Re: [Xen-devel] Read value of CR3 from DomU VCPU

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 21:28 +0100 on 04 May (1304544537), Nimgaonkar, Satyajeet wrote:
> Hi,
>     I intend to map the DomU kernel memory to the Dom0 using the
> function xc_map_foreign_range(). For this I need the machine frame
> number (mfn) for the page I want to map. To get the value of mfn I want
> to read the value of cr3 from the DomU Vcpu data structure i.e. the
> value of ctrlreg[3] from a vcpu_guest_context object.

Look at xc_translate_foreign_address() in tools/libxc/xc_pagetab.c; it
does VA->MFN translations, including extracting CR3.

Cheers,

Tim.

> Also I have implemented a hypercall and wish to read the cr3 value in the 
> hypercall handler.
> Can anyone share some information regarding how read the cr3 value. Any code 
> examples would help me significantly.
> Thanks a lot.
> 
> Regards,
> Jeet

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-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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