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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v13 1/3] x86emul: New return code for unimplemented instruction
Enforce the distinction between an instruction not implemented by the
emulator and the failure to emulate that instruction by defining a new
return code, X86EMUL_UNIMPLEMENTED.
This value should only be returned by the core emulator only if it fails to
properly decode the current instruction's opcode, and not by any of other
functions, such as the x86_emulate_ops or the hvm_io_ops callbacks.
e.g. hvm_process_io_intercept should not return X86EMUL_UNIMPLEMENTED.
The return value of this function depends on either the return code of
one of the hvm_io_ops handlers (read/write) or the value returned by
hvm_copy_guest_from_phys / hvm_copy_to_guest_phys.
Similary, none of this functions should return X86EMUL_UNIMPLEMENTED.
- hvm_io_intercept
- hvmemul_do_io
- hvm_send_buffered_ioreq
- hvm_send_ioreq
- hvm_broadcast_ioreq
- hvmemul_do_io_buffer
- hvmemul_validate
Also the behavior of hvm_emulate_one_insn and vmx_realmode_emulate_one
was modified to generate an Invalid Opcode trap when X86EMUL_UNRECOGNIZED
is returned by the emulator instead of just crash the domain.
Signed-off-by: Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>
---
Changed since v10:
* Added asserts to make sure the return code cannot be
X86EMUL_UNIMPLEMENTED.
* Add new return code (X86EMUL_UNRECOGNIZED) to be used when trying
to emulate an instruction with an invalid opcode.
Changed since v11:
* Fixed double negative in the patch description.
* Move assertion into the switch and use ASSERT_UNREACHABLE() when
applicable.
* Changed the description of X86EMUL_UNIMPLEMENTED / X86EMUL_UNRECOGNIZED
to reflect the differences between those 2 return codes.
* Changed the returned value to X86EMUL_UNRECOGNIZED in the
following cases:
X86EMUL_OPC(0x0f, 0x73): /* Group 14 */
X86EMUL_OPC_66(0x0f, 0x73):
X86EMUL_OPC_VEX_66(0x0f, 0x73):
- All valid opcodes are defined, so it should return
X86EMUL_UNRECOGNIZED if mod R/M bits are not matched.
X86EMUL_OPC(0x0f, 0xc7) /* Group 9 */
- For register type instructions all possible opcodes are
defined, so it should return X86EMUL_UNRECOGNIZED if
mod R/M bits are not matched.
X86EMUL_OPC_VEX(0x0f38, 0xf3): /* Group 17 */
- All valid opcodes are defined, so it should return
X86EMUL_UNRECOGNIZED if mod R/M bits are not matched.
X86EMUL_OPC_XOP(09, 0x01): /* XOP Grp1 */
X86EMUL_OPC_XOP(09, 0x02): /* XOP Grp2 */
- All valid opcodes are defined, so it should return
X86EMUL_UNRECOGNIZED if mod R/M bits are not matched.
X86EMUL_OPC(0x0f, 0x01): /* Grp7 */
- Not all valid opcodes are defined so it should return
X86EMUL_UNIMPLEMENTED if mod R/M bits are not matched.
(e.g. XGETBV)
X86EMUL_OPC_66(0x0f, 0x78):
- All valid opcodes are defined, so it should return
X86EMUL_UNRECOGNIZED if mod R/M bits are not matched.
X86EMUL_OPC(0x0f, 0xae):
X86EMUL_OPC_66(0x0f, 0xae): /* Grp15 */
- Not all valid opcodes are defined so it should return
X86EMUL_UNIMPLEMENTED if mod R/M bits are not matched.
(e.g. FXSAVE/FXRSTOR )
Changed since v12:
* return X86EMUL_UNIMPLEMENTED if HAVE_GAS_RDRAND is not defined
* create unrecognized_insn label
* return X86EMUL_UNRECOGNIZED in case of failure to decode Group #13
instructions.
* add a "TODO:" comment to the description of X86EMUL_UNRECOGNIZED
stating that for now it can be used interchangeably with
X86EMUL_UNIMPLEMENTED.
---
xen/arch/x86/hvm/emulate.c | 12 ++++++++
xen/arch/x86/hvm/hvm.c | 1 +
xen/arch/x86/hvm/io.c | 5 ++++
xen/arch/x86/hvm/vmx/realmode.c | 9 ++++++
xen/arch/x86/mm/shadow/multi.c | 2 +-
xen/arch/x86/x86_emulate/x86_emulate.c | 51 +++++++++++++++++++---------------
xen/arch/x86/x86_emulate/x86_emulate.h | 17 ++++++++++++
7 files changed, 74 insertions(+), 23 deletions(-)
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index cc874ce..385fe1e 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -284,10 +284,15 @@ static int hvmemul_do_io(
}
break;
}
+ case X86EMUL_UNIMPLEMENTED:
+ ASSERT_UNREACHABLE();
+ /* Fall-through */
default:
BUG();
}
+ ASSERT(rc != X86EMUL_UNIMPLEMENTED);
+
if ( rc != X86EMUL_OKAY )
return rc;
@@ -313,6 +318,9 @@ static int hvmemul_do_io_buffer(
rc = hvmemul_do_io(is_mmio, addr, reps, size, dir, df, 0,
(uintptr_t)buffer);
+
+ ASSERT(rc != X86EMUL_UNIMPLEMENTED);
+
if ( rc == X86EMUL_UNHANDLEABLE && dir == IOREQ_READ )
memset(buffer, 0xff, size);
@@ -405,6 +413,8 @@ static int hvmemul_do_io_addr(
rc = hvmemul_do_io(is_mmio, addr, &count, size, dir, df, 1,
ram_gpa);
+ ASSERT(rc != X86EMUL_UNIMPLEMENTED);
+
if ( rc == X86EMUL_OKAY )
v->arch.hvm_vcpu.hvm_io.mmio_retry = (count < *reps);
@@ -2045,6 +2055,7 @@ int hvm_emulate_one_mmio(unsigned long mfn, unsigned long
gla)
switch ( rc )
{
case X86EMUL_UNHANDLEABLE:
+ case X86EMUL_UNIMPLEMENTED:
hvm_dump_emulation_state(XENLOG_G_WARNING, "MMCFG", &ctxt);
break;
case X86EMUL_EXCEPTION:
@@ -2102,6 +2113,7 @@ void hvm_emulate_one_vm_event(enum emul_kind kind,
unsigned int trapnr,
* consistent with X86EMUL_RETRY.
*/
return;
+ case X86EMUL_UNIMPLEMENTED:
case X86EMUL_UNHANDLEABLE:
hvm_dump_emulation_state(XENLOG_G_DEBUG, "Mem event", &ctx);
hvm_inject_hw_exception(trapnr, errcode);
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index d99f4b4..57f3f76 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3735,6 +3735,7 @@ void hvm_ud_intercept(struct cpu_user_regs *regs)
switch ( hvm_emulate_one(&ctxt) )
{
case X86EMUL_UNHANDLEABLE:
+ case X86EMUL_UNIMPLEMENTED:
hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
break;
case X86EMUL_EXCEPTION:
diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index bf41954..b8c0ae7 100644
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -99,6 +99,11 @@ bool hvm_emulate_one_insn(hvm_emulate_validate_t *validate,
const char *descr)
hvm_dump_emulation_state(XENLOG_G_WARNING, descr, &ctxt);
return false;
+ case X86EMUL_UNRECOGNIZED:
+ hvm_dump_emulation_state(XENLOG_G_WARNING, descr, &ctxt);
+ hvm_inject_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC);
+ break;
+
case X86EMUL_EXCEPTION:
hvm_inject_event(&ctxt.ctxt.event);
break;
diff --git a/xen/arch/x86/hvm/vmx/realmode.c b/xen/arch/x86/hvm/vmx/realmode.c
index 12d43ad..b73fc80 100644
--- a/xen/arch/x86/hvm/vmx/realmode.c
+++ b/xen/arch/x86/hvm/vmx/realmode.c
@@ -112,6 +112,15 @@ void vmx_realmode_emulate_one(struct hvm_emulate_ctxt
*hvmemul_ctxt)
goto fail;
}
+ if ( rc == X86EMUL_UNRECOGNIZED )
+ {
+ gdprintk(XENLOG_ERR, "Unrecognized insn.\n");
+ if ( curr->arch.hvm_vcpu.guest_cr[0] & X86_CR0_PE )
+ goto fail;
+
+ realmode_deliver_exception(TRAP_invalid_op, 0, hvmemul_ctxt);
+ }
+
if ( rc == X86EMUL_EXCEPTION )
{
if ( unlikely(curr->domain->debugger_attached) &&
diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c
index 8d4f244..2557e21 100644
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -3488,7 +3488,7 @@ static int sh_page_fault(struct vcpu *v,
* would be a good unshadow hint. If we *do* decide to unshadow-on-fault
* then it must be 'failable': we cannot require the unshadow to succeed.
*/
- if ( r == X86EMUL_UNHANDLEABLE )
+ if ( r == X86EMUL_UNHANDLEABLE || r == X86EMUL_UNIMPLEMENTED )
{
perfc_incr(shadow_fault_emulate_failed);
#if SHADOW_OPTIMIZATIONS & SHOPT_FAST_EMULATION
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c
b/xen/arch/x86/x86_emulate/x86_emulate.c
index c1e2300..5be33d8 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -848,7 +848,8 @@ do{ asm volatile (
\
stub.func); \
generate_exception_if(res_.fields.trapnr == EXC_UD, EXC_UD); \
domain_crash(current->domain); \
- goto cannot_emulate; \
+ rc = X86EMUL_UNHANDLEABLE; \
+ goto done; \
} \
} while (0)
#else
@@ -2585,7 +2586,7 @@ x86_decode(
d = twobyte_table[0x3a].desc;
break;
default:
- rc = X86EMUL_UNHANDLEABLE;
+ rc = X86EMUL_UNRECOGNIZED;
goto done;
}
}
@@ -2599,7 +2600,7 @@ x86_decode(
}
else
{
- rc = X86EMUL_UNHANDLEABLE;
+ rc = X86EMUL_UNRECOGNIZED;
goto done;
}
@@ -2879,7 +2880,7 @@ x86_decode(
default:
ASSERT_UNREACHABLE();
- return X86EMUL_UNHANDLEABLE;
+ return X86EMUL_UNIMPLEMENTED;
}
if ( ea.type == OP_MEM )
@@ -4191,7 +4192,7 @@ x86_emulate(
break;
case 4: /* fldenv - TODO */
state->fpu_ctrl = true;
- goto cannot_emulate;
+ goto unimplemented_insn;
case 5: /* fldcw m2byte */
state->fpu_ctrl = true;
if ( (rc = ops->read(ea.mem.seg, ea.mem.off, &src.val,
@@ -4202,7 +4203,7 @@ x86_emulate(
break;
case 6: /* fnstenv - TODO */
state->fpu_ctrl = true;
- goto cannot_emulate;
+ goto unimplemented_insn;
case 7: /* fnstcw m2byte */
state->fpu_ctrl = true;
emulate_fpu_insn_memdst("fnstcw", dst.val);
@@ -4438,7 +4439,7 @@ x86_emulate(
case 4: /* frstor - TODO */
case 6: /* fnsave - TODO */
state->fpu_ctrl = true;
- goto cannot_emulate;
+ goto unimplemented_insn;
case 7: /* fnstsw m2byte */
state->fpu_ctrl = true;
emulate_fpu_insn_memdst("fnstsw", dst.val);
@@ -5197,7 +5198,7 @@ x86_emulate(
#undef _GRP7
default:
- goto cannot_emulate;
+ goto unimplemented_insn;
}
break;
}
@@ -6195,7 +6196,7 @@ x86_emulate(
/* vpsll{w,d} $imm8,{x,y}mm,{x,y}mm */
break;
default:
- goto cannot_emulate;
+ goto unrecognized_insn;
}
simd_0f_shift_imm:
generate_exception_if(ea.type != OP_REG, EXC_UD);
@@ -6243,7 +6244,7 @@ x86_emulate(
case 6: /* psllq $imm8,mm */
goto simd_0f_shift_imm;
}
- goto cannot_emulate;
+ goto unrecognized_insn;
case X86EMUL_OPC_66(0x0f, 0x73):
case X86EMUL_OPC_VEX_66(0x0f, 0x73):
@@ -6259,7 +6260,7 @@ x86_emulate(
/* vpslldq $imm8,{x,y}mm,{x,y}mm */
goto simd_0f_shift_imm;
}
- goto cannot_emulate;
+ goto unrecognized_insn;
case X86EMUL_OPC(0x0f, 0x77): /* emms */
case X86EMUL_OPC_VEX(0x0f, 0x77): /* vzero{all,upper} */
@@ -6323,7 +6324,7 @@ x86_emulate(
case 0: /* extrq $imm8,$imm8,xmm */
break;
default:
- goto cannot_emulate;
+ goto unrecognized_insn;
}
/* fall through */
case X86EMUL_OPC_F2(0x0f, 0x78): /* insertq $imm8,$imm8,xmm,xmm */
@@ -6518,7 +6519,7 @@ x86_emulate(
goto done;
break;
default:
- goto cannot_emulate;
+ goto unimplemented_insn;
}
break;
@@ -6534,7 +6535,7 @@ x86_emulate(
vcpu_must_have(avx);
goto stmxcsr;
}
- goto cannot_emulate;
+ goto unrecognized_insn;
case X86EMUL_OPC_F3(0x0f, 0xae): /* Grp15 */
fail_if(modrm_mod != 3);
@@ -6777,10 +6778,10 @@ x86_emulate(
switch ( modrm_reg & 7 )
{
default:
- goto cannot_emulate;
+ goto unrecognized_insn;
-#ifdef HAVE_GAS_RDRAND
case 6: /* rdrand */
+#ifdef HAVE_GAS_RDRAND
generate_exception_if(rep_prefix(), EXC_UD);
host_and_vcpu_must_have(rdrand);
dst = ea;
@@ -6805,6 +6806,8 @@ x86_emulate(
if ( carry )
_regs.eflags |= X86_EFLAGS_CF;
break;
+#else
+ goto unimplemented_insn;
#endif
case 7: /* rdseed / rdpid */
@@ -7359,7 +7362,7 @@ x86_emulate(
host_and_vcpu_must_have(bmi1);
break;
default:
- goto cannot_emulate;
+ goto unrecognized_insn;
}
generate_exception_if(vex.l, EXC_UD);
@@ -7670,7 +7673,7 @@ x86_emulate(
host_and_vcpu_must_have(tbm);
break;
default:
- goto cannot_emulate;
+ goto unrecognized_insn;
}
xop_09_rm_rv:
@@ -7704,7 +7707,7 @@ x86_emulate(
host_and_vcpu_must_have(tbm);
goto xop_09_rm_rv;
}
- goto cannot_emulate;
+ goto unrecognized_insn;
case X86EMUL_OPC_XOP(0a, 0x10): /* bextr imm,r/m,r */
{
@@ -7736,8 +7739,11 @@ x86_emulate(
}
default:
- cannot_emulate:
- rc = X86EMUL_UNHANDLEABLE;
+ unimplemented_insn:
+ rc = X86EMUL_UNIMPLEMENTED;
+ goto done;
+ unrecognized_insn:
+ rc = X86EMUL_UNRECOGNIZED;
goto done;
}
@@ -7789,7 +7795,8 @@ x86_emulate(
if ( (d & DstMask) != DstMem )
{
ASSERT_UNREACHABLE();
- goto cannot_emulate;
+ rc = X86EMUL_UNHANDLEABLE;
+ goto done;
}
break;
}
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.h
b/xen/arch/x86/x86_emulate/x86_emulate.h
index 4ddf111..0c8c80a 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -133,6 +133,23 @@ struct x86_emul_fpu_aux {
* Undefined behavior when used anywhere else.
*/
#define X86EMUL_DONE 4
+ /*
+ * Current instruction is not implemented by the emulator.
+ * This value should only be returned by the core emulator when a valid
+ * opcode is found but the execution logic for that instruction is missing.
+ * It should NOT be returned by any of the x86_emulate_ops callbacks.
+ */
+#define X86EMUL_UNIMPLEMENTED 5
+ /*
+ * The current instruction's opcode is not valid.
+ * If this error code is returned by a function, an #UD trap should be
+ * raised by the final consumer of it.
+ *
+ * TODO: For the moment X86EMUL_UNRECOGNIZED and X86EMUL_UNIMPLEMENTED
+ * can be used interchangeably therefore raising an #UD trap is not
+ * strictly expected for now.
+ */
+#define X86EMUL_UNRECOGNIZED X86EMUL_UNIMPLEMENTED
/* FPU sub-types which may be requested via ->get_fpu(). */
enum x86_emulate_fpu_type {
--
2.7.4
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