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freebsd-skq/sys/amd64/vmm/vmm_instruction_emul.c
Neel Natu d63e02ea96 Emulate "POP r/m". 
This is needed to boot OpenBSD/i386 MP kernel in bhyve.

Reported by:	grehan
MFC after:	1 week
2014-10-14 21:02:33 +00:00

1927 lines
44 KiB
C
Raw Blame History

/*-
* Copyright (c) 2012 Sandvine, Inc.
* Copyright (c) 2012 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 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.
*
* $FreeBSD$
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#ifdef _KERNEL
#include <sys/param.h>
#include <sys/pcpu.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <machine/vmparam.h>
#include <machine/vmm.h>
#else /* !_KERNEL */
#include <sys/types.h>
#include <sys/errno.h>
#include <sys/_iovec.h>
#include <machine/vmm.h>
#include <assert.h>
#include <vmmapi.h>
#define KASSERT(exp,msg) assert((exp))
#endif /* _KERNEL */
#include <machine/vmm_instruction_emul.h>
#include <x86/psl.h>
#include <x86/specialreg.h>
/* struct vie_op.op_type */
enum {
VIE_OP_TYPE_NONE = 0,
VIE_OP_TYPE_MOV,
VIE_OP_TYPE_MOVSX,
VIE_OP_TYPE_MOVZX,
VIE_OP_TYPE_AND,
VIE_OP_TYPE_OR,
VIE_OP_TYPE_SUB,
VIE_OP_TYPE_TWO_BYTE,
VIE_OP_TYPE_PUSH,
VIE_OP_TYPE_CMP,
VIE_OP_TYPE_POP,
VIE_OP_TYPE_LAST
};
/* struct vie_op.op_flags */
#define VIE_OP_F_IMM (1 << 0) /* 16/32-bit immediate operand */
#define VIE_OP_F_IMM8 (1 << 1) /* 8-bit immediate operand */
#define VIE_OP_F_MOFFSET (1 << 2) /* 16/32/64-bit immediate moffset */
#define VIE_OP_F_NO_MODRM (1 << 3)
static const struct vie_op two_byte_opcodes[256] = {
[0xB6] = {
.op_byte = 0xB6,
.op_type = VIE_OP_TYPE_MOVZX,
},
[0xB7] = {
.op_byte = 0xB7,
.op_type = VIE_OP_TYPE_MOVZX,
},
[0xBE] = {
.op_byte = 0xBE,
.op_type = VIE_OP_TYPE_MOVSX,
},
};
static const struct vie_op one_byte_opcodes[256] = {
[0x0F] = {
.op_byte = 0x0F,
.op_type = VIE_OP_TYPE_TWO_BYTE
},
[0x2B] = {
.op_byte = 0x2B,
.op_type = VIE_OP_TYPE_SUB,
},
[0x3B] = {
.op_byte = 0x3B,
.op_type = VIE_OP_TYPE_CMP,
},
[0x88] = {
.op_byte = 0x88,
.op_type = VIE_OP_TYPE_MOV,
},
[0x89] = {
.op_byte = 0x89,
.op_type = VIE_OP_TYPE_MOV,
},
[0x8A] = {
.op_byte = 0x8A,
.op_type = VIE_OP_TYPE_MOV,
},
[0x8B] = {
.op_byte = 0x8B,
.op_type = VIE_OP_TYPE_MOV,
},
[0xA1] = {
.op_byte = 0xA1,
.op_type = VIE_OP_TYPE_MOV,
.op_flags = VIE_OP_F_MOFFSET | VIE_OP_F_NO_MODRM,
},
[0xA3] = {
.op_byte = 0xA3,
.op_type = VIE_OP_TYPE_MOV,
.op_flags = VIE_OP_F_MOFFSET | VIE_OP_F_NO_MODRM,
},
[0xC6] = {
/* XXX Group 11 extended opcode - not just MOV */
.op_byte = 0xC6,
.op_type = VIE_OP_TYPE_MOV,
.op_flags = VIE_OP_F_IMM8,
},
[0xC7] = {
.op_byte = 0xC7,
.op_type = VIE_OP_TYPE_MOV,
.op_flags = VIE_OP_F_IMM,
},
[0x23] = {
.op_byte = 0x23,
.op_type = VIE_OP_TYPE_AND,
},
[0x81] = {
/* XXX Group 1 extended opcode - not just AND */
.op_byte = 0x81,
.op_type = VIE_OP_TYPE_AND,
.op_flags = VIE_OP_F_IMM,
},
[0x83] = {
/* XXX Group 1 extended opcode - not just OR */
.op_byte = 0x83,
.op_type = VIE_OP_TYPE_OR,
.op_flags = VIE_OP_F_IMM8,
},
[0x8F] = {
/* XXX Group 1A extended opcode - not just POP */
.op_byte = 0x8F,
.op_type = VIE_OP_TYPE_POP,
},
[0xFF] = {
/* XXX Group 5 extended opcode - not just PUSH */
.op_byte = 0xFF,
.op_type = VIE_OP_TYPE_PUSH,
}
};
/* struct vie.mod */
#define VIE_MOD_INDIRECT 0
#define VIE_MOD_INDIRECT_DISP8 1
#define VIE_MOD_INDIRECT_DISP32 2
#define VIE_MOD_DIRECT 3
/* struct vie.rm */
#define VIE_RM_SIB 4
#define VIE_RM_DISP32 5
#define GB (1024 * 1024 * 1024)
static enum vm_reg_name gpr_map[16] = {
VM_REG_GUEST_RAX,
VM_REG_GUEST_RCX,
VM_REG_GUEST_RDX,
VM_REG_GUEST_RBX,
VM_REG_GUEST_RSP,
VM_REG_GUEST_RBP,
VM_REG_GUEST_RSI,
VM_REG_GUEST_RDI,
VM_REG_GUEST_R8,
VM_REG_GUEST_R9,
VM_REG_GUEST_R10,
VM_REG_GUEST_R11,
VM_REG_GUEST_R12,
VM_REG_GUEST_R13,
VM_REG_GUEST_R14,
VM_REG_GUEST_R15
};
static uint64_t size2mask[] = {
[1] = 0xff,
[2] = 0xffff,
[4] = 0xffffffff,
[8] = 0xffffffffffffffff,
};
static int
vie_read_register(void *vm, int vcpuid, enum vm_reg_name reg, uint64_t *rval)
{
int error;
error = vm_get_register(vm, vcpuid, reg, rval);
return (error);
}
static void
vie_calc_bytereg(struct vie *vie, enum vm_reg_name *reg, int *lhbr)
{
*lhbr = 0;
*reg = gpr_map[vie->reg];
/*
* 64-bit mode imposes limitations on accessing legacy high byte
* registers (lhbr).
*
* The legacy high-byte registers cannot be addressed if the REX
* prefix is present. In this case the values 4, 5, 6 and 7 of the
* 'ModRM:reg' field address %spl, %bpl, %sil and %dil respectively.
*
* If the REX prefix is not present then the values 4, 5, 6 and 7
* of the 'ModRM:reg' field address the legacy high-byte registers,
* %ah, %ch, %dh and %bh respectively.
*/
if (!vie->rex_present) {
if (vie->reg & 0x4) {
*lhbr = 1;
*reg = gpr_map[vie->reg & 0x3];
}
}
}
static int
vie_read_bytereg(void *vm, int vcpuid, struct vie *vie, uint8_t *rval)
{
uint64_t val;
int error, lhbr;
enum vm_reg_name reg;
vie_calc_bytereg(vie, &reg, &lhbr);
error = vm_get_register(vm, vcpuid, reg, &val);
/*
* To obtain the value of a legacy high byte register shift the
* base register right by 8 bits (%ah = %rax >> 8).
*/
if (lhbr)
*rval = val >> 8;
else
*rval = val;
return (error);
}
static int
vie_write_bytereg(void *vm, int vcpuid, struct vie *vie, uint8_t byte)
{
uint64_t origval, val, mask;
int error, lhbr;
enum vm_reg_name reg;
vie_calc_bytereg(vie, &reg, &lhbr);
error = vm_get_register(vm, vcpuid, reg, &origval);
if (error == 0) {
val = byte;
mask = 0xff;
if (lhbr) {
/*
* Shift left by 8 to store 'byte' in a legacy high
* byte register.
*/
val <<= 8;
mask <<= 8;
}
val |= origval & ~mask;
error = vm_set_register(vm, vcpuid, reg, val);
}
return (error);
}
int
vie_update_register(void *vm, int vcpuid, enum vm_reg_name reg,
uint64_t val, int size)
{
int error;
uint64_t origval;
switch (size) {
case 1:
case 2:
error = vie_read_register(vm, vcpuid, reg, &origval);
if (error)
return (error);
val &= size2mask[size];
val |= origval & ~size2mask[size];
break;
case 4:
val &= 0xffffffffUL;
break;
case 8:
break;
default:
return (EINVAL);
}
error = vm_set_register(vm, vcpuid, reg, val);
return (error);
}
#define RFLAGS_STATUS_BITS (PSL_C | PSL_PF | PSL_AF | PSL_Z | PSL_N | PSL_V)
/*
* Return the status flags that would result from doing (x - y).
*/
#define GETCC(sz) \
static u_long \
getcc##sz(uint##sz##_t x, uint##sz##_t y) \
{ \
u_long rflags; \
\
__asm __volatile("sub %2,%1; pushfq; popq %0" : \
"=r" (rflags), "+r" (x) : "m" (y)); \
return (rflags); \
} struct __hack
GETCC(8);
GETCC(16);
GETCC(32);
GETCC(64);
static u_long
getcc(int opsize, uint64_t x, uint64_t y)
{
KASSERT(opsize == 1 || opsize == 2 || opsize == 4 || opsize == 8,
("getcc: invalid operand size %d", opsize));
if (opsize == 1)
return (getcc8(x, y));
else if (opsize == 2)
return (getcc16(x, y));
else if (opsize == 4)
return (getcc32(x, y));
else
return (getcc64(x, y));
}
static int
emulate_mov(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
{
int error, size;
enum vm_reg_name reg;
uint8_t byte;
uint64_t val;
size = vie->opsize;
error = EINVAL;
switch (vie->op.op_byte) {
case 0x88:
/*
* MOV byte from reg (ModRM:reg) to mem (ModRM:r/m)
* 88/r: mov r/m8, r8
* REX + 88/r: mov r/m8, r8 (%ah, %ch, %dh, %bh not available)
*/
size = 1; /* override for byte operation */
error = vie_read_bytereg(vm, vcpuid, vie, &byte);
if (error == 0)
error = memwrite(vm, vcpuid, gpa, byte, size, arg);
break;
case 0x89:
/*
* MOV from reg (ModRM:reg) to mem (ModRM:r/m)
* 89/r: mov r/m16, r16
* 89/r: mov r/m32, r32
* REX.W + 89/r mov r/m64, r64
*/
reg = gpr_map[vie->reg];
error = vie_read_register(vm, vcpuid, reg, &val);
if (error == 0) {
val &= size2mask[size];
error = memwrite(vm, vcpuid, gpa, val, size, arg);
}
break;
case 0x8A:
/*
* MOV byte from mem (ModRM:r/m) to reg (ModRM:reg)
* 8A/r: mov r8, r/m8
* REX + 8A/r: mov r8, r/m8
*/
size = 1; /* override for byte operation */
error = memread(vm, vcpuid, gpa, &val, size, arg);
if (error == 0)
error = vie_write_bytereg(vm, vcpuid, vie, val);
break;
case 0x8B:
/*
* MOV from mem (ModRM:r/m) to reg (ModRM:reg)
* 8B/r: mov r16, r/m16
* 8B/r: mov r32, r/m32
* REX.W 8B/r: mov r64, r/m64
*/
error = memread(vm, vcpuid, gpa, &val, size, arg);
if (error == 0) {
reg = gpr_map[vie->reg];
error = vie_update_register(vm, vcpuid, reg, val, size);
}
break;
case 0xA1:
/*
* MOV from seg:moffset to AX/EAX/RAX
* A1: mov AX, moffs16
* A1: mov EAX, moffs32
* REX.W + A1: mov RAX, moffs64
*/
error = memread(vm, vcpuid, gpa, &val, size, arg);
if (error == 0) {
reg = VM_REG_GUEST_RAX;
error = vie_update_register(vm, vcpuid, reg, val, size);
}
break;
case 0xA3:
/*
* MOV from AX/EAX/RAX to seg:moffset
* A3: mov moffs16, AX
* A3: mov moffs32, EAX
* REX.W + A3: mov moffs64, RAX
*/
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RAX, &val);
if (error == 0) {
val &= size2mask[size];
error = memwrite(vm, vcpuid, gpa, val, size, arg);
}
break;
case 0xC6:
/*
* MOV from imm8 to mem (ModRM:r/m)
* C6/0 mov r/m8, imm8
* REX + C6/0 mov r/m8, imm8
*/
size = 1; /* override for byte operation */
error = memwrite(vm, vcpuid, gpa, vie->immediate, size, arg);
break;
case 0xC7:
/*
* MOV from imm16/imm32 to mem (ModRM:r/m)
* C7/0 mov r/m16, imm16
* C7/0 mov r/m32, imm32
* REX.W + C7/0 mov r/m64, imm32 (sign-extended to 64-bits)
*/
val = vie->immediate & size2mask[size];
error = memwrite(vm, vcpuid, gpa, val, size, arg);
break;
default:
break;
}
return (error);
}
static int
emulate_movx(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
mem_region_read_t memread, mem_region_write_t memwrite,
void *arg)
{
int error, size;
enum vm_reg_name reg;
uint64_t val;
size = vie->opsize;
error = EINVAL;
switch (vie->op.op_byte) {
case 0xB6:
/*
* MOV and zero extend byte from mem (ModRM:r/m) to
* reg (ModRM:reg).
*
* 0F B6/r movzx r16, r/m8
* 0F B6/r movzx r32, r/m8
* REX.W + 0F B6/r movzx r64, r/m8
*/
/* get the first operand */
error = memread(vm, vcpuid, gpa, &val, 1, arg);
if (error)
break;
/* get the second operand */
reg = gpr_map[vie->reg];
/* zero-extend byte */
val = (uint8_t)val;
/* write the result */
error = vie_update_register(vm, vcpuid, reg, val, size);
break;
case 0xB7:
/*
* MOV and zero extend word from mem (ModRM:r/m) to
* reg (ModRM:reg).
*
* 0F B7/r movzx r32, r/m16
* REX.W + 0F B7/r movzx r64, r/m16
*/
error = memread(vm, vcpuid, gpa, &val, 2, arg);
if (error)
return (error);
reg = gpr_map[vie->reg];
/* zero-extend word */
val = (uint16_t)val;
error = vie_update_register(vm, vcpuid, reg, val, size);
break;
case 0xBE:
/*
* MOV and sign extend byte from mem (ModRM:r/m) to
* reg (ModRM:reg).
*
* 0F BE/r movsx r16, r/m8
* 0F BE/r movsx r32, r/m8
* REX.W + 0F BE/r movsx r64, r/m8
*/
/* get the first operand */
error = memread(vm, vcpuid, gpa, &val, 1, arg);
if (error)
break;
/* get the second operand */
reg = gpr_map[vie->reg];
/* sign extend byte */
val = (int8_t)val;
/* write the result */
error = vie_update_register(vm, vcpuid, reg, val, size);
break;
default:
break;
}
return (error);
}
static int
emulate_and(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
{
int error, size;
enum vm_reg_name reg;
uint64_t result, rflags, rflags2, val1, val2;
size = vie->opsize;
error = EINVAL;
switch (vie->op.op_byte) {
case 0x23:
/*
* AND reg (ModRM:reg) and mem (ModRM:r/m) and store the
* result in reg.
*
* 23/r and r16, r/m16
* 23/r and r32, r/m32
* REX.W + 23/r and r64, r/m64
*/
/* get the first operand */
reg = gpr_map[vie->reg];
error = vie_read_register(vm, vcpuid, reg, &val1);
if (error)
break;
/* get the second operand */
error = memread(vm, vcpuid, gpa, &val2, size, arg);
if (error)
break;
/* perform the operation and write the result */
result = val1 & val2;
error = vie_update_register(vm, vcpuid, reg, result, size);
break;
case 0x81:
/*
* AND/OR mem (ModRM:r/m) with immediate and store the
* result in mem.
*
* AND: i = 4
* OR: i = 1
* 81 /i op r/m16, imm16
* 81 /i op r/m32, imm32
* REX.W + 81 /i op r/m64, imm32 sign-extended to 64
*
*/
/* get the first operand */
error = memread(vm, vcpuid, gpa, &val1, size, arg);
if (error)
break;
/*
* perform the operation with the pre-fetched immediate
* operand and write the result
*/
switch (vie->reg & 7) {
case 0x4:
/* modrm:reg == b100, AND */
result = val1 & vie->immediate;
break;
case 0x1:
/* modrm:reg == b001, OR */
result = val1 | vie->immediate;
break;
default:
error = EINVAL;
break;
}
if (error)
break;
error = memwrite(vm, vcpuid, gpa, result, size, arg);
break;
default:
break;
}
if (error)
return (error);
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
if (error)
return (error);
/*
* OF and CF are cleared; the SF, ZF and PF flags are set according
* to the result; AF is undefined.
*
* The updated status flags are obtained by subtracting 0 from 'result'.
*/
rflags2 = getcc(size, result, 0);
rflags &= ~RFLAGS_STATUS_BITS;
rflags |= rflags2 & (PSL_PF | PSL_Z | PSL_N);
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, rflags, 8);
return (error);
}
static int
emulate_or(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
{
int error, size;
uint64_t val1, result, rflags, rflags2;
size = vie->opsize;
error = EINVAL;
switch (vie->op.op_byte) {
case 0x83:
/*
* OR mem (ModRM:r/m) with immediate and store the
* result in mem.
*
* 83 /1 OR r/m16, imm8 sign-extended to 16
* 83 /1 OR r/m32, imm8 sign-extended to 32
* REX.W + 83/1 OR r/m64, imm8 sign-extended to 64
*
* Currently, only the OR operation of the 0x83 opcode
* is implemented (ModRM:reg = b001).
*/
if ((vie->reg & 7) != 1)
break;
/* get the first operand */
error = memread(vm, vcpuid, gpa, &val1, size, arg);
if (error)
break;
/*
* perform the operation with the pre-fetched immediate
* operand and write the result
*/
result = val1 | vie->immediate;
error = memwrite(vm, vcpuid, gpa, result, size, arg);
break;
default:
break;
}
if (error)
return (error);
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
if (error)
return (error);
/*
* OF and CF are cleared; the SF, ZF and PF flags are set according
* to the result; AF is undefined.
*
* The updated status flags are obtained by subtracting 0 from 'result'.
*/
rflags2 = getcc(size, result, 0);
rflags &= ~RFLAGS_STATUS_BITS;
rflags |= rflags2 & (PSL_PF | PSL_Z | PSL_N);
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, rflags, 8);
return (error);
}
static int
emulate_cmp(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
{
int error, size;
uint64_t op1, op2, rflags, rflags2;
enum vm_reg_name reg;
size = vie->opsize;
switch (vie->op.op_byte) {
case 0x3B:
/*
* 3B/r CMP r16, r/m16
* 3B/r CMP r32, r/m32
* REX.W + 3B/r CMP r64, r/m64
*
* Compare first operand (reg) with second operand (r/m) and
* set status flags in EFLAGS register. The comparison is
* performed by subtracting the second operand from the first
* operand and then setting the status flags.
*/
/* Get the first operand */
reg = gpr_map[vie->reg];
error = vie_read_register(vm, vcpuid, reg, &op1);
if (error)
return (error);
/* Get the second operand */
error = memread(vm, vcpuid, gpa, &op2, size, arg);
if (error)
return (error);
break;
default:
return (EINVAL);
}
rflags2 = getcc(size, op1, op2);
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
if (error)
return (error);
rflags &= ~RFLAGS_STATUS_BITS;
rflags |= rflags2 & RFLAGS_STATUS_BITS;
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, rflags, 8);
return (error);
}
static int
emulate_sub(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
mem_region_read_t memread, mem_region_write_t memwrite, void *arg)
{
int error, size;
uint64_t nval, rflags, rflags2, val1, val2;
enum vm_reg_name reg;
size = vie->opsize;
error = EINVAL;
switch (vie->op.op_byte) {
case 0x2B:
/*
* SUB r/m from r and store the result in r
*
* 2B/r SUB r16, r/m16
* 2B/r SUB r32, r/m32
* REX.W + 2B/r SUB r64, r/m64
*/
/* get the first operand */
reg = gpr_map[vie->reg];
error = vie_read_register(vm, vcpuid, reg, &val1);
if (error)
break;
/* get the second operand */
error = memread(vm, vcpuid, gpa, &val2, size, arg);
if (error)
break;
/* perform the operation and write the result */
nval = val1 - val2;
error = vie_update_register(vm, vcpuid, reg, nval, size);
break;
default:
break;
}
if (!error) {
rflags2 = getcc(size, val1, val2);
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS,
&rflags);
if (error)
return (error);
rflags &= ~RFLAGS_STATUS_BITS;
rflags |= rflags2 & RFLAGS_STATUS_BITS;
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS,
rflags, 8);
}
return (error);
}
static int
emulate_stack_op(void *vm, int vcpuid, uint64_t mmio_gpa, struct vie *vie,
struct vm_guest_paging *paging, mem_region_read_t memread,
mem_region_write_t memwrite, void *arg)
{
#ifdef _KERNEL
struct vm_copyinfo copyinfo[2];
#else
struct iovec copyinfo[2];
#endif
struct seg_desc ss_desc;
uint64_t cr0, rflags, rsp, stack_gla, val;
int error, size, stackaddrsize, pushop;
val = 0;
size = vie->opsize;
pushop = (vie->op.op_type == VIE_OP_TYPE_PUSH) ? 1 : 0;
/*
* From "Address-Size Attributes for Stack Accesses", Intel SDL, Vol 1
*/
if (paging->cpu_mode == CPU_MODE_REAL) {
stackaddrsize = 2;
} else if (paging->cpu_mode == CPU_MODE_64BIT) {
/*
* "Stack Manipulation Instructions in 64-bit Mode", SDM, Vol 3
* - Stack pointer size is always 64-bits.
* - PUSH/POP of 32-bit values is not possible in 64-bit mode.
* - 16-bit PUSH/POP is supported by using the operand size
* override prefix (66H).
*/
stackaddrsize = 8;
size = vie->opsize_override ? 2 : 8;
} else {
/*
* In protected or compability mode the 'B' flag in the
* stack-segment descriptor determines the size of the
* stack pointer.
*/
error = vm_get_seg_desc(vm, vcpuid, VM_REG_GUEST_SS, &ss_desc);
KASSERT(error == 0, ("%s: error %d getting SS descriptor",
__func__, error));
if (SEG_DESC_DEF32(ss_desc.access))
stackaddrsize = 4;
else
stackaddrsize = 2;
}
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_CR0, &cr0);
KASSERT(error == 0, ("%s: error %d getting cr0", __func__, error));
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
KASSERT(error == 0, ("%s: error %d getting rflags", __func__, error));
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RSP, &rsp);
KASSERT(error == 0, ("%s: error %d getting rsp", __func__, error));
if (pushop) {
rsp -= size;
}
if (vie_calculate_gla(paging->cpu_mode, VM_REG_GUEST_SS, &ss_desc,
rsp, size, stackaddrsize, pushop ? PROT_WRITE : PROT_READ,
&stack_gla)) {
vm_inject_ss(vm, vcpuid, 0);
return (0);
}
if (vie_canonical_check(paging->cpu_mode, stack_gla)) {
vm_inject_ss(vm, vcpuid, 0);
return (0);
}
if (vie_alignment_check(paging->cpl, size, cr0, rflags, stack_gla)) {
vm_inject_ac(vm, vcpuid, 0);
return (0);
}
error = vm_copy_setup(vm, vcpuid, paging, stack_gla, size,
pushop ? PROT_WRITE : PROT_READ, copyinfo, nitems(copyinfo));
if (error == -1) {
/*
* XXX cannot return a negative error value here because it
* ends up being the return value of the VM_RUN() ioctl and
* is interpreted as a pseudo-error (for e.g. ERESTART).
*/
return (EFAULT);
} else if (error == 1) {
/* Resume guest execution to handle page fault */
return (0);
}
if (pushop) {
error = memread(vm, vcpuid, mmio_gpa, &val, size, arg);
if (error == 0)
vm_copyout(vm, vcpuid, &val, copyinfo, size);
} else {
vm_copyin(vm, vcpuid, copyinfo, &val, size);
error = memwrite(vm, vcpuid, mmio_gpa, val, size, arg);
rsp += size;
}
#ifdef _KERNEL
vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
#endif
if (error == 0) {
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RSP, rsp,
stackaddrsize);
KASSERT(error == 0, ("error %d updating rsp", error));
}
return (error);
}
static int
emulate_push(void *vm, int vcpuid, uint64_t mmio_gpa, struct vie *vie,
struct vm_guest_paging *paging, mem_region_read_t memread,
mem_region_write_t memwrite, void *arg)
{
int error;
/*
* Table A-6, "Opcode Extensions", Intel SDM, Vol 2.
*
* PUSH is part of the group 5 extended opcodes and is identified
* by ModRM:reg = b110.
*/
if ((vie->reg & 7) != 6)
return (EINVAL);
error = emulate_stack_op(vm, vcpuid, mmio_gpa, vie, paging, memread,
memwrite, arg);
return (error);
}
static int
emulate_pop(void *vm, int vcpuid, uint64_t mmio_gpa, struct vie *vie,
struct vm_guest_paging *paging, mem_region_read_t memread,
mem_region_write_t memwrite, void *arg)
{
int error;
/*
* Table A-6, "Opcode Extensions", Intel SDM, Vol 2.
*
* POP is part of the group 1A extended opcodes and is identified
* by ModRM:reg = b000.
*/
if ((vie->reg & 7) != 0)
return (EINVAL);
error = emulate_stack_op(vm, vcpuid, mmio_gpa, vie, paging, memread,
memwrite, arg);
return (error);
}
int
vmm_emulate_instruction(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
struct vm_guest_paging *paging, mem_region_read_t memread,
mem_region_write_t memwrite, void *memarg)
{
int error;
if (!vie->decoded)
return (EINVAL);
switch (vie->op.op_type) {
case VIE_OP_TYPE_POP:
error = emulate_pop(vm, vcpuid, gpa, vie, paging, memread,
memwrite, memarg);
break;
case VIE_OP_TYPE_PUSH:
error = emulate_push(vm, vcpuid, gpa, vie, paging, memread,
memwrite, memarg);
break;
case VIE_OP_TYPE_CMP:
error = emulate_cmp(vm, vcpuid, gpa, vie,
memread, memwrite, memarg);
break;
case VIE_OP_TYPE_MOV:
error = emulate_mov(vm, vcpuid, gpa, vie,
memread, memwrite, memarg);
break;
case VIE_OP_TYPE_MOVSX:
case VIE_OP_TYPE_MOVZX:
error = emulate_movx(vm, vcpuid, gpa, vie,
memread, memwrite, memarg);
break;
case VIE_OP_TYPE_AND:
error = emulate_and(vm, vcpuid, gpa, vie,
memread, memwrite, memarg);
break;
case VIE_OP_TYPE_OR:
error = emulate_or(vm, vcpuid, gpa, vie,
memread, memwrite, memarg);
break;
case VIE_OP_TYPE_SUB:
error = emulate_sub(vm, vcpuid, gpa, vie,
memread, memwrite, memarg);
break;
default:
error = EINVAL;
break;
}
return (error);
}
int
vie_alignment_check(int cpl, int size, uint64_t cr0, uint64_t rf, uint64_t gla)
{
KASSERT(size == 1 || size == 2 || size == 4 || size == 8,
("%s: invalid size %d", __func__, size));
KASSERT(cpl >= 0 && cpl <= 3, ("%s: invalid cpl %d", __func__, cpl));
if (cpl != 3 || (cr0 & CR0_AM) == 0 || (rf & PSL_AC) == 0)
return (0);
return ((gla & (size - 1)) ? 1 : 0);
}
int
vie_canonical_check(enum vm_cpu_mode cpu_mode, uint64_t gla)
{
uint64_t mask;
if (cpu_mode != CPU_MODE_64BIT)
return (0);
/*
* The value of the bit 47 in the 'gla' should be replicated in the
* most significant 16 bits.
*/
mask = ~((1UL << 48) - 1);
if (gla & (1UL << 47))
return ((gla & mask) != mask);
else
return ((gla & mask) != 0);
}
uint64_t
vie_size2mask(int size)
{
KASSERT(size == 1 || size == 2 || size == 4 || size == 8,
("vie_size2mask: invalid size %d", size));
return (size2mask[size]);
}
int
vie_calculate_gla(enum vm_cpu_mode cpu_mode, enum vm_reg_name seg,
struct seg_desc *desc, uint64_t offset, int length, int addrsize,
int prot, uint64_t *gla)
{
uint64_t firstoff, low_limit, high_limit, segbase;
int glasize, type;
KASSERT(seg >= VM_REG_GUEST_ES && seg <= VM_REG_GUEST_GS,
("%s: invalid segment %d", __func__, seg));
KASSERT(length == 1 || length == 2 || length == 4 || length == 8,
("%s: invalid operand size %d", __func__, length));
KASSERT((prot & ~(PROT_READ | PROT_WRITE)) == 0,
("%s: invalid prot %#x", __func__, prot));
firstoff = offset;
if (cpu_mode == CPU_MODE_64BIT) {
KASSERT(addrsize == 4 || addrsize == 8, ("%s: invalid address "
"size %d for cpu_mode %d", __func__, addrsize, cpu_mode));
glasize = 8;
} else {
KASSERT(addrsize == 2 || addrsize == 4, ("%s: invalid address "
"size %d for cpu mode %d", __func__, addrsize, cpu_mode));
glasize = 4;
/*
* If the segment selector is loaded with a NULL selector
* then the descriptor is unusable and attempting to use
* it results in a #GP(0).
*/
if (SEG_DESC_UNUSABLE(desc->access))
return (-1);
/*
* The processor generates a #NP exception when a segment
* register is loaded with a selector that points to a
* descriptor that is not present. If this was the case then
* it would have been checked before the VM-exit.
*/
KASSERT(SEG_DESC_PRESENT(desc->access),
("segment %d not present: %#x", seg, desc->access));
/*
* The descriptor type must indicate a code/data segment.
*/
type = SEG_DESC_TYPE(desc->access);
KASSERT(type >= 16 && type <= 31, ("segment %d has invalid "
"descriptor type %#x", seg, type));
if (prot & PROT_READ) {
/* #GP on a read access to a exec-only code segment */
if ((type & 0xA) == 0x8)
return (-1);
}
if (prot & PROT_WRITE) {
/*
* #GP on a write access to a code segment or a
* read-only data segment.
*/
if (type & 0x8) /* code segment */
return (-1);
if ((type & 0xA) == 0) /* read-only data seg */
return (-1);
}
/*
* 'desc->limit' is fully expanded taking granularity into
* account.
*/
if ((type & 0xC) == 0x4) {
/* expand-down data segment */
low_limit = desc->limit + 1;
high_limit = SEG_DESC_DEF32(desc->access) ?
0xffffffff : 0xffff;
} else {
/* code segment or expand-up data segment */
low_limit = 0;
high_limit = desc->limit;
}
while (length > 0) {
offset &= vie_size2mask(addrsize);
if (offset < low_limit || offset > high_limit)
return (-1);
offset++;
length--;
}
}
/*
* In 64-bit mode all segments except %fs and %gs have a segment
* base address of 0.
*/
if (cpu_mode == CPU_MODE_64BIT && seg != VM_REG_GUEST_FS &&
seg != VM_REG_GUEST_GS) {
segbase = 0;
} else {
segbase = desc->base;
}
/*
* Truncate 'firstoff' to the effective address size before adding
* it to the segment base.
*/
firstoff &= vie_size2mask(addrsize);
*gla = (segbase + firstoff) & vie_size2mask(glasize);
return (0);
}
#ifdef _KERNEL
void
vie_init(struct vie *vie)
{
bzero(vie, sizeof(struct vie));
vie->base_register = VM_REG_LAST;
vie->index_register = VM_REG_LAST;
}
static int
pf_error_code(int usermode, int prot, int rsvd, uint64_t pte)
{
int error_code = 0;
if (pte & PG_V)
error_code |= PGEX_P;
if (prot & VM_PROT_WRITE)
error_code |= PGEX_W;
if (usermode)
error_code |= PGEX_U;
if (rsvd)
error_code |= PGEX_RSV;
if (prot & VM_PROT_EXECUTE)
error_code |= PGEX_I;
return (error_code);
}
static void
ptp_release(void **cookie)
{
if (*cookie != NULL) {
vm_gpa_release(*cookie);
*cookie = NULL;
}
}
static void *
ptp_hold(struct vm *vm, vm_paddr_t ptpphys, size_t len, void **cookie)
{
void *ptr;
ptp_release(cookie);
ptr = vm_gpa_hold(vm, ptpphys, len, VM_PROT_RW, cookie);
return (ptr);
}
int
vmm_gla2gpa(struct vm *vm, int vcpuid, struct vm_guest_paging *paging,
uint64_t gla, int prot, uint64_t *gpa)
{
int nlevels, pfcode, ptpshift, ptpindex, retval, usermode, writable;
u_int retries;
uint64_t *ptpbase, ptpphys, pte, pgsize;
uint32_t *ptpbase32, pte32;
void *cookie;
usermode = (paging->cpl == 3 ? 1 : 0);
writable = prot & VM_PROT_WRITE;
cookie = NULL;
retval = 0;
retries = 0;
restart:
ptpphys = paging->cr3; /* root of the page tables */
ptp_release(&cookie);
if (retries++ > 0)
maybe_yield();
if (vie_canonical_check(paging->cpu_mode, gla)) {
/*
* XXX assuming a non-stack reference otherwise a stack fault
* should be generated.
*/
vm_inject_gp(vm, vcpuid);
goto fault;
}
if (paging->paging_mode == PAGING_MODE_FLAT) {
*gpa = gla;
goto done;
}
if (paging->paging_mode == PAGING_MODE_32) {
nlevels = 2;
while (--nlevels >= 0) {
/* Zero out the lower 12 bits. */
ptpphys &= ~0xfff;
ptpbase32 = ptp_hold(vm, ptpphys, PAGE_SIZE, &cookie);
if (ptpbase32 == NULL)
goto error;
ptpshift = PAGE_SHIFT + nlevels * 10;
ptpindex = (gla >> ptpshift) & 0x3FF;
pgsize = 1UL << ptpshift;
pte32 = ptpbase32[ptpindex];
if ((pte32 & PG_V) == 0 ||
(usermode && (pte32 & PG_U) == 0) ||
(writable && (pte32 & PG_RW) == 0)) {
pfcode = pf_error_code(usermode, prot, 0,
pte32);
vm_inject_pf(vm, vcpuid, pfcode, gla);
goto fault;
}
/*
* Emulate the x86 MMU's management of the accessed
* and dirty flags. While the accessed flag is set
* at every level of the page table, the dirty flag
* is only set at the last level providing the guest
* physical address.
*/
if ((pte32 & PG_A) == 0) {
if (atomic_cmpset_32(&ptpbase32[ptpindex],
pte32, pte32 | PG_A) == 0) {
goto restart;
}
}
/* XXX must be ignored if CR4.PSE=0 */
if (nlevels > 0 && (pte32 & PG_PS) != 0)
break;
ptpphys = pte32;
}
/* Set the dirty bit in the page table entry if necessary */
if (writable && (pte32 & PG_M) == 0) {
if (atomic_cmpset_32(&ptpbase32[ptpindex],
pte32, pte32 | PG_M) == 0) {
goto restart;
}
}
/* Zero out the lower 'ptpshift' bits */
pte32 >>= ptpshift; pte32 <<= ptpshift;
*gpa = pte32 | (gla & (pgsize - 1));
goto done;
}
if (paging->paging_mode == PAGING_MODE_PAE) {
/* Zero out the lower 5 bits and the upper 32 bits */
ptpphys &= 0xffffffe0UL;
ptpbase = ptp_hold(vm, ptpphys, sizeof(*ptpbase) * 4, &cookie);
if (ptpbase == NULL)
goto error;
ptpindex = (gla >> 30) & 0x3;
pte = ptpbase[ptpindex];
if ((pte & PG_V) == 0) {
pfcode = pf_error_code(usermode, prot, 0, pte);
vm_inject_pf(vm, vcpuid, pfcode, gla);
goto fault;
}
ptpphys = pte;
nlevels = 2;
} else
nlevels = 4;
while (--nlevels >= 0) {
/* Zero out the lower 12 bits and the upper 12 bits */
ptpphys >>= 12; ptpphys <<= 24; ptpphys >>= 12;
ptpbase = ptp_hold(vm, ptpphys, PAGE_SIZE, &cookie);
if (ptpbase == NULL)
goto error;
ptpshift = PAGE_SHIFT + nlevels * 9;
ptpindex = (gla >> ptpshift) & 0x1FF;
pgsize = 1UL << ptpshift;
pte = ptpbase[ptpindex];
if ((pte & PG_V) == 0 ||
(usermode && (pte & PG_U) == 0) ||
(writable && (pte & PG_RW) == 0)) {
pfcode = pf_error_code(usermode, prot, 0, pte);
vm_inject_pf(vm, vcpuid, pfcode, gla);
goto fault;
}
/* Set the accessed bit in the page table entry */
if ((pte & PG_A) == 0) {
if (atomic_cmpset_64(&ptpbase[ptpindex],
pte, pte | PG_A) == 0) {
goto restart;
}
}
if (nlevels > 0 && (pte & PG_PS) != 0) {
if (pgsize > 1 * GB) {
pfcode = pf_error_code(usermode, prot, 1, pte);
vm_inject_pf(vm, vcpuid, pfcode, gla);
goto fault;
}
break;
}
ptpphys = pte;
}
/* Set the dirty bit in the page table entry if necessary */
if (writable && (pte & PG_M) == 0) {
if (atomic_cmpset_64(&ptpbase[ptpindex], pte, pte | PG_M) == 0)
goto restart;
}
/* Zero out the lower 'ptpshift' bits and the upper 12 bits */
pte >>= ptpshift; pte <<= (ptpshift + 12); pte >>= 12;
*gpa = pte | (gla & (pgsize - 1));
done:
ptp_release(&cookie);
return (retval);
error:
retval = -1;
goto done;
fault:
retval = 1;
goto done;
}
int
vmm_fetch_instruction(struct vm *vm, int vcpuid, struct vm_guest_paging *paging,
uint64_t rip, int inst_length, struct vie *vie)
{
struct vm_copyinfo copyinfo[2];
int error, prot;
if (inst_length > VIE_INST_SIZE)
panic("vmm_fetch_instruction: invalid length %d", inst_length);
prot = PROT_READ | PROT_EXEC;
error = vm_copy_setup(vm, vcpuid, paging, rip, inst_length, prot,
copyinfo, nitems(copyinfo));
if (error == 0) {
vm_copyin(vm, vcpuid, copyinfo, vie->inst, inst_length);
vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
vie->num_valid = inst_length;
}
return (error);
}
static int
vie_peek(struct vie *vie, uint8_t *x)
{
if (vie->num_processed < vie->num_valid) {
*x = vie->inst[vie->num_processed];
return (0);
} else
return (-1);
}
static void
vie_advance(struct vie *vie)
{
vie->num_processed++;
}
static int
decode_prefixes(struct vie *vie, enum vm_cpu_mode cpu_mode, int cs_d)
{
uint8_t x;
while (1) {
if (vie_peek(vie, &x))
return (-1);
if (x == 0x66)
vie->opsize_override = 1;
else if (x == 0x67)
vie->addrsize_override = 1;
else
break;
vie_advance(vie);
}
/*
* From section 2.2.1, "REX Prefixes", Intel SDM Vol 2:
* - Only one REX prefix is allowed per instruction.
* - The REX prefix must immediately precede the opcode byte or the
* escape opcode byte.
* - If an instruction has a mandatory prefix (0x66, 0xF2 or 0xF3)
* the mandatory prefix must come before the REX prefix.
*/
if (cpu_mode == CPU_MODE_64BIT && x >= 0x40 && x <= 0x4F) {
vie->rex_present = 1;
vie->rex_w = x & 0x8 ? 1 : 0;
vie->rex_r = x & 0x4 ? 1 : 0;
vie->rex_x = x & 0x2 ? 1 : 0;
vie->rex_b = x & 0x1 ? 1 : 0;
vie_advance(vie);
}
/*
* Section "Operand-Size And Address-Size Attributes", Intel SDM, Vol 1
*/
if (cpu_mode == CPU_MODE_64BIT) {
/*
* Default address size is 64-bits and default operand size
* is 32-bits.
*/
vie->addrsize = vie->addrsize_override ? 4 : 8;
if (vie->rex_w)
vie->opsize = 8;
else if (vie->opsize_override)
vie->opsize = 2;
else
vie->opsize = 4;
} else if (cs_d) {
/* Default address and operand sizes are 32-bits */
vie->addrsize = vie->addrsize_override ? 2 : 4;
vie->opsize = vie->opsize_override ? 2 : 4;
} else {
/* Default address and operand sizes are 16-bits */
vie->addrsize = vie->addrsize_override ? 4 : 2;
vie->opsize = vie->opsize_override ? 4 : 2;
}
return (0);
}
static int
decode_two_byte_opcode(struct vie *vie)
{
uint8_t x;
if (vie_peek(vie, &x))
return (-1);
vie->op = two_byte_opcodes[x];
if (vie->op.op_type == VIE_OP_TYPE_NONE)
return (-1);
vie_advance(vie);
return (0);
}
static int
decode_opcode(struct vie *vie)
{
uint8_t x;
if (vie_peek(vie, &x))
return (-1);
vie->op = one_byte_opcodes[x];
if (vie->op.op_type == VIE_OP_TYPE_NONE)
return (-1);
vie_advance(vie);
if (vie->op.op_type == VIE_OP_TYPE_TWO_BYTE)
return (decode_two_byte_opcode(vie));
return (0);
}
static int
decode_modrm(struct vie *vie, enum vm_cpu_mode cpu_mode)
{
uint8_t x;
if (cpu_mode == CPU_MODE_REAL)
return (-1);
if (vie->op.op_flags & VIE_OP_F_NO_MODRM)
return (0);
if (vie_peek(vie, &x))
return (-1);
vie->mod = (x >> 6) & 0x3;
vie->rm = (x >> 0) & 0x7;
vie->reg = (x >> 3) & 0x7;
/*
* A direct addressing mode makes no sense in the context of an EPT
* fault. There has to be a memory access involved to cause the
* EPT fault.
*/
if (vie->mod == VIE_MOD_DIRECT)
return (-1);
if ((vie->mod == VIE_MOD_INDIRECT && vie->rm == VIE_RM_DISP32) ||
(vie->mod != VIE_MOD_DIRECT && vie->rm == VIE_RM_SIB)) {
/*
* Table 2-5: Special Cases of REX Encodings
*
* mod=0, r/m=5 is used in the compatibility mode to
* indicate a disp32 without a base register.
*
* mod!=3, r/m=4 is used in the compatibility mode to
* indicate that the SIB byte is present.
*
* The 'b' bit in the REX prefix is don't care in
* this case.
*/
} else {
vie->rm |= (vie->rex_b << 3);
}
vie->reg |= (vie->rex_r << 3);
/* SIB */
if (vie->mod != VIE_MOD_DIRECT && vie->rm == VIE_RM_SIB)
goto done;
vie->base_register = gpr_map[vie->rm];
switch (vie->mod) {
case VIE_MOD_INDIRECT_DISP8:
vie->disp_bytes = 1;
break;
case VIE_MOD_INDIRECT_DISP32:
vie->disp_bytes = 4;
break;
case VIE_MOD_INDIRECT:
if (vie->rm == VIE_RM_DISP32) {
vie->disp_bytes = 4;
/*
* Table 2-7. RIP-Relative Addressing
*
* In 64-bit mode mod=00 r/m=101 implies [rip] + disp32
* whereas in compatibility mode it just implies disp32.
*/
if (cpu_mode == CPU_MODE_64BIT)
vie->base_register = VM_REG_GUEST_RIP;
else
vie->base_register = VM_REG_LAST;
}
break;
}
done:
vie_advance(vie);
return (0);
}
static int
decode_sib(struct vie *vie)
{
uint8_t x;
/* Proceed only if SIB byte is present */
if (vie->mod == VIE_MOD_DIRECT || vie->rm != VIE_RM_SIB)
return (0);
if (vie_peek(vie, &x))
return (-1);
/* De-construct the SIB byte */
vie->ss = (x >> 6) & 0x3;
vie->index = (x >> 3) & 0x7;
vie->base = (x >> 0) & 0x7;
/* Apply the REX prefix modifiers */
vie->index |= vie->rex_x << 3;
vie->base |= vie->rex_b << 3;
switch (vie->mod) {
case VIE_MOD_INDIRECT_DISP8:
vie->disp_bytes = 1;
break;
case VIE_MOD_INDIRECT_DISP32:
vie->disp_bytes = 4;
break;
}
if (vie->mod == VIE_MOD_INDIRECT &&
(vie->base == 5 || vie->base == 13)) {
/*
* Special case when base register is unused if mod = 0
* and base = %rbp or %r13.
*
* Documented in:
* Table 2-3: 32-bit Addressing Forms with the SIB Byte
* Table 2-5: Special Cases of REX Encodings
*/
vie->disp_bytes = 4;
} else {
vie->base_register = gpr_map[vie->base];
}
/*
* All encodings of 'index' are valid except for %rsp (4).
*
* Documented in:
* Table 2-3: 32-bit Addressing Forms with the SIB Byte
* Table 2-5: Special Cases of REX Encodings
*/
if (vie->index != 4)
vie->index_register = gpr_map[vie->index];
/* 'scale' makes sense only in the context of an index register */
if (vie->index_register < VM_REG_LAST)
vie->scale = 1 << vie->ss;
vie_advance(vie);
return (0);
}
static int
decode_displacement(struct vie *vie)
{
int n, i;
uint8_t x;
union {
char buf[4];
int8_t signed8;
int32_t signed32;
} u;
if ((n = vie->disp_bytes) == 0)
return (0);
if (n != 1 && n != 4)
panic("decode_displacement: invalid disp_bytes %d", n);
for (i = 0; i < n; i++) {
if (vie_peek(vie, &x))
return (-1);
u.buf[i] = x;
vie_advance(vie);
}
if (n == 1)
vie->displacement = u.signed8; /* sign-extended */
else
vie->displacement = u.signed32; /* sign-extended */
return (0);
}
static int
decode_immediate(struct vie *vie)
{
int i, n;
uint8_t x;
union {
char buf[4];
int8_t signed8;
int16_t signed16;
int32_t signed32;
} u;
/* Figure out immediate operand size (if any) */
if (vie->op.op_flags & VIE_OP_F_IMM) {
/*
* Section 2.2.1.5 "Immediates", Intel SDM:
* In 64-bit mode the typical size of immediate operands
* remains 32-bits. When the operand size if 64-bits, the
* processor sign-extends all immediates to 64-bits prior
* to their use.
*/
if (vie->opsize == 4 || vie->opsize == 8)
vie->imm_bytes = 4;
else
vie->imm_bytes = 2;
} else if (vie->op.op_flags & VIE_OP_F_IMM8) {
vie->imm_bytes = 1;
}
if ((n = vie->imm_bytes) == 0)
return (0);
KASSERT(n == 1 || n == 2 || n == 4,
("%s: invalid number of immediate bytes: %d", __func__, n));
for (i = 0; i < n; i++) {
if (vie_peek(vie, &x))
return (-1);
u.buf[i] = x;
vie_advance(vie);
}
/* sign-extend the immediate value before use */
if (n == 1)
vie->immediate = u.signed8;
else if (n == 2)
vie->immediate = u.signed16;
else
vie->immediate = u.signed32;
return (0);
}
static int
decode_moffset(struct vie *vie)
{
int i, n;
uint8_t x;
union {
char buf[8];
uint64_t u64;
} u;
if ((vie->op.op_flags & VIE_OP_F_MOFFSET) == 0)
return (0);
/*
* Section 2.2.1.4, "Direct Memory-Offset MOVs", Intel SDM:
* The memory offset size follows the address-size of the instruction.
*/
n = vie->addrsize;
KASSERT(n == 2 || n == 4 || n == 8, ("invalid moffset bytes: %d", n));
u.u64 = 0;
for (i = 0; i < n; i++) {
if (vie_peek(vie, &x))
return (-1);
u.buf[i] = x;
vie_advance(vie);
}
vie->displacement = u.u64;
return (0);
}
/*
* Verify that all the bytes in the instruction buffer were consumed.
*/
static int
verify_inst_length(struct vie *vie)
{
if (vie->num_processed == vie->num_valid)
return (0);
else
return (-1);
}
/*
* Verify that the 'guest linear address' provided as collateral of the nested
* page table fault matches with our instruction decoding.
*/
static int
verify_gla(struct vm *vm, int cpuid, uint64_t gla, struct vie *vie)
{
int error;
uint64_t base, idx, gla2;
/* Skip 'gla' verification */
if (gla == VIE_INVALID_GLA)
return (0);
base = 0;
if (vie->base_register != VM_REG_LAST) {
error = vm_get_register(vm, cpuid, vie->base_register, &base);
if (error) {
printf("verify_gla: error %d getting base reg %d\n",
error, vie->base_register);
return (-1);
}
/*
* RIP-relative addressing starts from the following
* instruction
*/
if (vie->base_register == VM_REG_GUEST_RIP)
base += vie->num_valid;
}
idx = 0;
if (vie->index_register != VM_REG_LAST) {
error = vm_get_register(vm, cpuid, vie->index_register, &idx);
if (error) {
printf("verify_gla: error %d getting index reg %d\n",
error, vie->index_register);
return (-1);
}
}
/* XXX assuming that the base address of the segment is 0 */
gla2 = base + vie->scale * idx + vie->displacement;
gla2 &= size2mask[vie->addrsize];
if (gla != gla2) {
printf("verify_gla mismatch: "
"base(0x%0lx), scale(%d), index(0x%0lx), "
"disp(0x%0lx), gla(0x%0lx), gla2(0x%0lx)\n",
base, vie->scale, idx, vie->displacement, gla, gla2);
return (-1);
}
return (0);
}
int
vmm_decode_instruction(struct vm *vm, int cpuid, uint64_t gla,
enum vm_cpu_mode cpu_mode, int cs_d, struct vie *vie)
{
if (decode_prefixes(vie, cpu_mode, cs_d))
return (-1);
if (decode_opcode(vie))
return (-1);
if (decode_modrm(vie, cpu_mode))
return (-1);
if (decode_sib(vie))
return (-1);
if (decode_displacement(vie))
return (-1);
if (decode_immediate(vie))
return (-1);
if (decode_moffset(vie))
return (-1);
if (verify_inst_length(vie))
return (-1);
if (verify_gla(vm, cpuid, gla, vie))
return (-1);
vie->decoded = 1; /* success */
return (0);
}
#endif /* _KERNEL */
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