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>

1 files changed, 31 insertions, 49 deletions

diff --git a/drivers/kvm/x86_emulate.c b/drivers/kvm/x86_emulate.c
index 087a8208f873..58ceb6616364 100644
--- 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) {