Re: [Xen-devel] several Qs about domain live migration

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 18/11/08 01:17, "Zhai, Edwin" <edwin.zhai@xxxxxxxxx> wrote:

> We are trying to fix a HVM live migration bug, and found "Use main memory for
> video memory" in r18383 cause guest hang after restore.
> 
> Following changes make all valid pages migrated, including vlapic page
> (0xFEE00), and share page(0xFFFFF), so an extra memory population for these 2
> pages would override previous mapping then cause guest hang (if using vlapic
> acceleration).
> 
> What do you think of possible fixing? Skipping these specific pages in
> xc_domain_save except video memory, or change the HVM domain creation.

Try changing gmfn_to_mfn(FOREIGNDOM, l1e_get_pfn(nl1e)) in mod_l1_entry()
to:
  mfn = gfn_to_mfn(FOREIGNDOM, l1e_get_pfn(nl1e), &p2mt);
  if ( !p2m_is_ram(p2mt) || (mfn == INVALID_MFN) )
    ....

This will prevent foreign mappings of 'mmio' pages. Pretty sensible and will
fix this problem. 

 -- Keir



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