Re: [Xen-devel] Walking guest page tables...

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 10:23 -0400 on 22 Jul (1216722197), Matthew Donovan wrote:
> Is it possible to walk an HVM guest's page tables?  Can someone point me to
> code that does it?

>From inside Xen?  paging_gva_to_gfn().

> I read that the dirty page logging that occurs during live migration starts
> by making all the pages readonly but when I trace the code for
> paging_log_dirty_enable(), it doesn't look like that's happening.

There are two versions of log-dirty; by far the easier to understand is
the hardware-assisted paging code (aka NPT aka EPT); look at
hap_enable_log_dirty() &c in xen/arch/x86/mm/hap/hap.c, and 
svm_do_nested_pgfault() in xen/arch/x86/hvm/svm/svm.c

The other version is in the shadow pagetable code and actually removes
_all_ mappings of guest memory (by calling shadow_blow_tables) and
then marks pages dirty when it puts writeable mappings into the shadows
(enforced in _sh_propagate() in xen/arch/x86/mmshadow/multi.c.

Tim.

-- 
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Citrix Systems (R&D) Ltd.
[Company #02300071, SL9 0DZ, UK.]

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel