KVM: x86 emulator: allow specifying group directly in opcode

Instead of having a group number, store the group table pointer directly in
the opcode.

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

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 5e496127a01c4c92525301d93c176c51f965049d..f3b984427d10ed6bf6d3fc67f0dc37865d762275 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -110,10 +110,21 @@ enum {
 
 struct opcode {
        u32 flags;
+       union {
+               struct opcode *group;
+               struct group_dual *gdual;
+       } u;
+};
+
+struct group_dual {
+       struct opcode mod012[8];
+       struct opcode mod3[8];
 };
 
 #define D(_y) { .flags = (_y) }
 #define N    D(0)
+#define G(_f, _g) { .flags = ((_f) | Group), .u.group = (_g) }
+#define GD(_f, _g) { .flags = ((_f) | Group | GroupDual), .u.gdual = (_g) }
 
 static struct opcode group_table[] = {
        [Group1*8] =
@@ -331,6 +342,8 @@ static struct opcode twobyte_table[256] = {
 
 #undef D
 #undef N
+#undef G
+#undef GD
 
 /* EFLAGS bit definitions. */
 #define EFLG_ID (1<<21)
@@ -930,8 +943,8 @@ x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
        struct decode_cache *c = &ctxt->decode;
        int rc = X86EMUL_CONTINUE;
        int mode = ctxt->mode;
-       int def_op_bytes, def_ad_bytes, group, dual;
-
+       int def_op_bytes, def_ad_bytes, group, dual, goffset;
+       struct opcode opcode, *g_mod012, *g_mod3;
 
        /* we cannot decode insn before we complete previous rep insn */
        WARN_ON(ctxt->restart);
@@ -1018,15 +1031,16 @@ done_prefixes:
                        c->op_bytes = 8;        /* REX.W */
 
        /* Opcode byte(s). */
-       c->d = opcode_table[c->b].flags;
-       if (c->d == 0) {
+       opcode = opcode_table[c->b];
+       if (opcode.flags == 0) {
                /* Two-byte opcode? */
                if (c->b == 0x0f) {
                        c->twobyte = 1;
                        c->b = insn_fetch(u8, 1, c->eip);
-                       c->d = twobyte_table[c->b].flags;
+                       opcode = twobyte_table[c->b];
                }
        }
+       c->d = opcode.flags;
 
        if (c->d & Group) {
                group = c->d & GroupMask;
@@ -1034,12 +1048,27 @@ done_prefixes:
                c->modrm = insn_fetch(u8, 1, c->eip);
                --c->eip;
 
-               group = (group << 3) + ((c->modrm >> 3) & 7);
+               if (group) {
+                       g_mod012 = g_mod3 = &group_table[group * 8];
+                       if (c->d & GroupDual)
+                               g_mod3 = &group2_table[group * 8];
+               } else {
+                       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 | GroupMask);
-               if (dual && (c->modrm >> 6) == 3)
-                       c->d |= group2_table[group].flags;
+
+               goffset = (c->modrm >> 3) & 7;
+
+               if ((c->modrm >> 6) == 3)
+                       opcode = g_mod3[goffset];
                else
-                       c->d |= group_table[group].flags;
+                       opcode = g_mod012[goffset];
+               c->d |= opcode.flags;
        }
 
        /* Unrecognised? */