From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36AF8C3A5A4 for ; Fri, 30 Aug 2019 09:42:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0A1C721670 for ; Fri, 30 Aug 2019 09:42:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727923AbfH3Jmt (ORCPT ); Fri, 30 Aug 2019 05:42:49 -0400 Received: from foss.arm.com ([217.140.110.172]:57484 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727417AbfH3Jms (ORCPT ); Fri, 30 Aug 2019 05:42:48 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 722B4344; Fri, 30 Aug 2019 02:42:47 -0700 (PDT) Received: from localhost (e113682-lin.copenhagen.arm.com [10.32.144.41]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 05BDD3F718; Fri, 30 Aug 2019 02:42:46 -0700 (PDT) Date: Fri, 30 Aug 2019 11:42:45 +0200 From: Christoffer Dall To: Steven Price Cc: Marc Zyngier , Will Deacon , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Catalin Marinas , linux-doc@vger.kernel.org, Russell King , Paolo Bonzini Subject: Re: [PATCH v4 05/10] KVM: arm64: Support stolen time reporting via shared structure Message-ID: <20190830094245.GB5307@e113682-lin.lund.arm.com> References: <20190830084255.55113-1-steven.price@arm.com> <20190830084255.55113-6-steven.price@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190830084255.55113-6-steven.price@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 30, 2019 at 09:42:50AM +0100, Steven Price wrote: > Implement the service call for configuring a shared structure between a > VCPU and the hypervisor in which the hypervisor can write the time > stolen from the VCPU's execution time by other tasks on the host. > > The hypervisor allocates memory which is placed at an IPA chosen by user > space. The hypervisor then updates the shared structure using > kvm_put_guest() to ensure single copy atomicity of the 64-bit value > reporting the stolen time in nanoseconds. > > Whenever stolen time is enabled by the guest, the stolen time counter is > reset. > > The stolen time itself is retrieved from the sched_info structure > maintained by the Linux scheduler code. We enable SCHEDSTATS when > selecting KVM Kconfig to ensure this value is meaningful. > > Signed-off-by: Steven Price > --- > arch/arm/include/asm/kvm_host.h | 20 +++++++++++ > arch/arm64/include/asm/kvm_host.h | 21 +++++++++++- > arch/arm64/kvm/Kconfig | 1 + > include/linux/kvm_types.h | 2 ++ > virt/kvm/arm/arm.c | 11 ++++++ > virt/kvm/arm/hypercalls.c | 3 ++ > virt/kvm/arm/pvtime.c | 56 +++++++++++++++++++++++++++++++ > 7 files changed, 113 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > index 5a0c3569ebde..5c401482d62d 100644 > --- a/arch/arm/include/asm/kvm_host.h > +++ b/arch/arm/include/asm/kvm_host.h > @@ -39,6 +39,7 @@ > KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) > #define KVM_REQ_IRQ_PENDING KVM_ARCH_REQ(1) > #define KVM_REQ_VCPU_RESET KVM_ARCH_REQ(2) > +#define KVM_REQ_RECORD_STEAL KVM_ARCH_REQ(3) > > DECLARE_STATIC_KEY_FALSE(userspace_irqchip_in_use); > > @@ -329,6 +330,25 @@ static inline long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu) > return SMCCC_RET_NOT_SUPPORTED; > } > > +static inline long kvm_hypercall_stolen_time(struct kvm_vcpu *vcpu) > +{ > + return SMCCC_RET_NOT_SUPPORTED; > +} > + > +static inline int kvm_update_stolen_time(struct kvm_vcpu *vcpu, bool init) > +{ > + return -ENOTSUPP; > +} > + > +static inline void kvm_arm_pvtime_vcpu_init(struct kvm_vcpu_arch *vcpu_arch) > +{ > +} > + > +static inline bool kvm_arm_is_pvtime_enabled(struct kvm_vcpu_arch *vcpu_arch) > +{ > + return false; > +} > + > void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot); > > struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr); > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 93b46d9526d0..1697e63f6dd8 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -44,6 +44,7 @@ > KVM_ARCH_REQ_FLAGS(0, KVM_REQUEST_WAIT | KVM_REQUEST_NO_WAKEUP) > #define KVM_REQ_IRQ_PENDING KVM_ARCH_REQ(1) > #define KVM_REQ_VCPU_RESET KVM_ARCH_REQ(2) > +#define KVM_REQ_RECORD_STEAL KVM_ARCH_REQ(3) > > DECLARE_STATIC_KEY_FALSE(userspace_irqchip_in_use); > > @@ -338,8 +339,14 @@ struct kvm_vcpu_arch { > /* True when deferrable sysregs are loaded on the physical CPU, > * see kvm_vcpu_load_sysregs and kvm_vcpu_put_sysregs. */ > bool sysregs_loaded_on_cpu; > -}; > > + /* Guest PV state */ > + struct { > + u64 steal; > + u64 last_steal; > + gpa_t base; > + } steal; > +}; > /* Pointer to the vcpu's SVE FFR for sve_{save,load}_state() */ > #define vcpu_sve_pffr(vcpu) ((void *)((char *)((vcpu)->arch.sve_state) + \ > sve_ffr_offset((vcpu)->arch.sve_max_vl))) > @@ -479,6 +486,18 @@ int kvm_perf_init(void); > int kvm_perf_teardown(void); > > long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu); > +long kvm_hypercall_stolen_time(struct kvm_vcpu *vcpu); > +int kvm_update_stolen_time(struct kvm_vcpu *vcpu, bool init); > + > +static inline void kvm_arm_pvtime_vcpu_init(struct kvm_vcpu_arch *vcpu_arch) > +{ > + vcpu_arch->steal.base = GPA_INVALID; > +} > + > +static inline bool kvm_arm_is_pvtime_enabled(struct kvm_vcpu_arch *vcpu_arch) > +{ > + return (vcpu_arch->steal.base != GPA_INVALID); > +} > > void kvm_set_sei_esr(struct kvm_vcpu *vcpu, u64 syndrome); > > diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig > index a67121d419a2..d8b88e40d223 100644 > --- a/arch/arm64/kvm/Kconfig > +++ b/arch/arm64/kvm/Kconfig > @@ -39,6 +39,7 @@ config KVM > select IRQ_BYPASS_MANAGER > select HAVE_KVM_IRQ_BYPASS > select HAVE_KVM_VCPU_RUN_PID_CHANGE > + select SCHEDSTATS > ---help--- > Support hosting virtualized guest machines. > We don't support KVM with 16K page tables yet, due to the multiple > diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h > index bde5374ae021..1c88e69db3d9 100644 > --- a/include/linux/kvm_types.h > +++ b/include/linux/kvm_types.h > @@ -35,6 +35,8 @@ typedef unsigned long gva_t; > typedef u64 gpa_t; > typedef u64 gfn_t; > > +#define GPA_INVALID (~(gpa_t)0) > + > typedef unsigned long hva_t; > typedef u64 hpa_t; > typedef u64 hfn_t; > diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c > index 35a069815baf..eaceb2d0f0c0 100644 > --- a/virt/kvm/arm/arm.c > +++ b/virt/kvm/arm/arm.c > @@ -40,6 +40,10 @@ > #include > #include > > +#include > +#include > +#include > + > #ifdef REQUIRES_VIRT > __asm__(".arch_extension virt"); > #endif > @@ -350,6 +354,8 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu) > > kvm_arm_reset_debug_ptr(vcpu); > > + kvm_arm_pvtime_vcpu_init(&vcpu->arch); > + > return kvm_vgic_vcpu_init(vcpu); > } > > @@ -379,6 +385,8 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) > kvm_vcpu_load_sysregs(vcpu); > kvm_arch_vcpu_load_fp(vcpu); > kvm_vcpu_pmu_restore_guest(vcpu); > + if (kvm_arm_is_pvtime_enabled(&vcpu->arch)) > + kvm_make_request(KVM_REQ_RECORD_STEAL, vcpu); > > if (single_task_running()) > vcpu_clear_wfe_traps(vcpu); > @@ -644,6 +652,9 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu) > * that a VCPU sees new virtual interrupts. > */ > kvm_check_request(KVM_REQ_IRQ_PENDING, vcpu); > + > + if (kvm_check_request(KVM_REQ_RECORD_STEAL, vcpu)) > + kvm_update_stolen_time(vcpu, false); > } > } > > diff --git a/virt/kvm/arm/hypercalls.c b/virt/kvm/arm/hypercalls.c > index e2521e0d3978..3091a5d2e842 100644 > --- a/virt/kvm/arm/hypercalls.c > +++ b/virt/kvm/arm/hypercalls.c > @@ -56,6 +56,9 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu) > case ARM_SMCCC_HV_PV_FEATURES: > val = kvm_hypercall_pv_features(vcpu); > break; > + case ARM_SMCCC_HV_PV_TIME_ST: > + val = kvm_hypercall_stolen_time(vcpu); > + break; > default: > return kvm_psci_call(vcpu); > } > diff --git a/virt/kvm/arm/pvtime.c b/virt/kvm/arm/pvtime.c > index 7887a61651c6..d9d0dbc6994b 100644 > --- a/virt/kvm/arm/pvtime.c > +++ b/virt/kvm/arm/pvtime.c > @@ -3,8 +3,45 @@ > > #include > > +#include > + > #include > > +int kvm_update_stolen_time(struct kvm_vcpu *vcpu, bool init) > +{ > + struct kvm *kvm = vcpu->kvm; > + u64 steal; > + u64 steal_le; > + u64 offset; > + int idx; > + u64 base = vcpu->arch.steal.base; > + > + if (base == GPA_INVALID) > + return -ENOTSUPP; > + > + /* Let's do the local bookkeeping */ > + steal = vcpu->arch.steal.steal; > + steal += current->sched_info.run_delay - vcpu->arch.steal.last_steal; > + vcpu->arch.steal.last_steal = current->sched_info.run_delay; > + vcpu->arch.steal.steal = steal; > + > + steal_le = cpu_to_le64(steal); > + idx = srcu_read_lock(&kvm->srcu); > + if (init) { > + struct pvclock_vcpu_stolen_time init_values = { > + .revision = 0, > + .attributes = 0 > + }; > + kvm_write_guest(kvm, base, &init_values, > + sizeof(init_values)); > + } > + offset = offsetof(struct pvclock_vcpu_stolen_time, stolen_time); > + kvm_put_guest(kvm, base + offset, steal_le, u64); Let's hope we don't have thousands of memslots through which we have to do a linear scan on every vcpu load after this. If that were the case, I think the memslot search path would have to be updated anyhow. Otherwise looks reasonable to me. Thanks, Christoffer > + srcu_read_unlock(&kvm->srcu, idx); > + > + return 0; > +} > + > long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu) > { > u32 feature = smccc_get_arg1(vcpu); > @@ -12,6 +49,7 @@ long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu) > > switch (feature) { > case ARM_SMCCC_HV_PV_FEATURES: > + case ARM_SMCCC_HV_PV_TIME_ST: > val = SMCCC_RET_SUCCESS; > break; > } > @@ -19,3 +57,21 @@ long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu) > return val; > } > > +long kvm_hypercall_stolen_time(struct kvm_vcpu *vcpu) > +{ > + int err; > + > + /* > + * Start counting stolen time from the time the guest requests > + * the feature enabled. > + */ > + vcpu->arch.steal.steal = 0; > + vcpu->arch.steal.last_steal = current->sched_info.run_delay; > + > + err = kvm_update_stolen_time(vcpu, true); > + > + if (err) > + return SMCCC_RET_NOT_SUPPORTED; > + > + return vcpu->arch.steal.base; > +} > -- > 2.20.1 > > _______________________________________________ > kvmarm mailing list > kvmarm@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/kvmarm