Re: [Xen-devel] [PATCH] amd iommu: Do not adjust paging mode for dom0 devices

[Keir Fraser <keir@xxxxxxx>]

On 07/02/2011 13:30, "Wei Wang2" <wei.wang2@xxxxxxx> wrote:

> On Monday 07 February 2011 11:47:32 Keir Fraser wrote:
>> On 07/02/2011 10:33, "Wei Wang2" <wei.wang2@xxxxxxx> wrote:
> 
>> Personally I would suggest starting with small 2-level tables and
>> dynamically increase their height as bigger mappings are added to them.
>> Else stick with 4-level tables, or size tables according to global variable
>> max_page. I think basing anything on d->max_pages is not a good idea.
>> 
>>  -- Keir
> How does the attached patch look like? It uses global variable max_page for pv
> and dom0 and calculate maxpfn for hvm guest. This should cover gfn holes on
> hvm guests.

The p2m code already tracks the largest gfn for HVM guests. Try using
p2m_get_hostp2m(d)->max_mapped_pfn for HVM guests. Note that this could
increase after you sample it, however. Hence why you really need to have a
statically deep-enough table, or the ability to grow the table depth
dynamically.

Your change for PV guests would definitely be correct, however.

 -- Keir

> Thanks,
> Wei
> Signed-off-by: Wei Wang <wei.wang2@xxxxxxx>
> 
>>> I was assuming max_pdx is the index number... Or are
>>> you referring memory hot plug? If so, we might also need 4 level for
>>> dom0.
> 
> 



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