Re: [Xen-devel] Page Table Entry Modifications

[Gohar Irfan <goharirfan94@xxxxxxxxx>]

Could someone please help me with this? It's really important and urgent.Â

Thanks a lot!

On Wed, Sep 23, 2015 at 1:42 PM Gohar Irfan <goharirfan94@xxxxxxxxx> wrote:

It is for a project, I'm trying to experiment with a couple of things.Â

Could you please guide me how this could be achieved? Some relevant chunks of code, perhaps?Â

Thanks!

On Wed, Sep 23, 2015 at 1:35 PM Andrew Cooper <andrew.cooper3@xxxxxxxxxx> 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

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