KVM: x86 emulator: consolidate group handling

Move all groups into a single field and handle them in a single place.  This
saves bits when we add more group types (3 bits -> 7 groups types).

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

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index c1d9116cf3ac57a8b19106935785e7f5dd75bf27..7466abae84bf513d2879aa9c5a74f0e128141a83 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -73,11 +73,12 @@
 #define MemAbs      (1<<11)      /* Memory operand is absolute displacement */
 #define String      (1<<12)     /* String instruction (rep capable) */
 #define Stack       (1<<13)     /* Stack instruction (push/pop) */
+#define GroupMask   (7<<14)     /* Opcode uses one of the group mechanisms */
 #define Group       (1<<14)     /* Bits 3:5 of modrm byte extend opcode */
-#define GroupDual   (1<<15)     /* Alternate decoding of mod == 3 */
-#define Prefix      (1<<16)     /* Instruction varies with 66/f2/f3 prefix */
+#define GroupDual   (2<<14)     /* Alternate decoding of mod == 3 */
+#define Prefix      (3<<14)     /* Instruction varies with 66/f2/f3 prefix */
+#define RMExt       (4<<14)     /* Opcode extension in ModRM r/m if mod == 3 */
 #define Sse         (1<<17)     /* SSE Vector instruction */
-#define RMExt       (1<<18)     /* Opcode extension in ModRM r/m if mod == 3 */
 /* Misc flags */
 #define Prot        (1<<21) /* instruction generates #UD if not in prot-mode */
 #define VendorSpecific (1<<22) /* Vendor specific instruction */
@@ -2969,7 +2970,7 @@ static int check_perm_out(struct x86_emulate_ctxt *ctxt)
 #define N    D(0)
 #define EXT(_f, _e) { .flags = ((_f) | RMExt), .u.group = (_e) }
 #define G(_f, _g) { .flags = ((_f) | Group), .u.group = (_g) }
-#define GD(_f, _g) { .flags = ((_f) | Group | GroupDual), .u.gdual = (_g) }
+#define GD(_f, _g) { .flags = ((_f) | GroupDual), .u.gdual = (_g) }
 #define I(_f, _e) { .flags = (_f), .u.execute = (_e) }
 #define II(_f, _e, _i) \
        { .flags = (_f), .u.execute = (_e), .intercept = x86_intercept_##_i }
@@ -3337,9 +3338,9 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
        struct decode_cache *c = &ctxt->decode;
        int rc = X86EMUL_CONTINUE;
        int mode = ctxt->mode;
-       int def_op_bytes, def_ad_bytes, dual, goffset, simd_prefix;
+       int def_op_bytes, def_ad_bytes, goffset, simd_prefix;
        bool op_prefix = false;
-       struct opcode opcode, *g_mod012, *g_mod3;
+       struct opcode opcode;
        struct operand memop = { .type = OP_NONE };
 
        c->eip = ctxt->eip;
@@ -3433,44 +3434,43 @@ done_prefixes:
        }
        c->d = opcode.flags;
 
-       if (c->d & Group) {
-               dual = c->d & GroupDual;
-               c->modrm = insn_fetch(u8, 1, c->eip);
-               --c->eip;
-
-               if (c->d & GroupDual) {
-                       g_mod012 = opcode.u.gdual->mod012;
-                       g_mod3 = opcode.u.gdual->mod3;
-               } else
-                       g_mod012 = g_mod3 = opcode.u.group;
-
-               c->d &= ~(Group | GroupDual);
-
-               goffset = (c->modrm >> 3) & 7;
-
-               if ((c->modrm >> 6) == 3)
-                       opcode = g_mod3[goffset];
-               else
-                       opcode = g_mod012[goffset];
-
-               if (opcode.flags & RMExt) {
+       while (c->d & GroupMask) {
+               switch (c->d & GroupMask) {
+               case Group:
+                       c->modrm = insn_fetch(u8, 1, c->eip);
+                       --c->eip;
+                       goffset = (c->modrm >> 3) & 7;
+                       opcode = opcode.u.group[goffset];
+                       break;
+               case GroupDual:
+                       c->modrm = insn_fetch(u8, 1, c->eip);
+                       --c->eip;
+                       goffset = (c->modrm >> 3) & 7;
+                       if ((c->modrm >> 6) == 3)
+                               opcode = opcode.u.gdual->mod3[goffset];
+                       else
+                               opcode = opcode.u.gdual->mod012[goffset];
+                       break;
+               case RMExt:
                        goffset = c->modrm & 7;
                        opcode = opcode.u.group[goffset];
-               }
-
-               c->d |= opcode.flags;
-       }
-
-       if (c->d & Prefix) {
-               if (c->rep_prefix && op_prefix)
+                       break;
+               case Prefix:
+                       if (c->rep_prefix && op_prefix)
+                               return X86EMUL_UNHANDLEABLE;
+                       simd_prefix = op_prefix ? 0x66 : c->rep_prefix;
+                       switch (simd_prefix) {
+                       case 0x00: opcode = opcode.u.gprefix->pfx_no; break;
+                       case 0x66: opcode = opcode.u.gprefix->pfx_66; break;
+                       case 0xf2: opcode = opcode.u.gprefix->pfx_f2; break;
+                       case 0xf3: opcode = opcode.u.gprefix->pfx_f3; break;
+                       }
+                       break;
+               default:
                        return X86EMUL_UNHANDLEABLE;
-               simd_prefix = op_prefix ? 0x66 : c->rep_prefix;
-               switch (simd_prefix) {
-               case 0x00: opcode = opcode.u.gprefix->pfx_no; break;
-               case 0x66: opcode = opcode.u.gprefix->pfx_66; break;
-               case 0xf2: opcode = opcode.u.gprefix->pfx_f2; break;
-               case 0xf3: opcode = opcode.u.gprefix->pfx_f3; break;
                }
+
+               c->d &= ~GroupMask;
                c->d |= opcode.flags;
        }