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Emulate the 'bit test' instruction. Windows 7 uses 'bit test' to check the

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'Delivery Status' bit in APIC ICR register.

Reported by:	Leon Dang (ldang@nahannisys.com)
MFC after:	2 weeks
This commit is contained in:
Neel Natu 2015-04-29 02:01:46 +00:00
parent ad34cace15
commit b8070ef5b1
1 changed files with 52 additions and 0 deletions
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52
sys/amd64/vmm/vmm_instruction_emul.c
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@ -73,6 +73,7 @@ enum {
VIE_OP_TYPE_MOVS,
VIE_OP_TYPE_GROUP1,
VIE_OP_TYPE_STOS,
VIE_OP_TYPE_BITTEST,
VIE_OP_TYPE_LAST
};
@ -92,6 +93,11 @@ static const struct vie_op two_byte_opcodes[256] = {
.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,
@ -1335,6 +1341,48 @@ emulate_group1(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
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);
}
int
vmm_emulate_instruction(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
struct vm_guest_paging *paging, mem_region_read_t memread,
@ -1391,6 +1439,10 @@ vmm_emulate_instruction(void *vm, int vcpuid, uint64_t gpa, struct vie *vie,
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;
default:
error = EINVAL;
break;