// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2012 - ARM Ltd
 * Author: Marc Zyngier <marc.zyngier@arm.com>
 */

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

#include <asm/cputype.h>
#include <asm/kvm_emulate.h>

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

/*
 * This is an implementation of the Power State Coordination Interface
 * as described in ARM document number ARM DEN 0022A.
 */

#define AFFINITY_MASK(level)    ~((0x1UL << ((level) * MPIDR_LEVEL_BITS)) - 1)

static unsigned long psci_affinity_mask(unsigned long affinity_level)
{
        if (affinity_level <= 3)
                return MPIDR_HWID_BITMASK & AFFINITY_MASK(affinity_level);

        return 0;
}

static unsigned long kvm_psci_vcpu_suspend(struct kvm_vcpu *vcpu)
{
        /*
         * NOTE: For simplicity, we make VCPU suspend emulation to be
         * same-as WFI (Wait-for-interrupt) emulation.
         *
         * This means for KVM the wakeup events are interrupts and
         * this is consistent with intended use of StateID as described
         * in section 5.4.1 of PSCI v0.2 specification (ARM DEN 0022A).
         *
         * Further, we also treat power-down request to be same as
         * stand-by request as-per section 5.4.2 clause 3 of PSCI v0.2
         * specification (ARM DEN 0022A). This means all suspend states
         * for KVM will preserve the register state.
         */
        kvm_vcpu_wfi(vcpu);

        return PSCI_RET_SUCCESS;
}

static inline bool kvm_psci_valid_affinity(struct kvm_vcpu *vcpu,
                                           unsigned long affinity)
{
        return !(affinity & ~MPIDR_HWID_BITMASK);
}

static unsigned long kvm_psci_vcpu_on(struct kvm_vcpu *source_vcpu)
{
        struct vcpu_reset_state *reset_state;
        struct kvm *kvm = source_vcpu->kvm;
        struct kvm_vcpu *vcpu = NULL;
        int ret = PSCI_RET_SUCCESS;
        unsigned long cpu_id;

        cpu_id = smccc_get_arg1(source_vcpu);
        if (!kvm_psci_valid_affinity(source_vcpu, cpu_id))
                return PSCI_RET_INVALID_PARAMS;

        vcpu = kvm_mpidr_to_vcpu(kvm, cpu_id);

        /*
         * Make sure the caller requested a valid CPU and that the CPU is
         * turned off.
         */
        if (!vcpu)
                return PSCI_RET_INVALID_PARAMS;

        spin_lock(&vcpu->arch.mp_state_lock);
        if (!kvm_arm_vcpu_stopped(vcpu)) {
                if (kvm_psci_version(source_vcpu) != KVM_ARM_PSCI_0_1)
                        ret = PSCI_RET_ALREADY_ON;
                else
                        ret = PSCI_RET_INVALID_PARAMS;

                goto out_unlock;
        }

        reset_state = &vcpu->arch.reset_state;

        reset_state->pc = smccc_get_arg2(source_vcpu);

        /* Propagate caller endianness */
        reset_state->be = kvm_vcpu_is_be(source_vcpu);

        /*
         * NOTE: We always update r0 (or x0) because for PSCI v0.1
         * the general purpose registers are undefined upon CPU_ON.
         */
        reset_state->r0 = smccc_get_arg3(source_vcpu);

        reset_state->reset = true;
        kvm_make_request(KVM_REQ_VCPU_RESET, vcpu);

        /*
         * Make sure the reset request is observed if the RUNNABLE mp_state is
         * observed.
         */
        smp_wmb();

        WRITE_ONCE(vcpu->arch.mp_state.mp_state, KVM_MP_STATE_RUNNABLE);
        kvm_vcpu_wake_up(vcpu);

out_unlock:
        spin_unlock(&vcpu->arch.mp_state_lock);
        return ret;
}

static unsigned long kvm_psci_vcpu_affinity_info(struct kvm_vcpu *vcpu)
{
        int matching_cpus = 0;
        unsigned long i, mpidr;
        unsigned long target_affinity;
        unsigned long target_affinity_mask;
        unsigned long lowest_affinity_level;
        struct kvm *kvm = vcpu->kvm;
        struct kvm_vcpu *tmp;

        target_affinity = smccc_get_arg1(vcpu);
        lowest_affinity_level = smccc_get_arg2(vcpu);

        if (!kvm_psci_valid_affinity(vcpu, target_affinity))
                return PSCI_RET_INVALID_PARAMS;

        /* Determine target affinity mask */
        target_affinity_mask = psci_affinity_mask(lowest_affinity_level);
        if (!target_affinity_mask)
                return PSCI_RET_INVALID_PARAMS;

        /* Ignore other bits of target affinity */
        target_affinity &= target_affinity_mask;

        /*
         * If one or more VCPU matching target affinity are running
         * then ON else OFF
         */
        kvm_for_each_vcpu(i, tmp, kvm) {
                mpidr = kvm_vcpu_get_mpidr_aff(tmp);
                if ((mpidr & target_affinity_mask) == target_affinity) {
                        matching_cpus++;
                        if (!kvm_arm_vcpu_stopped(tmp))
                                return PSCI_0_2_AFFINITY_LEVEL_ON;
                }
        }

        if (!matching_cpus)
                return PSCI_RET_INVALID_PARAMS;

        return PSCI_0_2_AFFINITY_LEVEL_OFF;
}

static void kvm_prepare_system_event(struct kvm_vcpu *vcpu, u32 type, u64 flags)
{
        unsigned long i;
        struct kvm_vcpu *tmp;

        /*
         * The KVM ABI specifies that a system event exit may call KVM_RUN
         * again and may perform shutdown/reboot at a later time that when the
         * actual request is made.  Since we are implementing PSCI and a
         * caller of PSCI reboot and shutdown expects that the system shuts
         * down or reboots immediately, let's make sure that VCPUs are not run
         * after this call is handled and before the VCPUs have been
         * re-initialized.
         */
        kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
                spin_lock(&tmp->arch.mp_state_lock);
                WRITE_ONCE(tmp->arch.mp_state.mp_state, KVM_MP_STATE_STOPPED);
                spin_unlock(&tmp->arch.mp_state_lock);
        }
        kvm_make_all_cpus_request(vcpu->kvm, KVM_REQ_SLEEP);

        memset(&vcpu->run->system_event, 0, sizeof(vcpu->run->system_event));
        vcpu->run->system_event.type = type;
        vcpu->run->system_event.ndata = 1;
        vcpu->run->system_event.data[0] = flags;
        vcpu->run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
}

static void kvm_psci_system_off(struct kvm_vcpu *vcpu)
{
        kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN, 0);
}

static void kvm_psci_system_off2(struct kvm_vcpu *vcpu)
{
        kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_SHUTDOWN,
                                 KVM_SYSTEM_EVENT_SHUTDOWN_FLAG_PSCI_OFF2);
}

static void kvm_psci_system_reset(struct kvm_vcpu *vcpu)
{
        kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET, 0);
}

static void kvm_psci_system_reset2(struct kvm_vcpu *vcpu)
{
        kvm_prepare_system_event(vcpu, KVM_SYSTEM_EVENT_RESET,
                                 KVM_SYSTEM_EVENT_RESET_FLAG_PSCI_RESET2);
}

static void kvm_psci_system_suspend(struct kvm_vcpu *vcpu)
{
        struct kvm_run *run = vcpu->run;

        memset(&run->system_event, 0, sizeof(vcpu->run->system_event));
        run->system_event.type = KVM_SYSTEM_EVENT_SUSPEND;
        run->exit_reason = KVM_EXIT_SYSTEM_EVENT;
}

static void kvm_psci_narrow_to_32bit(struct kvm_vcpu *vcpu)
{
        int i;

        /*
         * Zero the input registers' upper 32 bits. They will be fully
         * zeroed on exit, so we're fine changing them in place.
         */
        for (i = 1; i < 4; i++)
                vcpu_set_reg(vcpu, i, lower_32_bits(vcpu_get_reg(vcpu, i)));
}

static unsigned long kvm_psci_check_allowed_function(struct kvm_vcpu *vcpu, u32 fn)
{
        /*
         * Prevent 32 bit guests from calling 64 bit PSCI functions.
         */
        if ((fn & PSCI_0_2_64BIT) && vcpu_mode_is_32bit(vcpu))
                return PSCI_RET_NOT_SUPPORTED;

        return 0;
}

static int kvm_psci_0_2_call(struct kvm_vcpu *vcpu)
{
        u32 psci_fn = smccc_get_function(vcpu);
        unsigned long val;
        int ret = 1;

        switch (psci_fn) {
        case PSCI_0_2_FN_PSCI_VERSION:
                /*
                 * Bits[31:16] = Major Version = 0
                 * Bits[15:0] = Minor Version = 2
                 */
                val = KVM_ARM_PSCI_0_2;
                break;
        case PSCI_0_2_FN_CPU_SUSPEND:
        case PSCI_0_2_FN64_CPU_SUSPEND:
                val = kvm_psci_vcpu_suspend(vcpu);
                break;
        case PSCI_0_2_FN_CPU_OFF:
                kvm_arm_vcpu_power_off(vcpu);
                val = PSCI_RET_SUCCESS;
                break;
        case PSCI_0_2_FN_CPU_ON:
                kvm_psci_narrow_to_32bit(vcpu);
                fallthrough;
        case PSCI_0_2_FN64_CPU_ON:
                val = kvm_psci_vcpu_on(vcpu);
                break;
        case PSCI_0_2_FN_AFFINITY_INFO:
                kvm_psci_narrow_to_32bit(vcpu);
                fallthrough;
        case PSCI_0_2_FN64_AFFINITY_INFO:
                val = kvm_psci_vcpu_affinity_info(vcpu);
                break;
        case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
                /*
                 * Trusted OS is MP hence does not require migration
                 * or
                 * Trusted OS is not present
                 */
                val = PSCI_0_2_TOS_MP;
                break;
        case PSCI_0_2_FN_SYSTEM_OFF:
                kvm_psci_system_off(vcpu);
                /*
                 * We shouldn't be going back to guest VCPU after
                 * receiving SYSTEM_OFF request.
                 *
                 * If user space accidentally/deliberately resumes
                 * guest VCPU after SYSTEM_OFF request then guest
                 * VCPU should see internal failure from PSCI return
                 * value. To achieve this, we preload r0 (or x0) with
                 * PSCI return value INTERNAL_FAILURE.
                 */
                val = PSCI_RET_INTERNAL_FAILURE;
                ret = 0;
                break;
        case PSCI_0_2_FN_SYSTEM_RESET:
                kvm_psci_system_reset(vcpu);
                /*
                 * Same reason as SYSTEM_OFF for preloading r0 (or x0)
                 * with PSCI return value INTERNAL_FAILURE.
                 */
                val = PSCI_RET_INTERNAL_FAILURE;
                ret = 0;
                break;
        default:
                val = PSCI_RET_NOT_SUPPORTED;
                break;
        }

        smccc_set_retval(vcpu, val, 0, 0, 0);
        return ret;
}

static int kvm_psci_1_x_call(struct kvm_vcpu *vcpu, u32 minor)
{
        unsigned long val = PSCI_RET_NOT_SUPPORTED;
        u32 psci_fn = smccc_get_function(vcpu);
        struct kvm *kvm = vcpu->kvm;
        u32 arg;
        int ret = 1;

        switch(psci_fn) {
        case PSCI_0_2_FN_PSCI_VERSION:
                val = PSCI_VERSION(1, minor);
                break;
        case PSCI_1_0_FN_PSCI_FEATURES:
                arg = smccc_get_arg1(vcpu);
                val = kvm_psci_check_allowed_function(vcpu, arg);
                if (val)
                        break;

                val = PSCI_RET_NOT_SUPPORTED;

                switch(arg) {
                case PSCI_0_2_FN_PSCI_VERSION:
                case PSCI_0_2_FN_CPU_SUSPEND:
                case PSCI_0_2_FN64_CPU_SUSPEND:
                case PSCI_0_2_FN_CPU_OFF:
                case PSCI_0_2_FN_CPU_ON:
                case PSCI_0_2_FN64_CPU_ON:
                case PSCI_0_2_FN_AFFINITY_INFO:
                case PSCI_0_2_FN64_AFFINITY_INFO:
                case PSCI_0_2_FN_MIGRATE_INFO_TYPE:
                case PSCI_0_2_FN_SYSTEM_OFF:
                case PSCI_0_2_FN_SYSTEM_RESET:
                case PSCI_1_0_FN_PSCI_FEATURES:
                case ARM_SMCCC_VERSION_FUNC_ID:
                        val = 0;
                        break;
                case PSCI_1_0_FN_SYSTEM_SUSPEND:
                case PSCI_1_0_FN64_SYSTEM_SUSPEND:
                        if (test_bit(KVM_ARCH_FLAG_SYSTEM_SUSPEND_ENABLED, &kvm->arch.flags))
                                val = 0;
                        break;
                case PSCI_1_1_FN_SYSTEM_RESET2:
                case PSCI_1_1_FN64_SYSTEM_RESET2:
                        if (minor >= 1)
                                val = 0;
                        break;
                case PSCI_1_3_FN_SYSTEM_OFF2:
                case PSCI_1_3_FN64_SYSTEM_OFF2:
                        if (minor >= 3)
                                val = PSCI_1_3_OFF_TYPE_HIBERNATE_OFF;
                        break;
                }
                break;
        case PSCI_1_0_FN_SYSTEM_SUSPEND:
                kvm_psci_narrow_to_32bit(vcpu);
                fallthrough;
        case PSCI_1_0_FN64_SYSTEM_SUSPEND:
                /*
                 * Return directly to userspace without changing the vCPU's
                 * registers. Userspace depends on reading the SMCCC parameters
                 * to implement SYSTEM_SUSPEND.
                 */
                if (test_bit(KVM_ARCH_FLAG_SYSTEM_SUSPEND_ENABLED, &kvm->arch.flags)) {
                        kvm_psci_system_suspend(vcpu);
                        return 0;
                }
                break;
        case PSCI_1_1_FN_SYSTEM_RESET2:
                kvm_psci_narrow_to_32bit(vcpu);
                fallthrough;
        case PSCI_1_1_FN64_SYSTEM_RESET2:
                if (minor >= 1) {
                        arg = smccc_get_arg1(vcpu);

                        if (arg <= PSCI_1_1_RESET_TYPE_SYSTEM_WARM_RESET ||
                            arg >= PSCI_1_1_RESET_TYPE_VENDOR_START) {
                                kvm_psci_system_reset2(vcpu);
                                vcpu_set_reg(vcpu, 0, PSCI_RET_INTERNAL_FAILURE);
                                return 0;
                        }

                        val = PSCI_RET_INVALID_PARAMS;
                        break;
                }
                break;
        case PSCI_1_3_FN_SYSTEM_OFF2:
                kvm_psci_narrow_to_32bit(vcpu);
                fallthrough;
        case PSCI_1_3_FN64_SYSTEM_OFF2:
                if (minor < 3)
                        break;

                arg = smccc_get_arg1(vcpu);
                /*
                 * SYSTEM_OFF2 defaults to HIBERNATE_OFF if arg1 is zero. arg2
                 * must be zero.
                 */
                if ((arg && arg != PSCI_1_3_OFF_TYPE_HIBERNATE_OFF) ||
                    smccc_get_arg2(vcpu) != 0) {
                        val = PSCI_RET_INVALID_PARAMS;
                        break;
                }
                kvm_psci_system_off2(vcpu);
                /*
                 * We shouldn't be going back to the guest after receiving a
                 * SYSTEM_OFF2 request. Preload a return value of
                 * INTERNAL_FAILURE should userspace ignore the exit and resume
                 * the vCPU.
                 */
                val = PSCI_RET_INTERNAL_FAILURE;
                ret = 0;
                break;
        default:
                return kvm_psci_0_2_call(vcpu);
        }

        smccc_set_retval(vcpu, val, 0, 0, 0);
        return ret;
}

static int kvm_psci_0_1_call(struct kvm_vcpu *vcpu)
{
        u32 psci_fn = smccc_get_function(vcpu);
        unsigned long val;

        switch (psci_fn) {
        case KVM_PSCI_FN_CPU_OFF:
                kvm_arm_vcpu_power_off(vcpu);
                val = PSCI_RET_SUCCESS;
                break;
        case KVM_PSCI_FN_CPU_ON:
                val = kvm_psci_vcpu_on(vcpu);
                break;
        default:
                val = PSCI_RET_NOT_SUPPORTED;
                break;
        }

        smccc_set_retval(vcpu, val, 0, 0, 0);
        return 1;
}

/**
 * kvm_psci_call - handle PSCI call if r0 value is in range
 * @vcpu: Pointer to the VCPU struct
 *
 * Handle PSCI calls from guests through traps from HVC instructions.
 * The calling convention is similar to SMC calls to the secure world
 * where the function number is placed in r0.
 *
 * This function returns: > 0 (success), 0 (success but exit to user
 * space), and < 0 (errors)
 *
 * Errors:
 * -EINVAL: Unrecognized PSCI function
 */
int kvm_psci_call(struct kvm_vcpu *vcpu)
{
        u32 psci_fn = smccc_get_function(vcpu);
        int version = kvm_psci_version(vcpu);
        unsigned long val;

        val = kvm_psci_check_allowed_function(vcpu, psci_fn);
        if (val) {
                smccc_set_retval(vcpu, val, 0, 0, 0);
                return 1;
        }

        switch (version) {
        case KVM_ARM_PSCI_1_3:
                return kvm_psci_1_x_call(vcpu, 3);
        case KVM_ARM_PSCI_1_2:
                return kvm_psci_1_x_call(vcpu, 2);
        case KVM_ARM_PSCI_1_1:
                return kvm_psci_1_x_call(vcpu, 1);
        case KVM_ARM_PSCI_1_0:
                return kvm_psci_1_x_call(vcpu, 0);
        case KVM_ARM_PSCI_0_2:
                return kvm_psci_0_2_call(vcpu);
        case KVM_ARM_PSCI_0_1:
                return kvm_psci_0_1_call(vcpu);
        default:
                WARN_ONCE(1, "Unknown PSCI version %d", version);
                smccc_set_retval(vcpu, SMCCC_RET_NOT_SUPPORTED, 0, 0, 0);
                return 1;
        }
}