/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2015 Neel Natu <neel@freebsd.org>
 * All rights reserved.
 *
 * 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 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/param.h>

#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>

#include <machine/vmm.h>

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

#include <vmmapi.h>

#include "bhyverun.h"
#include "bootrom.h"
#include "debug.h"
#include "mem.h"

#define BOOTROM_SIZE    (16 * 1024 * 1024)      /* 16 MB */

/*
 * ROM region is 16 MB at the top of 4GB ("low") memory.
 *
 * The size is limited so it doesn't encroach into reserved MMIO space (e.g.,
 * APIC, HPET, MSI).
 *
 * It is allocated in page-multiple blocks on a first-come first-serve basis,
 * from high to low, during initialization, and does not change at runtime.
 */
static char *romptr;    /* Pointer to userspace-mapped bootrom region. */
static vm_paddr_t gpa_base;     /* GPA of low end of region. */
static vm_paddr_t gpa_allocbot; /* Low GPA of free region. */
static vm_paddr_t gpa_alloctop; /* High GPA, minus 1, of free region. */

#define CFI_BCS_WRITE_BYTE      0x10
#define CFI_BCS_CLEAR_STATUS    0x50
#define CFI_BCS_READ_STATUS     0x70
#define CFI_BCS_READ_ARRAY      0xff

static struct bootrom_var_state {
        uint8_t         *mmap;
        uint64_t        gpa;
        off_t           size;
        uint8_t         cmd;
} var = { NULL, 0, 0, CFI_BCS_READ_ARRAY };

/*
 * Emulate just those CFI basic commands that will convince EDK II
 * that the Firmware Volume area is writable and persistent.
 */
static int
bootrom_var_mem_handler(struct vcpu *vcpu __unused, int dir, uint64_t addr,
    int size, uint64_t *val, void *arg1 __unused, long arg2 __unused)
{
        off_t offset;

        offset = addr - var.gpa;
        if (offset + size > var.size || offset < 0 || offset + size <= offset)
                return (EINVAL);

        if (dir == MEM_F_WRITE) {
                switch (var.cmd) {
                case CFI_BCS_WRITE_BYTE:
                        memcpy(var.mmap + offset, val, size);
                        var.cmd = CFI_BCS_READ_ARRAY;
                        break;
                default:
                        var.cmd = *(uint8_t *)val;
                }
        } else {
                switch (var.cmd) {
                case CFI_BCS_CLEAR_STATUS:
                case CFI_BCS_READ_STATUS:
                        memset(val, 0, size);
                        var.cmd = CFI_BCS_READ_ARRAY;
                        break;
                default:
                        memcpy(val, var.mmap + offset, size);
                        break;
                }
        }
        return (0);
}

void
init_bootrom(struct vmctx *ctx)
{
        vm_paddr_t highmem;

        romptr = vm_create_devmem(ctx, VM_BOOTROM, "bootrom", BOOTROM_SIZE);
        if (romptr == MAP_FAILED)
                err(4, "%s: vm_create_devmem", __func__);
        highmem = vm_get_highmem_base(ctx);
        gpa_base = highmem - BOOTROM_SIZE;
        gpa_allocbot = gpa_base;
        gpa_alloctop = highmem - 1;
}

int
bootrom_alloc(struct vmctx *ctx, size_t len, int prot, int flags,
    char **region_out, uint64_t *gpa_out)
{
        static const int bootrom_valid_flags = BOOTROM_ALLOC_TOP;

        vm_paddr_t gpa;
        vm_ooffset_t segoff;

        if (flags & ~bootrom_valid_flags) {
                warnx("%s: Invalid flags: %x", __func__,
                    flags & ~bootrom_valid_flags);
                return (EINVAL);
        }
        if (prot & ~_PROT_ALL) {
                warnx("%s: Invalid protection: %x", __func__,
                    prot & ~_PROT_ALL);
                return (EINVAL);
        }

        if (len == 0 || len > BOOTROM_SIZE) {
                warnx("ROM size %zu is invalid", len);
                return (EINVAL);
        }
        if (len & PAGE_MASK) {
                warnx("ROM size %zu is not a multiple of the page size",
                    len);
                return (EINVAL);
        }

        if (flags & BOOTROM_ALLOC_TOP) {
                gpa = (gpa_alloctop - len) + 1;
                if (gpa < gpa_allocbot) {
                        warnx("No room for %zu ROM in bootrom region", len);
                        return (ENOMEM);
                }
        } else {
                gpa = gpa_allocbot;
                if (gpa > (gpa_alloctop - len) + 1) {
                        warnx("No room for %zu ROM in bootrom region", len);
                        return (ENOMEM);
                }
        }

        segoff = gpa - gpa_base;
        if (vm_mmap_memseg(ctx, gpa, VM_BOOTROM, segoff, len, prot) != 0) {
                int serrno = errno;
                warn("%s: vm_mmap_mapseg", __func__);
                return (serrno);
        }

        if (flags & BOOTROM_ALLOC_TOP)
                gpa_alloctop = gpa - 1;
        else
                gpa_allocbot = gpa + len;

        *region_out = romptr + segoff;
        if (gpa_out != NULL)
                *gpa_out = gpa;
        return (0);
}

int
bootrom_loadrom(struct vmctx *ctx)
{
        struct stat sbuf;
        ssize_t rlen;
        off_t rom_size, var_size, total_size;
        char *ptr, *romfile;
        int fd, varfd, i, rv;
        const char *bootrom, *varfile;

        rv = -1;
        varfd = -1;

        bootrom = get_config_value("bootrom");
        if (bootrom == NULL) {
                return (0);
        }

        /*
         * get_config_value_node may use a thread local buffer to return
         * variables. So, when we query the second variable, the first variable
         * might get overwritten. For that reason, the bootrom should be
         * duplicated.
         */
        romfile = strdup(bootrom);
        if (romfile == NULL) {
                return (-1);
        }

        fd = open(romfile, O_RDONLY);
        if (fd < 0) {
                EPRINTLN("Error opening bootrom \"%s\": %s",
                    romfile, strerror(errno));
                goto done;
        }

        if (fstat(fd, &sbuf) < 0) {
                EPRINTLN("Could not fstat bootrom file \"%s\": %s", romfile,
                    strerror(errno));
                goto done;
        }

        rom_size = sbuf.st_size;

        varfile = get_config_value("bootvars");
        var_size = 0;
        if (varfile != NULL) {
                varfd = open(varfile, O_RDWR);
                if (varfd < 0) {
                        EPRINTLN("Error opening bootrom variable file "
                            "\"%s\": %s", varfile, strerror(errno));
                        goto done;
                }

                if (fstat(varfd, &sbuf) < 0) {
                        EPRINTLN(
                            "Could not fstat bootrom variable file \"%s\": %s",
                            varfile, strerror(errno));
                        goto done;
                }

                var_size = sbuf.st_size;
        }

        if (var_size > BOOTROM_SIZE ||
            (var_size != 0 && var_size < PAGE_SIZE)) {
                EPRINTLN("Invalid bootrom variable size %ld",
                    var_size);
                goto done;
        }

        total_size = rom_size + var_size;

        if (total_size > BOOTROM_SIZE) {
                EPRINTLN("Invalid bootrom and variable aggregate size %ld",
                    total_size);
                goto done;
        }

        /* Map the bootrom into the guest address space */
        if (bootrom_alloc(ctx, rom_size, PROT_READ | PROT_EXEC,
            BOOTROM_ALLOC_TOP, &ptr, NULL) != 0) {
                goto done;
        }

        /* Read 'romfile' into the guest address space */
        for (i = 0; i < rom_size / PAGE_SIZE; i++) {
                rlen = read(fd, ptr + i * PAGE_SIZE, PAGE_SIZE);
                if (rlen != PAGE_SIZE) {
                        EPRINTLN("Incomplete read of page %d of bootrom "
                            "file %s: %ld bytes", i, romfile, rlen);
                        goto done;
                }
        }

        if (varfd >= 0) {
#ifdef __FreeBSD__
                var.mmap = mmap(NULL, var_size, PROT_READ | PROT_WRITE,
                    MAP_SHARED, varfd, 0);
#else
                var.mmap = (uint8_t *)mmap(NULL, var_size,
                    PROT_READ | PROT_WRITE, MAP_SHARED, varfd, 0);
#endif
                if (var.mmap == MAP_FAILED)
                        goto done;
                var.size = var_size;
                var.gpa = (gpa_alloctop - var_size) + 1;
                gpa_alloctop = var.gpa - 1;
                rv = register_mem(&(struct mem_range){
                    .name = "bootrom variable",
                    .flags = MEM_F_RW,
                    .handler = bootrom_var_mem_handler,
                    .base = var.gpa,
                    .size = var.size,
                });
                if (rv != 0)
                        goto done;
        }

        rv = 0;
done:
        if (varfd >= 0)
                close(varfd);
        if (fd >= 0)
                close(fd);
        free(romfile);
        return (rv);
}

/*
 * Are we relying on a bootrom to initialize the guest's CPU context?
 */
bool
bootrom_boot(void)
{
        return (get_config_value("bootrom") != NULL);
}