Re: CR3 Virtual Address

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 28/11/12 14:48, emdel wrote:
> Hello everybody,
>
> I have to work with the Xen 4.2 memory management code for a research
> project and I have some questions.
>
> 1) Since I have to change and/or remove some entries in the hypervisor
>    page table, I would like to know the "virtual address" of the CR3
>    register.

CR3 is a register, not memory mapped.  Do you mean the virtual address
of the top level pagetable?  That will depend on which mode you are
running in, and which CR3 you are actually looking for.

>
> 2) I would also like to know if the VMCS virtual address is mapped
> inside the
>    page table pointed by the HOST_CR3.

The host cr3 is the set of pagetables to use when a VMEXIT happens.  The
VCMS of the HVM guest in question will be mapped into this address space.

>
> 3) Are there functions to perform the page walking on the hypervisor
>    page tables?

There are generic page walk functions, which can be used to walk the
hypervisor tables.  Why do you want to do this?

~Andrew

>
>
> Thank you for the attention,
>
>
> Best Regards.

-- 
Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer
T: +44 (0)1223 225 900, http://www.citrix.com