Re: [Xen-devel] [PATCH v4 3/3] x86/ioreq server: Add HVMOP to map guest ram with p2m_ioreq_server to an ioreq server.

[Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>]

On 6/21/2016 5:47 PM, Jan Beulich wrote:
> > On 6/21/2016 4:22 PM, Jan Beulich wrote:
> > > Above modification would convert _all_ p2m_ioreq_server into
> > > p2m_ram_rw, irrespective of log-dirty mode being active. Which
> > > I don't think is what you want.
> > Well, this is another situation I found very interesting: without log-dirty,
> > this approach actually works. :)
> And what if the recalc flag gets set for some other reason?
Then the previous assumption will not hold. :)
But for now, the log dirty code is the only place I have found in 
hypervisor which
will turn on the recalc flag.

> > > I agree - this would seem to be the simpler model here, despite (as
> > > George validly says) the more consistent model would be for the
> > > hypervisor to do the cleanup. Such cleanup would imo be reasonable
> > > only if there was an easy way for the hypervisor to enumerate all
> > > p2m_ioreq_server pages.
> > Well, for me, the "easy way" means we should avoid traversing the whole ept
> > paging structure all at once, right?
> Yes.
>
> > I have not figured out any clean
> > solution
> > in hypervisor side, that's one reason I'd like to left this job to
> > device model
> > side(another reason is that I do think device model should take this
> > responsibility).
> Let's see if we can get George to agree.
OK. Thanks!

Yu

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