Re: [Xen-devel] [PATCH RFC V8 4/5] xen, libxc: Request page fault injection via libxc

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Razvan Cojocaru [mailto:rcojocaru@xxxxxxxxxxxxxxx]
> Sent: Thursday, August 28, 2014 12:55 AM
> 
> On 08/27/2014 11:59 PM, Tian, Kevin wrote:
> >> From: Razvan Cojocaru [mailto:rcojocaru@xxxxxxxxxxxxxxx]
> >> Sent: Wednesday, August 27, 2014 7:02 AM
> >>
> >> Added new XEN_DOMCTL_set_pagefault_info hypercall, used by libxc's
> >> new xc_domain_set_pagefault_info() function to set per-domain page
> >> fault injection information. All a call does is set per-domain info,
> >> and nothing actually happens until VMENTRY time, and then only if
> >> all conditions are met (the guest is in user mode, the set value
> >> matches CR3, and there are no other pending traps).
> >> This mechanism allows bringing in swapped-out pages for inspection.
> >
> > Is there any impact on the whole introspection process, regarding to when
> > next VM exit on the inspected address space actually comes?
> >
> > btw how is the whole flow of inspecting swapped-out pages with this
> > interface?
> 
> Andrei has explained the flow here:
> http://lists.xen.org/archives/html/xen-devel/2014-07/msg03013.html

Thanks for the link.

I think a vcpu kick would be better here, if we only look at this PF injection
interface w/o assuming any specific knowledge into your production. That
looks more sane from exception p.o.v.

Thanks,
Kevin

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