Re: [Xen-devel] [PATCH v2] x86/HVM: change the flags cpu context field to uint64_t

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.01.16 at 16:09, <roger.pau@xxxxxxxxxx> wrote:
> --- a/xen/include/public/arch-x86/hvm/save.h
> +++ b/xen/include/public/arch-x86/hvm/save.h
> @@ -161,8 +161,8 @@ struct hvm_hw_cpu {
>      uint32_t error_code;
>  
>  #define _XEN_X86_FPU_INITIALISED        0
> -#define XEN_X86_FPU_INITIALISED         (1U<<_XEN_X86_FPU_INITIALISED)
> -    uint32_t flags;
> +#define XEN_X86_FPU_INITIALISED         (1UL<<_XEN_X86_FPU_INITIALISED)
> +    uint64_t flags;
>  };

How is the UL going to make this safe for a 32-bit consumer?
Makes me think that, other than just said in reply to v1, it'll
indeed be better to have a separate field (with a separate
zero-check)... The (undesirable imo) alternative being to use
1L instead.

Jan


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