[Xen-devel] [PATCH] Support swap a page from user space tools -- Was RE: [RFC][PATCH] Basic support for page offline

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

Tim, this is the implementation as discussed.
The swap_page.patch is for HV side change, basically it call the mod_lx_entry 
to update the table.
The free_page.patch is the function from user space tools to offlien a page.

Thanks
Yunhong Jiang

Jiang, Yunhong <> wrote:
> Tim Deegan <mailto:Tim.Deegan@xxxxxxxxxx> wrote:
>> 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.
> 
> Sure, I will do this way.
> 
> Thanks
> Yunhong Jiang
> 
>> 
>> Cheers,
>> 
>> Tim.
>> 
>> --
>> Tim Deegan <Tim.Deegan@xxxxxxxxxx>
>> Principal Software Engineer, Citrix Systems (R&D) Ltd.
>> [Company #02300071, SL9 0DZ, UK.]

Attachment: swap_page.patch
Description: swap_page.patch

Attachment: free_page.patch
Description: free_page.patch

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