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freebsd-skq/sys/amd64/vmm/vmm_instruction_emul.c
Rodney W. Grimes e4da41f932 Emulate the "TEST r/m{16,32,64}, imm{16,32,32}" instructions (opcode F7H). 
This adds emulation for:
	test r/m16, imm16
	test r/m32, imm32
	test r/m64, imm32 sign-extended to 64

OpenBSD guests compiled with clang 8.0.0 use TEST directly against a
Local APIC register instead of separate read via MOV followed by a
TEST against the register.

PR:		238794
Submitted by:	jhb
Reported by:	Jason Tubnor jason@tubnor.net
Tested by:	Jason Tubnor jason@tubnor.net
Reviewed by:	markj, Patrick Mooney patrick.mooney@joyent.com
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D20755
2019-06-26 21:19:43 +00:00

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/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* 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_MOVS,
VIE_OP_TYPE_GROUP1,
VIE_OP_TYPE_STOS,
VIE_OP_TYPE_BITTEST,
VIE_OP_TYPE_TWOB_GRP15,
VIE_OP_TYPE_ADD,
VIE_OP_TYPE_TEST,
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)
#define VIE_OP_F_NO_GLA_VERIFICATION (1 << 4)
static const struct vie_op two_byte_opcodes[256] = {
[0xAE] = {
.op_byte = 0xAE,
.op_type = VIE_OP_TYPE_TWOB_GRP15,
},
[0xB6] = {
.op_byte = 0xB6,
.op_type = VIE_OP_TYPE_MOVZX,
},
[0xB7] = {
.op_byte = 0xB7,
.op_type = VIE_OP_TYPE_MOVZX,
},
[0xBA] = {
.op_byte = 0xBA,
.op_type = VIE_OP_TYPE_BITTEST,
.op_flags = VIE_OP_F_IMM8,
},
[0xBE] = {
.op_byte = 0xBE,
.op_type = VIE_OP_TYPE_MOVSX,
},
};
static const struct vie_op one_byte_opcodes[256] = {
[0x03] = {
.op_byte = 0x03,
.op_type = VIE_OP_TYPE_ADD,
},
[0x0F] = {
.op_byte = 0x0F,
.op_type = VIE_OP_TYPE_TWO_BYTE
},
[0x0B] = {
.op_byte = 0x0B,
.op_type = VIE_OP_TYPE_OR,
},
[0x2B] = {
.op_byte = 0x2B,
.op_type = VIE_OP_TYPE_SUB,
},
[0x39] = {
.op_byte = 0x39,
.op_type = VIE_OP_TYPE_CMP,
},
[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,
},
[0xA4] = {
.op_byte = 0xA4,
.op_type = VIE_OP_TYPE_MOVS,
.op_flags = VIE_OP_F_NO_MODRM | VIE_OP_F_NO_GLA_VERIFICATION
},
[0xA5] = {
.op_byte = 0xA5,
.op_type = VIE_OP_TYPE_MOVS,
.op_flags = VIE_OP_F_NO_MODRM | VIE_OP_F_NO_GLA_VERIFICATION
},
[0xAA] = {
.op_byte = 0xAA,
.op_type = VIE_OP_TYPE_STOS,
.op_flags = VIE_OP_F_NO_MODRM | VIE_OP_F_NO_GLA_VERIFICATION
},
[0xAB] = {
.op_byte = 0xAB,
.op_type = VIE_OP_TYPE_STOS,
.op_flags = VIE_OP_F_NO_MODRM | VIE_OP_F_NO_GLA_VERIFICATION
},
[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,
},
[0x80] = {
/* Group 1 extended opcode */
.op_byte = 0x80,
.op_type = VIE_OP_TYPE_GROUP1,
.op_flags = VIE_OP_F_IMM8,
},
[0x81] = {
/* Group 1 extended opcode */
.op_byte = 0x81,
.op_type = VIE_OP_TYPE_GROUP1,
.op_flags = VIE_OP_F_IMM,
},
[0x83] = {
/* Group 1 extended opcode */
.op_byte = 0x83,
.op_type = VIE_OP_TYPE_GROUP1,
.op_flags = VIE_OP_F_IMM8,
},
[0x8F] = {
/* XXX Group 1A extended opcode - not just POP */
.op_byte = 0x8F,
.op_type = VIE_OP_TYPE_POP,
},
[0xF7] = {
/* XXX Group 3 extended opcode - not just TEST */
.op_byte = 0xF7,
.op_type = VIE_OP_TYPE_TEST,
.op_flags = VIE_OP_F_IMM,
},
[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));
}
/*
* Macro creation of functions getaddflags{8,16,32,64}
*/
#define GETADDFLAGS(sz) \
static u_long \
getaddflags##sz(uint##sz##_t x, uint##sz##_t y) \
{ \
u_long rflags; \
\
__asm __volatile("add %2,%1; pushfq; popq %0" : \
"=r" (rflags), "+r" (x) : "m" (y)); \
return (rflags); \
} struct __hack
GETADDFLAGS(8);
GETADDFLAGS(16);
GETADDFLAGS(32);
GETADDFLAGS(64);
static u_long
getaddflags(int opsize, uint64_t x, uint64_t y)
{
KASSERT(opsize == 1 || opsize == 2 || opsize == 4 || opsize == 8,
("getaddflags: invalid operand size %d", opsize));
if (opsize == 1)
return (getaddflags8(x, y));
else if (opsize == 2)
return (getaddflags16(x, y));
else if (opsize == 4)
return (getaddflags32(x, y));
else
return (getaddflags64(x, y));
}
/*
* Return the status flags that would result from doing (x & y).
*/
#define GETANDFLAGS(sz) \
static u_long \
getandflags##sz(uint##sz##_t x, uint##sz##_t y) \
{ \
u_long rflags; \
\
__asm __volatile("and %2,%1; pushfq; popq %0" : \
"=r" (rflags), "+r" (x) : "m" (y)); \
return (rflags); \
} struct __hack
GETANDFLAGS(8);
GETANDFLAGS(16);
GETANDFLAGS(32);
GETANDFLAGS(64);
static u_long
getandflags(int opsize, uint64_t x, uint64_t y)
{
KASSERT(opsize == 1 || opsize == 2 || opsize == 4 || opsize == 8,
("getandflags: invalid operand size %d", opsize));
if (opsize == 1)
return (getandflags8(x, y));
else if (opsize == 2)
return (getandflags16(x, y));
else if (opsize == 4)
return (getandflags32(x, y));
else
return (getandflags64(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);
}
/*
* Helper function to calculate and validate a linear address.
*/
static int
get_gla(void *vm, int vcpuid, struct vie *vie, struct vm_guest_paging *paging,
int opsize, int addrsize, int prot, enum vm_reg_name seg,
enum vm_reg_name gpr, uint64_t *gla, int *fault)
{
struct seg_desc desc;
uint64_t cr0, val, rflags;
int error;
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 = vm_get_seg_desc(vm, vcpuid, seg, &desc);
KASSERT(error == 0, ("%s: error %d getting segment descriptor %d",
__func__, error, seg));
error = vie_read_register(vm, vcpuid, gpr, &val);
KASSERT(error == 0, ("%s: error %d getting register %d", __func__,
error, gpr));
if (vie_calculate_gla(paging->cpu_mode, seg, &desc, val, opsize,
addrsize, prot, gla)) {
if (seg == VM_REG_GUEST_SS)
vm_inject_ss(vm, vcpuid, 0);
else
vm_inject_gp(vm, vcpuid);
goto guest_fault;
}
if (vie_canonical_check(paging->cpu_mode, *gla)) {
if (seg == VM_REG_GUEST_SS)
vm_inject_ss(vm, vcpuid, 0);
else
vm_inject_gp(vm, vcpuid);
goto guest_fault;
}
if (vie_alignment_check(paging->cpl, opsize, cr0, rflags, *gla)) {
vm_inject_ac(vm, vcpuid, 0);
goto guest_fault;
}
*fault = 0;
return (0);
guest_fault:
*fault = 1;
return (0);
}
static int
emulate_movs(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 *arg)
{
#ifdef _KERNEL
struct vm_copyinfo copyinfo[2];
#else
struct iovec copyinfo[2];
#endif
uint64_t dstaddr, srcaddr, dstgpa, srcgpa, val;
uint64_t rcx, rdi, rsi, rflags;
int error, fault, opsize, seg, repeat;
opsize = (vie->op.op_byte == 0xA4) ? 1 : vie->opsize;
val = 0;
error = 0;
/*
* XXX although the MOVS instruction is only supposed to be used with
* the "rep" prefix some guests like FreeBSD will use "repnz" instead.
*
* Empirically the "repnz" prefix has identical behavior to "rep"
* and the zero flag does not make a difference.
*/
repeat = vie->repz_present | vie->repnz_present;
if (repeat) {
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RCX, &rcx);
KASSERT(!error, ("%s: error %d getting rcx", __func__, error));
/*
* The count register is %rcx, %ecx or %cx depending on the
* address size of the instruction.
*/
if ((rcx & vie_size2mask(vie->addrsize)) == 0) {
error = 0;
goto done;
}
}
/*
* Source Destination Comments
* --------------------------------------------
* (1) memory memory n/a
* (2) memory mmio emulated
* (3) mmio memory emulated
* (4) mmio mmio emulated
*
* At this point we don't have sufficient information to distinguish
* between (2), (3) and (4). We use 'vm_copy_setup()' to tease this
* out because it will succeed only when operating on regular memory.
*
* XXX the emulation doesn't properly handle the case where 'gpa'
* is straddling the boundary between the normal memory and MMIO.
*/
seg = vie->segment_override ? vie->segment_register : VM_REG_GUEST_DS;
error = get_gla(vm, vcpuid, vie, paging, opsize, vie->addrsize,
PROT_READ, seg, VM_REG_GUEST_RSI, &srcaddr, &fault);
if (error || fault)
goto done;
error = vm_copy_setup(vm, vcpuid, paging, srcaddr, opsize, PROT_READ,
copyinfo, nitems(copyinfo), &fault);
if (error == 0) {
if (fault)
goto done; /* Resume guest to handle fault */
/*
* case (2): read from system memory and write to mmio.
*/
vm_copyin(vm, vcpuid, copyinfo, &val, opsize);
vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
error = memwrite(vm, vcpuid, gpa, val, opsize, arg);
if (error)
goto done;
} else {
/*
* 'vm_copy_setup()' is expected to fail for cases (3) and (4)
* if 'srcaddr' is in the mmio space.
*/
error = get_gla(vm, vcpuid, vie, paging, opsize, vie->addrsize,
PROT_WRITE, VM_REG_GUEST_ES, VM_REG_GUEST_RDI, &dstaddr,
&fault);
if (error || fault)
goto done;
error = vm_copy_setup(vm, vcpuid, paging, dstaddr, opsize,
PROT_WRITE, copyinfo, nitems(copyinfo), &fault);
if (error == 0) {
if (fault)
goto done; /* Resume guest to handle fault */
/*
* case (3): read from MMIO and write to system memory.
*
* A MMIO read can have side-effects so we
* commit to it only after vm_copy_setup() is
* successful. If a page-fault needs to be
* injected into the guest then it will happen
* before the MMIO read is attempted.
*/
error = memread(vm, vcpuid, gpa, &val, opsize, arg);
if (error)
goto done;
vm_copyout(vm, vcpuid, &val, copyinfo, opsize);
vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
} else {
/*
* Case (4): read from and write to mmio.
*
* Commit to the MMIO read/write (with potential
* side-effects) only after we are sure that the
* instruction is not going to be restarted due
* to address translation faults.
*/
error = vm_gla2gpa(vm, vcpuid, paging, srcaddr,
PROT_READ, &srcgpa, &fault);
if (error || fault)
goto done;
error = vm_gla2gpa(vm, vcpuid, paging, dstaddr,
PROT_WRITE, &dstgpa, &fault);
if (error || fault)
goto done;
error = memread(vm, vcpuid, srcgpa, &val, opsize, arg);
if (error)
goto done;
error = memwrite(vm, vcpuid, dstgpa, val, opsize, arg);
if (error)
goto done;
}
}
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RSI, &rsi);
KASSERT(error == 0, ("%s: error %d getting rsi", __func__, error));
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RDI, &rdi);
KASSERT(error == 0, ("%s: error %d getting rdi", __func__, error));
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
KASSERT(error == 0, ("%s: error %d getting rflags", __func__, error));
if (rflags & PSL_D) {
rsi -= opsize;
rdi -= opsize;
} else {
rsi += opsize;
rdi += opsize;
}
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RSI, rsi,
vie->addrsize);
KASSERT(error == 0, ("%s: error %d updating rsi", __func__, error));
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RDI, rdi,
vie->addrsize);
KASSERT(error == 0, ("%s: error %d updating rdi", __func__, error));
if (repeat) {
rcx = rcx - 1;
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RCX,
rcx, vie->addrsize);
KASSERT(!error, ("%s: error %d updating rcx", __func__, error));
/*
* Repeat the instruction if the count register is not zero.
*/
if ((rcx & vie_size2mask(vie->addrsize)) != 0)
vm_restart_instruction(vm, vcpuid);
}
done:
KASSERT(error == 0 || error == EFAULT, ("%s: unexpected error %d",
__func__, error));
return (error);
}
static int
emulate_stos(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 *arg)
{
int error, opsize, repeat;
uint64_t val;
uint64_t rcx, rdi, rflags;
opsize = (vie->op.op_byte == 0xAA) ? 1 : vie->opsize;
repeat = vie->repz_present | vie->repnz_present;
if (repeat) {
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RCX, &rcx);
KASSERT(!error, ("%s: error %d getting rcx", __func__, error));
/*
* The count register is %rcx, %ecx or %cx depending on the
* address size of the instruction.
*/
if ((rcx & vie_size2mask(vie->addrsize)) == 0)
return (0);
}
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RAX, &val);
KASSERT(!error, ("%s: error %d getting rax", __func__, error));
error = memwrite(vm, vcpuid, gpa, val, opsize, arg);
if (error)
return (error);
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RDI, &rdi);
KASSERT(error == 0, ("%s: error %d getting rdi", __func__, error));
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
KASSERT(error == 0, ("%s: error %d getting rflags", __func__, error));
if (rflags & PSL_D)
rdi -= opsize;
else
rdi += opsize;
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RDI, rdi,
vie->addrsize);
KASSERT(error == 0, ("%s: error %d updating rdi", __func__, error));
if (repeat) {
rcx = rcx - 1;
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RCX,
rcx, vie->addrsize);
KASSERT(!error, ("%s: error %d updating rcx", __func__, error));
/*
* Repeat the instruction if the count register is not zero.
*/
if ((rcx & vie_size2mask(vie->addrsize)) != 0)
vm_restart_instruction(vm, vcpuid);
}
return (0);
}
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:
case 0x83:
/*
* AND mem (ModRM:r/m) with immediate and store the
* result in mem.
*
* 81 /4 and r/m16, imm16
* 81 /4 and r/m32, imm32
* REX.W + 81 /4 and r/m64, imm32 sign-extended to 64
*
* 83 /4 and r/m16, imm8 sign-extended to 16
* 83 /4 and r/m32, imm8 sign-extended to 32
* REX.W + 83/4 and r/m64, imm8 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
*/
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_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;
enum vm_reg_name reg;
uint64_t result, rflags, rflags2, val1, val2;
size = vie->opsize;
error = EINVAL;
switch (vie->op.op_byte) {
case 0x0B:
/*
* OR reg (ModRM:reg) and mem (ModRM:r/m) and store the
* result in reg.
*
* 0b/r or r16, r/m16
* 0b/r or r32, r/m32
* REX.W + 0b/r or 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:
case 0x83:
/*
* OR mem (ModRM:r/m) with immediate and store the
* result in mem.
*
* 81 /1 or r/m16, imm16
* 81 /1 or r/m32, imm32
* REX.W + 81 /1 or r/m64, imm32 sign-extended to 64
*
* 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
*/
/* 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 regop, memop, op1, op2, rflags, rflags2;
enum vm_reg_name reg;
size = vie->opsize;
switch (vie->op.op_byte) {
case 0x39:
case 0x3B:
/*
* 39/r CMP r/m16, r16
* 39/r CMP r/m32, r32
* REX.W 39/r CMP r/m64, r64
*
* 3B/r CMP r16, r/m16
* 3B/r CMP r32, r/m32
* REX.W + 3B/r CMP r64, r/m64
*
* Compare the first operand with the second operand 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 register operand */
reg = gpr_map[vie->reg];
error = vie_read_register(vm, vcpuid, reg, &regop);
if (error)
return (error);
/* Get the memory operand */
error = memread(vm, vcpuid, gpa, &memop, size, arg);
if (error)
return (error);
if (vie->op.op_byte == 0x3B) {
op1 = regop;
op2 = memop;
} else {
op1 = memop;
op2 = regop;
}
rflags2 = getcc(size, op1, op2);
break;
case 0x80:
case 0x81:
case 0x83:
/*
* 80 /7 cmp r/m8, imm8
* REX + 80 /7 cmp r/m8, imm8
*
* 81 /7 cmp r/m16, imm16
* 81 /7 cmp r/m32, imm32
* REX.W + 81 /7 cmp r/m64, imm32 sign-extended to 64
*
* 83 /7 cmp r/m16, imm8 sign-extended to 16
* 83 /7 cmp r/m32, imm8 sign-extended to 32
* REX.W + 83 /7 cmp r/m64, imm8 sign-extended to 64
*
* Compare mem (ModRM:r/m) with immediate and set
* status flags according to the results. The
* comparison is performed by subtracting the
* immediate from the first operand and then setting
* the status flags.
*
*/
if (vie->op.op_byte == 0x80)
size = 1;
/* get the first operand */
error = memread(vm, vcpuid, gpa, &op1, size, arg);
if (error)
return (error);
rflags2 = getcc(size, op1, vie->immediate);
break;
default:
return (EINVAL);
}
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_test(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, rflags, rflags2;
size = vie->opsize;
error = EINVAL;
switch (vie->op.op_byte) {
case 0xF7:
/*
* F7 /0 test r/m16, imm16
* F7 /0 test r/m32, imm32
* REX.W + F7 /0 test r/m64, imm32 sign-extended to 64
*
* Test mem (ModRM:r/m) with immediate and set status
* flags according to the results. The comparison is
* performed by anding the immediate from the first
* operand and then setting the status flags.
*/
if ((vie->reg & 7) != 0)
return (EINVAL);
error = memread(vm, vcpuid, gpa, &op1, size, arg);
if (error)
return (error);
rflags2 = getandflags(size, op1, vie->immediate);
break;
default:
return (EINVAL);
}
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.
*/
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_add(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 0x03:
/*
* ADD r/m to r and store the result in r
*
* 03/r ADD r16, r/m16
* 03/r ADD r32, r/m32
* REX.W + 03/r ADD 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 = getaddflags(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_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, fault, 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 compatibility 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),
&fault);
if (error || fault)
return (error);
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;
}
vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
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);
}
static int
emulate_group1(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;
switch (vie->reg & 7) {
case 0x1: /* OR */
error = emulate_or(vm, vcpuid, gpa, vie,
memread, memwrite, memarg);
break;
case 0x4: /* AND */
error = emulate_and(vm, vcpuid, gpa, vie,
memread, memwrite, memarg);
break;
case 0x7: /* CMP */
error = emulate_cmp(vm, vcpuid, gpa, vie,
memread, memwrite, memarg);
break;
default:
error = EINVAL;
break;
}
return (error);
}
static int
emulate_bittest(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
mem_region_read_t memread, mem_region_write_t memwrite, void *memarg)
{
uint64_t val, rflags;
int error, bitmask, bitoff;
/*
* 0F BA is a Group 8 extended opcode.
*
* Currently we only emulate the 'Bit Test' instruction which is
* identified by a ModR/M:reg encoding of 100b.
*/
if ((vie->reg & 7) != 4)
return (EINVAL);
error = vie_read_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, &rflags);
KASSERT(error == 0, ("%s: error %d getting rflags", __func__, error));
error = memread(vm, vcpuid, gpa, &val, vie->opsize, memarg);
if (error)
return (error);
/*
* Intel SDM, Vol 2, Table 3-2:
* "Range of Bit Positions Specified by Bit Offset Operands"
*/
bitmask = vie->opsize * 8 - 1;
bitoff = vie->immediate & bitmask;
/* Copy the bit into the Carry flag in %rflags */
if (val & (1UL << bitoff))
rflags |= PSL_C;
else
rflags &= ~PSL_C;
error = vie_update_register(vm, vcpuid, VM_REG_GUEST_RFLAGS, rflags, 8);
KASSERT(error == 0, ("%s: error %d updating rflags", __func__, error));
return (0);
}
static int
emulate_twob_group15(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
mem_region_read_t memread, mem_region_write_t memwrite, void *memarg)
{
int error;
uint64_t buf;
switch (vie->reg & 7) {
case 0x7: /* CLFLUSH, CLFLUSHOPT, and SFENCE */
if (vie->mod == 0x3) {
/*
* SFENCE. Ignore it, VM exit provides enough
* barriers on its own.
*/
error = 0;
} else {
/*
* CLFLUSH, CLFLUSHOPT. Only check for access
* rights.
*/
error = memread(vm, vcpuid, gpa, &buf, 1, memarg);
}
break;
default:
error = EINVAL;
break;
}
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_GROUP1:
error = emulate_group1(vm, vcpuid, gpa, vie, paging, memread,
memwrite, memarg);
break;
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_MOVS:
error = emulate_movs(vm, vcpuid, gpa, vie, paging, memread,
memwrite, memarg);
break;
case VIE_OP_TYPE_STOS:
error = emulate_stos(vm, vcpuid, gpa, vie, paging, 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;
case VIE_OP_TYPE_BITTEST:
error = emulate_bittest(vm, vcpuid, gpa, vie,
memread, memwrite, memarg);
break;
case VIE_OP_TYPE_TWOB_GRP15:
error = emulate_twob_group15(vm, vcpuid, gpa, vie,
memread, memwrite, memarg);
break;
case VIE_OP_TYPE_ADD:
error = emulate_add(vm, vcpuid, gpa, vie, memread,
memwrite, memarg);
break;
case VIE_OP_TYPE_TEST:
error = emulate_test(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, const char *inst_bytes, int inst_length)
{
KASSERT(inst_length >= 0 && inst_length <= VIE_INST_SIZE,
("%s: invalid instruction length (%d)", __func__, inst_length));
bzero(vie, sizeof(struct vie));
vie->base_register = VM_REG_LAST;
vie->index_register = VM_REG_LAST;
vie->segment_register = VM_REG_LAST;
if (inst_length) {
bcopy(inst_bytes, vie->inst, inst_length);
vie->num_valid = inst_length;
}
}
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, int vcpu, vm_paddr_t ptpphys, size_t len, void **cookie)
{
void *ptr;
ptp_release(cookie);
ptr = vm_gpa_hold(vm, vcpu, ptpphys, len, VM_PROT_RW, cookie);
return (ptr);
}
static int
_vm_gla2gpa(struct vm *vm, int vcpuid, struct vm_guest_paging *paging,
uint64_t gla, int prot, uint64_t *gpa, int *guest_fault, bool check_only)
{
int nlevels, pfcode, ptpshift, ptpindex, retval, usermode, writable;
u_int retries;
uint64_t *ptpbase, ptpphys, pte, pgsize;
uint32_t *ptpbase32, pte32;
void *cookie;
*guest_fault = 0;
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.
*/
if (!check_only)
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, vcpuid, 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)) {
if (!check_only) {
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 (!check_only && (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 (!check_only && 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, vcpuid, ptpphys, sizeof(*ptpbase) * 4,
&cookie);
if (ptpbase == NULL)
goto error;
ptpindex = (gla >> 30) & 0x3;
pte = ptpbase[ptpindex];
if ((pte & PG_V) == 0) {
if (!check_only) {
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, vcpuid, 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)) {
if (!check_only) {
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 (!check_only && (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) {
if (!check_only) {
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 (!check_only && 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);
KASSERT(retval == 0 || retval == EFAULT, ("%s: unexpected retval %d",
__func__, retval));
return (retval);
error:
retval = EFAULT;
goto done;
fault:
*guest_fault = 1;
goto done;
}
int
vm_gla2gpa(struct vm *vm, int vcpuid, struct vm_guest_paging *paging,
uint64_t gla, int prot, uint64_t *gpa, int *guest_fault)
{
return (_vm_gla2gpa(vm, vcpuid, paging, gla, prot, gpa, guest_fault,
false));
}
int
vm_gla2gpa_nofault(struct vm *vm, int vcpuid, struct vm_guest_paging *paging,
uint64_t gla, int prot, uint64_t *gpa, int *guest_fault)
{
return (_vm_gla2gpa(vm, vcpuid, paging, gla, prot, gpa, guest_fault,
true));
}
int
vmm_fetch_instruction(struct vm *vm, int vcpuid, struct vm_guest_paging *paging,
uint64_t rip, int inst_length, struct vie *vie, int *faultptr)
{
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), faultptr);
if (error || *faultptr)
return (error);
vm_copyin(vm, vcpuid, copyinfo, vie->inst, inst_length);
vm_copy_teardown(vm, vcpuid, copyinfo, nitems(copyinfo));
vie->num_valid = inst_length;
return (0);
}
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 bool
segment_override(uint8_t x, int *seg)
{
switch (x) {
case 0x2E:
*seg = VM_REG_GUEST_CS;
break;
case 0x36:
*seg = VM_REG_GUEST_SS;
break;
case 0x3E:
*seg = VM_REG_GUEST_DS;
break;
case 0x26:
*seg = VM_REG_GUEST_ES;
break;
case 0x64:
*seg = VM_REG_GUEST_FS;
break;
case 0x65:
*seg = VM_REG_GUEST_GS;
break;
default:
return (false);
}
return (true);
}
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 if (x == 0xF3)
vie->repz_present = 1;
else if (x == 0xF2)
vie->repnz_present = 1;
else if (segment_override(x, &vie->segment_register))
vie->segment_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 (vie->op.op_flags & VIE_OP_F_NO_MODRM)
return (0);
if (cpu_mode == CPU_MODE_REAL)
return (-1);
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 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,
enum vm_cpu_mode cpu_mode)
{
int error;
uint64_t base, segbase, idx, gla2;
enum vm_reg_name seg;
struct seg_desc desc;
/* 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_processed;
}
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);
}
}
/*
* From "Specifying a Segment Selector", Intel SDM, Vol 1
*
* In 64-bit mode, segmentation is generally (but not
* completely) disabled. The exceptions are the FS and GS
* segments.
*
* In legacy IA-32 mode, when the ESP or EBP register is used
* as the base, the SS segment is the default segment. For
* other data references, except when relative to stack or
* string destination the DS segment is the default. These
* can be overridden to allow other segments to be accessed.
*/
if (vie->segment_override)
seg = vie->segment_register;
else if (vie->base_register == VM_REG_GUEST_RSP ||
vie->base_register == VM_REG_GUEST_RBP)
seg = VM_REG_GUEST_SS;
else
seg = VM_REG_GUEST_DS;
if (cpu_mode == CPU_MODE_64BIT && seg != VM_REG_GUEST_FS &&
seg != VM_REG_GUEST_GS) {
segbase = 0;
} else {
error = vm_get_seg_desc(vm, cpuid, seg, &desc);
if (error) {
printf("verify_gla: error %d getting segment"
" descriptor %d", error,
vie->segment_register);
return (-1);
}
segbase = desc.base;
}
gla2 = segbase + base + vie->scale * idx + vie->displacement;
gla2 &= size2mask[vie->addrsize];
if (gla != gla2) {
printf("verify_gla mismatch: segbase(0x%0lx)"
"base(0x%0lx), scale(%d), index(0x%0lx), "
"disp(0x%0lx), gla(0x%0lx), gla2(0x%0lx)\n",
segbase, 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 ((vie->op.op_flags & VIE_OP_F_NO_GLA_VERIFICATION) == 0) {
if (verify_gla(vm, cpuid, gla, vie, cpu_mode))
return (-1);
}
vie->decoded = 1; /* success */
return (0);
}
#endif /* _KERNEL */
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