KVM: x86 emulator: emulate MOVNTDQ

Windows 8.1 guest with NVIDIA driver and GPU fails to boot with an
emulation failure.  The KVM spew suggests the fault is with lack of
movntdq emulation (courtesy of Paolo):

Code=02 00 00 b8 08 00 00 00 f3 0f 6f 44 0a f0 f3 0f 6f 4c 0a e0 <66> 0f e7 41 f0 66 0f e7 49 e0 48 83 e9 40 f3 0f 6f 44 0a 10 f3 0f 6f 0c 0a 66 0f e7 41 10

$ as -o a.out
        .section .text
        .byte 0x66, 0x0f, 0xe7, 0x41, 0xf0
        .byte 0x66, 0x0f, 0xe7, 0x49, 0xe0
$ objdump -d a.out
    0:  66 0f e7 41 f0          movntdq %xmm0,-0x10(%rcx)
    5:  66 0f e7 49 e0          movntdq %xmm1,-0x20(%rcx)

Add the necessary emulation.
Signed-off-by: NAlex Williamson <alex.williamson@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/emulate.c

@@ -3696,6 +3696,10 @@ static const struct gprefix pfx_0f_28_0f_29 = {
 	I(Aligned, em_mov), I(Aligned, em_mov), N, N,
 };
 
+static const struct gprefix pfx_0f_e7 = {
+	N, I(Sse, em_mov), N, N,
+};
+
 static const struct escape escape_d9 = { {
 	N, N, N, N, N, N, N, I(DstMem, em_fnstcw),
 }, {
@@ -3966,7 +3970,8 @@ static const struct opcode twobyte_table[256] = {
 	/* 0xD0 - 0xDF */
 	N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N,
 	/* 0xE0 - 0xEF */
-	N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N,
+	N, N, N, N, N, N, N, GP(SrcReg | DstMem | ModRM | Mov, &pfx_0f_e7),
+	N, N, N, N, N, N, N, N,
 	/* 0xF0 - 0xFF */
 	N, N, N, N, N, N, N, N, N, N, N, N, N, N, N, N
 };