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6971cc832a
acrn-hypervisor/hypervisor/arch/x86/guest/instr_emul.c
Shiqing Gao 6971cc832a hv: fix '(void) missing for discarded return value' 
MISRA-C requires that the function call in which the returned
value is discarded shall be clearly indicated using (void).

This patch fixes the violations related to the following
function calls.
- instr_check_gva
- vlapic_set_local_intr
- prepare_vm
- enter_s3
- emulate_instruction
- ptdev_intx_pin_remap
- register_mmio_emulation_handler

v1 -> v2:
 * discard the return value of enter_s3

Tracked-On: #861
Signed-off-by: Shiqing Gao <shiqing.gao@intel.com>
2018-11-15 10:54:42 +08:00

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/*-
* Copyright (c) 2012 Sandvine, Inc.
* Copyright (c) 2012 NetApp, Inc.
* Copyright (c) 2017 Intel Corporation
* 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 <hypervisor.h>
#include "instr_emul.h"
/* struct vie_op.op_type */
#define VIE_OP_TYPE_NONE 0U
#define VIE_OP_TYPE_MOV 1U
#define VIE_OP_TYPE_MOVSX 2U
#define VIE_OP_TYPE_MOVZX 3U
#define VIE_OP_TYPE_AND 4U
#define VIE_OP_TYPE_OR 5U
#define VIE_OP_TYPE_SUB 6U
#define VIE_OP_TYPE_TWO_BYTE 7U
#define VIE_OP_TYPE_PUSH 8U
#define VIE_OP_TYPE_CMP 9U
#define VIE_OP_TYPE_POP 10U
#define VIE_OP_TYPE_MOVS 11U
#define VIE_OP_TYPE_GROUP1 12U
#define VIE_OP_TYPE_STOS 13U
#define VIE_OP_TYPE_BITTEST 14U
#define VIE_OP_TYPE_TEST 15U
/* struct vie_op.op_flags */
#define VIE_OP_F_IMM (1U << 0U) /* 16/32-bit immediate operand */
#define VIE_OP_F_IMM8 (1U << 1U) /* 8-bit immediate operand */
#define VIE_OP_F_MOFFSET (1U << 2U) /* 16/32/64-bit immediate moffset */
#define VIE_OP_F_NO_MODRM (1U << 3U)
#define VIE_OP_F_CHECK_GVA_DI (1U << 4U) /* for movs, need to check DI */
static const struct instr_emul_vie_op two_byte_opcodes[256] = {
[0xB6] = {
.op_type = VIE_OP_TYPE_MOVZX,
},
[0xB7] = {
.op_type = VIE_OP_TYPE_MOVZX,
},
[0xBA] = {
.op_type = VIE_OP_TYPE_BITTEST,
.op_flags = VIE_OP_F_IMM8,
},
[0xBE] = {
.op_type = VIE_OP_TYPE_MOVSX,
},
};
static const struct instr_emul_vie_op one_byte_opcodes[256] = {
[0x0F] = {
.op_type = VIE_OP_TYPE_TWO_BYTE
},
[0x2B] = {
.op_type = VIE_OP_TYPE_SUB,
},
[0x39] = {
.op_type = VIE_OP_TYPE_CMP,
},
[0x3B] = {
.op_type = VIE_OP_TYPE_CMP,
},
[0x88] = {
.op_type = VIE_OP_TYPE_MOV,
},
[0x89] = {
.op_type = VIE_OP_TYPE_MOV,
},
[0x8A] = {
.op_type = VIE_OP_TYPE_MOV,
},
[0x8B] = {
.op_type = VIE_OP_TYPE_MOV,
},
[0xA1] = {
.op_type = VIE_OP_TYPE_MOV,
.op_flags = VIE_OP_F_MOFFSET | VIE_OP_F_NO_MODRM,
},
[0xA3] = {
.op_type = VIE_OP_TYPE_MOV,
.op_flags = VIE_OP_F_MOFFSET | VIE_OP_F_NO_MODRM,
},
[0xA4] = {
.op_type = VIE_OP_TYPE_MOVS,
.op_flags = VIE_OP_F_NO_MODRM | VIE_OP_F_CHECK_GVA_DI
},
[0xA5] = {
.op_type = VIE_OP_TYPE_MOVS,
.op_flags = VIE_OP_F_NO_MODRM | VIE_OP_F_CHECK_GVA_DI
},
[0xAA] = {
.op_type = VIE_OP_TYPE_STOS,
.op_flags = VIE_OP_F_NO_MODRM
},
[0xAB] = {
.op_type = VIE_OP_TYPE_STOS,
.op_flags = VIE_OP_F_NO_MODRM
},
[0xC6] = {
/* XXX Group 11 extended opcode - not just MOV */
.op_type = VIE_OP_TYPE_MOV,
.op_flags = VIE_OP_F_IMM8,
},
[0xC7] = {
.op_type = VIE_OP_TYPE_MOV,
.op_flags = VIE_OP_F_IMM,
},
[0x23] = {
.op_type = VIE_OP_TYPE_AND,
},
[0x80] = {
/* Group 1 extended opcode */
.op_type = VIE_OP_TYPE_GROUP1,
.op_flags = VIE_OP_F_IMM8,
},
[0x81] = {
/* Group 1 extended opcode */
.op_type = VIE_OP_TYPE_GROUP1,
.op_flags = VIE_OP_F_IMM,
},
[0x83] = {
/* Group 1 extended opcode */
.op_type = VIE_OP_TYPE_GROUP1,
.op_flags = VIE_OP_F_IMM8,
},
[0x84] = {
.op_type = VIE_OP_TYPE_TEST,
},
[0x85] = {
.op_type = VIE_OP_TYPE_TEST,
},
[0x08] = {
.op_type = VIE_OP_TYPE_OR,
},
[0x09] = {
.op_type = VIE_OP_TYPE_OR,
},
};
/* struct vie.mod */
#define VIE_MOD_INDIRECT 0U
#define VIE_MOD_INDIRECT_DISP8 1U
#define VIE_MOD_INDIRECT_DISP32 2U
#define VIE_MOD_DIRECT 3U
/* struct vie.rm */
#define VIE_RM_SIB 4U
#define VIE_RM_DISP32 5U
static uint64_t size2mask[9] = {
[1] = (1UL << 8U) - 1UL,
[2] = (1UL << 16U) - 1UL,
[4] = (1UL << 32U) - 1UL,
[8] = ~0UL,
};
#define VMX_INVALID_VMCS_FIELD 0xffffffffU
/*
* This struct vmcs_seg_field is defined separately to hold the vmcs field
* address of segment selector.
*/
struct vmcs_seg_field {
uint32_t base_field;
uint32_t limit_field;
uint32_t access_field;
};
static void encode_vmcs_seg_desc(enum cpu_reg_name seg,
struct vmcs_seg_field *desc)
{
switch (seg) {
case CPU_REG_ES:
desc->base_field = VMX_GUEST_ES_BASE;
desc->limit_field = VMX_GUEST_ES_LIMIT;
desc->access_field = VMX_GUEST_ES_ATTR;
break;
case CPU_REG_CS:
desc->base_field = VMX_GUEST_CS_BASE;
desc->limit_field = VMX_GUEST_CS_LIMIT;
desc->access_field = VMX_GUEST_CS_ATTR;
break;
case CPU_REG_SS:
desc->base_field = VMX_GUEST_SS_BASE;
desc->limit_field = VMX_GUEST_SS_LIMIT;
desc->access_field = VMX_GUEST_SS_ATTR;
break;
case CPU_REG_DS:
desc->base_field = VMX_GUEST_DS_BASE;
desc->limit_field = VMX_GUEST_DS_LIMIT;
desc->access_field = VMX_GUEST_DS_ATTR;
break;
case CPU_REG_FS:
desc->base_field = VMX_GUEST_FS_BASE;
desc->limit_field = VMX_GUEST_FS_LIMIT;
desc->access_field = VMX_GUEST_FS_ATTR;
break;
case CPU_REG_GS:
desc->base_field = VMX_GUEST_GS_BASE;
desc->limit_field = VMX_GUEST_GS_LIMIT;
desc->access_field = VMX_GUEST_GS_ATTR;
break;
case CPU_REG_TR:
desc->base_field = VMX_GUEST_TR_BASE;
desc->limit_field = VMX_GUEST_TR_LIMIT;
desc->access_field = VMX_GUEST_TR_ATTR;
break;
case CPU_REG_LDTR:
desc->base_field = VMX_GUEST_LDTR_BASE;
desc->limit_field = VMX_GUEST_LDTR_LIMIT;
desc->access_field = VMX_GUEST_LDTR_ATTR;
break;
case CPU_REG_IDTR:
desc->base_field = VMX_GUEST_IDTR_BASE;
desc->limit_field = VMX_GUEST_IDTR_LIMIT;
desc->access_field = 0xffffffffU;
break;
case CPU_REG_GDTR:
desc->base_field = VMX_GUEST_GDTR_BASE;
desc->limit_field = VMX_GUEST_GDTR_LIMIT;
desc->access_field = 0xffffffffU;
break;
default:
desc->base_field = 0U;
desc->limit_field = 0U;
desc->access_field = 0U;
pr_err("%s: invalid seg %d", __func__, seg);
break;
}
}
/**
*
*Description:
*This local function is to covert register names into
*the corresponding field index MACROs in VMCS.
*
*Post Condition:
*In the non-general register names group (CPU_REG_CR0~CPU_REG_GDTR),
*for register names CPU_REG_CR2, CPU_REG_IDTR and CPU_REG_GDTR,
*this function returns VMX_INVALID_VMCS_FIELD;
*for other register names, it returns correspoding field index MACROs
*in VMCS.
*
**/
static uint32_t get_vmcs_field(enum cpu_reg_name ident)
{
switch (ident) {
case CPU_REG_CR0:
return VMX_GUEST_CR0;
case CPU_REG_CR3:
return VMX_GUEST_CR3;
case CPU_REG_CR4:
return VMX_GUEST_CR4;
case CPU_REG_DR7:
return VMX_GUEST_DR7;
case CPU_REG_RSP:
return VMX_GUEST_RSP;
case CPU_REG_RIP:
return VMX_GUEST_RIP;
case CPU_REG_RFLAGS:
return VMX_GUEST_RFLAGS;
case CPU_REG_ES:
return VMX_GUEST_ES_SEL;
case CPU_REG_CS:
return VMX_GUEST_CS_SEL;
case CPU_REG_SS:
return VMX_GUEST_SS_SEL;
case CPU_REG_DS:
return VMX_GUEST_DS_SEL;
case CPU_REG_FS:
return VMX_GUEST_FS_SEL;
case CPU_REG_GS:
return VMX_GUEST_GS_SEL;
case CPU_REG_TR:
return VMX_GUEST_TR_SEL;
case CPU_REG_LDTR:
return VMX_GUEST_LDTR_SEL;
case CPU_REG_EFER:
return VMX_GUEST_IA32_EFER_FULL;
case CPU_REG_PDPTE0:
return VMX_GUEST_PDPTE0_FULL;
case CPU_REG_PDPTE1:
return VMX_GUEST_PDPTE1_FULL;
case CPU_REG_PDPTE2:
return VMX_GUEST_PDPTE2_FULL;
case CPU_REG_PDPTE3:
return VMX_GUEST_PDPTE3_FULL;
default: /* Never get here */
return VMX_INVALID_VMCS_FIELD;
}
}
/**
* @pre vcpu != NULL
* @pre ((reg <= CPU_REG_LAST) && (reg >= CPU_REG_FIRST))
* @pre ((reg != CPU_REG_CR2) && (reg != CPU_REG_IDTR) && (reg != CPU_REG_GDTR))
*/
static uint64_t vm_get_register(const struct acrn_vcpu *vcpu, enum cpu_reg_name reg)
{
uint64_t reg_val = 0UL;
if ((reg >= CPU_REG_GENERAL_FIRST) && (reg <= CPU_REG_GENERAL_LAST)) {
reg_val = vcpu_get_gpreg(vcpu, reg);
} else if ((reg >= CPU_REG_NONGENERAL_FIRST) &&
(reg <= CPU_REG_NONGENERAL_LAST)) {
uint32_t field = get_vmcs_field(reg);
if (reg <= CPU_REG_NATURAL_LAST) {
reg_val = exec_vmread(field);
} else if (reg <= CPU_REG_64BIT_LAST) {
reg_val = exec_vmread64(field);
} else {
reg_val = (uint64_t)exec_vmread16(field);
}
}
return reg_val;
}
/**
* @pre vcpu != NULL
* @pre ((reg <= CPU_REG_LAST) && (reg >= CPU_REG_FIRST))
* @pre ((reg != CPU_REG_CR2) && (reg != CPU_REG_IDTR) && (reg != CPU_REG_GDTR))
*/
static void vm_set_register(struct acrn_vcpu *vcpu, enum cpu_reg_name reg,
uint64_t val)
{
if ((reg >= CPU_REG_GENERAL_FIRST) && (reg <= CPU_REG_GENERAL_LAST)) {
vcpu_set_gpreg(vcpu, reg, val);
} else if ((reg >= CPU_REG_NONGENERAL_FIRST) &&
(reg <= CPU_REG_NONGENERAL_LAST)) {
uint32_t field = get_vmcs_field(reg);
if (reg <= CPU_REG_NATURAL_LAST) {
exec_vmwrite(field, val);
} else if (reg <= CPU_REG_64BIT_LAST) {
exec_vmwrite64(field, val);
} else {
exec_vmwrite16(field, (uint16_t)val);
}
}
}
/**
* @pre vcpu != NULL
* @pre desc != NULL
* @pre seg must be one of segment register (CPU_REG_CS/ES/DS/SS/FS/GS)
* or CPU_REG_TR/LDTR
*/
static void vm_get_seg_desc(enum cpu_reg_name seg, struct seg_desc *desc)
{
struct vmcs_seg_field tdesc;
/* tdesc->access != 0xffffffffU in this function */
encode_vmcs_seg_desc(seg, &tdesc);
desc->base = exec_vmread(tdesc.base_field);
desc->limit = exec_vmread32(tdesc.limit_field);
desc->access = exec_vmread32(tdesc.access_field);
}
static void get_guest_paging_info(struct acrn_vcpu *vcpu, struct instr_emul_ctxt *emul_ctxt,
uint32_t csar)
{
uint8_t cpl;
cpl = (uint8_t)((csar >> 5U) & 3U);
emul_ctxt->paging.cr3 = exec_vmread(VMX_GUEST_CR3);
emul_ctxt->paging.cpl = cpl;
emul_ctxt->paging.cpu_mode = get_vcpu_mode(vcpu);
emul_ctxt->paging.paging_mode = get_vcpu_paging_mode(vcpu);
}
static 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 << 48U) - 1UL);
if ((gla & (1UL << 47U)) != 0U) {
return ((gla & mask) != mask) ? 1 : 0;
} else {
return ((gla & mask) != 0U) ? 1 : 0;
}
}
static bool is_desc_valid(struct seg_desc *desc, uint32_t prot)
{
uint32_t type;
/* The descriptor type must indicate a code/data segment. */
type = seg_desc_type(desc->access);
if (type < 16U || type > 31U) {
return false;
}
if ((prot & PROT_READ) != 0U) {
/* #GP on a read access to a exec-only code segment */
if ((type & 0xAU) == 0x8U) {
return false;
}
}
if ((prot & PROT_WRITE) != 0U) {
/*
* #GP on a write access to a code segment or a
* read-only data segment.
*/
if ((type & 0x8U) != 0U) { /* code segment */
return false;
}
if ((type & 0xAU) == 0U) { /* read-only data seg */
return false;
}
}
return true;
}
/*
*@pre seg must be segment register index
*@pre length_arg must be 1, 2, 4 or 8
*@pre prot must be PROT_READ or PROT_WRITE
*
*return 0 - on success
*return -1 - on failure
*/
static int vie_calculate_gla(enum vm_cpu_mode cpu_mode, enum cpu_reg_name seg,
struct seg_desc *desc, uint64_t offset_arg, uint8_t addrsize,
uint64_t *gla)
{
uint64_t firstoff, segbase;
uint64_t offset = offset_arg;
uint8_t glasize;
firstoff = offset;
glasize = (cpu_mode == CPU_MODE_64BIT) ? 8U: 4U;
/*
* In 64-bit mode all segments except %fs and %gs have a segment
* base address of 0.
*/
if (cpu_mode == CPU_MODE_64BIT && seg != CPU_REG_FS &&
seg != CPU_REG_GS) {
segbase = 0UL;
} else {
segbase = desc->base;
}
/*
* Truncate 'firstoff' to the effective address size before adding
* it to the segment base.
*/
firstoff &= size2mask[addrsize];
*gla = (segbase + firstoff) & size2mask[glasize];
return 0;
}
/*
* @pre vcpu != NULL
*/
static inline void vie_mmio_read(const struct acrn_vcpu *vcpu, uint64_t *rval)
{
*rval = vcpu->req.reqs.mmio.value;
}
/*
* @pre vcpu != NULL
*/
static inline void vie_mmio_write(struct acrn_vcpu *vcpu, uint64_t wval)
{
vcpu->req.reqs.mmio.value = wval;
}
static void vie_calc_bytereg(const struct instr_emul_vie *vie,
enum cpu_reg_name *reg, int *lhbr)
{
*lhbr = 0;
*reg = 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 == 0U) {
if ((vie->reg & 0x4U) != 0U) {
*lhbr = 1;
*reg = vie->reg & 0x3U;
}
}
}
static uint8_t vie_read_bytereg(const struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
int lhbr;
uint64_t val;
uint8_t reg_val;
enum cpu_reg_name reg;
vie_calc_bytereg(vie, &reg, &lhbr);
val = vm_get_register(vcpu, reg);
/*
* To obtain the value of a legacy high byte register shift the
* base register right by 8 bits (%ah = %rax >> 8).
*/
if (lhbr != 0) {
reg_val = (uint8_t)(val >> 8U);
} else {
reg_val = (uint8_t)val;
}
return reg_val;
}
static void vie_write_bytereg(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie,
uint8_t byte)
{
uint64_t origval, val, mask;
enum cpu_reg_name reg;
int lhbr;
vie_calc_bytereg(vie, &reg, &lhbr);
origval = vm_get_register(vcpu, reg);
val = byte;
mask = 0xffU;
if (lhbr != 0) {
/*
* Shift left by 8 to store 'byte' in a legacy high
* byte register.
*/
val <<= 8U;
mask <<= 8U;
}
val |= origval & ~mask;
vm_set_register(vcpu, reg, val);
}
/**
* @pre vcpu != NULL
* @pre size = 1, 2, 4 or 8
* @pre ((reg <= CPU_REG_LAST) && (reg >= CPU_REG_FIRST))
* @pre ((reg != CPU_REG_CR2) && (reg != CPU_REG_IDTR) && (reg != CPU_REG_GDTR))
*/
static void vie_update_register(struct acrn_vcpu *vcpu, enum cpu_reg_name reg,
uint64_t val_arg, uint8_t size)
{
uint64_t origval;
uint64_t val = val_arg;
switch (size) {
case 1U:
case 2U:
origval = vm_get_register(vcpu, reg);
val &= size2mask[size];
val |= origval & ~size2mask[size];
break;
case 4U:
val &= 0xffffffffUL;
break;
default: /* size == 8 */
break;
}
vm_set_register(vcpu, reg, val);
}
#define RFLAGS_STATUS_BITS (PSL_C | PSL_PF | PSL_AF | PSL_Z | PSL_N | PSL_V)
static void vie_update_rflags(struct acrn_vcpu *vcpu, uint64_t rflags2, uint64_t psl)
{
uint8_t size;
uint64_t rflags;
rflags = vm_get_register(vcpu, CPU_REG_RFLAGS);
rflags &= ~RFLAGS_STATUS_BITS;
rflags |= rflags2 & psl;
size = 8U;
vie_update_register(vcpu, CPU_REG_RFLAGS, rflags, size);
}
/*
* Return the status flags that would result from doing (x - y).
*/
#define build_getcc(name, type) \
static uint64_t name(type x, type y) \
{ \
uint64_t rflags; \
\
__asm __volatile("sub %2,%1; pushfq; popq %0" : \
"=r" (rflags), "+r" (x) : "m" (y)); \
return rflags; \
}
build_getcc(getcc8, uint8_t)
build_getcc(getcc16, uint16_t)
build_getcc(getcc32, uint32_t)
build_getcc(getcc64, uint64_t)
/**
* @pre opsize = 1, 2, 4 or 8
*/
static uint64_t getcc(uint8_t opsize, uint64_t x, uint64_t y)
{
switch (opsize) {
case 1U:
return getcc8((uint8_t) x, (uint8_t) y);
case 2U:
return getcc16((uint16_t) x, (uint16_t) y);
case 4U:
return getcc32((uint32_t) x, (uint32_t) y);
default: /* opsize == 8 */
return getcc64(x, y);
}
}
static int emulate_mov(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
int error;
uint8_t size;
enum cpu_reg_name reg;
uint8_t byte;
uint64_t val;
size = vie->opsize;
error = 0;
switch (vie->opcode) {
case 0x88U:
/*
* 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 = 1U; /* override for byte operation */
byte = vie_read_bytereg(vcpu, vie);
vie_mmio_write(vcpu, byte);
break;
case 0x89U:
/*
* 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 = vie->reg;
val = vm_get_register(vcpu, reg);
val &= size2mask[size];
vie_mmio_write(vcpu, val);
break;
case 0x8AU:
/*
* 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 = 1U; /* override for byte operation */
vie_mmio_read(vcpu, &val);
vie_write_bytereg(vcpu, vie, (uint8_t)val);
break;
case 0x8BU:
/*
* 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
*/
vie_mmio_read(vcpu, &val);
reg = vie->reg;
vie_update_register(vcpu, reg, val, size);
break;
case 0xA1U:
/*
* MOV from seg:moffset to AX/EAX/RAX
* A1: mov AX, moffs16
* A1: mov EAX, moffs32
* REX.W + A1: mov RAX, moffs64
*/
vie_mmio_read(vcpu, &val);
reg = CPU_REG_RAX;
vie_update_register(vcpu, reg, val, size);
break;
case 0xA3U:
/*
* MOV from AX/EAX/RAX to seg:moffset
* A3: mov moffs16, AX
* A3: mov moffs32, EAX
* REX.W + A3: mov moffs64, RAX
*/
val = vm_get_register(vcpu, CPU_REG_RAX);
val &= size2mask[size];
vie_mmio_write(vcpu, val);
break;
case 0xC6U:
/*
* MOV from imm8 to mem (ModRM:r/m)
* C6/0 mov r/m8, imm8
* REX + C6/0 mov r/m8, imm8
*/
size = 1U; /* override for byte operation */
vie_mmio_write(vcpu, (uint64_t)vie->immediate);
break;
case 0xC7U:
/*
* 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 = (uint64_t)vie->immediate & size2mask[size];
vie_mmio_write(vcpu, val);
break;
default:
/*
* For the opcode that is not handled (an invalid opcode), the
* error code is assigned to a default value (-EINVAL).
* Gracefully return this error code if prior case clauses have
* not been met.
*/
error = -EINVAL;
break;
}
return error;
}
static int emulate_movx(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
int error;
uint8_t size;
enum cpu_reg_name reg;
uint64_t val;
size = vie->opsize;
error = 0;
switch (vie->opcode) {
case 0xB6U:
/*
* 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 */
vie_mmio_read(vcpu, &val);
/* get the second operand */
reg = vie->reg;
/* zero-extend byte */
val = (uint8_t)val;
/* write the result */
vie_update_register(vcpu, reg, val, size);
break;
case 0xB7U:
/*
* 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
*/
vie_mmio_read(vcpu, &val);
reg = vie->reg;
/* zero-extend word */
val = (uint16_t)val;
vie_update_register(vcpu, reg, val, size);
break;
case 0xBEU:
/*
* 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 */
vie_mmio_read(vcpu, &val);
/* get the second operand */
reg = vie->reg;
/* sign extend byte */
val = (int8_t)val;
/* write the result */
vie_update_register(vcpu, reg, val, size);
break;
default:
/*
* For the opcode that is not handled (an invalid opcode), the
* error code is assigned to a default value (-EINVAL).
* Gracefully return this error code if prior case clauses have
* not been met.
*/
error = -EINVAL;
break;
}
return error;
}
/**
* @pre only called by instruction emulation and check was done during
* instruction decode
*
* @remark This function can only be called in instruction emulation and
* suppose always success because the check was done during instruction
* decode.
*
* It's only used by MOVS/STO
*/
static void get_gva_si_nocheck(const struct acrn_vcpu *vcpu, uint8_t addrsize,
enum cpu_reg_name seg, uint64_t *gva)
{
uint64_t val;
struct seg_desc desc;
enum vm_cpu_mode cpu_mode;
val = vm_get_register(vcpu, CPU_REG_RSI);
vm_get_seg_desc(seg, &desc);
cpu_mode = get_vcpu_mode(vcpu);
(void)vie_calculate_gla(cpu_mode, seg, &desc, val, addrsize, gva);
return;
}
/*
* @pre only called during instruction decode phase
*
* @remark This function get gva from ES:DI. And do check the failure
* condition and inject exception to guest accordingly.
*
* It's only used by MOVS/STO
*/
static int get_gva_di_check(struct acrn_vcpu *vcpu, struct instr_emul_vie *vie,
uint8_t addrsize, uint64_t *gva)
{
int ret;
uint32_t err_code;
struct seg_desc desc;
enum vm_cpu_mode cpu_mode;
uint64_t val, gpa;
val = vm_get_register(vcpu, CPU_REG_RDI);
vm_get_seg_desc(CPU_REG_ES, &desc);
cpu_mode = get_vcpu_mode(vcpu);
if (cpu_mode == CPU_MODE_64BIT) {
if ((addrsize != 4U) && (addrsize != 8U)) {
goto exception_inject;
}
} else {
if ((addrsize != 2U) && (addrsize != 4U)) {
goto exception_inject;
}
if (!is_desc_valid(&desc, PROT_WRITE)) {
goto exception_inject;
}
}
if (vie_calculate_gla(cpu_mode, CPU_REG_ES, &desc, val, addrsize, gva)
!= 0) {
goto exception_inject;
}
if (vie_canonical_check(cpu_mode, *gva) != 0) {
goto exception_inject;
}
err_code = PAGE_FAULT_WR_FLAG;
ret = gva2gpa(vcpu, *gva, &gpa, &err_code);
if (ret < 0) {
if (ret == -EFAULT) {
vcpu_inject_pf(vcpu, (uint64_t)gva, err_code);
}
return ret;
}
/* If we are checking the dest operand for movs instruction,
* we cache the gpa if check pass. It will be used during
* movs instruction emulation.
*/
vie->dst_gpa = gpa;
return 0;
exception_inject:
vcpu_inject_gp(vcpu, 0U);
return -EFAULT;
}
/* MOVs gets the operands from RSI and RDI. Both operands could be memory.
* With VMX enabled, one of the operand triggers EPT voilation.
*
* If it's RSI access trigger EPT voilation, it's source operands and always
* read operations. Not neccesary to check whether need to inject fault (done
* by VMX already). We do need to check the RDI.
*
* If it's RDI access trigger EPT voilation, we need to check RDI because it's
* always write operations and VMX doens't cover write access check.
* Not neccesary to check RSI, because VMX cover it for us.
*
* In summary,
* For MOVs instruction, we always check RDI during instruction decoding phase.
* And access RSI without any check during instruction emulation phase.
*/
static int emulate_movs(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
uint64_t src_gva, gpa, val = 0UL;
uint64_t *dst_hva, *src_hva;
uint64_t rcx, rdi, rsi, rflags;
uint32_t err_code;
enum cpu_reg_name seg;
int error, repeat;
uint8_t opsize = vie->opsize;
bool is_mmio_write;
error = 0;
is_mmio_write = (vcpu->req.reqs.mmio.direction == REQUEST_WRITE);
/*
* 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 != 0) {
rcx = vm_get_register(vcpu, CPU_REG_RCX);
/*
* The count register is %rcx, %ecx or %cx depending on the
* address size of the instruction.
*/
if ((rcx & size2mask[vie->addrsize]) == 0UL) {
error = 0;
goto done;
}
}
seg = (vie->seg_override != 0U) ? (vie->segment_register) : CPU_REG_DS;
if (is_mmio_write) {
get_gva_si_nocheck(vcpu, vie->addrsize, seg, &src_gva);
/* we are sure it will success */
(void)gva2gpa(vcpu, src_gva, &gpa, &err_code);
src_hva = gpa2hva(vcpu->vm, gpa);
(void)memcpy_s(&val, opsize, src_hva, opsize);
vie_mmio_write(vcpu, val);
} else {
vie_mmio_read(vcpu, &val);
/* The dest gpa is saved during dst check instruction
* decoding.
*/
dst_hva = gpa2hva(vcpu->vm, vie->dst_gpa);
(void)memcpy_s(dst_hva, opsize, &val, opsize);
}
rsi = vm_get_register(vcpu, CPU_REG_RSI);
rdi = vm_get_register(vcpu, CPU_REG_RDI);
rflags = vm_get_register(vcpu, CPU_REG_RFLAGS);
if ((rflags & PSL_D) != 0U) {
rsi -= opsize;
rdi -= opsize;
} else {
rsi += opsize;
rdi += opsize;
}
vie_update_register(vcpu, CPU_REG_RSI, rsi, vie->addrsize);
vie_update_register(vcpu, CPU_REG_RDI, rdi, vie->addrsize);
if (repeat != 0) {
rcx = rcx - 1;
vie_update_register(vcpu, CPU_REG_RCX, rcx, vie->addrsize);
/*
* Repeat the instruction if the count register is not zero.
*/
if ((rcx & size2mask[vie->addrsize]) != 0UL) {
vcpu_retain_rip(vcpu);
}
}
done:
return error;
}
static int emulate_stos(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
int repeat;
uint8_t opsize = vie->opsize;
uint64_t val;
uint64_t rcx, rdi, rflags;
repeat = vie->repz_present | vie->repnz_present;
if (repeat != 0) {
rcx = vm_get_register(vcpu, CPU_REG_RCX);
/*
* The count register is %rcx, %ecx or %cx depending on the
* address size of the instruction.
*/
if ((rcx & size2mask[vie->addrsize]) == 0UL) {
return 0;
}
}
val = vm_get_register(vcpu, CPU_REG_RAX);
vie_mmio_write(vcpu, val);
rdi = vm_get_register(vcpu, CPU_REG_RDI);
rflags = vm_get_register(vcpu, CPU_REG_RFLAGS);
if ((rflags & PSL_D) != 0U) {
rdi -= opsize;
} else {
rdi += opsize;
}
vie_update_register(vcpu, CPU_REG_RDI, rdi, vie->addrsize);
if (repeat != 0) {
rcx = rcx - 1;
vie_update_register(vcpu, CPU_REG_RCX, rcx, vie->addrsize);
/*
* Repeat the instruction if the count register is not zero.
*/
if ((rcx & size2mask[vie->addrsize]) != 0UL) {
vcpu_retain_rip(vcpu);
}
}
return 0;
}
static int emulate_test(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
int error;
uint8_t size;
enum cpu_reg_name reg;
uint64_t result, rflags2, val1, val2;
size = vie->opsize;
error = 0;
switch (vie->opcode) {
case 0x84U:
/*
* 84/r test r8, r/m8
*/
size = 1U; /*override size for 8-bit operation*/
/* fallthrough */
case 0x85U:
/*
* AND reg (ModRM:reg) and mem (ModRM:r/m) and discard
* the result.
*
*
* 85/r test r16, r/m16
* 85/r test r32, r/m32
* REX.W + 85/r test r64, r/m64
*/
/* get the first operand */
reg = vie->reg;
val1 = vm_get_register(vcpu, reg);
/* get the second operand */
vie_mmio_read(vcpu, &val2);
/* perform the operation and write the result */
result = val1 & val2;
break;
default:
/*
* For the opcode that is not handled (an invalid opcode), the
* error code is assigned to a default value (-EINVAL).
* Gracefully return this error code if prior case clauses have
* not been met.
*/
error = -EINVAL;
break;
}
if (error == 0) {
/*
* 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, 0UL);
vie_update_rflags(vcpu, rflags2, PSL_PF | PSL_Z | PSL_N);
}
return error;
}
static int emulate_and(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
int error;
uint8_t size;
enum cpu_reg_name reg;
uint64_t result, rflags2, val1, val2;
size = vie->opsize;
error = 0;
switch (vie->opcode) {
case 0x23U:
/*
* 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 = vie->reg;
val1 = vm_get_register(vcpu, reg);
/* get the second operand */
vie_mmio_read(vcpu, &val2);
/* perform the operation and write the result */
result = val1 & val2;
vie_update_register(vcpu, reg, result, size);
break;
case 0x81U:
case 0x83U:
/*
* 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 */
vie_mmio_read(vcpu, &val1);
/*
* perform the operation with the pre-fetched immediate
* operand and write the result
*/
result = val1 & vie->immediate;
vie_mmio_write(vcpu, result);
break;
default:
/*
* For the opcode that is not handled (an invalid opcode), the
* error code is assigned to a default value (-EINVAL).
* Gracefully return this error code if prior case clauses have
* not been met.
*/
error = -EINVAL;
break;
}
if (error == 0) {
/*
* 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, 0UL);
vie_update_rflags(vcpu, rflags2, PSL_PF | PSL_Z | PSL_N);
}
return error;
}
static int emulate_or(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
int error;
uint8_t size;
enum cpu_reg_name reg;
uint64_t val1, val2, result, rflags2;
size = vie->opsize;
error = 0;
switch (vie->opcode) {
case 0x81U:
case 0x83U:
/*
* 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 */
vie_mmio_read(vcpu, &val1);
/*
* perform the operation with the pre-fetched immediate
* operand and write the result
*/
result = val1 | (uint64_t)vie->immediate;
vie_mmio_write(vcpu, result);
break;
case 0x09U:
/*
* OR mem (ModRM:r/m) with reg (ModRM:reg) and store the
* result in mem.
* 09/r: OR r/m16, r16
* 09/r: OR r/m32, r32
*/
/* get the first operand */
vie_mmio_read(vcpu, &val1);
/* get the second operand */
reg = vie->reg;
val2 = vm_get_register(vcpu, reg);
/* perform the operation and write the result */
result = val1 | val2;
result &= size2mask[size];
vie_mmio_write(vcpu, result);
break;
default:
/*
* For the opcode that is not handled (an invalid opcode), the
* error code is assigned to a default value (-EINVAL).
* Gracefully return this error code if prior case clauses have
* not been met.
*/
error = -EINVAL;
break;
}
if (error == 0) {
/*
* 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, 0UL);
vie_update_rflags(vcpu, rflags2, PSL_PF | PSL_Z | PSL_N);
}
return error;
}
static int emulate_cmp(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
int error;
uint8_t size;
uint64_t regop, memop, op1, op2, rflags2;
enum cpu_reg_name reg;
size = vie->opsize;
switch (vie->opcode) {
case 0x39U:
case 0x3BU:
/*
* 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 = vie->reg;
regop = vm_get_register(vcpu, reg);
/* Get the memory operand */
vie_mmio_read(vcpu, &memop);
if (vie->opcode == 0x3BU) {
op1 = regop;
op2 = memop;
} else {
op1 = memop;
op2 = regop;
}
rflags2 = getcc(size, op1, op2);
break;
case 0x80U:
case 0x81U:
case 0x83U:
/*
* 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->opcode == 0x80U) {
size = 1U;
}
/* get the first operand */
vie_mmio_read(vcpu, &op1);
rflags2 = getcc(size, op1, (uint64_t)vie->immediate);
break;
default:
return -EINVAL;
}
vie_update_rflags(vcpu, rflags2, RFLAGS_STATUS_BITS);
return error;
}
static int emulate_sub(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
int error;
uint8_t size;
uint64_t nval, rflags2, val1, val2;
enum cpu_reg_name reg;
size = vie->opsize;
error = 0;
switch (vie->opcode) {
case 0x2BU:
/*
* 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 = vie->reg;
val1 = vm_get_register(vcpu, reg);
/* get the second operand */
vie_mmio_read(vcpu, &val2);
/* perform the operation and write the result */
nval = val1 - val2;
vie_update_register(vcpu, reg, nval, size);
break;
default:
/*
* For the opcode that is not handled (an invalid opcode), the
* error code is assigned to a default value (-EINVAL).
* Gracefully return this error code if prior case clauses have
* not been met.
*/
error = -EINVAL;
break;
}
if (error != 0) {
return error;
}
rflags2 = getcc(size, val1, val2);
vie_update_rflags(vcpu, rflags2, RFLAGS_STATUS_BITS);
return error;
}
static int emulate_group1(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
int error;
switch (vie->reg & 7U) {
case 0x1U: /* OR */
error = emulate_or(vcpu, vie);
break;
case 0x4U: /* AND */
error = emulate_and(vcpu, vie);
break;
case 0x7U: /* CMP */
error = emulate_cmp(vcpu, vie);
break;
default:
error = EINVAL;
break;
}
return error;
}
static int emulate_bittest(struct acrn_vcpu *vcpu, const struct instr_emul_vie *vie)
{
uint64_t val, rflags, bitmask;
uint64_t bitoff;
uint8_t size;
/*
* 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 & 7U) != 4U) {
return -EINVAL;
}
rflags = vm_get_register(vcpu, CPU_REG_RFLAGS);
vie_mmio_read(vcpu, &val);
/*
* Intel SDM, Vol 2, Table 3-2:
* "Range of Bit Positions Specified by Bit Offset Operands"
*/
bitmask = ((uint64_t)vie->opsize * 8UL) - 1UL;
bitoff = (uint64_t)vie->immediate & bitmask;
/* Copy the bit into the Carry flag in %rflags */
if ((val & (1UL << bitoff)) != 0U) {
rflags |= PSL_C;
} else {
rflags &= ~PSL_C;
}
size = 8U;
vie_update_register(vcpu, CPU_REG_RFLAGS, rflags, size);
return 0;
}
static int vmm_emulate_instruction(struct instr_emul_ctxt *ctxt)
{
struct instr_emul_vie *vie = &ctxt->vie;
struct acrn_vcpu *vcpu = ctxt->vcpu;
int error;
if (vie->decoded == 0U) {
return -EINVAL;
}
switch (vie->op.op_type) {
case VIE_OP_TYPE_GROUP1:
error = emulate_group1(vcpu, vie);
break;
case VIE_OP_TYPE_CMP:
error = emulate_cmp(vcpu, vie);
break;
case VIE_OP_TYPE_MOV:
error = emulate_mov(vcpu, vie);
break;
case VIE_OP_TYPE_MOVSX:
case VIE_OP_TYPE_MOVZX:
error = emulate_movx(vcpu, vie);
break;
case VIE_OP_TYPE_MOVS:
error = emulate_movs(vcpu, vie);
break;
case VIE_OP_TYPE_STOS:
error = emulate_stos(vcpu, vie);
break;
case VIE_OP_TYPE_AND:
error = emulate_and(vcpu, vie);
break;
case VIE_OP_TYPE_TEST:
error = emulate_test(vcpu, vie);
break;
case VIE_OP_TYPE_OR:
error = emulate_or(vcpu, vie);
break;
case VIE_OP_TYPE_SUB:
error = emulate_sub(vcpu, vie);
break;
case VIE_OP_TYPE_BITTEST:
error = emulate_bittest(vcpu, vie);
break;
default:
error = -EINVAL;
break;
}
return error;
}
static int vie_init(struct instr_emul_vie *vie, struct acrn_vcpu *vcpu)
{
uint64_t guest_rip_gva = vcpu_get_rip(vcpu);
uint32_t inst_len = vcpu->arch.inst_len;
uint32_t err_code;
uint64_t fault_addr;
int ret;
if ((inst_len > VIE_INST_SIZE) || (inst_len == 0U)) {
pr_err("%s: invalid instruction length (%d)",
__func__, inst_len);
return -EINVAL;
}
(void)memset(vie, 0U, sizeof(struct instr_emul_vie));
/* init register fields in vie. */
vie->base_register = CPU_REG_LAST;
vie->index_register = CPU_REG_LAST;
vie->segment_register = CPU_REG_LAST;
err_code = PAGE_FAULT_ID_FLAG;
ret = copy_from_gva(vcpu, vie->inst, guest_rip_gva,
inst_len, &err_code, &fault_addr);
if (ret < 0) {
if (ret == -EFAULT) {
vcpu_inject_pf(vcpu, fault_addr, err_code);
}
return ret;
}
vie->num_valid = (uint8_t)inst_len;
return 0;
}
static int vie_peek(const struct instr_emul_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 instr_emul_vie *vie)
{
vie->num_processed++;
}
static bool segment_override(uint8_t x, enum cpu_reg_name *seg)
{
switch (x) {
case 0x2EU:
*seg = CPU_REG_CS;
break;
case 0x36U:
*seg = CPU_REG_SS;
break;
case 0x3EU:
*seg = CPU_REG_DS;
break;
case 0x26U:
*seg = CPU_REG_ES;
break;
case 0x64U:
*seg = CPU_REG_FS;
break;
case 0x65U:
*seg = CPU_REG_GS;
break;
default:
return false;
}
return true;
}
static int decode_prefixes(struct instr_emul_vie *vie,
enum vm_cpu_mode cpu_mode, bool cs_d)
{
uint8_t x;
while (1) {
if (vie_peek(vie, &x) != 0) {
return -1;
}
if (x == 0x66U) {
vie->opsize_override = 1U;
} else if (x == 0x67U) {
vie->addrsize_override = 1U;
} else if (x == 0xF3U) {
vie->repz_present = 1U;
} else if (x == 0xF2U) {
vie->repnz_present = 1U;
} else if (segment_override(x, &vie->segment_register)) {
vie->seg_override = 1U;
} 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 >= 0x40U) && (x <= 0x4FU)) {
vie->rex_present = 1U;
vie->rex_w = (x & 0x8U) != 0U ? 1U : 0U;
vie->rex_r = (x & 0x4U) != 0U ? 1U : 0U;
vie->rex_x = (x & 0x2U) != 0U ? 1U : 0U;
vie->rex_b = (x & 0x1U) != 0U ? 1U : 0U;
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 != 0U)? 4U : 8U;
if (vie->rex_w != 0U) {
vie->opsize = 8U;
} else if (vie->opsize_override != 0U) {
vie->opsize = 2U;
} else {
vie->opsize = 4U;
}
} else if (cs_d) {
/* Default address and operand sizes are 32-bits */
vie->addrsize = vie->addrsize_override != 0U ? 2U : 4U;
vie->opsize = vie->opsize_override != 0U ? 2U : 4U;
} else {
/* Default address and operand sizes are 16-bits */
vie->addrsize = vie->addrsize_override != 0U ? 4U : 2U;
vie->opsize = vie->opsize_override != 0U ? 4U : 2U;
}
return 0;
}
static int decode_two_byte_opcode(struct instr_emul_vie *vie)
{
uint8_t x;
if (vie_peek(vie, &x) != 0) {
return -1;
}
vie->opcode = x;
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 instr_emul_vie *vie)
{
int ret = 0;
uint8_t x;
if (vie_peek(vie, &x) != 0) {
return -1;
}
vie->opcode = x;
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) {
ret = decode_two_byte_opcode(vie);
}
/* Fixup the opsize according to opcode w bit:
* If w bit of opcode is 0, the operand size is 1 byte
* If w bit of opcode is 1, the operand size is decided
* by prefix and default operand size attribute (handled
* in decode_prefixes).
*/
if ((ret == 0) && ((vie->opcode & 0x1U) == 0U)) {
vie->opsize = 1U;
}
return ret;
}
static int decode_modrm(struct instr_emul_vie *vie, enum vm_cpu_mode cpu_mode)
{
uint8_t x;
if ((vie->op.op_flags & VIE_OP_F_NO_MODRM) != 0U) {
return 0;
}
if (cpu_mode == CPU_MODE_REAL) {
return -1;
}
if (vie_peek(vie, &x) != 0) {
return -1;
}
vie->mod = (x >> 6U) & 0x3U;
vie->rm = (x >> 0U) & 0x7U;
vie->reg = (x >> 3U) & 0x7U;
/*
* 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 << 3U);
}
vie->reg |= (vie->rex_r << 3U);
/* SIB */
if (vie->mod != VIE_MOD_DIRECT && vie->rm == VIE_RM_SIB) {
goto done;
}
vie->base_register = vie->rm;
switch (vie->mod) {
case VIE_MOD_INDIRECT_DISP8:
vie->disp_bytes = 1U;
break;
case VIE_MOD_INDIRECT_DISP32:
vie->disp_bytes = 4U;
break;
case VIE_MOD_INDIRECT:
if (vie->rm == VIE_RM_DISP32) {
vie->disp_bytes = 4U;
/*
* 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 = CPU_REG_RIP;
pr_err("VM exit with RIP as indirect access");
}
else {
vie->base_register = CPU_REG_LAST;
}
}
break;
}
done:
vie_advance(vie);
return 0;
}
static int decode_sib(struct instr_emul_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) != 0) {
return -1;
}
/* De-construct the SIB byte */
vie->ss = (x >> 6U) & 0x3U;
vie->index = (x >> 3U) & 0x7U;
vie->base = (x >> 0U) & 0x7U;
/* Apply the REX prefix modifiers */
vie->index |= vie->rex_x << 3U;
vie->base |= vie->rex_b << 3U;
switch (vie->mod) {
case VIE_MOD_INDIRECT_DISP8:
vie->disp_bytes = 1U;
break;
case VIE_MOD_INDIRECT_DISP32:
vie->disp_bytes = 4U;
break;
default:
/*
* All possible values of 'vie->mod':
* 1. VIE_MOD_DIRECT
* has been handled at the start of this function
* 2. VIE_MOD_INDIRECT_DISP8
* has been handled in prior case clauses
* 3. VIE_MOD_INDIRECT_DISP32
* has been handled in prior case clauses
* 4. VIE_MOD_INDIRECT
* will be handled later after this switch statement
*/
break;
}
if ((vie->mod == VIE_MOD_INDIRECT) &&
((vie->base == 5U) || (vie->base == 13U))) {
/*
* 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 = 4U;
} else {
vie->base_register = 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 != 4U) {
vie->index_register = vie->index;
}
/* 'scale' makes sense only in the context of an index register */
if (vie->index_register < CPU_REG_LAST) {
vie->scale = 1U << vie->ss;
}
vie_advance(vie);
return 0;
}
static int decode_displacement(struct instr_emul_vie *vie)
{
int n, i;
uint8_t x;
union {
uint8_t buf[4];
int8_t signed8;
int32_t signed32;
} u;
n = vie->disp_bytes;
if (n == 0) {
return 0;
}
if ((n != 1) && (n != 4)) {
pr_err("%s: decode_displacement: invalid disp_bytes %d",
__func__, n);
return -EINVAL;
}
for (i = 0; i < n; i++) {
if (vie_peek(vie, &x) != 0) {
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 instr_emul_vie *vie)
{
int i, n;
uint8_t x;
union {
uint8_t 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) != 0U) {
/*
* 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 == 4U) || (vie->opsize == 8U)) {
vie->imm_bytes = 4U;
}
else {
vie->imm_bytes = 2U;
}
} else if ((vie->op.op_flags & VIE_OP_F_IMM8) != 0U) {
vie->imm_bytes = 1U;
} else {
/* No op_flag on immediate operand size */
}
n = vie->imm_bytes;
if (n == 0) {
return 0;
}
if ((n != 1) && (n != 2) && (n != 4)) {
pr_err("%s: invalid number of immediate bytes: %d",
__func__, n);
return -EINVAL;
}
for (i = 0; i < n; i++) {
if (vie_peek(vie, &x) != 0) {
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 instr_emul_vie *vie)
{
uint8_t i, n, x;
union {
uint8_t buf[8];
uint64_t u64;
} u;
if ((vie->op.op_flags & VIE_OP_F_MOFFSET) == 0U) {
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;
if ((n != 2U) && (n != 4U) && (n != 8U)) {
pr_err("%s: invalid moffset bytes: %hhu", __func__, n);
return -EINVAL;
}
u.u64 = 0UL;
for (i = 0U; i < n; i++) {
if (vie_peek(vie, &x) != 0) {
return -1;
}
u.buf[i] = x;
vie_advance(vie);
}
vie->displacement = (int64_t)u.u64;
return 0;
}
static int local_decode_instruction(enum vm_cpu_mode cpu_mode,
bool cs_d, struct instr_emul_vie *vie)
{
if (decode_prefixes(vie, cpu_mode, cs_d) != 0) {
return -1;
}
if (decode_opcode(vie) != 0) {
return -1;
}
if (decode_modrm(vie, cpu_mode) != 0) {
return -1;
}
if (decode_sib(vie) != 0) {
return -1;
}
if (decode_displacement(vie) != 0) {
return -1;
}
if (decode_immediate(vie) != 0) {
return -1;
}
if (decode_moffset(vie) != 0) {
return -1;
}
vie->decoded = 1U; /* success */
return 0;
}
/* for instruction MOVS/STO, check the gva gotten from DI/SI. */
static int instr_check_di(struct acrn_vcpu *vcpu, struct instr_emul_ctxt *emul_ctxt)
{
int ret;
struct instr_emul_vie *vie = &emul_ctxt->vie;
uint64_t gva;
ret = get_gva_di_check(vcpu, vie, vie->addrsize, &gva);
if (ret < 0) {
return -EFAULT;
}
return 0;
}
static int instr_check_gva(struct acrn_vcpu *vcpu, struct instr_emul_ctxt *emul_ctxt,
enum vm_cpu_mode cpu_mode)
{
int ret;
uint64_t base, segbase, idx, gva, gpa;
uint32_t err_code;
enum cpu_reg_name seg;
struct instr_emul_vie *vie = &emul_ctxt->vie;
base = 0UL;
if (vie->base_register != CPU_REG_LAST) {
base = vm_get_register(vcpu, vie->base_register);
/* RIP relative addressing starts from the
* following instruction
*/
if (vie->base_register == CPU_REG_RIP) {
base += vie->num_processed;
}
}
idx = 0UL;
if (vie->index_register != CPU_REG_LAST) {
idx = vm_get_register(vcpu, vie->index_register);
}
/* "Specifying a Segment Selector" of SDM Vol1 3.7.4
*
* In legacy IA-32 mode, when ESP or EBP register is used as
* base, the SS segment is default segment.
*
* All data references, except when relative to stack or
* string destination, DS is default segment.
*
* segment override could overwrite the default segment
*
* 64bit mode, segmentation is generally disabled. The
* exception are FS and GS.
*/
if (vie->seg_override != 0U) {
seg = vie->segment_register;
} else if ((vie->base_register == CPU_REG_RSP) ||
(vie->base_register == CPU_REG_RBP)) {
seg = CPU_REG_SS;
} else {
seg = CPU_REG_DS;
}
if ((cpu_mode == CPU_MODE_64BIT) && (seg != CPU_REG_FS) &&
(seg != CPU_REG_GS)) {
segbase = 0UL;
} else {
struct seg_desc desc;
vm_get_seg_desc(seg, &desc);
segbase = desc.base;
}
gva = segbase + base + (uint64_t)vie->scale * idx + (uint64_t)vie->displacement;
if (vie_canonical_check(cpu_mode, gva) != 0) {
if (seg == CPU_REG_SS) {
vcpu_inject_ss(vcpu);
} else {
vcpu_inject_gp(vcpu, 0U);
}
return -EFAULT;
}
err_code = (vcpu->req.reqs.mmio.direction == REQUEST_WRITE) ?
PAGE_FAULT_WR_FLAG : 0U;
ret = gva2gpa(vcpu, gva, &gpa, &err_code);
if (ret < 0) {
if (ret == -EFAULT) {
vcpu_inject_pf(vcpu, gva,
err_code);
}
return ret;
}
return 0;
}
int decode_instruction(struct acrn_vcpu *vcpu)
{
struct instr_emul_ctxt *emul_ctxt;
uint32_t csar;
int retval;
enum vm_cpu_mode cpu_mode;
emul_ctxt = &per_cpu(g_inst_ctxt, vcpu->pcpu_id);
if (emul_ctxt == NULL) {
pr_err("%s: Failed to get emul_ctxt", __func__);
return -1;
}
emul_ctxt->vcpu = vcpu;
retval = vie_init(&emul_ctxt->vie, vcpu);
if (retval < 0) {
if (retval != -EFAULT) {
pr_err("init vie failed @ 0x%016llx:",
vcpu_get_rip(vcpu));
}
return retval;
}
csar = exec_vmread32(VMX_GUEST_CS_ATTR);
get_guest_paging_info(vcpu, emul_ctxt, csar);
cpu_mode = get_vcpu_mode(vcpu);
retval = local_decode_instruction(cpu_mode, seg_desc_def32(csar),
&emul_ctxt->vie);
if (retval != 0) {
pr_err("decode instruction failed @ 0x%016llx:",
vcpu_get_rip(vcpu));
vcpu_inject_ud(vcpu);
return -EFAULT;
}
/*
* We do operand check in instruction decode phase and
* inject exception accordingly. In late instruction
* emulation, it will always sucess.
*
* We only need to do dst check for movs. For other instructions,
* they always has one register and one mmio which trigger EPT
* by access mmio. With VMX enabled, the related check is done
* by VMX itself before hit EPT violation.
*
*/
if ((emul_ctxt->vie.op.op_flags & VIE_OP_F_CHECK_GVA_DI) != 0U) {
retval = instr_check_di(vcpu, emul_ctxt);
if (retval < 0) {
return retval;
}
} else {
retval = instr_check_gva(vcpu, emul_ctxt, cpu_mode);
if (retval < 0) {
return retval;
}
}
return (int)(emul_ctxt->vie.opsize);
}
int emulate_instruction(const struct acrn_vcpu *vcpu)
{
struct instr_emul_ctxt *ctxt = &per_cpu(g_inst_ctxt, vcpu->pcpu_id);
if (ctxt == NULL) {
pr_err("%s: Failed to get instr_emul_ctxt", __func__);
return -1;
}
return vmm_emulate_instruction(ctxt);
}
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