arch/arm64/kvm/hypercalls.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 // Copyright (C) 2019 Arm Ltd.

 #include <linux/arm-smccc.h>
 #include <linux/kvm_host.h>

 #include <asm/kvm_emulate.h>

 #include <kvm/arm_hypercalls.h>
 #include <kvm/arm_psci.h>

 #define KVM_ARM_SMCCC_STD_FEATURES				\
 	GENMASK(KVM_REG_ARM_STD_BMAP_BIT_COUNT - 1, 0)
 #define KVM_ARM_SMCCC_STD_HYP_FEATURES				\
 	GENMASK(KVM_REG_ARM_STD_HYP_BMAP_BIT_COUNT - 1, 0)
 #define KVM_ARM_SMCCC_VENDOR_HYP_FEATURES			\
 	GENMASK(KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_COUNT - 1, 0)

 static void kvm_ptp_get_time(struct kvm_vcpu *vcpu, u64 *val)
 {
 	struct system_time_snapshot systime_snapshot;
 	u64 cycles = ~0UL;
 	u32 feature;

 	/*
 	 * system time and counter value must captured at the same
 	 * time to keep consistency and precision.
 	 */
 	ktime_get_snapshot(&systime_snapshot);

 	/*
 	 * This is only valid if the current clocksource is the
 	 * architected counter, as this is the only one the guest
 	 * can see.
 	 */
 	if (systime_snapshot.cs_id != CSID_ARM_ARCH_COUNTER)
 		return;

 	/*
 	 * The guest selects one of the two reference counters
 	 * (virtual or physical) with the first argument of the SMCCC
 	 * call. In case the identifier is not supported, error out.
 	 */
 	feature = smccc_get_arg1(vcpu);
 	switch (feature) {
 	case KVM_PTP_VIRT_COUNTER:
 		cycles = systime_snapshot.cycles - vcpu->kvm->arch.timer_data.voffset;
 		break;
 	case KVM_PTP_PHYS_COUNTER:
 		cycles = systime_snapshot.cycles - vcpu->kvm->arch.timer_data.poffset;
 		break;
 	default:
 		return;
 	}

 	/*
 	 * This relies on the top bit of val[0] never being set for
 	 * valid values of system time, because that is *really* far
 	 * in the future (about 292 years from 1970, and at that stage
 	 * nobody will give a damn about it).
 	 */
 	val[0] = upper_32_bits(systime_snapshot.real);
 	val[1] = lower_32_bits(systime_snapshot.real);
 	val[2] = upper_32_bits(cycles);
 	val[3] = lower_32_bits(cycles);
 }

 static bool kvm_smccc_default_allowed(u32 func_id)
 {
 	switch (func_id) {
 	/*
 	 * List of function-ids that are not gated with the bitmapped
 	 * feature firmware registers, and are to be allowed for
 	 * servicing the call by default.
 	 */
 	case ARM_SMCCC_VERSION_FUNC_ID:
 	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
 		return true;
 	default:
 		/* PSCI 0.2 and up is in the 0:0x1f range */
 		if (ARM_SMCCC_OWNER_NUM(func_id) == ARM_SMCCC_OWNER_STANDARD &&
 		    ARM_SMCCC_FUNC_NUM(func_id) <= 0x1f)
 			return true;

 		/*
 		 * KVM's PSCI 0.1 doesn't comply with SMCCC, and has
 		 * its own function-id base and range
 		 */
 		if (func_id >= KVM_PSCI_FN(0) && func_id <= KVM_PSCI_FN(3))
 			return true;

 		return false;
 	}
 }

 static bool kvm_smccc_test_fw_bmap(struct kvm_vcpu *vcpu, u32 func_id)
 {
 	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;

 	switch (func_id) {
 	case ARM_SMCCC_TRNG_VERSION:
 	case ARM_SMCCC_TRNG_FEATURES:
 	case ARM_SMCCC_TRNG_GET_UUID:
 	case ARM_SMCCC_TRNG_RND32:
 	case ARM_SMCCC_TRNG_RND64:
 		return test_bit(KVM_REG_ARM_STD_BIT_TRNG_V1_0,
 				&smccc_feat->std_bmap);
 	case ARM_SMCCC_HV_PV_TIME_FEATURES:
 	case ARM_SMCCC_HV_PV_TIME_ST:
 		return test_bit(KVM_REG_ARM_STD_HYP_BIT_PV_TIME,
 				&smccc_feat->std_hyp_bmap);
 	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
 	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
 		return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT,
 				&smccc_feat->vendor_hyp_bmap);
 	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
 		return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_PTP,
 				&smccc_feat->vendor_hyp_bmap);
 	default:
 		return false;
 	}
 }

 #define SMC32_ARCH_RANGE_BEGIN	ARM_SMCCC_VERSION_FUNC_ID
 #define SMC32_ARCH_RANGE_END	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,		\
 						   ARM_SMCCC_SMC_32,		\
 						   0, ARM_SMCCC_FUNC_MASK)

 #define SMC64_ARCH_RANGE_BEGIN	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,		\
 						   ARM_SMCCC_SMC_64,		\
 						   0, 0)
 #define SMC64_ARCH_RANGE_END	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,		\
 						   ARM_SMCCC_SMC_64,		\
 						   0, ARM_SMCCC_FUNC_MASK)

 static void init_smccc_filter(struct kvm *kvm)
 {
 	int r;

 	mt_init(&kvm->arch.smccc_filter);

 	/*
 	 * Prevent userspace from handling any SMCCC calls in the architecture
 	 * range, avoiding the risk of misrepresenting Spectre mitigation status
 	 * to the guest.
 	 */
 	r = mtree_insert_range(&kvm->arch.smccc_filter,
 			       SMC32_ARCH_RANGE_BEGIN, SMC32_ARCH_RANGE_END,
 			       xa_mk_value(KVM_SMCCC_FILTER_HANDLE),
 			       GFP_KERNEL_ACCOUNT);
 	WARN_ON_ONCE(r);

 	r = mtree_insert_range(&kvm->arch.smccc_filter,
 			       SMC64_ARCH_RANGE_BEGIN, SMC64_ARCH_RANGE_END,
 			       xa_mk_value(KVM_SMCCC_FILTER_HANDLE),
 			       GFP_KERNEL_ACCOUNT);
 	WARN_ON_ONCE(r);

 }

 static int kvm_smccc_set_filter(struct kvm *kvm, struct kvm_smccc_filter __user *uaddr)
 {
 	const void *zero_page = page_to_virt(ZERO_PAGE(0));
 	struct kvm_smccc_filter filter;
 	u32 start, end;
 	int r;

 	if (copy_from_user(&filter, uaddr, sizeof(filter)))
 		return -EFAULT;

 	if (memcmp(filter.pad, zero_page, sizeof(filter.pad)))
 		return -EINVAL;

 	start = filter.base;
 	end = start + filter.nr_functions - 1;

 	if (end < start || filter.action >= NR_SMCCC_FILTER_ACTIONS)
 		return -EINVAL;

 	mutex_lock(&kvm->arch.config_lock);

 	if (kvm_vm_has_ran_once(kvm)) {
 		r = -EBUSY;
 		goto out_unlock;
 	}

 	r = mtree_insert_range(&kvm->arch.smccc_filter, start, end,
 			       xa_mk_value(filter.action), GFP_KERNEL_ACCOUNT);
 	if (r)
 		goto out_unlock;

 	set_bit(KVM_ARCH_FLAG_SMCCC_FILTER_CONFIGURED, &kvm->arch.flags);

 out_unlock:
 	mutex_unlock(&kvm->arch.config_lock);
 	return r;
 }

 static u8 kvm_smccc_filter_get_action(struct kvm *kvm, u32 func_id)
 {
 	unsigned long idx = func_id;
 	void *val;

 	if (!test_bit(KVM_ARCH_FLAG_SMCCC_FILTER_CONFIGURED, &kvm->arch.flags))
 		return KVM_SMCCC_FILTER_HANDLE;

 	/*
 	 * But where's the error handling, you say?
 	 *
 	 * mt_find() returns NULL if no entry was found, which just so happens
 	 * to match KVM_SMCCC_FILTER_HANDLE.
 	 */
 	val = mt_find(&kvm->arch.smccc_filter, &idx, idx);
 	return xa_to_value(val);
 }

 static u8 kvm_smccc_get_action(struct kvm_vcpu *vcpu, u32 func_id)
 {
 	/*
 	 * Intervening actions in the SMCCC filter take precedence over the
 	 * pseudo-firmware register bitmaps.
 	 */
 	u8 action = kvm_smccc_filter_get_action(vcpu->kvm, func_id);
 	if (action != KVM_SMCCC_FILTER_HANDLE)
 		return action;

 	if (kvm_smccc_test_fw_bmap(vcpu, func_id) ||
 	    kvm_smccc_default_allowed(func_id))
 		return KVM_SMCCC_FILTER_HANDLE;

 	return KVM_SMCCC_FILTER_DENY;
 }

 static void kvm_prepare_hypercall_exit(struct kvm_vcpu *vcpu, u32 func_id)
 {
 	u8 ec = ESR_ELx_EC(kvm_vcpu_get_esr(vcpu));
 	struct kvm_run *run = vcpu->run;
 	u64 flags = 0;

 	if (ec == ESR_ELx_EC_SMC32 || ec == ESR_ELx_EC_SMC64)
 		flags |= KVM_HYPERCALL_EXIT_SMC;

 	if (!kvm_vcpu_trap_il_is32bit(vcpu))
 		flags |= KVM_HYPERCALL_EXIT_16BIT;

 	run->exit_reason = KVM_EXIT_HYPERCALL;
 	run->hypercall = (typeof(run->hypercall)) {
 		.nr	= func_id,
 		.flags	= flags,
 	};
 }

 int kvm_smccc_call_handler(struct kvm_vcpu *vcpu)
 {
 	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
 	u32 func_id = smccc_get_function(vcpu);
 	u64 val[4] = {SMCCC_RET_NOT_SUPPORTED};
 	u32 feature;
 	u8 action;
 	gpa_t gpa;

 	action = kvm_smccc_get_action(vcpu, func_id);
 	switch (action) {
 	case KVM_SMCCC_FILTER_HANDLE:
 		break;
 	case KVM_SMCCC_FILTER_DENY:
 		goto out;
 	case KVM_SMCCC_FILTER_FWD_TO_USER:
 		kvm_prepare_hypercall_exit(vcpu, func_id);
 		return 0;
 	default:
 		WARN_RATELIMIT(1, "Unhandled SMCCC filter action: %d\n", action);
 		goto out;
 	}

 	switch (func_id) {
 	case ARM_SMCCC_VERSION_FUNC_ID:
 		val[0] = ARM_SMCCC_VERSION_1_1;
 		break;
 	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
 		feature = smccc_get_arg1(vcpu);
 		switch (feature) {
 		case ARM_SMCCC_ARCH_WORKAROUND_1:
 			switch (arm64_get_spectre_v2_state()) {
 			case SPECTRE_VULNERABLE:
 				break;
 			case SPECTRE_MITIGATED:
 				val[0] = SMCCC_RET_SUCCESS;
 				break;
 			case SPECTRE_UNAFFECTED:
 				val[0] = SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED;
 				break;
 			}
 			break;
 		case ARM_SMCCC_ARCH_WORKAROUND_2:
 			switch (arm64_get_spectre_v4_state()) {
 			case SPECTRE_VULNERABLE:
 				break;
 			case SPECTRE_MITIGATED:
 				/*
 				 * SSBS everywhere: Indicate no firmware
 				 * support, as the SSBS support will be
 				 * indicated to the guest and the default is
 				 * safe.
 				 *
 				 * Otherwise, expose a permanent mitigation
 				 * to the guest, and hide SSBS so that the
 				 * guest stays protected.
 				 */
 				if (cpus_have_final_cap(ARM64_SSBS))
 					break;
 				fallthrough;
 			case SPECTRE_UNAFFECTED:
 				val[0] = SMCCC_RET_NOT_REQUIRED;
 				break;
 			}
 			break;
 		case ARM_SMCCC_ARCH_WORKAROUND_3:
 			switch (arm64_get_spectre_bhb_state()) {
 			case SPECTRE_VULNERABLE:
 				break;
 			case SPECTRE_MITIGATED:
 				val[0] = SMCCC_RET_SUCCESS;
 				break;
 			case SPECTRE_UNAFFECTED:
 				val[0] = SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED;
 				break;
 			}
 			break;
 		case ARM_SMCCC_HV_PV_TIME_FEATURES:
 			if (test_bit(KVM_REG_ARM_STD_HYP_BIT_PV_TIME,
 				     &smccc_feat->std_hyp_bmap))
 				val[0] = SMCCC_RET_SUCCESS;
 			break;
 		}
 		break;
 	case ARM_SMCCC_HV_PV_TIME_FEATURES:
 		val[0] = kvm_hypercall_pv_features(vcpu);
 		break;
 	case ARM_SMCCC_HV_PV_TIME_ST:
 		gpa = kvm_init_stolen_time(vcpu);
 		if (gpa != INVALID_GPA)
 			val[0] = gpa;
 		break;
 	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
 		val[0] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0;
 		val[1] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1;
 		val[2] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_2;
 		val[3] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3;
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
 		val[0] = smccc_feat->vendor_hyp_bmap;
 		break;
 	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
 		kvm_ptp_get_time(vcpu, val);
 		break;
 	case ARM_SMCCC_TRNG_VERSION:
 	case ARM_SMCCC_TRNG_FEATURES:
 	case ARM_SMCCC_TRNG_GET_UUID:
 	case ARM_SMCCC_TRNG_RND32:
 	case ARM_SMCCC_TRNG_RND64:
 		return kvm_trng_call(vcpu);
 	default:
 		return kvm_psci_call(vcpu);
 	}

 out:
 	smccc_set_retval(vcpu, val[0], val[1], val[2], val[3]);
 	return 1;
 }

 static const u64 kvm_arm_fw_reg_ids[] = {
 	KVM_REG_ARM_PSCI_VERSION,
 	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
 	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
 	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
 	KVM_REG_ARM_STD_BMAP,
 	KVM_REG_ARM_STD_HYP_BMAP,
 	KVM_REG_ARM_VENDOR_HYP_BMAP,
 };

 void kvm_arm_init_hypercalls(struct kvm *kvm)
 {
 	struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;

 	smccc_feat->std_bmap = KVM_ARM_SMCCC_STD_FEATURES;
 	smccc_feat->std_hyp_bmap = KVM_ARM_SMCCC_STD_HYP_FEATURES;
 	smccc_feat->vendor_hyp_bmap = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES;

 	init_smccc_filter(kvm);
 }

 void kvm_arm_teardown_hypercalls(struct kvm *kvm)
 {
 	mtree_destroy(&kvm->arch.smccc_filter);
 }

 int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
 {
 	return ARRAY_SIZE(kvm_arm_fw_reg_ids);
 }

 int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
 {
 	int i;

 	for (i = 0; i < ARRAY_SIZE(kvm_arm_fw_reg_ids); i++) {
 		if (put_user(kvm_arm_fw_reg_ids[i], uindices++))
 			return -EFAULT;
 	}

 	return 0;
 }

 #define KVM_REG_FEATURE_LEVEL_MASK	GENMASK(3, 0)

 /*
  * Convert the workaround level into an easy-to-compare number, where higher
  * values mean better protection.
  */
 static int get_kernel_wa_level(u64 regid)
 {
 	switch (regid) {
 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
 		switch (arm64_get_spectre_v2_state()) {
 		case SPECTRE_VULNERABLE:
 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
 		case SPECTRE_MITIGATED:
 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL;
 		case SPECTRE_UNAFFECTED:
 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED;
 		}
 		return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
 		switch (arm64_get_spectre_v4_state()) {
 		case SPECTRE_MITIGATED:
 			/*
 			 * As for the hypercall discovery, we pretend we
 			 * don't have any FW mitigation if SSBS is there at
 			 * all times.
 			 */
 			if (cpus_have_final_cap(ARM64_SSBS))
 				return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
 			fallthrough;
 		case SPECTRE_UNAFFECTED:
 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
 		case SPECTRE_VULNERABLE:
 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
 		}
 		break;
 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
 		switch (arm64_get_spectre_bhb_state()) {
 		case SPECTRE_VULNERABLE:
 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
 		case SPECTRE_MITIGATED:
 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_AVAIL;
 		case SPECTRE_UNAFFECTED:
 			return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_REQUIRED;
 		}
 		return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
 	}

 	return -EINVAL;
 }

 int kvm_arm_get_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 {
 	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
 	void __user *uaddr = (void __user *)(long)reg->addr;
 	u64 val;

 	switch (reg->id) {
 	case KVM_REG_ARM_PSCI_VERSION:
 		val = kvm_psci_version(vcpu);
 		break;
 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
 		val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
 		break;
 	case KVM_REG_ARM_STD_BMAP:
 		val = READ_ONCE(smccc_feat->std_bmap);
 		break;
 	case KVM_REG_ARM_STD_HYP_BMAP:
 		val = READ_ONCE(smccc_feat->std_hyp_bmap);
 		break;
 	case KVM_REG_ARM_VENDOR_HYP_BMAP:
 		val = READ_ONCE(smccc_feat->vendor_hyp_bmap);
 		break;
 	default:
 		return -ENOENT;
 	}

 	if (copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)))
 		return -EFAULT;

 	return 0;
 }

 static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
 {
 	int ret = 0;
 	struct kvm *kvm = vcpu->kvm;
 	struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;
 	unsigned long *fw_reg_bmap, fw_reg_features;

 	switch (reg_id) {
 	case KVM_REG_ARM_STD_BMAP:
 		fw_reg_bmap = &smccc_feat->std_bmap;
 		fw_reg_features = KVM_ARM_SMCCC_STD_FEATURES;
 		break;
 	case KVM_REG_ARM_STD_HYP_BMAP:
 		fw_reg_bmap = &smccc_feat->std_hyp_bmap;
 		fw_reg_features = KVM_ARM_SMCCC_STD_HYP_FEATURES;
 		break;
 	case KVM_REG_ARM_VENDOR_HYP_BMAP:
 		fw_reg_bmap = &smccc_feat->vendor_hyp_bmap;
 		fw_reg_features = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES;
 		break;
 	default:
 		return -ENOENT;
 	}

 	/* Check for unsupported bit */
 	if (val & ~fw_reg_features)
 		return -EINVAL;

 	mutex_lock(&kvm->arch.config_lock);

 	if (kvm_vm_has_ran_once(kvm) && val != *fw_reg_bmap) {
 		ret = -EBUSY;
 		goto out;
 	}

 	WRITE_ONCE(*fw_reg_bmap, val);
 out:
 	mutex_unlock(&kvm->arch.config_lock);
 	return ret;
 }

 int kvm_arm_set_fw_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 {
 	void __user *uaddr = (void __user *)(long)reg->addr;
 	u64 val;
 	int wa_level;

 	if (KVM_REG_SIZE(reg->id) != sizeof(val))
 		return -ENOENT;
 	if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
 		return -EFAULT;

 	switch (reg->id) {
 	case KVM_REG_ARM_PSCI_VERSION:
 	{
 		bool wants_02;

 		wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);

 		switch (val) {
 		case KVM_ARM_PSCI_0_1:
 			if (wants_02)
 				return -EINVAL;
 			vcpu->kvm->arch.psci_version = val;
 			return 0;
 		case KVM_ARM_PSCI_0_2:
 		case KVM_ARM_PSCI_1_0:
 		case KVM_ARM_PSCI_1_1:
 			if (!wants_02)
 				return -EINVAL;
 			vcpu->kvm->arch.psci_version = val;
 			return 0;
 		}
 		break;
 	}

 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
 		if (val & ~KVM_REG_FEATURE_LEVEL_MASK)
 			return -EINVAL;

 		if (get_kernel_wa_level(reg->id) < val)
 			return -EINVAL;

 		return 0;

 	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
 		if (val & ~(KVM_REG_FEATURE_LEVEL_MASK |
 			    KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED))
 			return -EINVAL;

 		/* The enabled bit must not be set unless the level is AVAIL. */
 		if ((val & KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED) &&
 		    (val & KVM_REG_FEATURE_LEVEL_MASK) != KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL)
 			return -EINVAL;

 		/*
 		 * Map all the possible incoming states to the only two we
 		 * really want to deal with.
 		 */
 		switch (val & KVM_REG_FEATURE_LEVEL_MASK) {
 		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL:
 		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN:
 			wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
 			break;
 		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL:
 		case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
 			wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
 			break;
 		default:
 			return -EINVAL;
 		}

 		/*
 		 * We can deal with NOT_AVAIL on NOT_REQUIRED, but not the
 		 * other way around.
 		 */
 		if (get_kernel_wa_level(reg->id) < wa_level)
 			return -EINVAL;

 		return 0;
 	case KVM_REG_ARM_STD_BMAP:
 	case KVM_REG_ARM_STD_HYP_BMAP:
 	case KVM_REG_ARM_VENDOR_HYP_BMAP:
 		return kvm_arm_set_fw_reg_bmap(vcpu, reg->id, val);
 	default:
 		return -ENOENT;
 	}

 	return -EINVAL;
 }

 int kvm_vm_smccc_has_attr(struct kvm *kvm, struct kvm_device_attr *attr)
 {
 	switch (attr->attr) {
 	case KVM_ARM_VM_SMCCC_FILTER:
 		return 0;
 	default:
 		return -ENXIO;
 	}
 }

 int kvm_vm_smccc_set_attr(struct kvm *kvm, struct kvm_device_attr *attr)
 {
 	void __user *uaddr = (void __user *)attr->addr;

 	switch (attr->attr) {
 	case KVM_ARM_VM_SMCCC_FILTER:
 		return kvm_smccc_set_filter(kvm, uaddr);
 	default:
 		return -ENXIO;
 	}
 }
	// SPDX-License-Identifier: GPL-2.0
	// Copyright (C) 2019 Arm Ltd.

	#include <linux/arm-smccc.h>
	#include <linux/kvm_host.h>

	#include <asm/kvm_emulate.h>

	#include <kvm/arm_hypercalls.h>
	#include <kvm/arm_psci.h>

	#define KVM_ARM_SMCCC_STD_FEATURES \
	GENMASK(KVM_REG_ARM_STD_BMAP_BIT_COUNT - 1, 0)
	#define KVM_ARM_SMCCC_STD_HYP_FEATURES \
	GENMASK(KVM_REG_ARM_STD_HYP_BMAP_BIT_COUNT - 1, 0)
	#define KVM_ARM_SMCCC_VENDOR_HYP_FEATURES \
	GENMASK(KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_COUNT - 1, 0)

	static void kvm_ptp_get_time(struct kvm_vcpu vcpu, u64 val)
	{
	struct system_time_snapshot systime_snapshot;
	u64 cycles = ~0UL;
	u32 feature;

	/*
	* system time and counter value must captured at the same
	* time to keep consistency and precision.
	*/
	ktime_get_snapshot(&systime_snapshot);

	/*
	* This is only valid if the current clocksource is the
	* architected counter, as this is the only one the guest
	* can see.
	*/
	if (systime_snapshot.cs_id != CSID_ARM_ARCH_COUNTER)
	return;

	/*
	* The guest selects one of the two reference counters
	* (virtual or physical) with the first argument of the SMCCC
	* call. In case the identifier is not supported, error out.
	*/
	feature = smccc_get_arg1(vcpu);
	switch (feature) {
	case KVM_PTP_VIRT_COUNTER:
	cycles = systime_snapshot.cycles - vcpu->kvm->arch.timer_data.voffset;
	break;
	case KVM_PTP_PHYS_COUNTER:
	cycles = systime_snapshot.cycles - vcpu->kvm->arch.timer_data.poffset;
	break;
	default:
	return;
	}

	/*
	* This relies on the top bit of val[0] never being set for
	* valid values of system time, because that is really far
	* in the future (about 292 years from 1970, and at that stage
	* nobody will give a damn about it).
	*/
	val[0] = upper_32_bits(systime_snapshot.real);
	val[1] = lower_32_bits(systime_snapshot.real);
	val[2] = upper_32_bits(cycles);
	val[3] = lower_32_bits(cycles);
	}

	static bool kvm_smccc_default_allowed(u32 func_id)
	{
	switch (func_id) {
	/*
	* List of function-ids that are not gated with the bitmapped
	* feature firmware registers, and are to be allowed for
	* servicing the call by default.
	*/
	case ARM_SMCCC_VERSION_FUNC_ID:
	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
	return true;
	default:
	/* PSCI 0.2 and up is in the 0:0x1f range */
	if (ARM_SMCCC_OWNER_NUM(func_id) == ARM_SMCCC_OWNER_STANDARD &&
	ARM_SMCCC_FUNC_NUM(func_id) <= 0x1f)
	return true;

	/*
	* KVM's PSCI 0.1 doesn't comply with SMCCC, and has
	* its own function-id base and range
	*/
	if (func_id >= KVM_PSCI_FN(0) && func_id <= KVM_PSCI_FN(3))
	return true;

	return false;
	}
	}

	static bool kvm_smccc_test_fw_bmap(struct kvm_vcpu *vcpu, u32 func_id)
	{
	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;

	switch (func_id) {
	case ARM_SMCCC_TRNG_VERSION:
	case ARM_SMCCC_TRNG_FEATURES:
	case ARM_SMCCC_TRNG_GET_UUID:
	case ARM_SMCCC_TRNG_RND32:
	case ARM_SMCCC_TRNG_RND64:
	return test_bit(KVM_REG_ARM_STD_BIT_TRNG_V1_0,
	&smccc_feat->std_bmap);
	case ARM_SMCCC_HV_PV_TIME_FEATURES:
	case ARM_SMCCC_HV_PV_TIME_ST:
	return test_bit(KVM_REG_ARM_STD_HYP_BIT_PV_TIME,
	&smccc_feat->std_hyp_bmap);
	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
	return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT,
	&smccc_feat->vendor_hyp_bmap);
	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
	return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_PTP,
	&smccc_feat->vendor_hyp_bmap);
	default:
	return false;
	}
	}

	#define SMC32_ARCH_RANGE_BEGIN ARM_SMCCC_VERSION_FUNC_ID
	#define SMC32_ARCH_RANGE_END ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
	ARM_SMCCC_SMC_32, \
	0, ARM_SMCCC_FUNC_MASK)

	#define SMC64_ARCH_RANGE_BEGIN ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
	ARM_SMCCC_SMC_64, \
	0, 0)
	#define SMC64_ARCH_RANGE_END ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
	ARM_SMCCC_SMC_64, \
	0, ARM_SMCCC_FUNC_MASK)

	static void init_smccc_filter(struct kvm *kvm)
	{
	int r;

	mt_init(&kvm->arch.smccc_filter);

	/*
	* Prevent userspace from handling any SMCCC calls in the architecture
	* range, avoiding the risk of misrepresenting Spectre mitigation status
	* to the guest.
	*/
	r = mtree_insert_range(&kvm->arch.smccc_filter,
	SMC32_ARCH_RANGE_BEGIN, SMC32_ARCH_RANGE_END,
	xa_mk_value(KVM_SMCCC_FILTER_HANDLE),
	GFP_KERNEL_ACCOUNT);
	WARN_ON_ONCE(r);

	r = mtree_insert_range(&kvm->arch.smccc_filter,
	SMC64_ARCH_RANGE_BEGIN, SMC64_ARCH_RANGE_END,
	xa_mk_value(KVM_SMCCC_FILTER_HANDLE),
	GFP_KERNEL_ACCOUNT);
	WARN_ON_ONCE(r);

	}

	static int kvm_smccc_set_filter(struct kvm kvm, struct kvm_smccc_filter __user uaddr)
	{
	const void *zero_page = page_to_virt(ZERO_PAGE(0));
	struct kvm_smccc_filter filter;
	u32 start, end;
	int r;

	if (copy_from_user(&filter, uaddr, sizeof(filter)))
	return -EFAULT;

	if (memcmp(filter.pad, zero_page, sizeof(filter.pad)))
	return -EINVAL;

	start = filter.base;
	end = start + filter.nr_functions - 1;

	if (end < start \|\| filter.action >= NR_SMCCC_FILTER_ACTIONS)
	return -EINVAL;

	mutex_lock(&kvm->arch.config_lock);

	if (kvm_vm_has_ran_once(kvm)) {
	r = -EBUSY;
	goto out_unlock;
	}

	r = mtree_insert_range(&kvm->arch.smccc_filter, start, end,
	xa_mk_value(filter.action), GFP_KERNEL_ACCOUNT);
	if (r)
	goto out_unlock;

	set_bit(KVM_ARCH_FLAG_SMCCC_FILTER_CONFIGURED, &kvm->arch.flags);

	out_unlock:
	mutex_unlock(&kvm->arch.config_lock);
	return r;
	}

	static u8 kvm_smccc_filter_get_action(struct kvm *kvm, u32 func_id)
	{
	unsigned long idx = func_id;
	void *val;

	if (!test_bit(KVM_ARCH_FLAG_SMCCC_FILTER_CONFIGURED, &kvm->arch.flags))
	return KVM_SMCCC_FILTER_HANDLE;

	/*
	* But where's the error handling, you say?
	*
	* mt_find() returns NULL if no entry was found, which just so happens
	* to match KVM_SMCCC_FILTER_HANDLE.
	*/
	val = mt_find(&kvm->arch.smccc_filter, &idx, idx);
	return xa_to_value(val);
	}

	static u8 kvm_smccc_get_action(struct kvm_vcpu *vcpu, u32 func_id)
	{
	/*
	* Intervening actions in the SMCCC filter take precedence over the
	* pseudo-firmware register bitmaps.
	*/
	u8 action = kvm_smccc_filter_get_action(vcpu->kvm, func_id);
	if (action != KVM_SMCCC_FILTER_HANDLE)
	return action;

	if (kvm_smccc_test_fw_bmap(vcpu, func_id) \|\|
	kvm_smccc_default_allowed(func_id))
	return KVM_SMCCC_FILTER_HANDLE;

	return KVM_SMCCC_FILTER_DENY;
	}

	static void kvm_prepare_hypercall_exit(struct kvm_vcpu *vcpu, u32 func_id)
	{
	u8 ec = ESR_ELx_EC(kvm_vcpu_get_esr(vcpu));
	struct kvm_run *run = vcpu->run;
	u64 flags = 0;

	if (ec == ESR_ELx_EC_SMC32 \|\| ec == ESR_ELx_EC_SMC64)
	flags \|= KVM_HYPERCALL_EXIT_SMC;

	if (!kvm_vcpu_trap_il_is32bit(vcpu))
	flags \|= KVM_HYPERCALL_EXIT_16BIT;

	run->exit_reason = KVM_EXIT_HYPERCALL;
	run->hypercall = (typeof(run->hypercall)) {
	.nr = func_id,
	.flags = flags,
	};
	}

	int kvm_smccc_call_handler(struct kvm_vcpu *vcpu)
	{
	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
	u32 func_id = smccc_get_function(vcpu);
	u64 val[4] = {SMCCC_RET_NOT_SUPPORTED};
	u32 feature;
	u8 action;
	gpa_t gpa;

	action = kvm_smccc_get_action(vcpu, func_id);
	switch (action) {
	case KVM_SMCCC_FILTER_HANDLE:
	break;
	case KVM_SMCCC_FILTER_DENY:
	goto out;
	case KVM_SMCCC_FILTER_FWD_TO_USER:
	kvm_prepare_hypercall_exit(vcpu, func_id);
	return 0;
	default:
	WARN_RATELIMIT(1, "Unhandled SMCCC filter action: %d\n", action);
	goto out;
	}

	switch (func_id) {
	case ARM_SMCCC_VERSION_FUNC_ID:
	val[0] = ARM_SMCCC_VERSION_1_1;
	break;
	case ARM_SMCCC_ARCH_FEATURES_FUNC_ID:
	feature = smccc_get_arg1(vcpu);
	switch (feature) {
	case ARM_SMCCC_ARCH_WORKAROUND_1:
	switch (arm64_get_spectre_v2_state()) {
	case SPECTRE_VULNERABLE:
	break;
	case SPECTRE_MITIGATED:
	val[0] = SMCCC_RET_SUCCESS;
	break;
	case SPECTRE_UNAFFECTED:
	val[0] = SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED;
	break;
	}
	break;
	case ARM_SMCCC_ARCH_WORKAROUND_2:
	switch (arm64_get_spectre_v4_state()) {
	case SPECTRE_VULNERABLE:
	break;
	case SPECTRE_MITIGATED:
	/*
	* SSBS everywhere: Indicate no firmware
	* support, as the SSBS support will be
	* indicated to the guest and the default is
	* safe.
	*
	* Otherwise, expose a permanent mitigation
	* to the guest, and hide SSBS so that the
	* guest stays protected.
	*/
	if (cpus_have_final_cap(ARM64_SSBS))
	break;
	fallthrough;
	case SPECTRE_UNAFFECTED:
	val[0] = SMCCC_RET_NOT_REQUIRED;
	break;
	}
	break;
	case ARM_SMCCC_ARCH_WORKAROUND_3:
	switch (arm64_get_spectre_bhb_state()) {
	case SPECTRE_VULNERABLE:
	break;
	case SPECTRE_MITIGATED:
	val[0] = SMCCC_RET_SUCCESS;
	break;
	case SPECTRE_UNAFFECTED:
	val[0] = SMCCC_ARCH_WORKAROUND_RET_UNAFFECTED;
	break;
	}
	break;
	case ARM_SMCCC_HV_PV_TIME_FEATURES:
	if (test_bit(KVM_REG_ARM_STD_HYP_BIT_PV_TIME,
	&smccc_feat->std_hyp_bmap))
	val[0] = SMCCC_RET_SUCCESS;
	break;
	}
	break;
	case ARM_SMCCC_HV_PV_TIME_FEATURES:
	val[0] = kvm_hypercall_pv_features(vcpu);
	break;
	case ARM_SMCCC_HV_PV_TIME_ST:
	gpa = kvm_init_stolen_time(vcpu);
	if (gpa != INVALID_GPA)
	val[0] = gpa;
	break;
	case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
	val[0] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0;
	val[1] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1;
	val[2] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_2;
	val[3] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_3;
	break;
	case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
	val[0] = smccc_feat->vendor_hyp_bmap;
	break;
	case ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID:
	kvm_ptp_get_time(vcpu, val);
	break;
	case ARM_SMCCC_TRNG_VERSION:
	case ARM_SMCCC_TRNG_FEATURES:
	case ARM_SMCCC_TRNG_GET_UUID:
	case ARM_SMCCC_TRNG_RND32:
	case ARM_SMCCC_TRNG_RND64:
	return kvm_trng_call(vcpu);
	default:
	return kvm_psci_call(vcpu);
	}

	out:
	smccc_set_retval(vcpu, val[0], val[1], val[2], val[3]);
	return 1;
	}

	static const u64 kvm_arm_fw_reg_ids[] = {
	KVM_REG_ARM_PSCI_VERSION,
	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1,
	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2,
	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3,
	KVM_REG_ARM_STD_BMAP,
	KVM_REG_ARM_STD_HYP_BMAP,
	KVM_REG_ARM_VENDOR_HYP_BMAP,
	};

	void kvm_arm_init_hypercalls(struct kvm *kvm)
	{
	struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;

	smccc_feat->std_bmap = KVM_ARM_SMCCC_STD_FEATURES;
	smccc_feat->std_hyp_bmap = KVM_ARM_SMCCC_STD_HYP_FEATURES;
	smccc_feat->vendor_hyp_bmap = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES;

	init_smccc_filter(kvm);
	}

	void kvm_arm_teardown_hypercalls(struct kvm *kvm)
	{
	mtree_destroy(&kvm->arch.smccc_filter);
	}

	int kvm_arm_get_fw_num_regs(struct kvm_vcpu *vcpu)
	{
	return ARRAY_SIZE(kvm_arm_fw_reg_ids);
	}

	int kvm_arm_copy_fw_reg_indices(struct kvm_vcpu vcpu, u64 __user uindices)
	{
	int i;

	for (i = 0; i < ARRAY_SIZE(kvm_arm_fw_reg_ids); i++) {
	if (put_user(kvm_arm_fw_reg_ids[i], uindices++))
	return -EFAULT;
	}

	return 0;
	}

	#define KVM_REG_FEATURE_LEVEL_MASK GENMASK(3, 0)

	/*
	* Convert the workaround level into an easy-to-compare number, where higher
	* values mean better protection.
	*/
	static int get_kernel_wa_level(u64 regid)
	{
	switch (regid) {
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
	switch (arm64_get_spectre_v2_state()) {
	case SPECTRE_VULNERABLE:
	return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
	case SPECTRE_MITIGATED:
	return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL;
	case SPECTRE_UNAFFECTED:
	return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED;
	}
	return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL;
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
	switch (arm64_get_spectre_v4_state()) {
	case SPECTRE_MITIGATED:
	/*
	* As for the hypercall discovery, we pretend we
	* don't have any FW mitigation if SSBS is there at
	* all times.
	*/
	if (cpus_have_final_cap(ARM64_SSBS))
	return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
	fallthrough;
	case SPECTRE_UNAFFECTED:
	return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
	case SPECTRE_VULNERABLE:
	return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
	}
	break;
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
	switch (arm64_get_spectre_bhb_state()) {
	case SPECTRE_VULNERABLE:
	return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
	case SPECTRE_MITIGATED:
	return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_AVAIL;
	case SPECTRE_UNAFFECTED:
	return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_REQUIRED;
	}
	return KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3_NOT_AVAIL;
	}

	return -EINVAL;
	}

	int kvm_arm_get_fw_reg(struct kvm_vcpu vcpu, const struct kvm_one_reg reg)
	{
	struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
	void __user uaddr = (void __user )(long)reg->addr;
	u64 val;

	switch (reg->id) {
	case KVM_REG_ARM_PSCI_VERSION:
	val = kvm_psci_version(vcpu);
	break;
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
	val = get_kernel_wa_level(reg->id) & KVM_REG_FEATURE_LEVEL_MASK;
	break;
	case KVM_REG_ARM_STD_BMAP:
	val = READ_ONCE(smccc_feat->std_bmap);
	break;
	case KVM_REG_ARM_STD_HYP_BMAP:
	val = READ_ONCE(smccc_feat->std_hyp_bmap);
	break;
	case KVM_REG_ARM_VENDOR_HYP_BMAP:
	val = READ_ONCE(smccc_feat->vendor_hyp_bmap);
	break;
	default:
	return -ENOENT;
	}

	if (copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id)))
	return -EFAULT;

	return 0;
	}

	static int kvm_arm_set_fw_reg_bmap(struct kvm_vcpu *vcpu, u64 reg_id, u64 val)
	{
	int ret = 0;
	struct kvm *kvm = vcpu->kvm;
	struct kvm_smccc_features *smccc_feat = &kvm->arch.smccc_feat;
	unsigned long *fw_reg_bmap, fw_reg_features;

	switch (reg_id) {
	case KVM_REG_ARM_STD_BMAP:
	fw_reg_bmap = &smccc_feat->std_bmap;
	fw_reg_features = KVM_ARM_SMCCC_STD_FEATURES;
	break;
	case KVM_REG_ARM_STD_HYP_BMAP:
	fw_reg_bmap = &smccc_feat->std_hyp_bmap;
	fw_reg_features = KVM_ARM_SMCCC_STD_HYP_FEATURES;
	break;
	case KVM_REG_ARM_VENDOR_HYP_BMAP:
	fw_reg_bmap = &smccc_feat->vendor_hyp_bmap;
	fw_reg_features = KVM_ARM_SMCCC_VENDOR_HYP_FEATURES;
	break;
	default:
	return -ENOENT;
	}

	/* Check for unsupported bit */
	if (val & ~fw_reg_features)
	return -EINVAL;

	mutex_lock(&kvm->arch.config_lock);

	if (kvm_vm_has_ran_once(kvm) && val != *fw_reg_bmap) {
	ret = -EBUSY;
	goto out;
	}

	WRITE_ONCE(*fw_reg_bmap, val);
	out:
	mutex_unlock(&kvm->arch.config_lock);
	return ret;
	}

	int kvm_arm_set_fw_reg(struct kvm_vcpu vcpu, const struct kvm_one_reg reg)
	{
	void __user uaddr = (void __user )(long)reg->addr;
	u64 val;
	int wa_level;

	if (KVM_REG_SIZE(reg->id) != sizeof(val))
	return -ENOENT;
	if (copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id)))
	return -EFAULT;

	switch (reg->id) {
	case KVM_REG_ARM_PSCI_VERSION:
	{
	bool wants_02;

	wants_02 = test_bit(KVM_ARM_VCPU_PSCI_0_2, vcpu->arch.features);

	switch (val) {
	case KVM_ARM_PSCI_0_1:
	if (wants_02)
	return -EINVAL;
	vcpu->kvm->arch.psci_version = val;
	return 0;
	case KVM_ARM_PSCI_0_2:
	case KVM_ARM_PSCI_1_0:
	case KVM_ARM_PSCI_1_1:
	if (!wants_02)
	return -EINVAL;
	vcpu->kvm->arch.psci_version = val;
	return 0;
	}
	break;
	}

	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_3:
	if (val & ~KVM_REG_FEATURE_LEVEL_MASK)
	return -EINVAL;

	if (get_kernel_wa_level(reg->id) < val)
	return -EINVAL;

	return 0;

	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
	if (val & ~(KVM_REG_FEATURE_LEVEL_MASK \|
	KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED))
	return -EINVAL;

	/* The enabled bit must not be set unless the level is AVAIL. */
	if ((val & KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED) &&
	(val & KVM_REG_FEATURE_LEVEL_MASK) != KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL)
	return -EINVAL;

	/*
	* Map all the possible incoming states to the only two we
	* really want to deal with.
	*/
	switch (val & KVM_REG_FEATURE_LEVEL_MASK) {
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL:
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN:
	wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL;
	break;
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL:
	case KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED:
	wa_level = KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED;
	break;
	default:
	return -EINVAL;
	}

	/*
	* We can deal with NOT_AVAIL on NOT_REQUIRED, but not the
	* other way around.
	*/
	if (get_kernel_wa_level(reg->id) < wa_level)
	return -EINVAL;

	return 0;
	case KVM_REG_ARM_STD_BMAP:
	case KVM_REG_ARM_STD_HYP_BMAP:
	case KVM_REG_ARM_VENDOR_HYP_BMAP:
	return kvm_arm_set_fw_reg_bmap(vcpu, reg->id, val);
	default:
	return -ENOENT;
	}

	return -EINVAL;
	}

	int kvm_vm_smccc_has_attr(struct kvm kvm, struct kvm_device_attr attr)
	{
	switch (attr->attr) {
	case KVM_ARM_VM_SMCCC_FILTER:
	return 0;
	default:
	return -ENXIO;
	}
	}

	int kvm_vm_smccc_set_attr(struct kvm kvm, struct kvm_device_attr attr)
	{
	void __user uaddr = (void __user )attr->addr;

	switch (attr->attr) {
	case KVM_ARM_VM_SMCCC_FILTER:
	return kvm_smccc_set_filter(kvm, uaddr);
	default:
	return -ENXIO;
	}
	}