Re: [Xen-devel] update_runstate_area and Linux KPTI

[Julien Grall <julien.grall@xxxxxxx>]

On 02/03/18 16:18, Jan Beulich wrote:
> > > > On 02.03.18 at 17:04, <andrew.cooper3@xxxxxxxxxx> wrote:
> > The proper way to do this is indeed by a nominated (guest) physical
> > address, at which point Xen can make all/any updates at times of its
> > choosing, and the guests pagetable/permissions state at an instantaneous
> > moment don't matter.
> >
> > If you've got time to do this, then please do.  It will be a definite
> > improvement.
> Just to be avoid unnecessary effort in the wrong direction: I don't
> think you can alter the current interface. You'd have to add a new
> one, and we could then deprecate (but never abandon) the current
> one.
I was only planning to store the guest physical address rather than the 
virtual address as we do today. Is that considered as an alteration of 
the current interface?
In other words, the current version (e.g store virtual address) is just 
broken and going to be worst with KPTI kernel. I can't see how this 
could ever work properly on OS with different set of page-tables.
Cheers,

--
Julien Grall

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