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 if (!reg->kaddr) { 54 pr_warn_once("stolen time enabled but not configured for cpu %d\n", 55 cpu); 56 return 0; 57 } 58 59 return le64_to_cpu(READ_ONCE(reg->kaddr->stolen_time)); 60 } 61 62 static int stolen_time_dying_cpu(unsigned int cpu) 63 { 64 struct pv_time_stolen_time_region *reg; 65 66 reg = this_cpu_ptr(&stolen_time_region); 67 if (!reg->kaddr) 68 return 0; 69 70 memunmap(reg->kaddr); 71 memset(reg, 0, sizeof(*reg)); 72 73 return 0; 74 } 75 76 static int init_stolen_time_cpu(unsigned int cpu) 77 { 78 struct pv_time_stolen_time_region *reg; 79 struct arm_smccc_res res; 80 81 reg = this_cpu_ptr(&stolen_time_region); 82 83 arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_ST, &res); 84 85 if (res.a0 == SMCCC_RET_NOT_SUPPORTED) 86 return -EINVAL; 87 88 reg->kaddr = memremap(res.a0, 89 sizeof(struct pvclock_vcpu_stolen_time), 90 MEMREMAP_WB); 91 92 if (!reg->kaddr) { 93 pr_warn("Failed to map stolen time data structure\n"); 94 return -ENOMEM; 95 } 96 97 if (le32_to_cpu(reg->kaddr->revision) != 0 || 98 le32_to_cpu(reg->kaddr->attributes) != 0) { 99 pr_warn_once("Unexpected revision or attributes in stolen time data\n"); 100 return -ENXIO; 101 } 102 103 return 0; 104 } 105 106 static int pv_time_init_stolen_time(void) 107 { 108 int ret; 109 110 ret = cpuhp_setup_state(CPUHP_AP_ARM_KVMPV_STARTING, 111 "hypervisor/arm/pvtime:starting", 112 init_stolen_time_cpu, stolen_time_dying_cpu); 113 if (ret < 0) 114 return ret; 115 return 0; 116 } 117 118 static bool has_pv_steal_clock(void) 119 { 120 struct arm_smccc_res res; 121 122 /* To detect the presence of PV time support we require SMCCC 1.1+ */ 123 if (psci_ops.smccc_version < SMCCC_VERSION_1_1) 124 return false; 125 126 arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, 127 ARM_SMCCC_HV_PV_TIME_FEATURES, &res); 128 129 if (res.a0 != SMCCC_RET_SUCCESS) 130 return false; 131 132 arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_TIME_FEATURES, 133 ARM_SMCCC_HV_PV_TIME_ST, &res); 134 135 return (res.a0 == SMCCC_RET_SUCCESS); 136 } 137 138 int __init pv_time_init(void) 139 { 140 int ret; 141 142 if (!has_pv_steal_clock()) 143 return 0; 144 145 ret = pv_time_init_stolen_time(); 146 if (ret) 147 return ret; 148 149 pv_ops.time.steal_clock = pv_steal_clock; 150 151 static_key_slow_inc(¶virt_steal_enabled); 152 if (steal_acc) 153 static_key_slow_inc(¶virt_steal_rq_enabled); 154 155 pr_info("using stolen time PV\n"); 156 157 return 0; 158 } 159