// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2021 Western Digital Corporation or its affiliates.
 *
 * Authors:
 *     Atish Patra <atish.patra@wdc.com>
 */

#include <linux/errno.h>
#include <linux/err.h>
#include <linux/kvm_host.h>
#include <linux/wordpart.h>
#include <asm/sbi.h>
#include <asm/kvm_vcpu_sbi.h>

static int kvm_sbi_hsm_vcpu_start(struct kvm_vcpu *vcpu)
{
        struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
        struct kvm_vcpu *target_vcpu;
        unsigned long target_vcpuid = cp->a0;
        int ret = 0;

        target_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, target_vcpuid);
        if (!target_vcpu)
                return SBI_ERR_INVALID_PARAM;

        spin_lock(&target_vcpu->arch.mp_state_lock);

        if (!kvm_riscv_vcpu_stopped(target_vcpu)) {
                ret = SBI_ERR_ALREADY_AVAILABLE;
                goto out;
        }

        kvm_riscv_vcpu_sbi_request_reset(target_vcpu, cp->a1, cp->a2);

        __kvm_riscv_vcpu_power_on(target_vcpu);

out:
        spin_unlock(&target_vcpu->arch.mp_state_lock);

        return ret;
}

static int kvm_sbi_hsm_vcpu_stop(struct kvm_vcpu *vcpu)
{
        int ret = 0;

        spin_lock(&vcpu->arch.mp_state_lock);

        if (kvm_riscv_vcpu_stopped(vcpu)) {
                ret = SBI_ERR_FAILURE;
                goto out;
        }

        __kvm_riscv_vcpu_power_off(vcpu);

out:
        spin_unlock(&vcpu->arch.mp_state_lock);

        return ret;
}

static int kvm_sbi_hsm_vcpu_get_status(struct kvm_vcpu *vcpu)
{
        struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
        unsigned long target_vcpuid = cp->a0;
        struct kvm_vcpu *target_vcpu;

        target_vcpu = kvm_get_vcpu_by_id(vcpu->kvm, target_vcpuid);
        if (!target_vcpu)
                return SBI_ERR_INVALID_PARAM;
        if (kvm_riscv_vcpu_stopped(target_vcpu))
                return SBI_HSM_STATE_STOPPED;
        else if (target_vcpu->stat.generic.blocking)
                return SBI_HSM_STATE_SUSPENDED;
        else
                return SBI_HSM_STATE_STARTED;
}

static int kvm_sbi_ext_hsm_handler(struct kvm_vcpu *vcpu, struct kvm_run *run,
                                   struct kvm_vcpu_sbi_return *retdata)
{
        int ret = 0;
        struct kvm_cpu_context *cp = &vcpu->arch.guest_context;
        unsigned long funcid = cp->a6;

        switch (funcid) {
        case SBI_EXT_HSM_HART_START:
                ret = kvm_sbi_hsm_vcpu_start(vcpu);
                break;
        case SBI_EXT_HSM_HART_STOP:
                ret = kvm_sbi_hsm_vcpu_stop(vcpu);
                break;
        case SBI_EXT_HSM_HART_STATUS:
                ret = kvm_sbi_hsm_vcpu_get_status(vcpu);
                if (ret >= 0) {
                        retdata->out_val = ret;
                        retdata->err_val = 0;
                }
                return 0;
        case SBI_EXT_HSM_HART_SUSPEND:
                switch (lower_32_bits(cp->a0)) {
                case SBI_HSM_SUSPEND_RET_DEFAULT:
                        kvm_riscv_vcpu_wfi(vcpu);
                        break;
                case SBI_HSM_SUSPEND_NON_RET_DEFAULT:
                        ret = SBI_ERR_NOT_SUPPORTED;
                        break;
                default:
                        ret = SBI_ERR_INVALID_PARAM;
                }
                break;
        default:
                ret = SBI_ERR_NOT_SUPPORTED;
        }

        retdata->err_val = ret;

        return 0;
}

const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_hsm = {
        .extid_start = SBI_EXT_HSM,
        .extid_end = SBI_EXT_HSM,
        .handler = kvm_sbi_ext_hsm_handler,
};