/*
 * Copyright (c) 2018-2021 Maxime Villard, m00nbsd.net
 * All rights reserved.
 *
 * This code is part of the NVMM hypervisor.
 *
 * 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 THE AUTHOR ``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 THE AUTHOR 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/cdefs.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/queue.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#include "nvmm.h"

static struct nvmm_capability __capability;

#ifdef __x86_64__
#include "libnvmm_x86.c"
#endif

#ifdef __DragonFly__
#define LIST_FOREACH_SAFE       LIST_FOREACH_MUTABLE
#endif

typedef struct __area {
        LIST_ENTRY(__area) list;
        gpaddr_t gpa;
        uintptr_t hva;
        size_t size;
        nvmm_prot_t prot;
} area_t;

typedef LIST_HEAD(, __area) area_list_t;

static int nvmm_fd = -1;

/* -------------------------------------------------------------------------- */

static bool
__area_isvalid(struct nvmm_machine *mach, gpaddr_t gpa, size_t size)
{
        area_list_t *areas = mach->areas;
        area_t *ent;

        LIST_FOREACH(ent, areas, list) {
                /* Collision on GPA */
                if (gpa >= ent->gpa && gpa < ent->gpa + ent->size) {
                        return false;
                }
                if (gpa + size > ent->gpa &&
                    gpa + size <= ent->gpa + ent->size) {
                        return false;
                }
                if (gpa <= ent->gpa && gpa + size >= ent->gpa + ent->size) {
                        return false;
                }
        }

        return true;
}

static int
__area_add(struct nvmm_machine *mach, uintptr_t hva, gpaddr_t gpa, size_t size,
    int prot)
{
        area_list_t *areas = mach->areas;
        nvmm_prot_t nprot;
        area_t *area;

        nprot = 0;
        if (prot & PROT_READ)
                nprot |= NVMM_PROT_READ;
        if (prot & PROT_WRITE)
                nprot |= NVMM_PROT_WRITE;
        if (prot & PROT_EXEC)
                nprot |= NVMM_PROT_EXEC;

        if (!__area_isvalid(mach, gpa, size)) {
                errno = EINVAL;
                return -1;
        }

        area = malloc(sizeof(*area));
        if (area == NULL)
                return -1;
        area->gpa = gpa;
        area->hva = hva;
        area->size = size;
        area->prot = nprot;

        LIST_INSERT_HEAD(areas, area, list);

        return 0;
}

static int
__area_delete(struct nvmm_machine *mach, uintptr_t hva, gpaddr_t gpa,
    size_t size)
{
        area_list_t *areas = mach->areas;
        area_t *ent, *nxt;

        LIST_FOREACH_SAFE(ent, areas, list, nxt) {
                if (hva == ent->hva && gpa == ent->gpa && size == ent->size) {
                        LIST_REMOVE(ent, list);
                        free(ent);
                        return 0;
                }
        }

        return -1;
}

static void
__area_remove_all(struct nvmm_machine *mach)
{
        area_list_t *areas = mach->areas;
        area_t *ent;

        while ((ent = LIST_FIRST(areas)) != NULL) {
                LIST_REMOVE(ent, list);
                free(ent);
        }

        free(areas);
}

/* -------------------------------------------------------------------------- */

int
nvmm_init(void)
{
        if (nvmm_fd != -1)
                return 0;
        nvmm_fd = open("/dev/nvmm", O_RDONLY | O_CLOEXEC);
        if (nvmm_fd == -1)
                return -1;
        if (nvmm_capability(&__capability) == -1) {
                close(nvmm_fd);
                nvmm_fd = -1;
                return -1;
        }
        if (__capability.version != NVMM_KERN_VERSION) {
                close(nvmm_fd);
                nvmm_fd = -1;
                errno = EPROGMISMATCH;
                return -1;
        }

        return 0;
}

int
nvmm_root_init(void)
{
        if (nvmm_fd != -1)
                return 0;
        nvmm_fd = open("/dev/nvmm", O_WRONLY | O_CLOEXEC);
        if (nvmm_fd == -1)
                return -1;
        if (nvmm_capability(&__capability) == -1) {
                close(nvmm_fd);
                nvmm_fd = -1;
                return -1;
        }
        if (__capability.version != NVMM_KERN_VERSION) {
                close(nvmm_fd);
                nvmm_fd = -1;
                errno = EPROGMISMATCH;
                return -1;
        }

        return 0;
}

int
nvmm_capability(struct nvmm_capability *cap)
{
        struct nvmm_ioc_capability args;
        int ret;

        ret = ioctl(nvmm_fd, NVMM_IOC_CAPABILITY, &args);
        if (ret == -1)
                return -1;

        memcpy(cap, &args.cap, sizeof(args.cap));

        return 0;
}

int
nvmm_machine_create(struct nvmm_machine *mach)
{
        struct nvmm_ioc_machine_create args;
        struct nvmm_comm_page **pages;
        area_list_t *areas;
        int ret;

        areas = calloc(1, sizeof(*areas));
        if (areas == NULL)
                return -1;

        pages = calloc(__capability.max_vcpus, sizeof(*pages));
        if (pages == NULL) {
                free(areas);
                return -1;
        }

        ret = ioctl(nvmm_fd, NVMM_IOC_MACHINE_CREATE, &args);
        if (ret == -1) {
                free(areas);
                free(pages);
                return -1;
        }

        LIST_INIT(areas);

        memset(mach, 0, sizeof(*mach));
        mach->machid = args.machid;
        mach->pages = pages;
        mach->areas = areas;

        return 0;
}

int
nvmm_machine_destroy(struct nvmm_machine *mach)
{
        struct nvmm_ioc_machine_destroy args;
        int ret;

        args.machid = mach->machid;

        ret = ioctl(nvmm_fd, NVMM_IOC_MACHINE_DESTROY, &args);
        if (ret == -1)
                return -1;

        __area_remove_all(mach);
        free(mach->pages);

        return 0;
}

int
nvmm_machine_configure(struct nvmm_machine *mach, uint64_t op, void *conf)
{
        struct nvmm_ioc_machine_configure args;
        int ret;

        args.machid = mach->machid;
        args.op = op;
        args.conf = conf;

        ret = ioctl(nvmm_fd, NVMM_IOC_MACHINE_CONFIGURE, &args);
        if (ret == -1)
                return -1;

        return 0;
}

int
nvmm_vcpu_create(struct nvmm_machine *mach, nvmm_cpuid_t cpuid,
    struct nvmm_vcpu *vcpu)
{
        struct nvmm_ioc_vcpu_create args;
        int ret;

        vcpu->exit = malloc(sizeof(*vcpu->exit));
        if (vcpu->exit == NULL)
                return -1;

        args.machid = mach->machid;
        args.cpuid = cpuid;
        args.comm = NULL;

        ret = ioctl(nvmm_fd, NVMM_IOC_VCPU_CREATE, &args);
        if (ret == -1) {
                free(vcpu->exit);
                return -1;
        }

        mach->pages[cpuid] = args.comm;

        vcpu->cpuid = cpuid;
        vcpu->state = &args.comm->state;
        vcpu->event = &args.comm->event;

        return 0;
}

int
nvmm_vcpu_destroy(struct nvmm_machine *mach, struct nvmm_vcpu *vcpu)
{
        struct nvmm_ioc_vcpu_destroy args;
        struct nvmm_comm_page *comm;
        int ret;

        args.machid = mach->machid;
        args.cpuid = vcpu->cpuid;

        ret = ioctl(nvmm_fd, NVMM_IOC_VCPU_DESTROY, &args);
        if (ret == -1)
                return -1;

        /*
         * Need to unmap the comm page on the user side, because the
         * kernel has no guarantee to get the correct address space to
         * do the unmapping at the point of closing fd.
         */
        comm = mach->pages[vcpu->cpuid];
        munmap(comm, __capability.comm_size);

        free(vcpu->exit);

        return 0;
}

int
nvmm_vcpu_configure(struct nvmm_machine *mach, struct nvmm_vcpu *vcpu,
    uint64_t op, void *conf)
{
        struct nvmm_ioc_vcpu_configure args;
        int ret;

        switch (op) {
        case NVMM_VCPU_CONF_CALLBACKS:
                memcpy(&vcpu->cbs, conf, sizeof(vcpu->cbs));
                return 0;
        }

        args.machid = mach->machid;
        args.cpuid = vcpu->cpuid;
        args.op = op;
        args.conf = conf;

        ret = ioctl(nvmm_fd, NVMM_IOC_VCPU_CONFIGURE, &args);
        if (ret == -1)
                return -1;

        return 0;
}

int
nvmm_vcpu_setstate(struct nvmm_machine *mach, struct nvmm_vcpu *vcpu,
    uint64_t flags)
{
        struct nvmm_comm_page *comm;

        comm = mach->pages[vcpu->cpuid];
        comm->state_commit |= flags;
        comm->state_cached |= flags;

        return 0;
}

int
nvmm_vcpu_getstate(struct nvmm_machine *mach, struct nvmm_vcpu *vcpu,
    uint64_t flags)
{
        struct nvmm_ioc_vcpu_getstate args;
        struct nvmm_comm_page *comm;
        int ret;

        comm = mach->pages[vcpu->cpuid];

        if (__predict_true((flags & ~comm->state_cached) == 0)) {
                return 0;
        }
        comm->state_wanted = flags & ~comm->state_cached;

        args.machid = mach->machid;
        args.cpuid = vcpu->cpuid;

        ret = ioctl(nvmm_fd, NVMM_IOC_VCPU_GETSTATE, &args);
        if (ret == -1)
                return -1;

        return 0;
}

int
nvmm_vcpu_inject(struct nvmm_machine *mach, struct nvmm_vcpu *vcpu)
{
        struct nvmm_comm_page *comm;

        comm = mach->pages[vcpu->cpuid];
        comm->event_commit = true;

        return 0;
}

int
nvmm_vcpu_run(struct nvmm_machine *mach, struct nvmm_vcpu *vcpu)
{
        struct nvmm_ioc_vcpu_run args;
        int ret;

        args.machid = mach->machid;
        args.cpuid = vcpu->cpuid;
        memset(&args.exit, 0, sizeof(args.exit));

        ret = ioctl(nvmm_fd, NVMM_IOC_VCPU_RUN, &args);
        if (ret == -1)
                return -1;

        /* No comm support yet, just copy. */
        memcpy(vcpu->exit, &args.exit, sizeof(args.exit));

        return 0;
}

int
nvmm_gpa_map(struct nvmm_machine *mach, uintptr_t hva, gpaddr_t gpa,
    size_t size, int prot)
{
        struct nvmm_ioc_gpa_map args;
        int ret;

        ret = __area_add(mach, hva, gpa, size, prot);
        if (ret == -1)
                return -1;

        args.machid = mach->machid;
        args.hva = hva;
        args.gpa = gpa;
        args.size = size;
        args.prot = prot;

        ret = ioctl(nvmm_fd, NVMM_IOC_GPA_MAP, &args);
        if (ret == -1) {
                /* Can't recover. */
                abort();
        }

        return 0;
}

int
nvmm_gpa_unmap(struct nvmm_machine *mach, uintptr_t hva, gpaddr_t gpa,
    size_t size)
{
        struct nvmm_ioc_gpa_unmap args;
        int ret;

        ret = __area_delete(mach, hva, gpa, size);
        if (ret == -1)
                return -1;

        args.machid = mach->machid;
        args.gpa = gpa;
        args.size = size;

        ret = ioctl(nvmm_fd, NVMM_IOC_GPA_UNMAP, &args);
        if (ret == -1) {
                /* Can't recover. */
                abort();
        }

        return 0;
}

int
nvmm_hva_map(struct nvmm_machine *mach, uintptr_t hva, size_t size)
{
        struct nvmm_ioc_hva_map args;
        int ret;

        args.machid = mach->machid;
        args.hva = hva;
        args.size = size;

        ret = ioctl(nvmm_fd, NVMM_IOC_HVA_MAP, &args);
        if (ret == -1)
                return -1;

        return 0;
}

int
nvmm_hva_unmap(struct nvmm_machine *mach, uintptr_t hva, size_t size)
{
        struct nvmm_ioc_hva_unmap args;
        int ret;

        args.machid = mach->machid;
        args.hva = hva;
        args.size = size;

        ret = ioctl(nvmm_fd, NVMM_IOC_HVA_UNMAP, &args);
        if (ret == -1)
                return -1;

        return 0;
}

/*
 * nvmm_gva_to_gpa(): architecture-specific.
 */

int
nvmm_gpa_to_hva(struct nvmm_machine *mach, gpaddr_t gpa, uintptr_t *hva,
    nvmm_prot_t *prot)
{
        area_list_t *areas = mach->areas;
        area_t *ent;

        LIST_FOREACH(ent, areas, list) {
                if (gpa >= ent->gpa && gpa < ent->gpa + ent->size) {
                        *hva = ent->hva + (gpa - ent->gpa);
                        *prot = ent->prot;
                        return 0;
                }
        }

        errno = ENOENT;
        return -1;
}

/*
 * nvmm_assist_io(): architecture-specific.
 */

/*
 * nvmm_assist_mem(): architecture-specific.
 */

int
nvmm_ctl(int op, void *data, size_t size)
{
        struct nvmm_ioc_ctl args;
        int ret;

        args.op = op;
        args.data = data;
        args.size = size;

        ret = ioctl(nvmm_fd, NVMM_IOC_CTL, &args);
        if (ret == -1)
                return -1;

        return 0;
}