[4/5,-v3.1] kvm, emulator: Add initial three-byte insns support

Commit Message

Borislav Petkov Oct. 29, 2013, 11:54 a.m. UTC

From: Borislav Petkov <[e-mail]>

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

Signed-off-by: Borislav Petkov <[e-mail]>
---
 arch/x86/kvm/emulate.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

Patch

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;