr_state(struct kvm_vcpu *vcpu, struct p9_host_os_sprs *host_os_sprs) { mtspr(SPRN_TAR, vcpu->arch.tar); - mtspr(SPRN_EBBHR, vcpu->arch.ebbhr); - mtspr(SPRN_EBBRR, vcpu->arch.ebbrr); - mtspr(SPRN_BESCR, vcpu->arch.bescr); + + if (vcpu->arch.hfscr & HFSCR_EBB) { + mtspr(SPRN_EBBHR, vcpu->arch.ebbhr); + mtspr(SPRN_EBBRR, vcpu->arch.ebbrr); + mtspr(SPRN_BESCR, vcpu->arch.bescr); + } if (!cpu_has_feature(CPU_FTR_ARCH_31)) mtspr(SPRN_TIDR, vcpu->arch.tid); @@ -251,9 +254,20 @@ static void load_spr_state(struct kvm_vcpu *vcpu, static void store_spr_state(struct kvm_vcpu *vcpu) { vcpu->arch.tar = mfspr(SPRN_TAR); - vcpu->arch.ebbhr = mfspr(SPRN_EBBHR); - vcpu->arch.ebbrr = mfspr(SPRN_EBBRR); - vcpu->arch.bescr = mfspr(SPRN_BESCR); + + if (vcpu->arch.hfscr & HFSCR_EBB) { + vcpu->arch.ebbhr = mfspr(SPRN_EBBHR); + vcpu->arch.ebbrr = mfspr(SPRN_EBBRR); + vcpu->arch.bescr = mfspr(SPRN_BESCR); + /* + * This is like load_fp in context switching, turn off the + * facility after it wraps the u8 to try avoiding saving + * and restoring the registers each partition switch. + */ + vcpu->arch.load_ebb++; + if (!vcpu->arch.load_ebb) + vcpu->arch.hfscr &= ~HFSCR_EBB; + } if (!cpu_has_feature(CPU_FTR_ARCH_31)) vcpu->arch.tid = mfspr(SPRN_TIDR); -- 2.23.0