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

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.07.16 at 14:47, <czuzu@xxxxxxxxxxxxxxx> wrote:
> On 7/4/2016 3:37 PM, Jan Beulich wrote:
>>>>> 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?
> 
> AFAIK, the full register state cannot be updated _at once_, that is: 
> after each trapped register update monitor_write_data must _always_ be 
> handled _before reentering the vCPU_.

I'm thinking about operations like VCPUOP_initialise here. Of course
operations on current can't possibly update more than one register
at a time.

Jan


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