[PATCH] KVM: x86 emulator: emulate MOVNTDQ

[Alex Williamson <alex.williamson@redhat.com>]

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: Alex Williamson <alex.williamson@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
---

Hope I got all the flags correct from copying similar MOV ops, but it
allows the guest to boot, so I suspect it's ok.

 arch/x86/kvm/emulate.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index e4e833d..ae39f08 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -3681,6 +3681,10 @@ 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),
 }, {
@@ -3951,7 +3955,8 @@ 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
 };