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 #include <asm/kvm_host.h>
16 
17 #include <kvm/arm_psci.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 
smccc_get_function(struct kvm_vcpu * vcpu)26 static u32 smccc_get_function(struct kvm_vcpu *vcpu)
27 {
28 	return vcpu_get_reg(vcpu, 0);
29 }
30 
smccc_get_arg1(struct kvm_vcpu * vcpu)31 static unsigned long smccc_get_arg1(struct kvm_vcpu *vcpu)
32 {
33 	return vcpu_get_reg(vcpu, 1);
34 }
35 
smccc_get_arg2(struct kvm_vcpu * vcpu)36 static unsigned long smccc_get_arg2(struct kvm_vcpu *vcpu)
37 {
38 	return vcpu_get_reg(vcpu, 2);
39 }
40 
smccc_get_arg3(struct kvm_vcpu * vcpu)41 static unsigned long smccc_get_arg3(struct kvm_vcpu *vcpu)
42 {
43 	return vcpu_get_reg(vcpu, 3);
44 }
45 
smccc_set_retval(struct kvm_vcpu * vcpu,unsigned long a0,unsigned long a1,unsigned long a2,unsigned long a3)46 static void smccc_set_retval(struct kvm_vcpu *vcpu,
47 			     unsigned long a0,
48 			     unsigned long a1,
49 			     unsigned long a2,
50 			     unsigned long a3)
51 {
52 	vcpu_set_reg(vcpu, 0, a0);
53 	vcpu_set_reg(vcpu, 1, a1);
54 	vcpu_set_reg(vcpu, 2, a2);
55 	vcpu_set_reg(vcpu, 3, a3);
56 }
57 
psci_affinity_mask(unsigned long affinity_level)58 static unsigned long psci_affinity_mask(unsigned long affinity_level)
59 {
60 	if (affinity_level <= 3)
61 		return MPIDR_HWID_BITMASK & AFFINITY_MASK(affinity_level);
62 
63 	return 0;
64 }
65 
kvm_psci_vcpu_suspend(struct kvm_vcpu * vcpu)66 static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu)
67 {
68 	/*
69 	 * NOTE: For simplicity, we make VCPU suspend emulation to be
70 	 * same-as WFI (Wait-for-interrupt) emulation.
71 	 *
72 	 * This means for KVM the wakeup events are interrupts and
73 	 * this is consistent with intended use of StateID as described
74 	 * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A).
75 	 *
76 	 * Further, we also treat power-down request to be same as
77 	 * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2
78 	 * specification (ARM DEN 0022A). This means all suspend states
79 	 * for KVM will preserve the register state.
80 	 */
81 	kvm_vcpu_block(vcpu);
82 	kvm_clear_request(KVM_REQ_UNHALT, vcpu);
83 
84 	return PSCI_RET_SUCCESS;
85 }
86 
kvm_psci_vcpu_off(struct kvm_vcpu * vcpu)87 static void kvm_psci_vcpu_off(struct kvm_vcpu *vcpu)
88 {
89 	vcpu->arch.power_off = true;
90 	kvm_make_request(KVM_REQ_SLEEP, vcpu);
91 	kvm_vcpu_kick(vcpu);
92 }
93 
kvm_psci_vcpu_on(struct kvm_vcpu * source_vcpu)94 static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
95 {
96 	struct vcpu_reset_state *reset_state;
97 	struct kvm *kvm = source_vcpu->kvm;
98 	struct kvm_vcpu *vcpu = NULL;
99 	unsigned long cpu_id;
100 
101 	cpu_id = smccc_get_arg1(source_vcpu) & MPIDR_HWID_BITMASK;
102 	if (vcpu_mode_is_32bit(source_vcpu))
103 		cpu_id &= ~((u32) 0);
104 
105 	vcpu = kvm_mpidr_to_vcpu(kvm, cpu_id);
106 
107 	/*
108 	 * Make sure the caller requested a valid CPU and that the CPU is
109 	 * turned off.
110 	 */
111 	if (!vcpu)
112 		return PSCI_RET_INVALID_PARAMS;
113 	if (!vcpu->arch.power_off) {
114 		if (kvm_psci_version(source_vcpu, kvm) != KVM_ARM_PSCI_0_1)
115 			return PSCI_RET_ALREADY_ON;
116 		else
117 			return PSCI_RET_INVALID_PARAMS;
118 	}
119 
120 	reset_state = &vcpu->arch.reset_state;
121 
122 	reset_state->pc = smccc_get_arg2(source_vcpu);
123 
124 	/* Propagate caller endianness */
125 	reset_state->be = kvm_vcpu_is_be(source_vcpu);
126 
127 	/*
128 	 * NOTE: We always update r0 (or x0) because for PSCI v0.1
129 	 * the general puspose registers are undefined upon CPU_ON.
130 	 */
131 	reset_state->r0 = smccc_get_arg3(source_vcpu);
132 
133 	WRITE_ONCE(reset_state->reset, true);
134 	kvm_make_request(KVM_REQ_VCPU_RESET, vcpu);
135 
136 	/*
137 	 * Make sure the reset request is observed if the change to
138 	 * power_state is observed.
139 	 */
140 	smp_wmb();
141 
142 	vcpu->arch.power_off = false;
143 	kvm_vcpu_wake_up(vcpu);
144 
145 	return PSCI_RET_SUCCESS;
146 }
147 
kvm_psci_vcpu_affinity_info(struct kvm_vcpu * vcpu)148 static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
149 {
150 	int i, matching_cpus = 0;
151 	unsigned long mpidr;
152 	unsigned long target_affinity;
153 	unsigned long target_affinity_mask;
154 	unsigned long lowest_affinity_level;
155 	struct kvm *kvm = vcpu->kvm;
156 	struct kvm_vcpu *tmp;
157 
158 	target_affinity = smccc_get_arg1(vcpu);
159 	lowest_affinity_level = smccc_get_arg2(vcpu);
160 
161 	/* Determine target affinity mask */
162 	target_affinity_mask = psci_affinity_mask(lowest_affinity_level);
163 	if (!target_affinity_mask)
164 		return PSCI_RET_INVALID_PARAMS;
165 
166 	/* Ignore other bits of target affinity */
167 	target_affinity &= target_affinity_mask;
168 
169 	/*
170 	 * If one or more VCPU matching target affinity are running
171 	 * then ON else OFF
172 	 */
173 	kvm_for_each_vcpu(i, tmp, kvm) {
174 		mpidr = kvm_vcpu_get_mpidr_aff(tmp);
175 		if ((mpidr & target_affinity_mask) == target_affinity) {
176 			matching_cpus++;
177 			if (!tmp->arch.power_off)
178 				return PSCI_0_2_AFFINITY_LEVEL_ON;
179 		}
180 	}
181 
182 	if (!matching_cpus)
183 		return PSCI_RET_INVALID_PARAMS;
184 
185 	return PSCI_0_2_AFFINITY_LEVEL_OFF;
186 }
187 
kvm_prepare_system_event(struct kvm_vcpu * vcpu,u32 type)188 static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type)
189 {
190 	int i;
191 	struct kvm_vcpu *tmp;
192 
193 	/*
194 	 * The KVM ABI specifies that a system event exit may call KVM_RUN
195 	 * again and may perform shutdown/reboot at a later time that when the
196 	 * actual request is made.  Since we are implementing PSCI and a
197 	 * caller of PSCI reboot and shutdown expects that the system shuts
198 	 * down or reboots immediately, let's make sure that VCPUs are not run
199 	 * after this call is handled and before the VCPUs have been
200 	 * re-initialized.
201 	 */
202 	kvm_for_each_vcpu(i, tmp, vcpu->kvm)
203 		tmp->arch.power_off = true;
204 	kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_SLEEP);
205 
206 	memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
207 	vcpu->run->system_event.type = type;
208 	vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
209 }
210 
kvm_psci_system_off(struct kvm_vcpu * vcpu)211 static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
212 {
213 	kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN);
214 }
215 
kvm_psci_system_reset(struct kvm_vcpu * vcpu)216 static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
217 {
218 	kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET);
219 }
220 
kvm_psci_0_2_call(struct kvm_vcpu * vcpu)221 static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
222 {
223 	struct kvm *kvm = vcpu->kvm;
224 	u32 psci_fn = smccc_get_function(vcpu);
225 	unsigned long val;
226 	int ret = 1;
227 
228 	switch (psci_fn) {
229 	case PSCI_0_2_FN_PSCI_VERSION:
230 		/*
231 		 * Bits[31:16] = Major Version = 0
232 		 * Bits[15:0] = Minor Version = 2
233 		 */
234 		val = KVM_ARM_PSCI_0_2;
235 		break;
236 	case PSCI_0_2_FN_CPU_SUSPEND:
237 	case PSCI_0_2_FN64_CPU_SUSPEND:
238 		val = kvm_psci_vcpu_suspend(vcpu);
239 		break;
240 	case PSCI_0_2_FN_CPU_OFF:
241 		kvm_psci_vcpu_off(vcpu);
242 		val = PSCI_RET_SUCCESS;
243 		break;
244 	case PSCI_0_2_FN_CPU_ON:
245 	case PSCI_0_2_FN64_CPU_ON:
246 		mutex_lock(&kvm->lock);
247 		val = kvm_psci_vcpu_on(vcpu);
248 		mutex_unlock(&kvm->lock);
249 		break;
250 	case PSCI_0_2_FN_AFFINITY_INFO:
251 	case PSCI_0_2_FN64_AFFINITY_INFO:
252 		val = kvm_psci_vcpu_affinity_info(vcpu);
253 		break;
254 	case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
255 		/*
256 		 * Trusted OS is MP hence does not require migration
257 	         * or
258 		 * Trusted OS is not present
259 		 */
260 		val = PSCI_0_2_TOS_MP;
261 		break;
262 	case PSCI_0_2_FN_SYSTEM_OFF:
263 		kvm_psci_system_off(vcpu);
264 		/*
265 		 * We should'nt be going back to guest VCPU after
266 		 * receiving SYSTEM_OFF request.
267 		 *
268 		 * If user space accidently/deliberately resumes
269 		 * guest VCPU after SYSTEM_OFF request then guest
270 		 * VCPU should see internal failure from PSCI return
271 		 * value. To achieve this, we preload r0 (or x0) with
272 		 * PSCI return value INTERNAL_FAILURE.
273 		 */
274 		val = PSCI_RET_INTERNAL_FAILURE;
275 		ret = 0;
276 		break;
277 	case PSCI_0_2_FN_SYSTEM_RESET:
278 		kvm_psci_system_reset(vcpu);
279 		/*
280 		 * Same reason as SYSTEM_OFF for preloading r0 (or x0)
281 		 * with PSCI return value INTERNAL_FAILURE.
282 		 */
283 		val = PSCI_RET_INTERNAL_FAILURE;
284 		ret = 0;
285 		break;
286 	default:
287 		val = PSCI_RET_NOT_SUPPORTED;
288 		break;
289 	}
290 
291 	smccc_set_retval(vcpu, val, 0, 0, 0);
292 	return ret;
293 }
294 
kvm_psci_1_0_call(struct kvm_vcpu * vcpu)295 static int kvm_psci_1_0_call(struct kvm_vcpu *vcpu)
296 {
297 	u32 psci_fn = smccc_get_function(vcpu);
298 	u32 feature;
299 	unsigned long val;
300 	int ret = 1;
301 
302 	switch(psci_fn) {
303 	case PSCI_0_2_FN_PSCI_VERSION:
304 		val = KVM_ARM_PSCI_1_0;
305 		break;
306 	case PSCI_1_0_FN_PSCI_FEATURES:
307 		feature = smccc_get_arg1(vcpu);
308 		switch(feature) {
309 		case PSCI_0_2_FN_PSCI_VERSION:
310 		case PSCI_0_2_FN_CPU_SUSPEND:
311 		case PSCI_0_2_FN64_CPU_SUSPEND:
312 		case PSCI_0_2_FN_CPU_OFF:
313 		case PSCI_0_2_FN_CPU_ON:
314 		case PSCI_0_2_FN64_CPU_ON:
315 		case PSCI_0_2_FN_AFFINITY_INFO:
316 		case PSCI_0_2_FN64_AFFINITY_INFO:
317 		case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
318 		case PSCI_0_2_FN_SYSTEM_OFF:
319 		case PSCI_0_2_FN_SYSTEM_RESET:
320 		case PSCI_1_0_FN_PSCI_FEATURES:
321 		case ARM_SMCCC_VERSION_FUNC_ID:
322 			val = 0;
323 			break;
324 		default:
325 			val = PSCI_RET_NOT_SUPPORTED;
326 			break;
327 		}
328 		break;
329 	default:
330 		return kvm_psci_0_2_call(vcpu);
331 	}
332 
333 	smccc_set_retval(vcpu, val, 0, 0, 0);
334 	return ret;
335 }
336 
kvm_psci_0_1_call(struct kvm_vcpu * vcpu)337 static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
338 {
339 	struct kvm *kvm = vcpu->kvm;
340 	u32 psci_fn = smccc_get_function(vcpu);
341 	unsigned long val;
342 
343 	switch (psci_fn) {
344 	case KVM_PSCI_FN_CPU_OFF:
345 		kvm_psci_vcpu_off(vcpu);
346 		val = PSCI_RET_SUCCESS;
347 		break;
348 	case KVM_PSCI_FN_CPU_ON:
349 		mutex_lock(&kvm->lock);
350 		val = kvm_psci_vcpu_on(vcpu);
351 		mutex_unlock(&kvm->lock);
352 		break;
353 	default:
354 		val = PSCI_RET_NOT_SUPPORTED;
355 		break;
356 	}
357 
358 	smccc_set_retval(vcpu, val, 0, 0, 0);
359 	return 1;
360 }
361 
362 /**
363  * kvm_psci_call - handle PSCI call if r0 value is in range
364  * @vcpu: Pointer to the VCPU struct
365  *
366  * Handle PSCI calls from guests through traps from HVC instructions.
367  * The calling convention is similar to SMC calls to the secure world
368  * where the function number is placed in r0.
369  *
370  * This function returns: > 0 (success), 0 (success but exit to user
371  * space), and < 0 (errors)
372  *
373  * Errors:
374  * -EINVAL: Unrecognized PSCI function
375  */
kvm_psci_call(struct kvm_vcpu * vcpu)376 static int kvm_psci_call(struct kvm_vcpu *vcpu)
377 {
378 	switch (kvm_psci_version(vcpu, vcpu->kvm)) {
379 	case KVM_ARM_PSCI_1_0:
380 		return kvm_psci_1_0_call(vcpu);
381 	case KVM_ARM_PSCI_0_2:
382 		return kvm_psci_0_2_call(vcpu);
383 	case KVM_ARM_PSCI_0_1:
384 		return kvm_psci_0_1_call(vcpu);
385 	default:
386 		return -EINVAL;
387 	};
388 }
389 
kvm_hvc_call_handler(struct kvm_vcpu * vcpu)390 int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
391 {
392 	u32 func_id = smccc_get_function(vcpu);
393 	u32 val = SMCCC_RET_NOT_SUPPORTED;
394 	u32 feature;
395 
396 	switch (func_id) {
397 	case ARM_SMCCC_VERSION_FUNC_ID:
398 		val = ARM_SMCCC_VERSION_1_1;
399 		break;
400 	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
401 		feature = smccc_get_arg1(vcpu);
402 		switch(feature) {
403 		case ARM_SMCCC_ARCH_WORKAROUND_1:
404 			switch (kvm_arm_harden_branch_predictor()) {
405 			case KVM_BP_HARDEN_UNKNOWN:
406 				break;
407 			case KVM_BP_HARDEN_WA_NEEDED:
408 				val = SMCCC_RET_SUCCESS;
409 				break;
410 			case KVM_BP_HARDEN_NOT_REQUIRED:
411 				val = SMCCC_RET_NOT_REQUIRED;
412 				break;
413 			}
414 			break;
415 		case ARM_SMCCC_ARCH_WORKAROUND_2:
416 			switch (kvm_arm_have_ssbd()) {
417 			case KVM_SSBD_FORCE_DISABLE:
418 			case KVM_SSBD_UNKNOWN:
419 				break;
420 			case KVM_SSBD_KERNEL:
421 				val = SMCCC_RET_SUCCESS;
422 				break;
423 			case KVM_SSBD_FORCE_ENABLE:
424 			case KVM_SSBD_MITIGATED:
425 				val = SMCCC_RET_NOT_REQUIRED;
426 				break;
427 			}
428 			break;
429 		}
430 		break;
431 	default:
432 		return kvm_psci_call(vcpu);
433 	}
434 
435 	smccc_set_retval(vcpu, val, 0, 0, 0);
436 	return 1;
437 }
438 
kvm_arm_get_fw_num_regs(struct kvm_vcpu * vcpu)439 int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
440 {
441 	return 3;		/* PSCI version and two workaround registers */
442 }
443 
kvm_arm_copy_fw_reg_indices(struct kvm_vcpu * vcpu,u64 __user * uindices)444 int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
445 {
446 	if (put_user(KVM_REG_ARM_PSCI_VERSION, uindices++))
447 		return -EFAULT;
448 
449 	if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1, uindices++))
450 		return -EFAULT;
451 
452 	if (put_user(KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2, uindices++))
453 		return -EFAULT;
454 
455 	return 0;
456 }
457 
458 #define KVM_REG_FEATURE_LEVEL_WIDTH	4
459 #define KVM_REG_FEATURE_LEVEL_MASK	(BIT(KVM_REG_FEATURE_LEVEL_WIDTH) - 1)
460 
461 /*
462  * Convert the workaround level into an easy-to-compare number, where higher
463  * values mean better protection.
464  */
get_kernel_wa_level(u64 regid)465 static int get_kernel_wa_level(u64 regid)
466 {
467 	switch (regid) {
468 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
469 		switch (kvm_arm_harden_branch_predictor()) {
470 		case KVM_BP_HARDEN_UNKNOWN:
471 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
472 		case KVM_BP_HARDEN_WA_NEEDED:
473 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL;
474 		case KVM_BP_HARDEN_NOT_REQUIRED:
475 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED;
476 		}
477 		return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
478 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
479 		switch (kvm_arm_have_ssbd()) {
480 		case KVM_SSBD_FORCE_DISABLE:
481 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
482 		case KVM_SSBD_KERNEL:
483 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL;
484 		case KVM_SSBD_FORCE_ENABLE:
485 		case KVM_SSBD_MITIGATED:
486 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
487 		case KVM_SSBD_UNKNOWN:
488 		default:
489 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN;
490 		}
491 	}
492 
493 	return -EINVAL;
494 }
495 
kvm_arm_get_fw_reg(struct kvm_vcpu * vcpu,const struct kvm_one_reg * reg)496 int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
497 {
498 	void __user *uaddr = (void __user *)(long)reg->addr;
499 	u64 val;
500 
501 	switch (reg->id) {
502 	case KVM_REG_ARM_PSCI_VERSION:
503 		val = kvm_psci_version(vcpu, vcpu->kvm);
504 		break;
505 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
506 		val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
507 		break;
508 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
509 		val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
510 
511 		if (val == KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL &&
512 		    kvm_arm_get_vcpu_workaround_2_flag(vcpu))
513 			val |= KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED;
514 		break;
515 	default:
516 		return -ENOENT;
517 	}
518 
519 	if (copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)))
520 		return -EFAULT;
521 
522 	return 0;
523 }
524 
kvm_arm_set_fw_reg(struct kvm_vcpu * vcpu,const struct kvm_one_reg * reg)525 int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
526 {
527 	void __user *uaddr = (void __user *)(long)reg->addr;
528 	u64 val;
529 	int wa_level;
530 
531 	if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
532 		return -EFAULT;
533 
534 	switch (reg->id) {
535 	case KVM_REG_ARM_PSCI_VERSION:
536 	{
537 		bool wants_02;
538 
539 		wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);
540 
541 		switch (val) {
542 		case KVM_ARM_PSCI_0_1:
543 			if (wants_02)
544 				return -EINVAL;
545 			vcpu->kvm->arch.psci_version = val;
546 			return 0;
547 		case KVM_ARM_PSCI_0_2:
548 		case KVM_ARM_PSCI_1_0:
549 			if (!wants_02)
550 				return -EINVAL;
551 			vcpu->kvm->arch.psci_version = val;
552 			return 0;
553 		}
554 		break;
555 	}
556 
557 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
558 		if (val & ~KVM_REG_FEATURE_LEVEL_MASK)
559 			return -EINVAL;
560 
561 		if (get_kernel_wa_level(reg->id) < val)
562 			return -EINVAL;
563 
564 		return 0;
565 
566 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
567 		if (val & ~(KVM_REG_FEATURE_LEVEL_MASK |
568 			    KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED))
569 			return -EINVAL;
570 
571 		wa_level = val & KVM_REG_FEATURE_LEVEL_MASK;
572 
573 		if (get_kernel_wa_level(reg->id) < wa_level)
574 			return -EINVAL;
575 
576 		/* The enabled bit must not be set unless the level is AVAIL. */
577 		if (wa_level != KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL &&
578 		    wa_level != val)
579 			return -EINVAL;
580 
581 		/* Are we finished or do we need to check the enable bit ? */
582 		if (kvm_arm_have_ssbd() != KVM_SSBD_KERNEL)
583 			return 0;
584 
585 		/*
586 		 * If this kernel supports the workaround to be switched on
587 		 * or off, make sure it matches the requested setting.
588 		 */
589 		switch (wa_level) {
590 		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL:
591 			kvm_arm_set_vcpu_workaround_2_flag(vcpu,
592 			    val & KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED);
593 			break;
594 		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
595 			kvm_arm_set_vcpu_workaround_2_flag(vcpu, true);
596 			break;
597 		}
598 
599 		return 0;
600 	default:
601 		return -ENOENT;
602 	}
603 
604 	return -EINVAL;
605 }
606