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>

1 files changed, 23 insertions, 32 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index f6b124fcc3fd..003713041ce6 100644
--- 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 */