[PATCH non-atomic-injection] x86 emulator: Add cwd/cdq/cqo instruction (opcode 0x99)

[Mohammed Gamal]

Signed-off-by: Mohammed Gamal <m.gamal...@gmail.com>
---
 arch/x86/kvm/emulate.c |   16 +++++++++++++++-
 1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index ee4bb69..fddf76d 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2421,7 +2421,7 @@ static struct opcode opcode_table[256] = {
        /* 0x90 - 0x97 */
        X8(D(SrcAcc | DstReg)),
        /* 0x98 - 0x9F */
-       D(DstAcc | SrcNone), N, D(SrcImmFAddr | No64), N,
+       D(DstAcc | SrcNone), D(ImplicitOps), D(SrcImmFAddr | No64), N,
        D(ImplicitOps | Stack), D(ImplicitOps | Stack), N, N,
        /* 0xA0 - 0xA7 */
        D(ByteOp | DstAcc | SrcMem | Mov | MemAbs), D(DstAcc | SrcMem | Mov | 
MemAbs),
@@ -3161,6 +3161,20 @@ special_insn:
                case 8: c->dst.val = (s32)c->dst.val; break;
                }
                break;
+       case 0x99: /* cwd/cdq/cqo */ {
+               unsigned long rax = c->regs[VCPU_REGS_RAX];
+               unsigned long sign_bit = 1 << ((c->op_bytes * 8) - 1);
+
+               if (rax & sign_bit) {
+                       switch (c->op_bytes) {
+                       case 2: c->regs[VCPU_REGS_RDX] = 0xffff; break;
+                       case 4: c->regs[VCPU_REGS_RDX] = 0xffffffff; break;
+                       case 8: c->regs[VCPU_REGS_RDX] = 0xffffffffffffffff; 
break;
+                       }
+               } else 
+                       c->regs[VCPU_REGS_RDX] = 0;
+               }
+               break;
        case 0x9c: /* pushf */
                c->src.val =  (unsigned long) ctxt->eflags;
                emulate_push(ctxt, ops);
-- 
1.7.0.4

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