Re: [Xen-devel] [PATCH 4/8] x86/vm-event/monitor: turn monitor_write_data.do_write into enum

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 30.06.16 at 20:44, <czuzu@xxxxxxxxxxxxxxx> wrote:
> After trapping a control-register write vm-event and -until- deciding if that
> write is to be permitted or not (VM_EVENT_FLAG_DENY) and doing the actual 
> write,
> there cannot and should not be another trapped control-register write event.

Is that true even for the case where full register state gets updated
for a vCPU? Is that updating-all-context case of no interest to a
monitoring application, now and forever?

> --- a/xen/include/asm-x86/domain.h
> +++ b/xen/include/asm-x86/domain.h
> @@ -259,19 +259,19 @@ struct pv_domain
>      struct cpuidmasks *cpuidmasks;
>  };
>  
> -struct monitor_write_data {
> -    struct {
> -        unsigned int msr : 1;
> -        unsigned int cr0 : 1;
> -        unsigned int cr3 : 1;
> -        unsigned int cr4 : 1;
> -    } do_write;
> +enum monitor_write_status
> +{
> +    MWS_NOWRITE = 0,

Please omit the "= 0" here - MWS_NOWRITE will be zero even
without that.

Jan


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