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=unavailable 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 1AA14C31E40 for ; Fri, 9 Aug 2019 13:52:02 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 9253721773 for ; Fri, 9 Aug 2019 13:52:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9253721773 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 041CA4A549; Fri, 9 Aug 2019 09:52:01 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9sghuGtpPg9J; Fri, 9 Aug 2019 09:51:59 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 1CBB24A530; Fri, 9 Aug 2019 09:51:59 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 0D87B4A530 for ; Fri, 9 Aug 2019 09:51:58 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id PBhRKu2fLlVI for ; Fri, 9 Aug 2019 09:51:56 -0400 (EDT) Received: from huawei.com (szxga04-in.huawei.com [45.249.212.190]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 3D1824A4F6 for ; Fri, 9 Aug 2019 09:51:56 -0400 (EDT) Received: from DGGEMS412-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id ACB5A78427CCE41A010A; Fri, 9 Aug 2019 21:51:52 +0800 (CST) Received: from [127.0.0.1] (10.184.12.158) by DGGEMS412-HUB.china.huawei.com (10.3.19.212) with Microsoft SMTP Server id 14.3.439.0; Fri, 9 Aug 2019 21:51:43 +0800 Subject: Re: [PATCH 9/9] arm64: Retrieve stolen time as paravirtualized guest To: Steven Price References: <20190802145017.42543-1-steven.price@arm.com> <20190802145017.42543-10-steven.price@arm.com> From: Zenghui Yu Message-ID: <5d763c8e-9c06-c448-2644-25bfa0e57e8c@huawei.com> Date: Fri, 9 Aug 2019 21:51:39 +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: <20190802145017.42543-10-steven.price@arm.com> Content-Language: en-US X-Originating-IP: [10.184.12.158] X-CFilter-Loop: Reflected Cc: kvm@vger.kernel.org, linux-doc@vger.kernel.org, Catalin Marinas , Russell King , linux-kernel@vger.kernel.org, Marc Zyngier , Paolo Bonzini , Will Deacon , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 2019/8/2 22:50, Steven Price wrote: > Enable paravirtualization features when running under a hypervisor > supporting the PV_TIME_ST hypercall. > > For each (v)CPU, we ask the hypervisor for the location of a shared > page which the hypervisor will use to report stolen time to us. We set > pv_time_ops to the stolen time function which simply reads the stolen > value from the shared page for a VCPU. We guarantee single-copy > atomicity using READ_ONCE which means we can also read the stolen > time for another VCPU than the currently running one while it is > potentially being updated by the hypervisor. > > Signed-off-by: Steven Price > --- > arch/arm64/kernel/Makefile | 1 + > arch/arm64/kernel/kvm.c | 155 +++++++++++++++++++++++++++++++++++++ > include/linux/cpuhotplug.h | 1 + > 3 files changed, 157 insertions(+) > create mode 100644 arch/arm64/kernel/kvm.c > > diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile > index 478491f07b4f..eb36edf9b930 100644 > --- a/arch/arm64/kernel/Makefile > +++ b/arch/arm64/kernel/Makefile > @@ -63,6 +63,7 @@ obj-$(CONFIG_CRASH_CORE) += crash_core.o > obj-$(CONFIG_ARM_SDE_INTERFACE) += sdei.o > obj-$(CONFIG_ARM64_SSBD) += ssbd.o > obj-$(CONFIG_ARM64_PTR_AUTH) += pointer_auth.o > +obj-$(CONFIG_PARAVIRT) += kvm.o > > obj-y += vdso/ probes/ > obj-$(CONFIG_COMPAT_VDSO) += vdso32/ > diff --git a/arch/arm64/kernel/kvm.c b/arch/arm64/kernel/kvm.c > new file mode 100644 > index 000000000000..245398c79dae > --- /dev/null > +++ b/arch/arm64/kernel/kvm.c > @@ -0,0 +1,155 @@ > +// SPDX-License-Identifier: GPL-2.0 > +// Copyright (C) 2019 Arm Ltd. > + > +#define pr_fmt(fmt) "kvmarm-pv: " fmt > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#include > +#include > +#include > + > +struct kvmarm_stolen_time_region { > + struct pvclock_vcpu_stolen_time_info *kaddr; > +}; > + > +static DEFINE_PER_CPU(struct kvmarm_stolen_time_region, stolen_time_region); > + > +static bool steal_acc = true; > +static int __init parse_no_stealacc(char *arg) > +{ > + steal_acc = false; > + return 0; > +} > +early_param("no-steal-acc", parse_no_stealacc); > + > +/* return stolen time in ns by asking the hypervisor */ > +static u64 kvm_steal_clock(int cpu) > +{ > + struct kvmarm_stolen_time_region *reg; > + > + reg = per_cpu_ptr(&stolen_time_region, cpu); > + if (!reg->kaddr) { > + pr_warn_once("stolen time enabled but not configured for cpu %d\n", > + cpu); > + return 0; > + } > + > + return le64_to_cpu(READ_ONCE(reg->kaddr->stolen_time)); > +} > + > +static int disable_stolen_time_current_cpu(void) > +{ > + struct kvmarm_stolen_time_region *reg; > + > + reg = this_cpu_ptr(&stolen_time_region); > + if (!reg->kaddr) > + return 0; > + > + memunmap(reg->kaddr); > + memset(reg, 0, sizeof(*reg)); > + > + return 0; > +} > + > +static int stolen_time_dying_cpu(unsigned int cpu) > +{ > + return disable_stolen_time_current_cpu(); > +} > + > +static int init_stolen_time_cpu(unsigned int cpu) > +{ > + struct kvmarm_stolen_time_region *reg; > + struct arm_smccc_res res; > + > + reg = this_cpu_ptr(&stolen_time_region); > + > + if (reg->kaddr) > + return 0; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_ST, &res); > + > + if ((long)res.a0 < 0) > + return -EINVAL; Hi Steven, Since userspace is not involved yet (right?), no one will create the PV_TIME device for guest (and no one will specify the IPA of the shared stolen time region), and I guess we will get a "not supported" error here. So what should we do if we want to test this series now? Any userspace tools? If no, do you have any plans for userspace developing? ;-) Thanks, zenghui > + > + reg->kaddr = memremap(res.a0, > + sizeof(struct pvclock_vcpu_stolen_time_info), > + MEMREMAP_WB); > + > + if (reg->kaddr == NULL) { > + pr_warn("Failed to map stolen time data structure\n"); > + return -EINVAL; > + } > + > + if (le32_to_cpu(reg->kaddr->revision) != 0 || > + le32_to_cpu(reg->kaddr->attributes) != 0) { > + pr_warn("Unexpected revision or attributes in stolen time data\n"); > + return -ENXIO; > + } > + > + return 0; > +} > + > +static int kvm_arm_init_stolen_time(void) > +{ > + int ret; > + > + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVMPV_STARTING, > + "hypervisor/kvmarm/pv:starting", > + init_stolen_time_cpu, stolen_time_dying_cpu); > + if (ret < 0) > + return ret; > + return 0; > +} > + > +static bool has_kvm_steal_clock(void) > +{ > + struct arm_smccc_res res; > + > + /* To detect the presence of PV time support we require SMCCC 1.1+ */ > + if (psci_ops.smccc_version < SMCCC_VERSION_1_1) > + return false; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, > + ARM_SMCCC_HV_PV_FEATURES, &res); > + > + if (res.a0 != SMCCC_RET_SUCCESS) > + return false; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_FEATURES, > + ARM_SMCCC_HV_PV_TIME_ST, &res); > + > + if (res.a0 != SMCCC_RET_SUCCESS) > + return false; > + > + return true; > +} > + > +static int __init kvm_guest_init(void) > +{ > + int ret = 0; > + > + if (!has_kvm_steal_clock()) > + return 0; > + > + ret = kvm_arm_init_stolen_time(); > + if (ret) > + return ret; > + > + pv_ops.time.steal_clock = kvm_steal_clock; > + > + static_key_slow_inc(¶virt_steal_enabled); > + if (steal_acc) > + static_key_slow_inc(¶virt_steal_rq_enabled); > + > + pr_info("using stolen time PV\n"); > + > + return 0; > +} > +early_initcall(kvm_guest_init); > diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h > index 068793a619ca..89d75edb5750 100644 > --- a/include/linux/cpuhotplug.h > +++ b/include/linux/cpuhotplug.h > @@ -136,6 +136,7 @@ enum cpuhp_state { > /* Must be the last timer callback */ > CPUHP_AP_DUMMY_TIMER_STARTING, > CPUHP_AP_ARM_XEN_STARTING, > + CPUHP_AP_ARM_KVMPV_STARTING, > CPUHP_AP_ARM_CORESIGHT_STARTING, > CPUHP_AP_ARM64_ISNDEP_STARTING, > CPUHP_AP_SMPCFD_DYING, > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm