/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2011 NetApp, Inc.
 * All rights reserved.
 * Copyright (c) 2024 Ruslan Bukin <br@bsdpad.com>
 *
 * This software was developed by the University of Cambridge Computer
 * Laboratory (Department of Computer Science and Technology) under Innovate
 * UK project 105694, "Digital Security by Design (DSbD) Technology Platform
 * Prototype".
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/cpuset.h>

#include <machine/riscvreg.h>
#include <machine/cpu.h>
#include <machine/sbi.h>
#include <machine/vmm.h>
#include <machine/vmm_dev.h>
#include <machine/vmm_instruction_emul.h>

#include <assert.h>
#include <errno.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include <vmmapi.h>

#include "bhyverun.h"
#include "config.h"
#include "debug.h"
#include "mem.h"
#include "vmexit.h"
#include "riscv.h"

#define BHYVE_VERSION   ((uint64_t)__FreeBSD_version)
#define SBI_VERS_MAJOR  2
#define SBI_VERS_MINOR  0

static cpuset_t running_hartmask = CPUSET_T_INITIALIZER(0);

void
vmexit_set_bsp(int hart_id)
{

        CPU_SET_ATOMIC(hart_id, &running_hartmask);
}

static int
vmexit_inst_emul(struct vmctx *ctx __unused, struct vcpu *vcpu,
    struct vm_run *vmrun)
{
        struct vm_exit *vme;
        struct vie *vie;
        int err;

        vme = vmrun->vm_exit;
        vie = &vme->u.inst_emul.vie;

        err = emulate_mem(vcpu, vme->u.inst_emul.gpa, vie,
            &vme->u.inst_emul.paging);
        if (err) {
                if (err == ESRCH) {
                        EPRINTLN("Unhandled memory access to 0x%lx\n",
                            vme->u.inst_emul.gpa);
                }
                goto fail;
        }

        return (VMEXIT_CONTINUE);

fail:
        fprintf(stderr, "Failed to emulate instruction ");
        FPRINTLN(stderr, "at 0x%lx", vme->pc);
        return (VMEXIT_ABORT);
}

static int
vmexit_suspend(struct vmctx *ctx, struct vcpu *vcpu, struct vm_run *vmrun)
{
        struct vm_exit *vme;
        enum vm_suspend_how how;
        int vcpuid = vcpu_id(vcpu);

        vme = vmrun->vm_exit;
        how = vme->u.suspended.how;

        fbsdrun_deletecpu(vcpuid);

        switch (how) {
        case VM_SUSPEND_RESET:
                exit(BHYVE_EXIT_RESET);
        case VM_SUSPEND_POWEROFF:
                if (get_config_bool_default("destroy_on_poweroff", false))
                        vm_destroy(ctx);
                exit(BHYVE_EXIT_POWEROFF);
        case VM_SUSPEND_HALT:
                exit(BHYVE_EXIT_HALT);
        case VM_SUSPEND_DESTROY:
                exit(BHYVE_EXIT_ERROR);
        default:
                fprintf(stderr, "vmexit_suspend: invalid reason %d\n", how);
                exit(100);
        }

        /* NOT REACHED. */

        return (0);
}

static int
vmexit_debug(struct vmctx *ctx __unused, struct vcpu *vcpu __unused,
    struct vm_run *vmrun __unused)
{

        /*
         * XXX-MJ sleep for a short period to avoid chewing up the CPU in the
         * window between activation of the vCPU thread and the
         * SBI_HSM_HART_START request.
         */
        usleep(1000);
        return (VMEXIT_CONTINUE);
}

static int
vmexit_bogus(struct vmctx *ctx __unused, struct vcpu *vcpu __unused,
    struct vm_run *vmrun __unused)
{

        return (VMEXIT_CONTINUE);
}

static int
vmm_sbi_probe_extension(int ext_id)
{

        switch (ext_id) {
        case SBI_EXT_ID_HSM:
        case SBI_EXT_ID_TIME:
        case SBI_EXT_ID_IPI:
        case SBI_EXT_ID_RFNC:
        case SBI_EXT_ID_SRST:
        case SBI_CONSOLE_PUTCHAR:
        case SBI_CONSOLE_GETCHAR:
                break;
        default:
                return (0);
        }

        return (1);
}

static int
vmexit_ecall_hsm(struct vmctx *ctx __unused, struct vcpu *vcpu __unused,
    struct vm_exit *vme)
{
        struct vcpu *newvcpu;
        uint64_t hart_id;
        int func_id;
        int error;

        hart_id = vme->u.ecall.args[0];
        func_id = vme->u.ecall.args[6];

        if (HART_TO_CPU(hart_id) >= (uint64_t)guest_ncpus)
                return (SBI_ERR_INVALID_PARAM);

        newvcpu = fbsdrun_vcpu(HART_TO_CPU(hart_id));
        assert(newvcpu != NULL);

        switch (func_id) {
        case SBI_HSM_HART_START:
                if (CPU_ISSET(hart_id, &running_hartmask))
                        break;

                /* Set hart ID. */
                error = vm_set_register(newvcpu, VM_REG_GUEST_A0, hart_id);
                assert(error == 0);

                /* Set PC. */
                error = vm_set_register(newvcpu, VM_REG_GUEST_SEPC,
                    vme->u.ecall.args[1]);
                assert(error == 0);

                /* Pass private data. */
                error = vm_set_register(newvcpu, VM_REG_GUEST_A1,
                    vme->u.ecall.args[2]);
                assert(error == 0);

                vm_resume_cpu(newvcpu);
                CPU_SET_ATOMIC(hart_id, &running_hartmask);
                break;
        case SBI_HSM_HART_STOP:
                if (!CPU_ISSET(hart_id, &running_hartmask))
                        break;
                CPU_CLR_ATOMIC(hart_id, &running_hartmask);
                vm_suspend_cpu(newvcpu);
                break;
        case SBI_HSM_HART_STATUS:
                /* TODO. */
                break;
        default:
                return (SBI_ERR_NOT_SUPPORTED);
        }

        return (SBI_SUCCESS);
}

static int
vmexit_ecall_base(struct vmctx *ctx __unused, struct vcpu *vcpu,
    struct vm_exit *vme)
{
        int sbi_function_id;
        uint32_t val;
        int ext_id;
        int error;

        sbi_function_id = vme->u.ecall.args[6];

        switch (sbi_function_id) {
        case SBI_BASE_GET_SPEC_VERSION:
                val = SBI_VERS_MAJOR << SBI_SPEC_VERS_MAJOR_OFFSET;
                val |= SBI_VERS_MINOR << SBI_SPEC_VERS_MINOR_OFFSET;
                break;
        case SBI_BASE_GET_IMPL_ID:
                val = SBI_IMPL_ID_BHYVE;
                break;
        case SBI_BASE_GET_IMPL_VERSION:
                val = BHYVE_VERSION;
                break;
        case SBI_BASE_PROBE_EXTENSION:
                ext_id = vme->u.ecall.args[0];
                val = vmm_sbi_probe_extension(ext_id);
                break;
        case SBI_BASE_GET_MVENDORID:
                val = MVENDORID_UNIMPL;
                break;
        case SBI_BASE_GET_MARCHID:
                val = MARCHID_UNIMPL;
                break;
        case SBI_BASE_GET_MIMPID:
                val = 0;
                break;
        default:
                return (SBI_ERR_NOT_SUPPORTED);
        }

        error = vm_set_register(vcpu, VM_REG_GUEST_A1, val);
        assert(error == 0);

        return (SBI_SUCCESS);
}

static int
vmexit_ecall_srst(struct vmctx *ctx, struct vm_exit *vme)
{
        enum vm_suspend_how how;
        int func_id;
        int type;

        func_id = vme->u.ecall.args[6];
        type = vme->u.ecall.args[0];

        switch (func_id) {
        case SBI_SRST_SYSTEM_RESET:
                switch (type) {
                case SBI_SRST_TYPE_SHUTDOWN:
                case SBI_SRST_TYPE_COLD_REBOOT:
                case SBI_SRST_TYPE_WARM_REBOOT:
                        how = VM_SUSPEND_POWEROFF;
                        vm_suspend(ctx, how);
                        break;
                default:
                        return (SBI_ERR_NOT_SUPPORTED);
                }
                break;
        default:
                return (SBI_ERR_NOT_SUPPORTED);
        }

        return (SBI_SUCCESS);
}

static int
vmexit_ecall(struct vmctx *ctx, struct vcpu *vcpu, struct vm_run *vmrun)
{
        int sbi_extension_id;
        struct vm_exit *vme;
        int error;
        int ret;

        vme = vmrun->vm_exit;

        sbi_extension_id = vme->u.ecall.args[7];
        switch (sbi_extension_id) {
        case SBI_EXT_ID_SRST:
                ret = vmexit_ecall_srst(ctx, vme);
                break;
        case SBI_EXT_ID_BASE:
                ret = vmexit_ecall_base(ctx, vcpu, vme);
                break;
        case SBI_EXT_ID_HSM:
                ret = vmexit_ecall_hsm(ctx, vcpu, vme);
                break;
        case SBI_CONSOLE_PUTCHAR:
        case SBI_CONSOLE_GETCHAR:
        default:
                /* Unknown SBI extension. */
                ret = SBI_ERR_NOT_SUPPORTED;
                break;
        }

        error = vm_set_register(vcpu, VM_REG_GUEST_A0, ret);
        assert(error == 0);

        return (VMEXIT_CONTINUE);
}


static int
vmexit_hyp(struct vmctx *ctx __unused, struct vcpu *vcpu __unused,
    struct vm_run *vmrun)
{
        struct vm_exit *vme;

        vme = vmrun->vm_exit;

        printf("unhandled exception: scause %#lx\n", vme->u.hyp.scause);

        return (VMEXIT_ABORT);
}

const vmexit_handler_t vmexit_handlers[VM_EXITCODE_MAX] = {
        [VM_EXITCODE_BOGUS]  = vmexit_bogus,
        [VM_EXITCODE_HYP] = vmexit_hyp,
        [VM_EXITCODE_INST_EMUL] = vmexit_inst_emul,
        [VM_EXITCODE_SUSPENDED] = vmexit_suspend,
        [VM_EXITCODE_DEBUG] = vmexit_debug,
        [VM_EXITCODE_ECALL] = vmexit_ecall,
};