1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2020 - Google LLC
4 * Author: David Brazdil <dbrazdil@google.com>
5 */
6
7 #include <asm/kvm_asm.h>
8 #include <asm/kvm_hyp.h>
9 #include <asm/kvm_mmu.h>
10 #include <linux/arm-smccc.h>
11 #include <linux/kvm_host.h>
12 #include <uapi/linux/psci.h>
13
14 #include <nvhe/memory.h>
15 #include <nvhe/trap_handler.h>
16
17 void kvm_hyp_cpu_entry(unsigned long r0);
18 void kvm_hyp_cpu_resume(unsigned long r0);
19
20 void __noreturn __host_enter(struct kvm_cpu_context *host_ctxt);
21
22 /* Config options set by the host. */
23 struct kvm_host_psci_config __ro_after_init kvm_host_psci_config;
24
25 #define INVALID_CPU_ID UINT_MAX
26
27 struct psci_boot_args {
28 atomic_t lock;
29 unsigned long pc;
30 unsigned long r0;
31 };
32
33 #define PSCI_BOOT_ARGS_UNLOCKED 0
34 #define PSCI_BOOT_ARGS_LOCKED 1
35
36 #define PSCI_BOOT_ARGS_INIT \
37 ((struct psci_boot_args){ \
38 .lock = ATOMIC_INIT(PSCI_BOOT_ARGS_UNLOCKED), \
39 })
40
41 static DEFINE_PER_CPU(struct psci_boot_args, cpu_on_args) = PSCI_BOOT_ARGS_INIT;
42 static DEFINE_PER_CPU(struct psci_boot_args, suspend_args) = PSCI_BOOT_ARGS_INIT;
43
44 #define is_psci_0_1(what, func_id) \
45 (kvm_host_psci_config.psci_0_1_ ## what ## _implemented && \
46 (func_id) == kvm_host_psci_config.function_ids_0_1.what)
47
48 static bool is_psci_0_1_call(u64 func_id)
49 {
50 return (is_psci_0_1(cpu_suspend, func_id) ||
51 is_psci_0_1(cpu_on, func_id) ||
52 is_psci_0_1(cpu_off, func_id) ||
53 is_psci_0_1(migrate, func_id));
54 }
55
56 static bool is_psci_0_2_call(u64 func_id)
57 {
58 /* SMCCC reserves IDs 0x00-1F with the given 32/64-bit base for PSCI. */
59 return (PSCI_0_2_FN(0) <= func_id && func_id <= PSCI_0_2_FN(31)) ||
60 (PSCI_0_2_FN64(0) <= func_id && func_id <= PSCI_0_2_FN64(31));
61 }
62
63 static unsigned long psci_call(unsigned long fn, unsigned long arg0,
64 unsigned long arg1, unsigned long arg2)
65 {
66 struct arm_smccc_res res;
67
68 arm_smccc_1_1_smc(fn, arg0, arg1, arg2, &res);
69 return res.a0;
70 }
71
72 static unsigned long psci_forward(struct kvm_cpu_context *host_ctxt)
73 {
74 return psci_call(cpu_reg(host_ctxt, 0), cpu_reg(host_ctxt, 1),
75 cpu_reg(host_ctxt, 2), cpu_reg(host_ctxt, 3));
76 }
77
78 static unsigned int find_cpu_id(u64 mpidr)
79 {
80 unsigned int i;
81
82 /* Reject invalid MPIDRs */
83 if (mpidr & ~MPIDR_HWID_BITMASK)
84 return INVALID_CPU_ID;
85
86 for (i = 0; i < NR_CPUS; i++) {
87 if (cpu_logical_map(i) == mpidr)
88 return i;
89 }
90
91 return INVALID_CPU_ID;
92 }
93
94 static __always_inline bool try_acquire_boot_args(struct psci_boot_args *args)
95 {
96 return atomic_cmpxchg_acquire(&args->lock,
97 PSCI_BOOT_ARGS_UNLOCKED,
98 PSCI_BOOT_ARGS_LOCKED) ==
99 PSCI_BOOT_ARGS_UNLOCKED;
100 }
101
102 static __always_inline void release_boot_args(struct psci_boot_args *args)
103 {
104 atomic_set_release(&args->lock, PSCI_BOOT_ARGS_UNLOCKED);
105 }
106
107 static int psci_cpu_on(u64 func_id, struct kvm_cpu_context *host_ctxt)
108 {
109 DECLARE_REG(u64, mpidr, host_ctxt, 1);
110 DECLARE_REG(unsigned long, pc, host_ctxt, 2);
111 DECLARE_REG(unsigned long, r0, host_ctxt, 3);
112
113 unsigned int cpu_id;
114 struct psci_boot_args *boot_args;
115 struct kvm_nvhe_init_params *init_params;
116 int ret;
117
118 /*
119 * Find the logical CPU ID for the given MPIDR. The search set is
120 * the set of CPUs that were online at the point of KVM initialization.
121 * Booting other CPUs is rejected because their cpufeatures were not
122 * checked against the finalized capabilities. This could be relaxed
123 * by doing the feature checks in hyp.
124 */
125 cpu_id = find_cpu_id(mpidr);
126 if (cpu_id == INVALID_CPU_ID)
127 return PSCI_RET_INVALID_PARAMS;
128
129 boot_args = per_cpu_ptr(&cpu_on_args, cpu_id);
130 init_params = per_cpu_ptr(&kvm_init_params, cpu_id);
131
132 /* Check if the target CPU is already being booted. */
133 if (!try_acquire_boot_args(boot_args))
134 return PSCI_RET_ALREADY_ON;
135
136 boot_args->pc = pc;
137 boot_args->r0 = r0;
138 wmb();
139
140 ret = psci_call(func_id, mpidr,
141 __hyp_pa(&kvm_hyp_cpu_entry),
142 __hyp_pa(init_params));
143
144 /* If successful, the lock will be released by the target CPU. */
145 if (ret != PSCI_RET_SUCCESS)
146 release_boot_args(boot_args);
147
148 return ret;
149 }
150
151 static int psci_cpu_suspend(u64 func_id, struct kvm_cpu_context *host_ctxt)
152 {
153 DECLARE_REG(u64, power_state, host_ctxt, 1);
154 DECLARE_REG(unsigned long, pc, host_ctxt, 2);
155 DECLARE_REG(unsigned long, r0, host_ctxt, 3);
156
157 struct psci_boot_args *boot_args;
158 struct kvm_nvhe_init_params *init_params;
159
160 boot_args = this_cpu_ptr(&suspend_args);
161 init_params = this_cpu_ptr(&kvm_init_params);
162
163 /*
164 * No need to acquire a lock before writing to boot_args because a core
165 * can only suspend itself. Racy CPU_ON calls use a separate struct.
166 */
167 boot_args->pc = pc;
168 boot_args->r0 = r0;
169
170 /*
171 * Will either return if shallow sleep state, or wake up into the entry
172 * point if it is a deep sleep state.
173 */
174 return psci_call(func_id, power_state,
175 __hyp_pa(&kvm_hyp_cpu_resume),
176 __hyp_pa(init_params));
177 }
178
179 static int psci_system_suspend(u64 func_id, struct kvm_cpu_context *host_ctxt)
180 {
181 DECLARE_REG(unsigned long, pc, host_ctxt, 1);
182 DECLARE_REG(unsigned long, r0, host_ctxt, 2);
183
184 struct psci_boot_args *boot_args;
185 struct kvm_nvhe_init_params *init_params;
186
187 boot_args = this_cpu_ptr(&suspend_args);
188 init_params = this_cpu_ptr(&kvm_init_params);
189
190 /*
191 * No need to acquire a lock before writing to boot_args because a core
192 * can only suspend itself. Racy CPU_ON calls use a separate struct.
193 */
194 boot_args->pc = pc;
195 boot_args->r0 = r0;
196
197 /* Will only return on error. */
198 return psci_call(func_id,
199 __hyp_pa(&kvm_hyp_cpu_resume),
200 __hyp_pa(init_params), 0);
201 }
202
203 asmlinkage void __noreturn __kvm_host_psci_cpu_entry(bool is_cpu_on)
204 {
205 struct psci_boot_args *boot_args;
206 struct kvm_cpu_context *host_ctxt;
207
208 host_ctxt = host_data_ptr(host_ctxt);
209
210 if (is_cpu_on)
211 boot_args = this_cpu_ptr(&cpu_on_args);
212 else
213 boot_args = this_cpu_ptr(&suspend_args);
214
215 cpu_reg(host_ctxt, 0) = boot_args->r0;
216 write_sysreg_el2(boot_args->pc, SYS_ELR);
217
218 if (is_cpu_on)
219 release_boot_args(boot_args);
220
221 __host_enter(host_ctxt);
222 }
223
224 static unsigned long psci_0_1_handler(u64 func_id, struct kvm_cpu_context *host_ctxt)
225 {
226 if (is_psci_0_1(cpu_off, func_id) || is_psci_0_1(migrate, func_id))
227 return psci_forward(host_ctxt);
228 if (is_psci_0_1(cpu_on, func_id))
229 return psci_cpu_on(func_id, host_ctxt);
230 if (is_psci_0_1(cpu_suspend, func_id))
231 return psci_cpu_suspend(func_id, host_ctxt);
232
233 return PSCI_RET_NOT_SUPPORTED;
234 }
235
236 static unsigned long psci_0_2_handler(u64 func_id, struct kvm_cpu_context *host_ctxt)
237 {
238 switch (func_id) {
239 case PSCI_0_2_FN_PSCI_VERSION:
240 case PSCI_0_2_FN_CPU_OFF:
241 case PSCI_0_2_FN64_AFFINITY_INFO:
242 case PSCI_0_2_FN64_MIGRATE:
243 case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
244 case PSCI_0_2_FN64_MIGRATE_INFO_UP_CPU:
245 return psci_forward(host_ctxt);
246 /*
247 * SYSTEM_OFF/RESET should not return according to the spec.
248 * Allow it so as to stay robust to broken firmware.
249 */
250 case PSCI_0_2_FN_SYSTEM_OFF:
251 case PSCI_0_2_FN_SYSTEM_RESET:
252 return psci_forward(host_ctxt);
253 case PSCI_0_2_FN64_CPU_SUSPEND:
254 return psci_cpu_suspend(func_id, host_ctxt);
255 case PSCI_0_2_FN64_CPU_ON:
256 return psci_cpu_on(func_id, host_ctxt);
257 default:
258 return PSCI_RET_NOT_SUPPORTED;
259 }
260 }
261
262 static unsigned long psci_1_0_handler(u64 func_id, struct kvm_cpu_context *host_ctxt)
263 {
264 switch (func_id) {
265 case PSCI_1_0_FN_PSCI_FEATURES:
266 case PSCI_1_0_FN_SET_SUSPEND_MODE:
267 case PSCI_1_1_FN64_SYSTEM_RESET2:
268 return psci_forward(host_ctxt);
269 case PSCI_1_0_FN64_SYSTEM_SUSPEND:
270 return psci_system_suspend(func_id, host_ctxt);
271 default:
272 return psci_0_2_handler(func_id, host_ctxt);
273 }
274 }
275
276 bool kvm_host_psci_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
277 {
278 unsigned long ret;
279
280 switch (kvm_host_psci_config.version) {
281 case PSCI_VERSION(0, 1):
282 if (!is_psci_0_1_call(func_id))
283 return false;
284 ret = psci_0_1_handler(func_id, host_ctxt);
285 break;
286 case PSCI_VERSION(0, 2):
287 if (!is_psci_0_2_call(func_id))
288 return false;
289 ret = psci_0_2_handler(func_id, host_ctxt);
290 break;
291 default:
292 if (!is_psci_0_2_call(func_id))
293 return false;
294 ret = psci_1_0_handler(func_id, host_ctxt);
295 break;
296 }
297
298 cpu_reg(host_ctxt, 0) = ret;
299 cpu_reg(host_ctxt, 1) = 0;
300 cpu_reg(host_ctxt, 2) = 0;
301 cpu_reg(host_ctxt, 3) = 0;
302 return true;
303 }
304
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.