Re: [Xen-devel] [PATCH v3 2/2] xen: add update indicator to vcpu_runstate_info

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.06.16 at 07:26, <JGross@xxxxxxxx> wrote:
> In order to support reading another vcpu's mapped vcpu_runstate_info
> an indicator for an occurring update of the runstate information is
> needed.
> 
> Add the possibility to activate setting this indicator in the highest
> bit of state_entry_time via a vm_assist hypercall. When activated the
> update indicator will be set before the runstate information is
> modified in guest memory and it will be reset after modification is
> done. As state_entry_time is guaranteed to be different after each
> update the guest can detect any update (either in progress or while
> reading the runstate data) by comparing state_entry_time before and
> after reading runstate data: in case the values differ or the update
> indicator was set the data might be inconsistent and should be reread.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

But I'd really like to see some of the explanation why we want this
moved here from the cover letter. This of course can be done while
committing, if no other need for a v4 arises.

Jan


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