From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gohar Irfan Subject: Re: Page Table Entry Modifications Date: Sun, 27 Sep 2015 07:26:11 +0000 Message-ID: References: <56026447.7000901@citrix.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============6225013371408626047==" Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Andrew Cooper , xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org --===============6225013371408626047== Content-Type: multipart/alternative; boundary=f46d043bdb0e5c64590520b57f90 --f46d043bdb0e5c64590520b57f90 Content-Type: text/plain; charset=UTF-8 Could someone please help me with this? It's really important and urgent. Thanks a lot! On Wed, Sep 23, 2015 at 1:42 PM Gohar Irfan wrote: > It is for a project, I'm trying to experiment with a couple of things. > > Could you please guide me how this could be achieved? Some relevant chunks > of code, perhaps? > > Thanks! > > On Wed, Sep 23, 2015 at 1:35 PM Andrew Cooper > wrote: > >> On 22/09/15 20:35, Gohar Irfan wrote: >> >> Hi All, >> >> I want to know if, in the case of HVM (shadow page tables), we can change >> the machine frame number pointed to by a page table entry? >> >> >> Yes - Xen is able to change the mfn in a pte. >> >> >> An overly simplified example would be: let's say I have page number 10 >> that is pointing to machine frame number 10, but I would like it to point >> to machine frame number 1? >> >> >> Yes - that is in theory possible. >> >> >> Can this be achieved inside the "sh_page_fault" function inside >> "xen/arch/x86/mm/shadow/multi.c" as this seems like a relevant place for >> this modification to me. >> >> >> What are you trying to achieve? Modifications such as what you request >> are possible, but you are exceedingly likely to end up with memory >> corruption as a result. >> >> >> ~Andrew >> > --f46d043bdb0e5c64590520b57f90 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Could someone please help me with this? It's really im= portant and urgent.=C2=A0

Thanks a lot!

<= div class=3D"gmail_quote">
On Wed, Sep 23, 2015 at 1:42 PM = Gohar Irfan <goharirfan94@gmai= l.com> wrote:
It is for a project, I'm trying to experiment with a couple of thing= s.=C2=A0

Could you please guide me how this could be ach= ieved? Some relevant chunks of code, perhaps?=C2=A0

Thanks!

On Wed= , Sep 23, 2015 at 1:35 PM Andrew Cooper <andrew.cooper3@citrix.com> wrote:
On 22/09/15 20:35, Gohar Irfan wrote:
=20
Hi All,

I want to know if, in the case of HVM (shadow page tables), we can change the machine frame number pointed to by a page table entry?

Yes - Xen is able to change the mfn in a pte.


An overly simplified example would be: let's say I have page number 10 that is pointing to machine frame number 10, but I would like it to point to machine frame number 1?

Yes - that is in theory possible.


Can this be achieved inside the "sh_page_fault" fun= ction inside "xen/arch/x86/mm/shadow/multi.c" as this seems l= ike a relevant place for this modification to me.

What are you trying to achieve?=C2=A0 Modifications such as what you request are possible, but you are exceedingly likely to end up with memory corruption as a result.


~Andrew
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