Re: [Xen-devel] [PATCH 2/2] x86/hvm: honor guest's option when updating secondary system time for guest

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 08.07.14 at 01:18, <feng.wu@xxxxxxxxx> wrote:
> --- a/xen/include/public/vcpu.h
> +++ b/xen/include/public/vcpu.h
> @@ -227,6 +227,16 @@ struct vcpu_register_time_memory_area {
>  typedef struct vcpu_register_time_memory_area 
> vcpu_register_time_memory_area_t;
>  DEFINE_XEN_GUEST_HANDLE(vcpu_register_time_memory_area_t);
>  
> +/*
> + * Flags to tell Xen whether we need to do the SMAP check when updating
> + * the secondary copy of the vcpu time when SMAP is enabled. Since the
> + * memory location for the secondary copy of the vcpu time may be mapped
> + * into userspace by guests intendedly, we let the guest to determine
> + * whether the check is needed. The default behavior of hypevisor is
> + * not doing the check.
> + */
> +#define VCPUOP_enable_smap_check_vcpu_time_memory_area   14

I think the new op to be VCPUOP_register_vcpu_time_memory_area_smap,
identical to VCPUOP_register_vcpu_time_memory_area apart from also
setting the flag, would be more natural. But considering what I just wrote
in the reply to Tim I guess we can expect a nun-user mapping to be
presented here anyway, i.e. we wouldn't need to new operation at all.

Jan


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