1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * 4 * Copyright (C) 2013 Citrix Systems 5 * 6 * Author: Stefano Stabellini <stefano.stabellini@eu.citrix.com> 7 */ 8 9 #define pr_fmt(fmt) "arm-pv: " fmt 10 11 #include <linux/arm-smccc.h> 12 #include <linux/cpuhotplug.h> 13 #include <linux/export.h> 14 #include <linux/io.h> 15 #include <linux/jump_label.h> 16 #include <linux/printk.h> 17 #include <linux/psci.h> 18 #include <linux/reboot.h> 19 #include <linux/slab.h> 20 #include <linux/types.h> 21 22 #include <asm/paravirt.h> 23 #include <asm/pvclock-abi.h> 24 #include <asm/smp_plat.h> 25 26 struct static_key paravirt_steal_enabled; 27 struct static_key paravirt_steal_rq_enabled; 28 29 struct paravirt_patch_template pv_ops; 30 EXPORT_SYMBOL_GPL(pv_ops); 31 32 struct pv_time_stolen_time_region { 33 struct pvclock_vcpu_stolen_time *kaddr; 34 }; 35 36 static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region); 37 38 static bool steal_acc = true; 39 static int __init parse_no_stealacc(char *arg) 40 { 41 steal_acc = false; 42 return 0; 43 } 44 45 early_param("no-steal-acc", parse_no_stealacc); 46 47 /* return stolen time in ns by asking the hypervisor */ 48 static u64 pv_steal_clock(int cpu) 49 { 50 struct pv_time_stolen_time_region *reg; 51 52 reg = per_cpu_ptr(&stolen_time_region, cpu); 53 54 /* 55 * paravirt_steal_clock() may be called before the CPU 56 * online notification callback runs. Until the callback 57 * has run we just return zero. 58 */ 59 if (!reg->kaddr) 60 return 0; 61 62 return le64_to_cpu(READ_ONCE(reg->kaddr->stolen_time)); 63 } 64 65 static int stolen_time_cpu_down_prepare(unsigned int cpu) 66 { 67 struct pv_time_stolen_time_region *reg; 68 69 reg = this_cpu_ptr(&stolen_time_region); 70 if (!reg->kaddr) 71 return 0; 72 73 memunmap(reg->kaddr); 74 memset(reg, 0, sizeof(*reg)); 75 76 return 0; 77 } 78 79 static int stolen_time_cpu_online(unsigned int cpu) 80 { 81 struct pv_time_stolen_time_region *reg; 82 struct arm_smccc_res res; 83 84 reg = this_cpu_ptr(&stolen_time_region); 85 86 arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_ST, &res); 87 88 if (res.a0 == SMCCC_RET_NOT_SUPPORTED) 89 return -EINVAL; 90 91 reg->kaddr = memremap(res.a0, 92 sizeof(struct pvclock_vcpu_stolen_time), 93 MEMREMAP_WB); 94 95 if (!reg->kaddr) { 96 pr_warn("Failed to map stolen time data structure\n"); 97 return -ENOMEM; 98 } 99 100 if (le32_to_cpu(reg->kaddr->revision) != 0 || 101 le32_to_cpu(reg->kaddr->attributes) != 0) { 102 pr_warn_once("Unexpected revision or attributes in stolen time data\n"); 103 return -ENXIO; 104 } 105 106 return 0; 107 } 108 109 static int __init pv_time_init_stolen_time(void) 110 { 111 int ret; 112 113 ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, 114 "hypervisor/arm/pvtime:online", 115 stolen_time_cpu_online, 116 stolen_time_cpu_down_prepare); 117 if (ret < 0) 118 return ret; 119 return 0; 120 } 121 122 static bool __init has_pv_steal_clock(void) 123 { 124 struct arm_smccc_res res; 125 126 /* To detect the presence of PV time support we require SMCCC 1.1+ */ 127 if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE) 128 return false; 129 130 arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, 131 ARM_SMCCC_HV_PV_TIME_FEATURES, &res); 132 133 if (res.a0 != SMCCC_RET_SUCCESS) 134 return false; 135 136 arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_FEATURES, 137 ARM_SMCCC_HV_PV_TIME_ST, &res); 138 139 return (res.a0 == SMCCC_RET_SUCCESS); 140 } 141 142 int __init pv_time_init(void) 143 { 144 int ret; 145 146 if (!has_pv_steal_clock()) 147 return 0; 148 149 ret = pv_time_init_stolen_time(); 150 if (ret) 151 return ret; 152 153 pv_ops.time.steal_clock = pv_steal_clock; 154 155 static_key_slow_inc(¶virt_steal_enabled); 156 if (steal_acc) 157 static_key_slow_inc(¶virt_steal_rq_enabled); 158 159 pr_info("using stolen time PV\n"); 160 161 return 0; 162 } 163