SSE instruction emulation issues

[Andrew Cooper <andrew.cooper3@citrix.com>]

(breaking this thread away from the hijacked emulation cleanup and fixes
thread)

On 09/07/15 20:32, Zhi Wang wrote:
> Hi Gurus:
>     We found that MOVD instruction are used by some windows driver
> during developing XenGT, and also we found this one:
>
> (XEN) MMIO emulation failed: d7v1 64bit @ 0010:fffff8000294e273 -> 66
> 0f e7 00 48 83 c0 10 45 3
> b cb 73 f0 45 85 c9 

Disassembly:
   0:    66 0f e7 00              movntdq %xmm0,(%rax)
   4:    48 83 c0 10              add    $0x10,%rax
   8:    45 3b cb                 cmp    %r11d,%r9d
   b:    73 f0                    jae    0xfffffffffffffffd
   d:    45 85 c9                 test   %r9d,%r9d

The x86 instruction emulator does appear to have a decode for this
instruction.  This failure suggests that the implementation is buggy.

To start with diagnosing, add a test case to
tools/tests/x86_emulator/test_x86_emulator.c

Then, you will want to investigate the implementation in
xen/arch/x86/x86_emulate/x86_emulate.c around line 4245.

~Andrew