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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 563F2C3A5A2 for ; Fri, 23 Aug 2019 12:11:31 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 29D3622CE3 for ; Fri, 23 Aug 2019 12:11:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="dSrmtyZj" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 29D3622CE3 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=P4nowV1u0Cz1psrGmoFGk16Jk9vvnwvzo5RABHV8KJ4=; b=dSrmtyZj5+pCh+vrUCZIqgPsP gZWD0Z0c3c8hn+uVqhWxP6dFiIQzzUuxuknryclg4UMakjLethpkWPT9aY95wUmklpVfOXncgarpN wUEr/q88y+P2yPhoKSbUUgKkGUh8bFbP8iYISVv4mbJ9FrSckhhPcbU0rOpvyFhGbOSG/CM1xcOq9 e6yv9MM5GNeci7H5tmwSK0dB1jZU1DjAIJslV1Bvc6lJ57esOEgcFdH9YMHYR8LV99HGd4cysbmFq pbqAssgmLjs0kcJK+6dGoQoKMSdJY4fe4BB1EjPMmzBh1+qzQL6pPmWIBpOarMnUJ4p1kL+8o6T9D rLK5/Qb2Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1i18Pc-0002lg-GH; Fri, 23 Aug 2019 12:11:24 +0000 Received: from szxga07-in.huawei.com ([45.249.212.35] helo=huawei.com) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1i18PX-0002kI-Gx for linux-arm-kernel@lists.infradead.org; Fri, 23 Aug 2019 12:11:22 +0000 Received: from DGGEMS407-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id BE2BFF005BB6C6F12B79; Fri, 23 Aug 2019 20:11:13 +0800 (CST) Received: from [127.0.0.1] (10.184.12.158) by DGGEMS407-HUB.china.huawei.com (10.3.19.207) with Microsoft SMTP Server id 14.3.439.0; Fri, 23 Aug 2019 20:11:03 +0800 Subject: Re: [PATCH v3 05/10] KVM: arm64: Support stolen time reporting via shared structure To: Steven Price , Marc Zyngier , "Will Deacon" , , References: <20190821153656.33429-1-steven.price@arm.com> <20190821153656.33429-6-steven.price@arm.com> From: Zenghui Yu Message-ID: Date: Fri, 23 Aug 2019 20:07:29 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:64.0) Gecko/20100101 Thunderbird/64.0 MIME-Version: 1.0 In-Reply-To: <20190821153656.33429-6-steven.price@arm.com> Content-Language: en-US X-Originating-IP: [10.184.12.158] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190823_051120_323003_FA64E8ED X-CRM114-Status: GOOD ( 24.86 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kvm@vger.kernel.org, linux-doc@vger.kernel.org, Catalin Marinas , Russell King , linux-kernel@vger.kernel.org, Paolo Bonzini Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Steven, Only one comment, at the bottom. On 2019/8/21 23:36, 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 | 25 +++++++++++- > arch/arm64/kvm/Kconfig | 1 + > include/linux/kvm_types.h | 2 + > virt/kvm/arm/arm.c | 10 +++++ > virt/kvm/arm/hypercalls.c | 3 ++ > virt/kvm/arm/pvtime.c | 67 +++++++++++++++++++++++++++++++ > 7 files changed, 127 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > index 369b5d2d54bf..47d2ced99421 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 int kvm_hypercall_pv_features(struct kvm_vcpu *vcpu) > return SMCCC_RET_NOT_SUPPORTED; > } > > +static inline int 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_pvtime_init_vm(struct kvm_arch *kvm_arch) > +{ > +} > + > +static inline bool kvm_is_pvtime_enabled(struct kvm_arch *kvm_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 583b3639062a..b6fa7beffd8a 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); > > @@ -83,6 +84,11 @@ struct kvm_arch { > > /* Mandated version of PSCI */ > u32 psci_version; > + > + struct kvm_arch_pvtime { > + gpa_t st_base; > + u64 st_size; > + } pvtime; > }; > > #define KVM_NR_MEM_OBJS 40 > @@ -338,8 +344,13 @@ 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; > + } 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 +490,18 @@ int kvm_perf_init(void); > int kvm_perf_teardown(void); > > int kvm_hypercall_pv_features(struct kvm_vcpu *vcpu); > +int kvm_hypercall_stolen_time(struct kvm_vcpu *vcpu); > +int kvm_update_stolen_time(struct kvm_vcpu *vcpu, bool init); > + > +static inline void kvm_pvtime_init_vm(struct kvm_arch *kvm_arch) > +{ > + kvm_arch->pvtime.st_base = GPA_INVALID; > +} > + > +static inline bool kvm_is_pvtime_enabled(struct kvm_arch *kvm_arch) > +{ > + return (kvm_arch->pvtime.st_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..5e8343e2dd62 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 > @@ -135,6 +139,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) > kvm->arch.max_vcpus = vgic_present ? > kvm_vgic_get_max_vcpus() : KVM_MAX_VCPUS; > > + kvm_pvtime_init_vm(&kvm->arch); > return ret; > out_free_stage2_pgd: > kvm_free_stage2_pgd(kvm); > @@ -379,6 +384,8 @@ 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_is_pvtime_enabled(&vcpu->kvm->arch)) > + kvm_make_request(KVM_REQ_RECORD_STEAL, vcpu); > > if (single_task_running()) > vcpu_clear_wfe_traps(vcpu); > @@ -644,6 +651,9 @@ 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 63ae629c466a..ac678eabf15f 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 6201d71cb1f8..28603689f6e0 100644 > --- a/virt/kvm/arm/pvtime.c > +++ b/virt/kvm/arm/pvtime.c > @@ -3,8 +3,51 @@ > > #include > > +#include > + > #include > > +int kvm_update_stolen_time(struct kvm_vcpu *vcpu, bool init) > +{ > + struct kvm *kvm = vcpu->kvm; > + struct kvm_arch_pvtime *pvtime = &kvm->arch.pvtime; > + u64 steal; > + u64 steal_le; > + u64 offset; > + int idx; > + const int stride = sizeof(struct pvclock_vcpu_stolen_time); > + > + if (pvtime->st_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; > + > + offset = stride * kvm_vcpu_get_idx(vcpu); > + > + if (unlikely(offset + stride > pvtime->st_size)) > + return -EINVAL; > + > + 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, pvtime->st_base + offset, &init_values, > + sizeof(init_values)); > + } > + offset += offsetof(struct pvclock_vcpu_stolen_time, stolen_time); > + kvm_put_guest(kvm, pvtime->st_base + offset, steal_le, u64); > + srcu_read_unlock(&kvm->srcu, idx); > + > + return 0; > +} > + > int kvm_hypercall_pv_features(struct kvm_vcpu *vcpu) > { > u32 feature = smccc_get_arg1(vcpu); > @@ -12,6 +55,7 @@ int 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 +63,26 @@ int kvm_hypercall_pv_features(struct kvm_vcpu *vcpu) > return val; > } > > +int kvm_hypercall_stolen_time(struct kvm_vcpu *vcpu) > +{ > + u64 ret; > + 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) > + ret = SMCCC_RET_NOT_SUPPORTED; > + else > + ret = vcpu->kvm->arch.pvtime.st_base + > + (sizeof(struct pvclock_vcpu_stolen_time) * > + kvm_vcpu_get_idx(vcpu)); > + > + return ret; The *type* of the 'ret' here looks a bit messy to me: (1)u64 -> (2)int -> (3)u32 -> (4)unsigned long (1)->(2): just inside kvm_hypercall_stolen_time() (2)->(3): inside kvm_hvc_call_handler(), assign 'ret' to 'val' (3)->(4): through smccc_set_retval() I really have seen an issue caused by (2)->(3). When the PV guest running without PV_TIME device supporting, the result of the ARM_SMCCC_HV_PV_TIME_ST hypercall is expected to be -1 (which means "not supported"), but the actual result I got is 4294967295. Guest continues to run blindly, bad things would happen then... I think this needs a fix? Thanks, zenghui _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel