Re: [Xen-devel] [PATCH 08/18] xen/arm: Introduce a initcall to update cpu_hwcaps by serror_op

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 13 Mar 2017, Wei Chen wrote:
> In the later patches of this series, we want to use the alternative
> patching framework to avoid checking serror_op in every entries.
> So we define a new cpu feature "SKIP_CHECK_PENDING_VSERROR" for
> serror_op. When serror_op is not equal to SERROR_DIVERSE, this
> feature will be set to cpu_hwcaps.
> 
> But we could not update cpu_hwcaps directly in the serror parameter
> parsing function. Because if the serror parameter is not placed in
> the command line, the parsing function would not be invoked.

Wait, the only way to set serrors_op != SERRORS_DIVERSE is to pass the
"serror" command line parameter. The parsing function is always invoked
if serrors_op != SERRORS_DIVERSE.


> So, we introduce this initcall to guarantee the cpu_hwcaps can be
> updated no matter the serror parameter is placed in the command line
> or not.
> 
> Signed-off-by: Wei Chen <Wei.Chen@xxxxxxx>
> ---
>  xen/arch/arm/traps.c             | 9 +++++++++
>  xen/include/asm-arm/cpufeature.h | 3 ++-
>  2 files changed, 11 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index 5e31699..053b7fc 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -134,6 +134,15 @@ static void __init parse_serrors_behavior(const char 
> *str)
>  }
>  custom_param("serrors", parse_serrors_behavior);
>  
> +static __init int update_serrors_cpu_caps(void)

I think the coding style is "static int __init" ...


> +{
> +    if ( serrors_op != SERRORS_DIVERSE )
> +        cpus_set_cap(SKIP_CHECK_PENDING_VSERROR);
> +
> +    return 0;
> +}
> +__initcall(update_serrors_cpu_caps);
> +
>  register_t get_default_hcr_flags(void)
>  {
>      return  (HCR_PTW|HCR_BSU_INNER|HCR_AMO|HCR_IMO|HCR_FMO|HCR_VM|
> diff --git a/xen/include/asm-arm/cpufeature.h 
> b/xen/include/asm-arm/cpufeature.h
> index c0a25ae..ec3f9e5 100644
> --- a/xen/include/asm-arm/cpufeature.h
> +++ b/xen/include/asm-arm/cpufeature.h
> @@ -40,8 +40,9 @@
>  #define ARM32_WORKAROUND_766422 2
>  #define ARM64_WORKAROUND_834220 3
>  #define LIVEPATCH_FEATURE   4
> +#define SKIP_CHECK_PENDING_VSERROR 5
>  
> -#define ARM_NCAPS           5
> +#define ARM_NCAPS           6
>  
>  #ifndef __ASSEMBLY__
>  
> -- 
> 2.7.4
> 
> 
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> https://lists.xen.org/xen-devel
> 

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