[Xen-devel] Re: [RFC][PATCH] Basic support for page offline

[Tim Deegan <Tim.Deegan@xxxxxxxxxx>]

At 14:37 +0000 on 19 Feb (1235054276), Jiang, Yunhong wrote:
> 
> >> It should be possible to have the tools do all the PTE manipulations
> >> with MMU update hypercalls (I think -- Keir may correct me here). Then
> >> the final hypercall to surrender the page will fail if the grant tables
> >> are wrong; if it does, put the PTEs back and fall back to a live
> >> migration.  Isn't that what your in-xen code does anyway?
> 
> Tim, after checking the code more carefully, seems currently the MMU update 
> hypercalls (including mod_lx_entry ) assume it is for current domain, while 
> in our usage model, it will update MMU for other domain, so I will try to do 
> following changes: 1) change mod_lx_entry() to get a domain parameter 2) Add 
> a new hypercall (or a new command to do_mmu_update ) to update the MMU for 
> other domain. I'm not sure if there are other usage model for such 
> requirement, and if such changes acceptable? Any feedback is welcome.
> 

Sorry for the delay -- I was travelling around the summit and this got
lost.  Yes, I think this is an OK approach.  I doubt there will be many
other users of such a hypercall since most OSes will get upset by their
PTEs changing under their feet, but I prefer it to the current patch.

Cheers,

Tim.

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

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