Re: [PATCH RFC V3 4/5] xen, libxc: Request page fault injection via libxc

[Razvan Cojocaru <rcojocaru@bitdefender.com>]

On 07/24/2014 03:41 PM, Andrew Cooper wrote:
> On 24/07/14 13:38, Ian Jackson wrote:
>> Andrei LUTAS writes ("Re: [Xen-devel] [PATCH RFC V3 4/5] xen, libxc: Request page fault injection via libxc"):
>>> The logic with the #PF injection goes like this:
>> Sorry, I didn't see this message when I sent my last one asking about
>> the motivation.
>>
>>> - The memory introspection engine wants to inspect (for whatever reason) a
>>>    virtual page X insidevirtual address space Y(inside user-mode, although
>>>    with proper knowledge about the guest kernel,one can also inject #PF 
>>> inside
>>>    kernel-mode on Windows - proper IRQL, working set trim inactive, etc.)
>> I don't understand why this needs additional hypervisor code.  Can
>> this not be done by negotiating with the paging daemon ?
>>
>> Ian.
> 
> The purpose of this is to play with the paging algorithm inside the
> guest OS, which can only be done from outside by providing pagefaults
> when considered safe to do so.
> 
> This has nothing to do with xen-paging transparently playing with the
> guest physical address space behind the guests back.

Thanks, you beat me to it :)


Razvan Cojocaru