MOV immediate instruction (opcodes 0xB8-0xBF) may take 64-bit operand.
The previous emulation implementation assumes the operand is no longer than 32.
Signed-off-by: Nadav Amit <nadav.amit@xxxxxxxxx>
---
arch/x86/kvm/emulate.c | 6 +++++-
1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 05a562b..65d1d31 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3502,7 +3502,8 @@ static unsigned imm_size(struct x86_emulate_ctxt *ctxt)
unsigned size;
size = (ctxt->d & ByteOp) ? 1 : ctxt->op_bytes;
- if (size == 8)
+ /* Immediates are usually no longer than 4 bytes */
+ if (size == 8 && ((ctxt->b & 0xF8) != 0xB8 || ctxt->twobyte))
size = 4;
return size;
}
@@ -3526,6 +3527,9 @@ static int decode_imm(struct x86_emulate_ctxt *ctxt, struct operand *op,
case 4:
op->val = insn_fetch(s32, ctxt);
break;
+ case 8:
+ op->val = insn_fetch(s64, ctxt);
+ break;
}
if (!sign_extension) {
switch (op->bytes) {
--
1.7.4.1
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