KVM: x86 emulator: Extract the common code of SrcReg and DstReg

Share the common parts of SrcReg and DstReg decoding.

Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 087a820..58ceb66 100644 (file)
--- a/drivers/kvm/x86_emulate.c
+++ b/drivers/kvm/x86_emulate.c
@@ -520,6 +520,34 @@ static int test_cc(unsigned int condition, unsigned int flags)
        return (!!rc ^ (condition & 1));
 }
 
+static void decode_register_operand(struct operand *op,
+                                   struct decode_cache *c,
+                                   int highbyte_regs,
+                                   int inhibit_bytereg)
+{
+       op->type = OP_REG;
+       if ((c->d & ByteOp) && !inhibit_bytereg) {
+               op->ptr = decode_register(c->modrm_reg, c->regs, highbyte_regs);
+               op->val = *(u8 *)op->ptr;
+               op->bytes = 1;
+       } else {
+               op->ptr = decode_register(c->modrm_reg, c->regs, 0);
+               op->bytes = c->op_bytes;
+               switch (op->bytes) {
+               case 2:
+                       op->val = *(u16 *)op->ptr;
+                       break;
+               case 4:
+                       op->val = *(u32 *)op->ptr;
+                       break;
+               case 8:
+                       op->val = *(u64 *) op->ptr;
+                       break;
+               }
+       }
+       op->orig_val = op->val;
+}
+
 int
 x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 {
@@ -809,31 +837,7 @@ modrm_done:
        case SrcNone:
                break;
        case SrcReg:
-               c->src.type = OP_REG;
-               if (c->d & ByteOp) {
-                       c->src.ptr =
-                               decode_register(c->modrm_reg, c->regs,
-                                                 (rex_prefix == 0));
-                       c->src.val = c->src.orig_val = *(u8 *)c->src.ptr;
-                       c->src.bytes = 1;
-               } else {
-                       c->src.ptr =
-                           decode_register(c->modrm_reg, c->regs, 0);
-                       switch ((c->src.bytes = c->op_bytes)) {
-                       case 2:
-                               c->src.val = c->src.orig_val =
-                                                      *(u16 *) c->src.ptr;
-                               break;
-                       case 4:
-                               c->src.val = c->src.orig_val =
-                                                      *(u32 *) c->src.ptr;
-                               break;
-                       case 8:
-                               c->src.val = c->src.orig_val =
-                                                      *(u64 *) c->src.ptr;
-                               break;
-                       }
-               }
+               decode_register_operand(&c->src, c, rex_prefix == 0, 0);
                break;
        case SrcMem16:
                c->src.bytes = 2;
@@ -891,30 +895,8 @@ modrm_done:
                /* Special instructions do their own operand decoding. */
                return 0;
        case DstReg:
-               c->dst.type = OP_REG;
-               if ((c->d & ByteOp)
-                   && !(c->twobyte &&
-                       (c->b == 0xb6 || c->b == 0xb7))) {
-                       c->dst.ptr =
-                               decode_register(c->modrm_reg, c->regs,
-                                                 (rex_prefix == 0));
-                       c->dst.val = *(u8 *) c->dst.ptr;
-                       c->dst.bytes = 1;
-               } else {
-                       c->dst.ptr =
-                           decode_register(c->modrm_reg, c->regs, 0);
-                       switch ((c->dst.bytes = c->op_bytes)) {
-                       case 2:
-                               c->dst.val = *(u16 *)c->dst.ptr;
-                               break;
-                       case 4:
-                               c->dst.val = *(u32 *)c->dst.ptr;
-                               break;
-                       case 8:
-                               c->dst.val = *(u64 *)c->dst.ptr;
-                               break;
-                       }
-               }
+               decode_register_operand(&c->dst, c, rex_prefix == 0,
+                        c->twobyte && (c->b == 0xb6 || c->b == 0xb7));
                break;
        case DstMem:
                if ((c->d & ModRM) && c->modrm_mod == 3) {