Re: [Xen-devel] [PATCH] schedule: mask out XEN_RUNSTATE_UPDATE from state entry time

[Andrii Anisov <andrii.anisov@xxxxxxxxx>]

Hello Jan,

On 18.07.19 14:10, Jan Beulich wrote:
> A concrete scenario where update_runstate_area() and vcpu_runstate_change()
> can actually race would be very worthwhile to point out here. In particular
> on Arm I'm not (yet?) seeing how this could happen.
The scenario is quite trivial: some vcpu uptdating its runstate values (e.g. 
context switching) while those values are being read by a guest using other 
vcpu.

> Considering the value of XEN_RUNSTATE_UPDATE it must be a rather rare race
> anyway, I would guess.
I'm not sure how do you link the value of XEN_RUNSTATE_UPDATE and the issue 
occurrence rate. Could you please provide more details about the idea?

--
Sincerely,
Andrii Anisov.

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