kvm, emulator: Add initial three-byte insns support

Add initial support for handling three-byte instructions in the
emulator.

Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 541801527225..6c5cfe962b28 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3892,6 +3892,25 @@ static const struct opcode twobyte_table[256] = {
         N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N
 };
 
+static const struct gprefix three_byte_0f_38_f0 = {
+        N, N, N, N
+};
+
+static const struct gprefix three_byte_0f_38_f1 = {
+        N, N, N, N
+};
+
+/*
+ * Insns below are selected by the prefix which indexed by the third opcode
+ * byte.
+ */
+static const struct opcode opcode_map_0f_38[256] = {
+        /* 0x00 - 0x7f */
+        X16(N), X16(N), X16(N), X16(N), X16(N), X16(N), X16(N), X16(N),
+        /* 0x80 - 0xff */
+        X16(N), X16(N), X16(N), X16(N), X16(N), X16(N), X16(N), X16(N)
+};
+
 #undef D
 #undef N
 #undef G
@@ -4212,6 +4231,13 @@ done_prefixes:
                 ctxt->opcode_len = 2;
                 ctxt->b = insn_fetch(u8, ctxt);
                 opcode = twobyte_table[ctxt->b];
+
+                /* 0F_38 opcode map */
+                if (ctxt->b == 0x38) {
+                        ctxt->opcode_len = 3;
+                        ctxt->b = insn_fetch(u8, ctxt);
+                        opcode = opcode_map_0f_38[ctxt->b];
+                }
         }
         ctxt->d = opcode.flags;
 
@@ -4543,6 +4569,8 @@ special_insn:
 
         if (ctxt->opcode_len == 2)
                 goto twobyte_insn;
+        else if (ctxt->opcode_len == 3)
+                goto threebyte_insn;
 
         switch (ctxt->b) {
         case 0x63:              /* movsxd */
@@ -4727,6 +4755,8 @@ twobyte_insn:
                 goto cannot_emulate;
         }
 
+threebyte_insn:
+
         if (rc != X86EMUL_CONTINUE)
                 goto done;