xref: /openbmc/linux/arch/arm64/kvm/psci.c (revision 21bb8af5)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2012 - ARM Ltd
4  * Author: Marc Zyngier <marc.zyngier@arm.com>
5  */
6 
7 #include <linux/arm-smccc.h>
8 #include <linux/preempt.h>
9 #include <linux/kvm_host.h>
10 #include <linux/uaccess.h>
11 #include <linux/wait.h>
12 
13 #include <asm/cputype.h>
14 #include <asm/kvm_emulate.h>
15 
16 #include <kvm/arm_psci.h>
17 #include <kvm/arm_hypercalls.h>
18 
19 /*
20  * This is an implementation of the Power State Coordination Interface
21  * as described in ARM document number ARM DEN 0022A.
22  */
23 
24 #define AFFINITY_MASK(level)	~((0x1UL << ((level) * MPIDR_LEVEL_BITS)) - 1)
25 
26 static unsigned long psci_affinity_mask(unsigned long affinity_level)
27 {
28 	if (affinity_level <= 3)
29 		return MPIDR_HWID_BITMASK & AFFINITY_MASK(affinity_level);
30 
31 	return 0;
32 }
33 
34 static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu)
35 {
36 	/*
37 	 * NOTE: For simplicity, we make VCPU suspend emulation to be
38 	 * same-as WFI (Wait-for-interrupt) emulation.
39 	 *
40 	 * This means for KVM the wakeup events are interrupts and
41 	 * this is consistent with intended use of StateID as described
42 	 * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A).
43 	 *
44 	 * Further, we also treat power-down request to be same as
45 	 * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2
46 	 * specification (ARM DEN 0022A). This means all suspend states
47 	 * for KVM will preserve the register state.
48 	 */
49 	kvm_vcpu_wfi(vcpu);
50 
51 	return PSCI_RET_SUCCESS;
52 }
53 
54 static inline bool kvm_psci_valid_affinity(struct kvm_vcpu *vcpu,
55 					   unsigned long affinity)
56 {
57 	return !(affinity & ~MPIDR_HWID_BITMASK);
58 }
59 
60 static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
61 {
62 	struct vcpu_reset_state *reset_state;
63 	struct kvm *kvm = source_vcpu->kvm;
64 	struct kvm_vcpu *vcpu = NULL;
65 	unsigned long cpu_id;
66 
67 	cpu_id = smccc_get_arg1(source_vcpu);
68 	if (!kvm_psci_valid_affinity(source_vcpu, cpu_id))
69 		return PSCI_RET_INVALID_PARAMS;
70 
71 	vcpu = kvm_mpidr_to_vcpu(kvm, cpu_id);
72 
73 	/*
74 	 * Make sure the caller requested a valid CPU and that the CPU is
75 	 * turned off.
76 	 */
77 	if (!vcpu)
78 		return PSCI_RET_INVALID_PARAMS;
79 	if (!kvm_arm_vcpu_stopped(vcpu)) {
80 		if (kvm_psci_version(source_vcpu) != KVM_ARM_PSCI_0_1)
81 			return PSCI_RET_ALREADY_ON;
82 		else
83 			return PSCI_RET_INVALID_PARAMS;
84 	}
85 
86 	reset_state = &vcpu->arch.reset_state;
87 
88 	reset_state->pc = smccc_get_arg2(source_vcpu);
89 
90 	/* Propagate caller endianness */
91 	reset_state->be = kvm_vcpu_is_be(source_vcpu);
92 
93 	/*
94 	 * NOTE: We always update r0 (or x0) because for PSCI v0.1
95 	 * the general purpose registers are undefined upon CPU_ON.
96 	 */
97 	reset_state->r0 = smccc_get_arg3(source_vcpu);
98 
99 	WRITE_ONCE(reset_state->reset, true);
100 	kvm_make_request(KVM_REQ_VCPU_RESET, vcpu);
101 
102 	/*
103 	 * Make sure the reset request is observed if the RUNNABLE mp_state is
104 	 * observed.
105 	 */
106 	smp_wmb();
107 
108 	vcpu->arch.mp_state.mp_state = KVM_MP_STATE_RUNNABLE;
109 	kvm_vcpu_wake_up(vcpu);
110 
111 	return PSCI_RET_SUCCESS;
112 }
113 
114 static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
115 {
116 	int matching_cpus = 0;
117 	unsigned long i, mpidr;
118 	unsigned long target_affinity;
119 	unsigned long target_affinity_mask;
120 	unsigned long lowest_affinity_level;
121 	struct kvm *kvm = vcpu->kvm;
122 	struct kvm_vcpu *tmp;
123 
124 	target_affinity = smccc_get_arg1(vcpu);
125 	lowest_affinity_level = smccc_get_arg2(vcpu);
126 
127 	if (!kvm_psci_valid_affinity(vcpu, target_affinity))
128 		return PSCI_RET_INVALID_PARAMS;
129 
130 	/* Determine target affinity mask */
131 	target_affinity_mask = psci_affinity_mask(lowest_affinity_level);
132 	if (!target_affinity_mask)
133 		return PSCI_RET_INVALID_PARAMS;
134 
135 	/* Ignore other bits of target affinity */
136 	target_affinity &= target_affinity_mask;
137 
138 	/*
139 	 * If one or more VCPU matching target affinity are running
140 	 * then ON else OFF
141 	 */
142 	kvm_for_each_vcpu(i, tmp, kvm) {
143 		mpidr = kvm_vcpu_get_mpidr_aff(tmp);
144 		if ((mpidr & target_affinity_mask) == target_affinity) {
145 			matching_cpus++;
146 			if (!kvm_arm_vcpu_stopped(tmp))
147 				return PSCI_0_2_AFFINITY_LEVEL_ON;
148 		}
149 	}
150 
151 	if (!matching_cpus)
152 		return PSCI_RET_INVALID_PARAMS;
153 
154 	return PSCI_0_2_AFFINITY_LEVEL_OFF;
155 }
156 
157 static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type, u64 flags)
158 {
159 	unsigned long i;
160 	struct kvm_vcpu *tmp;
161 
162 	/*
163 	 * The KVM ABI specifies that a system event exit may call KVM_RUN
164 	 * again and may perform shutdown/reboot at a later time that when the
165 	 * actual request is made.  Since we are implementing PSCI and a
166 	 * caller of PSCI reboot and shutdown expects that the system shuts
167 	 * down or reboots immediately, let's make sure that VCPUs are not run
168 	 * after this call is handled and before the VCPUs have been
169 	 * re-initialized.
170 	 */
171 	kvm_for_each_vcpu(i, tmp, vcpu->kvm)
172 		tmp->arch.mp_state.mp_state = KVM_MP_STATE_STOPPED;
173 	kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_SLEEP);
174 
175 	memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
176 	vcpu->run->system_event.type = type;
177 	vcpu->run->system_event.ndata = 1;
178 	vcpu->run->system_event.data[0] = flags;
179 	vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
180 }
181 
182 static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
183 {
184 	kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN, 0);
185 }
186 
187 static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
188 {
189 	kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET, 0);
190 }
191 
192 static void kvm_psci_system_reset2(struct kvm_vcpu *vcpu)
193 {
194 	kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET,
195 				 KVM_SYSTEM_EVENT_RESET_FLAG_PSCI_RESET2);
196 }
197 
198 static void kvm_psci_system_suspend(struct kvm_vcpu *vcpu)
199 {
200 	struct kvm_run *run = vcpu->run;
201 
202 	memset(&run->system_event, 0, sizeof(vcpu->run->system_event));
203 	run->system_event.type = KVM_SYSTEM_EVENT_SUSPEND;
204 	run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
205 }
206 
207 static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
208 {
209 	int i;
210 
211 	/*
212 	 * Zero the input registers' upper 32 bits. They will be fully
213 	 * zeroed on exit, so we're fine changing them in place.
214 	 */
215 	for (i = 1; i < 4; i++)
216 		vcpu_set_reg(vcpu, i, lower_32_bits(vcpu_get_reg(vcpu, i)));
217 }
218 
219 static unsigned long kvm_psci_check_allowed_function(struct kvm_vcpu *vcpu, u32 fn)
220 {
221 	/*
222 	 * Prevent 32 bit guests from calling 64 bit PSCI functions.
223 	 */
224 	if ((fn & PSCI_0_2_64BIT) && vcpu_mode_is_32bit(vcpu))
225 		return PSCI_RET_NOT_SUPPORTED;
226 
227 	return 0;
228 }
229 
230 static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
231 {
232 	struct kvm *kvm = vcpu->kvm;
233 	u32 psci_fn = smccc_get_function(vcpu);
234 	unsigned long val;
235 	int ret = 1;
236 
237 	switch (psci_fn) {
238 	case PSCI_0_2_FN_PSCI_VERSION:
239 		/*
240 		 * Bits[31:16] = Major Version = 0
241 		 * Bits[15:0] = Minor Version = 2
242 		 */
243 		val = KVM_ARM_PSCI_0_2;
244 		break;
245 	case PSCI_0_2_FN_CPU_SUSPEND:
246 	case PSCI_0_2_FN64_CPU_SUSPEND:
247 		val = kvm_psci_vcpu_suspend(vcpu);
248 		break;
249 	case PSCI_0_2_FN_CPU_OFF:
250 		kvm_arm_vcpu_power_off(vcpu);
251 		val = PSCI_RET_SUCCESS;
252 		break;
253 	case PSCI_0_2_FN_CPU_ON:
254 		kvm_psci_narrow_to_32bit(vcpu);
255 		fallthrough;
256 	case PSCI_0_2_FN64_CPU_ON:
257 		mutex_lock(&kvm->lock);
258 		val = kvm_psci_vcpu_on(vcpu);
259 		mutex_unlock(&kvm->lock);
260 		break;
261 	case PSCI_0_2_FN_AFFINITY_INFO:
262 		kvm_psci_narrow_to_32bit(vcpu);
263 		fallthrough;
264 	case PSCI_0_2_FN64_AFFINITY_INFO:
265 		val = kvm_psci_vcpu_affinity_info(vcpu);
266 		break;
267 	case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
268 		/*
269 		 * Trusted OS is MP hence does not require migration
270 	         * or
271 		 * Trusted OS is not present
272 		 */
273 		val = PSCI_0_2_TOS_MP;
274 		break;
275 	case PSCI_0_2_FN_SYSTEM_OFF:
276 		kvm_psci_system_off(vcpu);
277 		/*
278 		 * We shouldn't be going back to guest VCPU after
279 		 * receiving SYSTEM_OFF request.
280 		 *
281 		 * If user space accidentally/deliberately resumes
282 		 * guest VCPU after SYSTEM_OFF request then guest
283 		 * VCPU should see internal failure from PSCI return
284 		 * value. To achieve this, we preload r0 (or x0) with
285 		 * PSCI return value INTERNAL_FAILURE.
286 		 */
287 		val = PSCI_RET_INTERNAL_FAILURE;
288 		ret = 0;
289 		break;
290 	case PSCI_0_2_FN_SYSTEM_RESET:
291 		kvm_psci_system_reset(vcpu);
292 		/*
293 		 * Same reason as SYSTEM_OFF for preloading r0 (or x0)
294 		 * with PSCI return value INTERNAL_FAILURE.
295 		 */
296 		val = PSCI_RET_INTERNAL_FAILURE;
297 		ret = 0;
298 		break;
299 	default:
300 		val = PSCI_RET_NOT_SUPPORTED;
301 		break;
302 	}
303 
304 	smccc_set_retval(vcpu, val, 0, 0, 0);
305 	return ret;
306 }
307 
308 static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor)
309 {
310 	unsigned long val = PSCI_RET_NOT_SUPPORTED;
311 	u32 psci_fn = smccc_get_function(vcpu);
312 	struct kvm *kvm = vcpu->kvm;
313 	u32 arg;
314 	int ret = 1;
315 
316 	switch(psci_fn) {
317 	case PSCI_0_2_FN_PSCI_VERSION:
318 		val = minor == 0 ? KVM_ARM_PSCI_1_0 : KVM_ARM_PSCI_1_1;
319 		break;
320 	case PSCI_1_0_FN_PSCI_FEATURES:
321 		arg = smccc_get_arg1(vcpu);
322 		val = kvm_psci_check_allowed_function(vcpu, arg);
323 		if (val)
324 			break;
325 
326 		val = PSCI_RET_NOT_SUPPORTED;
327 
328 		switch(arg) {
329 		case PSCI_0_2_FN_PSCI_VERSION:
330 		case PSCI_0_2_FN_CPU_SUSPEND:
331 		case PSCI_0_2_FN64_CPU_SUSPEND:
332 		case PSCI_0_2_FN_CPU_OFF:
333 		case PSCI_0_2_FN_CPU_ON:
334 		case PSCI_0_2_FN64_CPU_ON:
335 		case PSCI_0_2_FN_AFFINITY_INFO:
336 		case PSCI_0_2_FN64_AFFINITY_INFO:
337 		case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
338 		case PSCI_0_2_FN_SYSTEM_OFF:
339 		case PSCI_0_2_FN_SYSTEM_RESET:
340 		case PSCI_1_0_FN_PSCI_FEATURES:
341 		case ARM_SMCCC_VERSION_FUNC_ID:
342 			val = 0;
343 			break;
344 		case PSCI_1_0_FN_SYSTEM_SUSPEND:
345 		case PSCI_1_0_FN64_SYSTEM_SUSPEND:
346 			if (test_bit(KVM_ARCH_FLAG_SYSTEM_SUSPEND_ENABLED, &kvm->arch.flags))
347 				val = 0;
348 			break;
349 		case PSCI_1_1_FN_SYSTEM_RESET2:
350 		case PSCI_1_1_FN64_SYSTEM_RESET2:
351 			if (minor >= 1)
352 				val = 0;
353 			break;
354 		}
355 		break;
356 	case PSCI_1_0_FN_SYSTEM_SUSPEND:
357 		kvm_psci_narrow_to_32bit(vcpu);
358 		fallthrough;
359 	case PSCI_1_0_FN64_SYSTEM_SUSPEND:
360 		/*
361 		 * Return directly to userspace without changing the vCPU's
362 		 * registers. Userspace depends on reading the SMCCC parameters
363 		 * to implement SYSTEM_SUSPEND.
364 		 */
365 		if (test_bit(KVM_ARCH_FLAG_SYSTEM_SUSPEND_ENABLED, &kvm->arch.flags)) {
366 			kvm_psci_system_suspend(vcpu);
367 			return 0;
368 		}
369 		break;
370 	case PSCI_1_1_FN_SYSTEM_RESET2:
371 		kvm_psci_narrow_to_32bit(vcpu);
372 		fallthrough;
373 	case PSCI_1_1_FN64_SYSTEM_RESET2:
374 		if (minor >= 1) {
375 			arg = smccc_get_arg1(vcpu);
376 
377 			if (arg <= PSCI_1_1_RESET_TYPE_SYSTEM_WARM_RESET ||
378 			    arg >= PSCI_1_1_RESET_TYPE_VENDOR_START) {
379 				kvm_psci_system_reset2(vcpu);
380 				vcpu_set_reg(vcpu, 0, PSCI_RET_INTERNAL_FAILURE);
381 				return 0;
382 			}
383 
384 			val = PSCI_RET_INVALID_PARAMS;
385 			break;
386 		}
387 		break;
388 	default:
389 		return kvm_psci_0_2_call(vcpu);
390 	}
391 
392 	smccc_set_retval(vcpu, val, 0, 0, 0);
393 	return ret;
394 }
395 
396 static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
397 {
398 	struct kvm *kvm = vcpu->kvm;
399 	u32 psci_fn = smccc_get_function(vcpu);
400 	unsigned long val;
401 
402 	switch (psci_fn) {
403 	case KVM_PSCI_FN_CPU_OFF:
404 		kvm_arm_vcpu_power_off(vcpu);
405 		val = PSCI_RET_SUCCESS;
406 		break;
407 	case KVM_PSCI_FN_CPU_ON:
408 		mutex_lock(&kvm->lock);
409 		val = kvm_psci_vcpu_on(vcpu);
410 		mutex_unlock(&kvm->lock);
411 		break;
412 	default:
413 		val = PSCI_RET_NOT_SUPPORTED;
414 		break;
415 	}
416 
417 	smccc_set_retval(vcpu, val, 0, 0, 0);
418 	return 1;
419 }
420 
421 /**
422  * kvm_psci_call - handle PSCI call if r0 value is in range
423  * @vcpu: Pointer to the VCPU struct
424  *
425  * Handle PSCI calls from guests through traps from HVC instructions.
426  * The calling convention is similar to SMC calls to the secure world
427  * where the function number is placed in r0.
428  *
429  * This function returns: > 0 (success), 0 (success but exit to user
430  * space), and < 0 (errors)
431  *
432  * Errors:
433  * -EINVAL: Unrecognized PSCI function
434  */
435 int kvm_psci_call(struct kvm_vcpu *vcpu)
436 {
437 	u32 psci_fn = smccc_get_function(vcpu);
438 	unsigned long val;
439 
440 	val = kvm_psci_check_allowed_function(vcpu, psci_fn);
441 	if (val) {
442 		smccc_set_retval(vcpu, val, 0, 0, 0);
443 		return 1;
444 	}
445 
446 	switch (kvm_psci_version(vcpu)) {
447 	case KVM_ARM_PSCI_1_1:
448 		return kvm_psci_1_x_call(vcpu, 1);
449 	case KVM_ARM_PSCI_1_0:
450 		return kvm_psci_1_x_call(vcpu, 0);
451 	case KVM_ARM_PSCI_0_2:
452 		return kvm_psci_0_2_call(vcpu);
453 	case KVM_ARM_PSCI_0_1:
454 		return kvm_psci_0_1_call(vcpu);
455 	default:
456 		return -EINVAL;
457 	}
458 }
459