[ 004/102] KVM: emulator: emulate SALC

[Greg Kroah-Hartman]

3.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Paolo Bonzini <pbonzini@xxxxxxxxxx>

commit 326f578f7e1443bac2333712dd130a261ec15288 upstream.

This is an almost-undocumented instruction available in 32-bit mode.
I say "almost" undocumented because AMD documents it in their opcode
maps just to say that it is unavailable in 64-bit mode (sections
"A.2.1 One-Byte Opcodes" and "B.3 Invalid and Reassigned Instructions
in 64-Bit Mode").

It is roughly equivalent to "sbb %al, %al" except it does not
set the flags.  Use fastop to emulate it, but do not use the opcode
directly because it would fail if the host is 64-bit!

Reported-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/x86/kvm/emulate.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -534,6 +534,9 @@ FOP_SETCC(setle)
 FOP_SETCC(setnle)
 FOP_END;
 
+FOP_START(salc) "pushf; sbb %al, %al; popf \n\t" FOP_RET
+FOP_END;
+
 #define __emulate_1op_rax_rdx(ctxt, _op, _suffix, _ex)			\
 	do {								\
 		unsigned long _tmp;					\
@@ -3951,7 +3954,8 @@ static const struct opcode opcode_table[
 	G(Src2One | ByteOp, group2), G(Src2One, group2),
 	G(Src2CL | ByteOp, group2), G(Src2CL, group2),
 	I(DstAcc | SrcImmUByte | No64, em_aam),
-	I(DstAcc | SrcImmUByte | No64, em_aad), N,
+	I(DstAcc | SrcImmUByte | No64, em_aad),
+	F(DstAcc | ByteOp | No64, em_salc),
 	I(DstAcc | SrcXLat | ByteOp, em_mov),
 	/* 0xD8 - 0xDF */
 	N, E(0, &escape_d9), N, E(0, &escape_db), N, E(0, &escape_dd), N, N,


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/