[patch 38/45] KVM: x86 emulator: Implement zero-extended immediate decoding

[Greg KH]

2.6.31-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Avi Kivity <avi@xxxxxxxxxx>

commit c9eaf20f268c7051bfde2ba212c5ea76a6cbc7a1 upstream.

Absolute jumps use zero extended immediate operands.

Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 arch/x86/kvm/x86_emulate.c |   15 +++++++++++++++
 1 file changed, 15 insertions(+)

--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -60,6 +60,7 @@
 #define SrcImmByte  (6<<4)	/* 8-bit sign-extended immediate operand. */
 #define SrcOne      (7<<4)	/* Implied '1' */
 #define SrcImmUByte (8<<4)      /* 8-bit unsigned immediate operand. */
+#define SrcImmU     (9<<4)      /* Immediate operand, unsigned */
 #define SrcMask     (0xf<<4)
 /* Generic ModRM decode. */
 #define ModRM       (1<<8)
@@ -1027,6 +1028,7 @@ done_prefixes:
 		c->src.type = OP_MEM;
 		break;
 	case SrcImm:
+	case SrcImmU:
 		c->src.type = OP_IMM;
 		c->src.ptr = (unsigned long *)c->eip;
 		c->src.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
@@ -1044,6 +1046,19 @@ done_prefixes:
 			c->src.val = insn_fetch(s32, 4, c->eip);
 			break;
 		}
+		if ((c->d & SrcMask) == SrcImmU) {
+			switch (c->src.bytes) {
+			case 1:
+				c->src.val &= 0xff;
+				break;
+			case 2:
+				c->src.val &= 0xffff;
+				break;
+			case 4:
+				c->src.val &= 0xffffffff;
+				break;
+			}
+		}
 		break;
 	case SrcImmByte:
 	case SrcImmUByte:


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