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 #include <linux/static_call.h> 22 23 #include <asm/paravirt.h> 24 #include <asm/pvclock-abi.h> 25 #include <asm/smp_plat.h> 26 27 struct static_key paravirt_steal_enabled; 28 struct static_key paravirt_steal_rq_enabled; 29 30 static u64 native_steal_clock(int cpu) 31 { 32 return 0; 33 } 34 35 DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock); 36 37 struct pv_time_stolen_time_region { 38 struct pvclock_vcpu_stolen_time *kaddr; 39 }; 40 41 static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region); 42 43 static bool steal_acc = true; 44 static int __init parse_no_stealacc(char *arg) 45 { 46 steal_acc = false; 47 return 0; 48 } 49 50 early_param("no-steal-acc", parse_no_stealacc); 51 52 /* return stolen time in ns by asking the hypervisor */ 53 static u64 para_steal_clock(int cpu) 54 { 55 struct pv_time_stolen_time_region *reg; 56 57 reg = per_cpu_ptr(&stolen_time_region, cpu); 58 59 /* 60 * paravirt_steal_clock() may be called before the CPU 61 * online notification callback runs. Until the callback 62 * has run we just return zero. 63 */ 64 if (!reg->kaddr) 65 return 0; 66 67 return le64_to_cpu(READ_ONCE(reg->kaddr->stolen_time)); 68 } 69 70 static int stolen_time_cpu_down_prepare(unsigned int cpu) 71 { 72 struct pv_time_stolen_time_region *reg; 73 74 reg = this_cpu_ptr(&stolen_time_region); 75 if (!reg->kaddr) 76 return 0; 77 78 memunmap(reg->kaddr); 79 memset(reg, 0, sizeof(*reg)); 80 81 return 0; 82 } 83 84 static int stolen_time_cpu_online(unsigned int cpu) 85 { 86 struct pv_time_stolen_time_region *reg; 87 struct arm_smccc_res res; 88 89 reg = this_cpu_ptr(&stolen_time_region); 90 91 arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_ST, &res); 92 93 if (res.a0 == SMCCC_RET_NOT_SUPPORTED) 94 return -EINVAL; 95 96 reg->kaddr = memremap(res.a0, 97 sizeof(struct pvclock_vcpu_stolen_time), 98 MEMREMAP_WB); 99 100 if (!reg->kaddr) { 101 pr_warn("Failed to map stolen time data structure\n"); 102 return -ENOMEM; 103 } 104 105 if (le32_to_cpu(reg->kaddr->revision) != 0 || 106 le32_to_cpu(reg->kaddr->attributes) != 0) { 107 pr_warn_once("Unexpected revision or attributes in stolen time data\n"); 108 return -ENXIO; 109 } 110 111 return 0; 112 } 113 114 static int __init pv_time_init_stolen_time(void) 115 { 116 int ret; 117 118 ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, 119 "hypervisor/arm/pvtime:online", 120 stolen_time_cpu_online, 121 stolen_time_cpu_down_prepare); 122 if (ret < 0) 123 return ret; 124 return 0; 125 } 126 127 static bool __init has_pv_steal_clock(void) 128 { 129 struct arm_smccc_res res; 130 131 /* To detect the presence of PV time support we require SMCCC 1.1+ */ 132 if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE) 133 return false; 134 135 arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, 136 ARM_SMCCC_HV_PV_TIME_FEATURES, &res); 137 138 if (res.a0 != SMCCC_RET_SUCCESS) 139 return false; 140 141 arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_FEATURES, 142 ARM_SMCCC_HV_PV_TIME_ST, &res); 143 144 return (res.a0 == SMCCC_RET_SUCCESS); 145 } 146 147 int __init pv_time_init(void) 148 { 149 int ret; 150 151 if (!has_pv_steal_clock()) 152 return 0; 153 154 ret = pv_time_init_stolen_time(); 155 if (ret) 156 return ret; 157 158 static_call_update(pv_steal_clock, para_steal_clock); 159 160 static_key_slow_inc(¶virt_steal_enabled); 161 if (steal_acc) 162 static_key_slow_inc(¶virt_steal_rq_enabled); 163 164 pr_info("using stolen time PV\n"); 165 166 return 0; 167 } 168