Re: [PATCH] x86 emulator: Add call near absolute instruction (group5: opcode 0xff mod r/m 2)

[Guillaume Thouvenin <guillaume.thouvenin@ext.bull.net>]

On Mon, 8 Sep 2008 21:47:19 +0300
Mohammed Gamal <m.gamal005@gmail.com> wrote:


> +	SrcMem | ModRM | Stack, 0,

Are you sure about this? In Xen they use "DstMem | SrcNone | ModRM"
Anyway I tested the patch and the next problem is with the following
instruction:

emulation failed (emulation failure) rip 4423e 3c 25 0f 84

Thus I added the following patch (see the end of this email) and now
another problem:

emulation failed (mmio) rip 44b5b 03 84 c0 75

So it's not the same problem. I'm trying to fix that. It would be cool
to be able to boot a distribution with emulate_invalid_guest_state enabled ;)

Signed-off-by: Guillaume Thouvenin <guillaume.thouvenin@ext.bull.net>

---
diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index 30b93ee..b65bc94 100644
--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -107,7 +107,7 @@ static u16 opcode_table[256] = {
 	/* 0x38 - 0x3F */
 	ByteOp | DstMem | SrcReg | ModRM, DstMem | SrcReg | ModRM,
 	ByteOp | DstReg | SrcMem | ModRM, DstReg | SrcMem | ModRM,
-	0, 0, 0, 0,
+	ByteOp | DstReg |SrcImm, DstReg|SrcImm, 0, 0,
 	/* 0x40 - 0x47 */
 	DstReg, DstReg, DstReg, DstReg, DstReg, DstReg, DstReg, DstReg,
 	/* 0x48 - 0x4F */
@@ -1405,10 +1405,22 @@ special_insn:
 	      xor:		/* xor */
 		emulate_2op_SrcV("xor", c->src, c->dst, ctxt->eflags);
 		break;
-	case 0x38 ... 0x3d:
+	case 0x38 ... 0x3b:
 	      cmp:		/* cmp */
 		emulate_2op_SrcV("cmp", c->src, c->dst, ctxt->eflags);
 		break;
+	case 0x3c ... 0x3d:     /* cmp al imm8 or ax imm16 or eax imm32 */
+		c->dst.type = OP_REG;
+		c->dst.bytes = c->op_bytes;
+		c->dst.ptr = &c->regs[VCPU_REGS_RAX];
+		if (c->op_bytes == 1)
+			c->dst.val = *(u8 *)c->dst.ptr;
+		else if (c->op_bytes == 2)
+			c->dst.val = *(u16 *)c->dst.ptr;
+		else
+			c->dst.val = *(u32 *)c->dst.ptr;
+		c->dst.orig_val = c->dst.val;
+		goto cmp;
 	case 0x40 ... 0x47: /* inc r16/r32 */
 		emulate_1op("inc", c->dst, ctxt->eflags);
 		break;