KVM: x86 emulator: put register operand write back to a function

Introduce function write_register_operand() to write back the
register operand.

Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index f6b124f..0037130 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1020,6 +1020,25 @@ exception:
        return X86EMUL_PROPAGATE_FAULT;
 }
 
+static void write_register_operand(struct operand *op)
+{
+       /* The 4-byte case *is* correct: in 64-bit mode we zero-extend. */
+       switch (op->bytes) {
+       case 1:
+               *(u8 *)op->addr.reg = (u8)op->val;
+               break;
+       case 2:
+               *(u16 *)op->addr.reg = (u16)op->val;
+               break;
+       case 4:
+               *op->addr.reg = (u32)op->val;
+               break;  /* 64b: zero-extend */
+       case 8:
+               *op->addr.reg = op->val;
+               break;
+       }
+}
+
 static inline int writeback(struct x86_emulate_ctxt *ctxt,
                            struct x86_emulate_ops *ops)
 {
@@ -1029,23 +1048,7 @@ static inline int writeback(struct x86_emulate_ctxt *ctxt,
 
        switch (c->dst.type) {
        case OP_REG:
-               /* The 4-byte case *is* correct:
-                * in 64-bit mode we zero-extend.
-                */
-               switch (c->dst.bytes) {
-               case 1:
-                       *(u8 *)c->dst.addr.reg = (u8)c->dst.val;
-                       break;
-               case 2:
-                       *(u16 *)c->dst.addr.reg = (u16)c->dst.val;
-                       break;
-               case 4:
-                       *c->dst.addr.reg = (u32)c->dst.val;
-                       break;  /* 64b: zero-ext */
-               case 8:
-                       *c->dst.addr.reg = c->dst.val;
-                       break;
-               }
+               write_register_operand(&c->dst);
                break;
        case OP_MEM:
                if (c->lock_prefix)
@@ -2970,25 +2973,13 @@ special_insn:
        case 0x86 ... 0x87:     /* xchg */
        xchg:
                /* Write back the register source. */
-               switch (c->dst.bytes) {
-               case 1:
-                       *(u8 *) c->src.addr.reg = (u8) c->dst.val;
-                       break;
-               case 2:
-                       *(u16 *) c->src.addr.reg = (u16) c->dst.val;
-                       break;
-               case 4:
-                       *c->src.addr.reg = (u32) c->dst.val;
-                       break;  /* 64b reg: zero-extend */
-               case 8:
-                       *c->src.addr.reg = c->dst.val;
-                       break;
-               }
+               c->src.val = c->dst.val;
+               write_register_operand(&c->src);
                /*
                 * Write back the memory destination with implicit LOCK
                 * prefix.
                 */
-               c->dst.val = c->src.val;
+               c->dst.val = c->src.orig_val;
                c->lock_prefix = 1;
                break;
        case 0x88 ... 0x8b:     /* mov */