From patchwork Wed Dec 12 15:02:21 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Price X-Patchwork-Id: 10726507 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 6370514BD for ; Wed, 12 Dec 2018 15:04:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 524AD2B173 for ; Wed, 12 Dec 2018 15:04:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 466672B176; Wed, 12 Dec 2018 15:04:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id C001E2B173 for ; Wed, 12 Dec 2018 15:04:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=14oEP2cbdkprftreDAishbg96W+vw9XdCin2QBLiU8E=; b=kXvbCVsTaYxT0p +8whitIt2sU3MWXwvWpYCklTVxKUst3Dj+H4NdDqmzVWPFb2pli/Qdr1QsSzufN31FmzPgNkpf+hT 1LS/DNZd+pFqYySicQBDWxUp5+AXDibmporrs4Xq7BKQjfph66cV6L2zvVAyAGz3x9tVZKgMylghz NOmHBUzKyjXHtI6yWopftdQBFGvQ2NCe/yWgz9NgbadATp5nDYMotaP0X9cks/cQBl9Jqyx0I++qM /+labm9ggcHPytrsYn4DVkEXRxGwKGmxHknLr0AOOJKUdFks3yN/xwS4vj7kTxWYqNjNk9ikbb1Xx L/FYHiVZEUFA1U8SGbmg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gX63f-0007ld-6T; Wed, 12 Dec 2018 15:04:19 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gX62e-0006Rk-Fb for linux-arm-kernel@lists.infradead.org; Wed, 12 Dec 2018 15:03:28 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 54210EBD; Wed, 12 Dec 2018 07:03:11 -0800 (PST) Received: from e112269-lin.arm.com (e112269-lin.cambridge.arm.com [10.1.196.55]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CE0FA3F59C; Wed, 12 Dec 2018 07:03:09 -0800 (PST) From: Steven Price To: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: [RFC PATCH v2 07/12] arm64: Retrieve stolen time as paravirtualized guest Date: Wed, 12 Dec 2018 15:02:21 +0000 Message-Id: <20181212150226.38051-8-steven.price@arm.com> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181212150226.38051-1-steven.price@arm.com> References: <20181212150226.38051-1-steven.price@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181212_070317_022401_15D6129E X-CRM114-Status: GOOD ( 19.72 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Marc Zyngier , Catalin Marinas , Will Deacon , Christoffer Dall , Steven Price Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP 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 | 156 +++++++++++++++++++++++++++++++++++++ include/linux/cpuhotplug.h | 1 + 3 files changed, 158 insertions(+) create mode 100644 arch/arm64/kernel/kvm.c diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 4c8b13bede80..daaed14ed7a4 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -57,6 +57,7 @@ arm64-obj-$(CONFIG_CRASH_DUMP) += crash_dump.o arm64-obj-$(CONFIG_CRASH_CORE) += crash_core.o arm64-obj-$(CONFIG_ARM_SDE_INTERFACE) += sdei.o arm64-obj-$(CONFIG_ARM64_SSBD) += ssbd.o +arm64-obj-$(CONFIG_PARAVIRT) += kvm.o obj-y += $(arm64-obj-y) vdso/ probes/ obj-m += $(arm64-obj-m) diff --git a/arch/arm64/kernel/kvm.c b/arch/arm64/kernel/kvm.c new file mode 100644 index 000000000000..f7bc1f069dc0 --- /dev/null +++ b/arch/arm64/kernel/kvm.c @@ -0,0 +1,156 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (C) 2018 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 configued 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; + int ret; + struct arm_smccc_res res; + + reg = this_cpu_ptr(&stolen_time_region); + + if (reg->kaddr) + return 0; + + ret = arm_smccc_1_1_call(ARM_SMCCC_HV_PV_TIME_ST, &res); + + if ((long)res.a0 < 0) + return -EINVAL; + + 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_call(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, + ARM_SMCCC_HV_PV_FEATURES, &res); + + if (res.a0 != SMCCC_RET_SUCCESS) + return false; + + arm_smccc_1_1_call(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 e0cd2baa8380..5c176a31deb8 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -134,6 +134,7 @@ 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,