Re: [Xen-devel] [PATCH RFC 6/9] xen, libxc: Request page fault injection via libxc

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 02/07/14 16:51, Jan Beulich wrote:
>>>> On 02.07.14 at 15:33, <rcojocaru@xxxxxxxxxxxxxxx> wrote:
>> 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. This information is then used to call
>> hvm_inject_page_fault() at the first VMENTRY where the guest status
>> matches and there are no other pending traps.
> So the first question that strikes me here: What good can it do to be
> able to inject arbitrary page faults, possibly at times where the guest
> OS is absolutely not expecting them?

I would further this by suggesting that the only plausible case where
you could inject a pagefault is as a reply to a mem_event for which the
guest is already paused.

In which case it it would be better implemented as part of the mem_event
protocol than a plain hypercall in its own regard.

~Andrew

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