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

["Zhai, Edwin" <edwin.zhai@xxxxxxxxx>]

Keir Fraser wrote:
> 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. 
>   
It's great!
Does p2m_is_ram return 1 for video memory?
I'll make a small patch and test it.

Thanks,


>  -- Keir
>
>
>   
--
best rgds,
edwin


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