From mboxrd@z Thu Jan  1 00:00:00 1970
From: Razvan Cojocaru <rcojocaru@bitdefender.com>
Subject: Re: [PATCH RFC V3 4/5] xen,
 libxc: Request page fault injection via libxc
Date: Thu, 24 Jul 2014 15:44:07 +0300
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To: Andrew Cooper <andrew.cooper3@citrix.com>, Ian Jackson <Ian.Jackson@eu.citrix.com>, Andrei LUTAS <vlutas@bitdefender.com>
Cc: kevin.tian@intel.com, Ian Campbell <Ian.Campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, jun.nakajima@intel.com, Tamas Lengyel <tamas.lengyel@zentific.com>, eddie.dong@intel.com, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>, Andres Lagar-Cavilla <andres@lagarcavilla.org>, Jan Beulich <JBeulich@suse.com>
List-Id: xen-devel@lists.xenproject.org

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