Re: [Xen-devel] [PATCH 09/10] tools/x86emul: Advertise more CPUID features for testing purposes

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 27/03/17 10:56, Andrew Cooper wrote:
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> CC: Jan Beulich <JBeulich@xxxxxxxx>
> CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
> CC: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
> CC: Wei Liu <wei.liu2@xxxxxxxxxx>
> ---
>  tools/tests/x86_emulator/x86_emulate.c | 41 
> ++++++++++++++++++++++++----------
>  1 file changed, 29 insertions(+), 12 deletions(-)
> 
> diff --git a/tools/tests/x86_emulator/x86_emulate.c 
> b/tools/tests/x86_emulator/x86_emulate.c
> index cea0595..2c49954 100644
> --- a/tools/tests/x86_emulator/x86_emulate.c
> +++ b/tools/tests/x86_emulator/x86_emulate.c
> @@ -73,20 +73,37 @@ int emul_test_cpuid(
>           : "a" (leaf), "c" (subleaf));
>  Oh, s
>      /*
> -     * The emulator doesn't itself use MOVBE, so we can always run the
> -     * respective tests.
> +     * Some instructions and features can be emulated without specific
> +     * hardware support.  These features are unconditionally reported here,
> +     * for testing and fuzzing-coverage purposes.

But similarly to my question in patch 10 -- is there any chance that the
emulator will ever be called with a cpuid callback that returns 'false"
for these?  If so, isn't there therefore a chance that there will be
some sort of bug which only triggers if these bits are set to 'false'?

 -George



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel