Re: [Xen-devel] [PATCH v5 16/23] x86/mm: add pv prefix to {alloc, free}_page_type

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.09.17 at 16:07, <wei.liu2@xxxxxxxxxx> wrote:
> On Fri, Sep 22, 2017 at 07:40:04AM -0600, Jan Beulich wrote:
>> Additionally could you add (half) a sentence regarding the
>> PGT_l*_page_table uses outside of PV specific code, which I'm
>> sure you have verified can't make it into the stubs?
> 
> At this stage I can only verify it by reading the code. I can't turn off
> PV yet.

Of course, that's what I did mean.

> To allocate a PGT_l*_page_table type page, the guest must explicitly
> request such types via PV MMU hypercall; there is no code other than the
> PV dom0 builder and p2m_alloc_ptp  in the hypervisor would explicitly
> ask for PGT_l*_page_table type pages.
> 
> p2m_alloc_table is a bit tricky. I think it can get away with not using
> PGT_l*_page_table type pages, but that is work for another day.  Anyway,
> currently it frees the pages directly with free_page from different
> paging modes, all of which won't go into PV mm code.

Right, hence the request to extend the description a little.
shadow_enable() also has a use that's not so obviously not
a problem.

Jan


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