KVM: x86 emulator: allow storing emulator execution function in decode tables

Instead of looking up the opcode twice (once for decode flags, once for
the big execution switch) look up both flags and function in the decode tables.

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

2 files changed, 13 insertions, 0 deletions

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 9ddfa5ed2289..0f901c16cf1c 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -190,6 +190,7 @@ struct decode_cache {
         bool has_seg_override;
         u8 seg_override;
         unsigned int d;
+        int (*execute)(struct x86_emulate_ctxt *ctxt);
         unsigned long regs[NR_VCPU_REGS];
         unsigned long eip;
         /* modrm */
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 3689f34a303a..799e895fb08e 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -106,6 +106,7 @@
 struct opcode {
         u32 flags;
         union {
+                int (*execute)(struct x86_emulate_ctxt *ctxt);
                 struct opcode *group;
                 struct group_dual *gdual;
         } u;
@@ -120,6 +121,7 @@ struct group_dual {
 #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) }
+#define I(_f, _e) { .flags = (_f), .u.execute = (_e) }
 
 static struct opcode group1[] = {
         X7(D(Lock)), N
@@ -349,6 +351,7 @@ static struct opcode twobyte_table[256] = {
 #undef N
 #undef G
 #undef GD
+#undef I
 
 /* EFLAGS bit definitions. */
 #define EFLG_ID (1<<21)
@@ -1070,6 +1073,8 @@ done_prefixes:
                 c->d |= opcode.flags;
         }
 
+        c->execute = opcode.u.execute;
+
         /* Unrecognised? */
         if (c->d == 0 || (c->d & Undefined)) {
                 DPRINTF("Cannot emulate %02x\n", c->b);
@@ -2705,6 +2710,13 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
 
 special_insn:
 
+        if (c->execute) {
+                rc = c->execute(ctxt);
+                if (rc != X86EMUL_CONTINUE)
+                        goto done;
+                goto writeback;
+        }
+
         if (c->twobyte)
                 goto twobyte_insn;