/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2011 NetApp, Inc.
 * 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 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 <machine/specialreg.h>
#include <machine/segments.h>
#include <machine/vmm.h>

#include <errno.h>
#include <string.h>

#include "vmmapi.h"
#include "internal.h"

#define I386_TSS_SIZE           104

#define DESC_PRESENT            0x00000080
#define DESC_LONGMODE           0x00002000
#define DESC_DEF32              0x00004000
#define DESC_GRAN               0x00008000
#define DESC_UNUSABLE           0x00010000

#define GUEST_NULL_SEL          0
#define GUEST_CODE_SEL          1
#define GUEST_DATA_SEL          2
#define GUEST_TSS_SEL           3
#define GUEST_GDTR_LIMIT64      (3 * 8 - 1)

static struct segment_descriptor i386_gdt[] = {
        {},                                             /* NULL */
        { .sd_lolimit = 0xffff, .sd_type = SDT_MEMER,   /* CODE */
          .sd_p = 1, .sd_hilimit = 0xf, .sd_def32 = 1, .sd_gran = 1 }, 
        { .sd_lolimit = 0xffff, .sd_type = SDT_MEMRW,   /* DATA */
          .sd_p = 1, .sd_hilimit = 0xf, .sd_def32 = 1, .sd_gran = 1 },
        { .sd_lolimit = I386_TSS_SIZE - 1,              /* TSS */
          .sd_type = SDT_SYS386TSS, .sd_p = 1 }
};

/*
 * Setup the 'vcpu' register set such that it will begin execution at
 * 'eip' in flat mode.
 */
int
vm_setup_freebsd_registers_i386(struct vcpu *vcpu, uint32_t eip,
                                uint32_t gdtbase, uint32_t esp)
{
        uint64_t cr0, rflags, desc_base;
        uint32_t desc_access, desc_limit, tssbase;
        uint16_t gsel;
        struct segment_descriptor *gdt;
        int error, tmp;

        /* A 32-bit guest requires unrestricted mode. */        
        error = vm_get_capability(vcpu, VM_CAP_UNRESTRICTED_GUEST, &tmp);
        if (error)
                goto done;
        error = vm_set_capability(vcpu, VM_CAP_UNRESTRICTED_GUEST, 1);
        if (error)
                goto done;

        cr0 = CR0_PE | CR0_NE;
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_CR0, cr0)) != 0)
                goto done;

        if ((error = vm_set_register(vcpu, VM_REG_GUEST_CR4, 0)) != 0)
                goto done;

        /*
         * Forcing EFER to 0 causes bhyve to clear the "IA-32e guest
         * mode" entry control.
         */
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_EFER, 0)))
                goto done;

        gdt = vm_map_gpa(vcpu->ctx, gdtbase, 0x1000);
        if (gdt == NULL)
                return (EFAULT);
        memcpy(gdt, i386_gdt, sizeof(i386_gdt));
        desc_base = gdtbase;
        desc_limit = sizeof(i386_gdt) - 1;
        error = vm_set_desc(vcpu, VM_REG_GUEST_GDTR,
                            desc_base, desc_limit, 0);
        if (error != 0)
                goto done;

        /* Place the TSS one page above the GDT. */
        tssbase = gdtbase + 0x1000;
        gdt[3].sd_lobase = tssbase;     

        rflags = 0x2;
        error = vm_set_register(vcpu, VM_REG_GUEST_RFLAGS, rflags);
        if (error)
                goto done;

        desc_base = 0;
        desc_limit = 0xffffffff;
        desc_access = DESC_GRAN | DESC_DEF32 | DESC_PRESENT | SDT_MEMERA;
        error = vm_set_desc(vcpu, VM_REG_GUEST_CS,
                            desc_base, desc_limit, desc_access);

        desc_access = DESC_GRAN | DESC_DEF32 | DESC_PRESENT | SDT_MEMRWA;
        error = vm_set_desc(vcpu, VM_REG_GUEST_DS,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        error = vm_set_desc(vcpu, VM_REG_GUEST_ES,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        error = vm_set_desc(vcpu, VM_REG_GUEST_FS,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        error = vm_set_desc(vcpu, VM_REG_GUEST_GS,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        error = vm_set_desc(vcpu, VM_REG_GUEST_SS,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        desc_base = tssbase;
        desc_limit = I386_TSS_SIZE - 1;
        desc_access = DESC_PRESENT | SDT_SYS386BSY;
        error = vm_set_desc(vcpu, VM_REG_GUEST_TR,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        
        error = vm_set_desc(vcpu, VM_REG_GUEST_LDTR, 0, 0,
                            DESC_UNUSABLE);
        if (error)
                goto done;

        gsel = GSEL(GUEST_CODE_SEL, SEL_KPL);
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_CS, gsel)) != 0)
                goto done;
        
        gsel = GSEL(GUEST_DATA_SEL, SEL_KPL);
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_DS, gsel)) != 0)
                goto done;
        
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_ES, gsel)) != 0)
                goto done;

        if ((error = vm_set_register(vcpu, VM_REG_GUEST_FS, gsel)) != 0)
                goto done;
        
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_GS, gsel)) != 0)
                goto done;
        
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_SS, gsel)) != 0)
                goto done;

        gsel = GSEL(GUEST_TSS_SEL, SEL_KPL);
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_TR, gsel)) != 0)
                goto done;

        /* LDTR is pointing to the null selector */
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_LDTR, 0)) != 0)
                goto done;

        /* entry point */
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_RIP, eip)) != 0)
                goto done;

        if ((error = vm_set_register(vcpu, VM_REG_GUEST_RSP, esp)) != 0)
                goto done;

        error = 0;
done:
        return (error);
}

void     
vm_setup_freebsd_gdt(uint64_t *gdtr)
{       
        gdtr[GUEST_NULL_SEL] = 0;
        gdtr[GUEST_CODE_SEL] = 0x0020980000000000;
        gdtr[GUEST_DATA_SEL] = 0x0000900000000000;
}

/*
 * Setup the 'vcpu' register set such that it will begin execution at
 * 'rip' in long mode.
 */
int
vm_setup_freebsd_registers(struct vcpu *vcpu,
                           uint64_t rip, uint64_t cr3, uint64_t gdtbase,
                           uint64_t rsp)
{
        int error;
        uint64_t cr0, cr4, efer, rflags, desc_base;
        uint32_t desc_access, desc_limit;
        uint16_t gsel;

        cr0 = CR0_PE | CR0_PG | CR0_NE;
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_CR0, cr0)) != 0)
                goto done;

        cr4 = CR4_PAE;
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_CR4, cr4)) != 0)
                goto done;

        efer = EFER_LME | EFER_LMA;
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_EFER, efer)))
                goto done;

        rflags = 0x2;
        error = vm_set_register(vcpu, VM_REG_GUEST_RFLAGS, rflags);
        if (error)
                goto done;

        desc_base = 0;
        desc_limit = 0;
        desc_access = 0x0000209B;
        error = vm_set_desc(vcpu, VM_REG_GUEST_CS,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        desc_access = 0x00000093;
        error = vm_set_desc(vcpu, VM_REG_GUEST_DS,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        error = vm_set_desc(vcpu, VM_REG_GUEST_ES,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        error = vm_set_desc(vcpu, VM_REG_GUEST_FS,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        error = vm_set_desc(vcpu, VM_REG_GUEST_GS,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        error = vm_set_desc(vcpu, VM_REG_GUEST_SS,
                            desc_base, desc_limit, desc_access);
        if (error)
                goto done;

        /*
         * XXX TR is pointing to null selector even though we set the
         * TSS segment to be usable with a base address and limit of 0.
         */
        desc_access = 0x0000008b;
        error = vm_set_desc(vcpu, VM_REG_GUEST_TR, 0, 0, desc_access);
        if (error)
                goto done;

        error = vm_set_desc(vcpu, VM_REG_GUEST_LDTR, 0, 0,
                            DESC_UNUSABLE);
        if (error)
                goto done;

        gsel = GSEL(GUEST_CODE_SEL, SEL_KPL);
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_CS, gsel)) != 0)
                goto done;
        
        gsel = GSEL(GUEST_DATA_SEL, SEL_KPL);
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_DS, gsel)) != 0)
                goto done;
        
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_ES, gsel)) != 0)
                goto done;

        if ((error = vm_set_register(vcpu, VM_REG_GUEST_FS, gsel)) != 0)
                goto done;
        
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_GS, gsel)) != 0)
                goto done;
        
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_SS, gsel)) != 0)
                goto done;

        /* XXX TR is pointing to the null selector */
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_TR, 0)) != 0)
                goto done;

        /* LDTR is pointing to the null selector */
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_LDTR, 0)) != 0)
                goto done;

        /* entry point */
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_RIP, rip)) != 0)
                goto done;

        /* page table base */
        if ((error = vm_set_register(vcpu, VM_REG_GUEST_CR3, cr3)) != 0)
                goto done;

        desc_base = gdtbase;
        desc_limit = GUEST_GDTR_LIMIT64;
        error = vm_set_desc(vcpu, VM_REG_GUEST_GDTR,
                            desc_base, desc_limit, 0);
        if (error != 0)
                goto done;

        if ((error = vm_set_register(vcpu, VM_REG_GUEST_RSP, rsp)) != 0)
                goto done;

        error = 0;
done:
        return (error);
}