/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2004 Christian Limpach.
 * Copyright (c) 2004-2006,2008 Kip Macy
 * Copyright (c) 2008 The NetBSD Foundation, Inc.
 * Copyright (c) 2013 Roger Pau Monné <roger.pau@citrix.com>
 * 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 AND CONTRIBUTORS 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/cdefs.h>
#include "opt_ddb.h"
#include "opt_kstack_pages.h"

#include <sys/param.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/reboot.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/linker.h>
#include <sys/lock.h>
#include <sys/rwlock.h>
#include <sys/boot.h>
#include <sys/ctype.h>
#include <sys/mutex.h>
#include <sys/smp.h>
#include <sys/efi.h>
#include <sys/tslog.h>

#include <vm/vm.h>
#include <vm/vm_extern.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/vm_map.h>
#include <vm/vm_object.h>
#include <vm/vm_pager.h>
#include <vm/vm_param.h>

#include <machine/_inttypes.h>
#include <machine/intr_machdep.h>
#include <x86/acpica_machdep.h>
#include <x86/apicvar.h>
#include <x86/init.h>
#include <machine/pc/bios.h>
#include <machine/smp.h>
#include <machine/intr_machdep.h>
#include <machine/md_var.h>
#include <machine/metadata.h>
#include <machine/cpu.h>

#include <xen/xen-os.h>
#include <xen/hvm.h>
#include <xen/hypervisor.h>
#include <xen/xenstore/xenstorevar.h>
#include <xen/xen_pv.h>

#include <contrib/xen/arch-x86/cpuid.h>
#include <contrib/xen/arch-x86/hvm/start_info.h>
#include <contrib/xen/vcpu.h>

#include <dev/xen/timer/timer.h>

#ifdef DDB
#include <ddb/ddb.h>
#endif

/* Native initial function */
extern u_int64_t hammer_time(u_int64_t, u_int64_t);
/* Xen initial function */
uint64_t hammer_time_xen(vm_paddr_t);

#define MAX_E820_ENTRIES        128

/*--------------------------- Forward Declarations ---------------------------*/
static void xen_pvh_parse_preload_data(uint64_t);
static void pvh_parse_memmap(vm_paddr_t *, int *);

/*---------------------------- Extern Declarations ---------------------------*/
/*
 * Placed by the linker at the end of the bss section, which is the last
 * section loaded by Xen before loading the symtab and strtab.
 */
extern uint32_t end;

/*-------------------------------- Global Data -------------------------------*/
struct init_ops xen_pvh_init_ops = {
        .parse_preload_data             = xen_pvh_parse_preload_data,
        .early_clock_source_init        = xen_clock_init,
        .early_delay                    = xen_delay,
        .parse_memmap                   = pvh_parse_memmap,
};

static struct bios_smap xen_smap[MAX_E820_ENTRIES];

static struct hvm_start_info *start_info;

/*-------------------------------- Xen PV init -------------------------------*/

static int
isxen(void)
{
        static int xen = -1;
        uint32_t base;
        u_int regs[4];

        if (xen != -1)
                return (xen);

        /*
         * The full code for identifying which hypervisor we're running under
         * is in sys/x86/x86/identcpu.c and runs later in the boot process;
         * this is sufficient to distinguish Xen PVH booting from non-Xen PVH
         * and skip some very early Xen-specific code in the non-Xen case.
         */
        xen = 0;
        for (base = 0x40000000; base < 0x40010000; base += 0x100) {
                do_cpuid(base, regs);
                if (regs[1] == XEN_CPUID_SIGNATURE_EBX &&
                    regs[2] == XEN_CPUID_SIGNATURE_ECX &&
                    regs[3] == XEN_CPUID_SIGNATURE_EDX) {
                        xen = 1;
                        break;
                }
        }
        return (xen);
}

#define CRASH(...) do {                                 \
        if (isxen())                                    \
                xc_printf(__VA_ARGS__);                 \
        halt();                                         \
} while (0)

uint64_t
hammer_time_xen(vm_paddr_t start_info_paddr)
{
        struct hvm_modlist_entry *mod;
        uint64_t physfree;

        start_info = (struct hvm_start_info *)(start_info_paddr + KERNBASE);
        if (start_info->magic != XEN_HVM_START_MAGIC_VALUE) {
                CRASH("Unknown magic value in start_info struct: %#x\n",
                    start_info->magic);
        }

        /*
         * Select the higher address to use as physfree: either after
         * start_info, after the kernel, after the memory map or after any of
         * the modules.  We assume enough memory to be available after the
         * selected address for the needs of very early memory allocations.
         */
        physfree = roundup2(start_info_paddr + sizeof(struct hvm_start_info),
            PAGE_SIZE);
        physfree = MAX(roundup2((vm_paddr_t)_end - KERNBASE, PAGE_SIZE),
            physfree);

        if (start_info->memmap_paddr != 0)
                physfree = MAX(roundup2(start_info->memmap_paddr +
                    start_info->memmap_entries *
                    sizeof(struct hvm_memmap_table_entry), PAGE_SIZE),
                    physfree);

        if (start_info->modlist_paddr != 0) {
                unsigned int i;

                if (start_info->nr_modules == 0) {
                        CRASH(
                            "ERROR: modlist_paddr != 0 but nr_modules == 0\n");
                }
                mod = (struct hvm_modlist_entry *)
                    (start_info->modlist_paddr + KERNBASE);
                for (i = 0; i < start_info->nr_modules; i++)
                        physfree = MAX(roundup2(mod[i].paddr + mod[i].size,
                            PAGE_SIZE), physfree);
        }

        /* Set the hooks for early functions that diverge from bare metal */
        init_ops = xen_pvh_init_ops;
        hvm_start_flags = start_info->flags;

        /* Now we can jump into the native init function */
        return (hammer_time(0, physfree));
}

/*-------------------------------- PV specific -------------------------------*/

#ifdef DDB
/*
 * The way Xen loads the symtab is different from the native boot loader,
 * because it's tailored for NetBSD. So we have to adapt and use the same
 * method as NetBSD. Portions of the code below have been picked from NetBSD:
 * sys/kern/kern_ksyms.c CVS Revision 1.71.
 */
static void
xen_pvh_parse_symtab(void)
{
        Elf_Ehdr *ehdr;
        Elf_Shdr *shdr;
        int i, j;

        ehdr = (Elf_Ehdr *)(&end + 1);
        if (memcmp(ehdr->e_ident, ELFMAG, SELFMAG) ||
            ehdr->e_ident[EI_CLASS] != ELF_TARG_CLASS ||
            ehdr->e_version > 1) {
                if (isxen())
                        xc_printf("Unable to load ELF symtab: invalid symbol table\n");
                return;
        }

        shdr = (Elf_Shdr *)((uint8_t *)ehdr + ehdr->e_shoff);
        /* Find the symbol table and the corresponding string table. */
        for (i = 1; i < ehdr->e_shnum; i++) {
                if (shdr[i].sh_type != SHT_SYMTAB)
                        continue;
                if (shdr[i].sh_offset == 0)
                        continue;
                ksymtab = (uintptr_t)((uint8_t *)ehdr + shdr[i].sh_offset);
                ksymtab_size = shdr[i].sh_size;
                j = shdr[i].sh_link;
                if (shdr[j].sh_offset == 0)
                        continue; /* Can this happen? */
                kstrtab = (uintptr_t)((uint8_t *)ehdr + shdr[j].sh_offset);
                break;
        }

        if ((ksymtab == 0 || kstrtab == 0) && isxen())
                xc_printf(
    "Unable to load ELF symtab: could not find symtab or strtab\n");
}
#endif

static void
xen_pvh_parse_preload_data(uint64_t modulep)
{
        vm_ooffset_t off;
        vm_paddr_t metadata;
        char *envp;

        TSENTER();
        if (start_info->modlist_paddr != 0) {
                struct hvm_modlist_entry *mod;
                const char *cmdline;

                mod = (struct hvm_modlist_entry *)
                    (start_info->modlist_paddr + KERNBASE);
                cmdline = mod[0].cmdline_paddr ?
                    (const char *)(mod[0].cmdline_paddr + KERNBASE) : NULL;

                if (strcmp(cmdline, "header") == 0) {
                        struct xen_header *header;

                        header = (struct xen_header *)(mod[0].paddr + KERNBASE);

                        if ((header->flags & XENHEADER_HAS_MODULEP_OFFSET) !=
                            XENHEADER_HAS_MODULEP_OFFSET) {
                                xc_printf("Unable to load module metadata\n");
                                HYPERVISOR_shutdown(SHUTDOWN_crash);
                        }

                        preload_metadata = (caddr_t)(mod[0].paddr +
                            header->modulep_offset + KERNBASE);

                        /*
                         * Xen has relocated the metadata and the modules, so
                         * we need to recalculate it's position. This is done
                         * by saving the original modulep address and then
                         * calculating the offset from the real modulep
                         * position.
                         */
                        off = header->modulep_offset;
                } else {
                        preload_metadata = (caddr_t)(mod[0].paddr + KERNBASE);
                        off = 0;
                }

                /* Initialize preload_kmdp */
                preload_initkmdp(false);
                if (preload_kmdp == NULL) {
                        xc_printf("Unable to find kernel metadata\n");
                        HYPERVISOR_shutdown(SHUTDOWN_crash);
                }

                metadata = MD_FETCH(preload_kmdp, MODINFOMD_MODULEP,
                    vm_paddr_t);
                off += mod[0].paddr + KERNBASE - metadata;

                preload_bootstrap_relocate(off);

                boothowto = MD_FETCH(preload_kmdp, MODINFOMD_HOWTO, int);
                envp = MD_FETCH(preload_kmdp, MODINFOMD_ENVP, char *);
                if (envp != NULL)
                        envp += off;
                init_static_kenv(envp, 0);

                if (MD_FETCH(preload_kmdp, MODINFOMD_EFI_MAP, void *) != NULL)
                    strlcpy(bootmethod, "UEFI", sizeof(bootmethod));
                else
                    strlcpy(bootmethod, "BIOS", sizeof(bootmethod));
        } else {
                static char kenv_buffer[PAGE_SIZE];

                /* Provide a static kenv so the command line can be parsed. */
                init_static_kenv(kenv_buffer, sizeof(kenv_buffer));

                /* Parse the extra boot information given by Xen */
                if (start_info->cmdline_paddr != 0)
                        boot_parse_cmdline_delim(
                            (char *)(start_info->cmdline_paddr + KERNBASE),
                            ", \t\n");
                strlcpy(bootmethod, "PVH", sizeof(bootmethod));
        }

        boothowto |= boot_env_to_howto();

        /*
         * When booted as a PVH guest FreeBSD must not use the RSDP address
         * hint provided by the loader because it points to the native set of
         * ACPI tables instead of the ones crafted by Xen.
         */
        acpi_set_root(start_info->rsdp_paddr);

#ifdef DDB
        xen_pvh_parse_symtab();
#endif
        TSEXIT();
}

static void
pvh_parse_memmap_start_info(vm_paddr_t *physmap,
    int *physmap_idx)
{
        const struct hvm_memmap_table_entry * entries;
        size_t nentries;
        size_t i;

        /* Extract from HVM start_info. */
        entries = (struct hvm_memmap_table_entry *)(start_info->memmap_paddr + KERNBASE);
        nentries = start_info->memmap_entries;

        /* Convert into E820 format and handle one by one. */
        for (i = 0; i < nentries; i++) {
                struct bios_smap entry;

                entry.base = entries[i].addr;
                entry.length = entries[i].size;

                /*
                 * Luckily for us, the XEN_HVM_MEMMAP_TYPE_* values exactly
                 * match the SMAP_TYPE_* values so we don't need to translate
                 * anything here.
                 */
                entry.type = entries[i].type;

                bios_add_smap_entries(&entry, 1, physmap, physmap_idx);
        }
}

static void
xen_pvh_parse_memmap(vm_paddr_t *physmap, int *physmap_idx)
{
        struct xen_memory_map memmap;
        u_int32_t size;
        int rc;

        /* We should only reach here if we're running under Xen. */
        KASSERT(isxen(), ("xen_pvh_parse_memmap reached when !Xen"));

        /* Fetch the E820 map from Xen */
        memmap.nr_entries = MAX_E820_ENTRIES;
        set_xen_guest_handle(memmap.buffer, xen_smap);
        rc = HYPERVISOR_memory_op(XENMEM_memory_map, &memmap);
        if (rc) {
                xc_printf("ERROR: unable to fetch Xen E820 memory map: %d\n",
                    rc);
                HYPERVISOR_shutdown(SHUTDOWN_crash);
        }

        size = memmap.nr_entries * sizeof(xen_smap[0]);

        bios_add_smap_entries(xen_smap, size, physmap, physmap_idx);
}

static void
pvh_parse_memmap(vm_paddr_t *physmap, int *physmap_idx)
{

        /*
         * If version >= 1 and memmap_paddr != 0, use the memory map provided
         * in the start_info structure; if not, we're running under legacy
         * Xen and need to use the Xen hypercall.
         */
        if ((start_info->version >= 1) && (start_info->memmap_paddr != 0))
                pvh_parse_memmap_start_info(physmap, physmap_idx);
        else
                xen_pvh_parse_memmap(physmap, physmap_idx);
}