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;
parse_no_stealacc(char * arg)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 */
pv_steal_clock(int cpu)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
stolen_time_cpu_down_prepare(unsigned int cpu)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
stolen_time_cpu_online(unsigned int cpu)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
pv_time_init_stolen_time(void)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
has_pv_steal_clock(void)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
pv_time_init(void)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