1 /*
2 * Copyright (C) 2012 - ARM Ltd
3 * Author: Marc Zyngier <marc.zyngier@arm.com>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program. If not, see <http://www.gnu.org/licenses/>.
16 */
17
18 #include <linux/preempt.h>
19 #include <linux/kvm_host.h>
20 #include <linux/wait.h>
21
22 #include <asm/cputype.h>
23 #include <asm/kvm_emulate.h>
24 #include <asm/kvm_psci.h>
25 #include <asm/kvm_host.h>
26
27 #include <uapi/linux/psci.h>
28
29 /*
30 * This is an implementation of the Power State Coordination Interface
31 * as described in ARM document number ARM DEN 0022A.
32 */
33
34 #define AFFINITY_MASK(level) ~((0x1UL << ((level) * MPIDR_LEVEL_BITS)) - 1)
35
psci_affinity_mask(unsigned long affinity_level)36 static unsigned long psci_affinity_mask(unsigned long affinity_level)
37 {
38 if (affinity_level <= 3)
39 return MPIDR_HWID_BITMASK & AFFINITY_MASK(affinity_level);
40
41 return 0;
42 }
43
kvm_psci_vcpu_suspend(struct kvm_vcpu * vcpu)44 static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu)
45 {
46 /*
47 * NOTE: For simplicity, we make VCPU suspend emulation to be
48 * same-as WFI (Wait-for-interrupt) emulation.
49 *
50 * This means for KVM the wakeup events are interrupts and
51 * this is consistent with intended use of StateID as described
52 * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A).
53 *
54 * Further, we also treat power-down request to be same as
55 * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2
56 * specification (ARM DEN 0022A). This means all suspend states
57 * for KVM will preserve the register state.
58 */
59 kvm_vcpu_block(vcpu);
60
61 return PSCI_RET_SUCCESS;
62 }
63
kvm_psci_vcpu_off(struct kvm_vcpu * vcpu)64 static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
65 {
66 vcpu->arch.power_off = true;
67 }
68
kvm_psci_vcpu_on(struct kvm_vcpu * source_vcpu)69 static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
70 {
71 struct kvm *kvm = source_vcpu->kvm;
72 struct kvm_vcpu *vcpu = NULL;
73 wait_queue_head_t *wq;
74 unsigned long cpu_id;
75 unsigned long context_id;
76 phys_addr_t target_pc;
77
78 cpu_id = vcpu_get_reg(source_vcpu, 1) & MPIDR_HWID_BITMASK;
79 if (vcpu_mode_is_32bit(source_vcpu))
80 cpu_id &= ~((u32) 0);
81
82 vcpu = kvm_mpidr_to_vcpu(kvm, cpu_id);
83
84 /*
85 * Make sure the caller requested a valid CPU and that the CPU is
86 * turned off.
87 */
88 if (!vcpu)
89 return PSCI_RET_INVALID_PARAMS;
90 if (!vcpu->arch.power_off) {
91 if (kvm_psci_version(source_vcpu) != KVM_ARM_PSCI_0_1)
92 return PSCI_RET_ALREADY_ON;
93 else
94 return PSCI_RET_INVALID_PARAMS;
95 }
96
97 target_pc = vcpu_get_reg(source_vcpu, 2);
98 context_id = vcpu_get_reg(source_vcpu, 3);
99
100 kvm_reset_vcpu(vcpu);
101
102 /* Gracefully handle Thumb2 entry point */
103 if (vcpu_mode_is_32bit(vcpu) && (target_pc & 1)) {
104 target_pc &= ~((phys_addr_t) 1);
105 vcpu_set_thumb(vcpu);
106 }
107
108 /* Propagate caller endianness */
109 if (kvm_vcpu_is_be(source_vcpu))
110 kvm_vcpu_set_be(vcpu);
111
112 *vcpu_pc(vcpu) = target_pc;
113 /*
114 * NOTE: We always update r0 (or x0) because for PSCI v0.1
115 * the general puspose registers are undefined upon CPU_ON.
116 */
117 vcpu_set_reg(vcpu, 0, context_id);
118 vcpu->arch.power_off = false;
119 smp_mb(); /* Make sure the above is visible */
120
121 wq = kvm_arch_vcpu_wq(vcpu);
122 wake_up_interruptible(wq);
123
124 return PSCI_RET_SUCCESS;
125 }
126
kvm_psci_vcpu_affinity_info(struct kvm_vcpu * vcpu)127 static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
128 {
129 int i, matching_cpus = 0;
130 unsigned long mpidr;
131 unsigned long target_affinity;
132 unsigned long target_affinity_mask;
133 unsigned long lowest_affinity_level;
134 struct kvm *kvm = vcpu->kvm;
135 struct kvm_vcpu *tmp;
136
137 target_affinity = vcpu_get_reg(vcpu, 1);
138 lowest_affinity_level = vcpu_get_reg(vcpu, 2);
139
140 /* Determine target affinity mask */
141 target_affinity_mask = psci_affinity_mask(lowest_affinity_level);
142 if (!target_affinity_mask)
143 return PSCI_RET_INVALID_PARAMS;
144
145 /* Ignore other bits of target affinity */
146 target_affinity &= target_affinity_mask;
147
148 /*
149 * If one or more VCPU matching target affinity are running
150 * then ON else OFF
151 */
152 kvm_for_each_vcpu(i, tmp, kvm) {
153 mpidr = kvm_vcpu_get_mpidr_aff(tmp);
154 if ((mpidr & target_affinity_mask) == target_affinity) {
155 matching_cpus++;
156 if (!tmp->arch.power_off)
157 return PSCI_0_2_AFFINITY_LEVEL_ON;
158 }
159 }
160
161 if (!matching_cpus)
162 return PSCI_RET_INVALID_PARAMS;
163
164 return PSCI_0_2_AFFINITY_LEVEL_OFF;
165 }
166
kvm_prepare_system_event(struct kvm_vcpu * vcpu,u32 type)167 static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
168 {
169 int i;
170 struct kvm_vcpu *tmp;
171
172 /*
173 * The KVM ABI specifies that a system event exit may call KVM_RUN
174 * again and may perform shutdown/reboot at a later time that when the
175 * actual request is made. Since we are implementing PSCI and a
176 * caller of PSCI reboot and shutdown expects that the system shuts
177 * down or reboots immediately, let's make sure that VCPUs are not run
178 * after this call is handled and before the VCPUs have been
179 * re-initialized.
180 */
181 kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
182 tmp->arch.power_off = true;
183 kvm_vcpu_kick(tmp);
184 }
185
186 memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
187 vcpu->run->system_event.type = type;
188 vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
189 }
190
kvm_psci_system_off(struct kvm_vcpu * vcpu)191 static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
192 {
193 kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN);
194 }
195
kvm_psci_system_reset(struct kvm_vcpu * vcpu)196 static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
197 {
198 kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
199 }
200
kvm_psci_version(struct kvm_vcpu * vcpu)201 int kvm_psci_version(struct kvm_vcpu *vcpu)
202 {
203 if (test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features))
204 return KVM_ARM_PSCI_0_2;
205
206 return KVM_ARM_PSCI_0_1;
207 }
208
kvm_psci_0_2_call(struct kvm_vcpu * vcpu)209 static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
210 {
211 int ret = 1;
212 unsigned long psci_fn = vcpu_get_reg(vcpu, 0) & ~((u32) 0);
213 unsigned long val;
214
215 switch (psci_fn) {
216 case PSCI_0_2_FN_PSCI_VERSION:
217 /*
218 * Bits[31:16] = Major Version = 0
219 * Bits[15:0] = Minor Version = 2
220 */
221 val = 2;
222 break;
223 case PSCI_0_2_FN_CPU_SUSPEND:
224 case PSCI_0_2_FN64_CPU_SUSPEND:
225 val = kvm_psci_vcpu_suspend(vcpu);
226 break;
227 case PSCI_0_2_FN_CPU_OFF:
228 kvm_psci_vcpu_off(vcpu);
229 val = PSCI_RET_SUCCESS;
230 break;
231 case PSCI_0_2_FN_CPU_ON:
232 case PSCI_0_2_FN64_CPU_ON:
233 val = kvm_psci_vcpu_on(vcpu);
234 break;
235 case PSCI_0_2_FN_AFFINITY_INFO:
236 case PSCI_0_2_FN64_AFFINITY_INFO:
237 val = kvm_psci_vcpu_affinity_info(vcpu);
238 break;
239 case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
240 /*
241 * Trusted OS is MP hence does not require migration
242 * or
243 * Trusted OS is not present
244 */
245 val = PSCI_0_2_TOS_MP;
246 break;
247 case PSCI_0_2_FN_SYSTEM_OFF:
248 kvm_psci_system_off(vcpu);
249 /*
250 * We should'nt be going back to guest VCPU after
251 * receiving SYSTEM_OFF request.
252 *
253 * If user space accidently/deliberately resumes
254 * guest VCPU after SYSTEM_OFF request then guest
255 * VCPU should see internal failure from PSCI return
256 * value. To achieve this, we preload r0 (or x0) with
257 * PSCI return value INTERNAL_FAILURE.
258 */
259 val = PSCI_RET_INTERNAL_FAILURE;
260 ret = 0;
261 break;
262 case PSCI_0_2_FN_SYSTEM_RESET:
263 kvm_psci_system_reset(vcpu);
264 /*
265 * Same reason as SYSTEM_OFF for preloading r0 (or x0)
266 * with PSCI return value INTERNAL_FAILURE.
267 */
268 val = PSCI_RET_INTERNAL_FAILURE;
269 ret = 0;
270 break;
271 default:
272 val = PSCI_RET_NOT_SUPPORTED;
273 break;
274 }
275
276 vcpu_set_reg(vcpu, 0, val);
277 return ret;
278 }
279
kvm_psci_0_1_call(struct kvm_vcpu * vcpu)280 static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
281 {
282 unsigned long psci_fn = vcpu_get_reg(vcpu, 0) & ~((u32) 0);
283 unsigned long val;
284
285 switch (psci_fn) {
286 case KVM_PSCI_FN_CPU_OFF:
287 kvm_psci_vcpu_off(vcpu);
288 val = PSCI_RET_SUCCESS;
289 break;
290 case KVM_PSCI_FN_CPU_ON:
291 val = kvm_psci_vcpu_on(vcpu);
292 break;
293 default:
294 val = PSCI_RET_NOT_SUPPORTED;
295 break;
296 }
297
298 vcpu_set_reg(vcpu, 0, val);
299 return 1;
300 }
301
302 /**
303 * kvm_psci_call - handle PSCI call if r0 value is in range
304 * @vcpu: Pointer to the VCPU struct
305 *
306 * Handle PSCI calls from guests through traps from HVC instructions.
307 * The calling convention is similar to SMC calls to the secure world
308 * where the function number is placed in r0.
309 *
310 * This function returns: > 0 (success), 0 (success but exit to user
311 * space), and < 0 (errors)
312 *
313 * Errors:
314 * -EINVAL: Unrecognized PSCI function
315 */
kvm_psci_call(struct kvm_vcpu * vcpu)316 int kvm_psci_call(struct kvm_vcpu *vcpu)
317 {
318 switch (kvm_psci_version(vcpu)) {
319 case KVM_ARM_PSCI_0_2:
320 return kvm_psci_0_2_call(vcpu);
321 case KVM_ARM_PSCI_0_1:
322 return kvm_psci_0_1_call(vcpu);
323 default:
324 return -EINVAL;
325 };
326 }
327