Re: [Xen-devel] [PATCH v7] xen/sm{e, a}p: allow disabling sm{e, a}p for Xen itself

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.10.16 at 10:20, <he.chen@xxxxxxxxxxxxxxx> wrote:
> Changes in v7:
> * bugfix: fix the bug that this patch doesn't work on machine without SMAP.
> * test: This patch has not been tested (on 32-bit PV environment).
>         Really sorry for that since I have took several days trying to
>         setup a 32-bit PV guest but finally failed.

Well, I don't know what to say. And since you don't say what your
problem is/was, I also don't see how anyone could help.

> @@ -1404,12 +1448,16 @@ void __init noreturn __start_xen(unsigned long mbi_p)
>  
>      if ( !opt_smep )
>          setup_clear_cpu_cap(X86_FEATURE_SMEP);
> -    if ( cpu_has_smep )
> +    else if ( cpu_has_smep && opt_smep == 1 )

How about

    if ( cpu_has_smep && opt_smep != SMEP_HVM_ONLY )

(i.e. I dislike both the "else" and the hard-coded 1)? Or if you dislike
this, then at least > 0 instead of == 1 please, or provide a #define
just like you do for -1.

Jan


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