Re: [Xen-devel] [PATCH 1/3] x86/p2m: tighten conditions of IOMMU mapping updates

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.09.15 at 10:55, <kevin.tian@xxxxxxxxx> wrote:
>>  From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: Monday, September 21, 2015 10:03 PM
>> 
>> In the EPT case permission changes should also result in updates or
>> TLB flushes.
>> 
>> In the NPT case the old MFN does not depend on the new entry being
>> valid (but solely on the old one), and the need to update or TLB-flush
>> again also depends on permission changes.
>> 
>> In the shadow mode case, iommu_hap_pt_share should be ignored.
>> 
>> Furthermore in the NPT/shadow case old intermediate page tables must
>> be freed only after IOMMU side updates/flushes have got carried out.
>> 
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>

Thanks, but quite a bit more important would have been a reply
to this

>>In addition to the fixes here it looks to me as if both EPT and
>>NPT/shadow code lack invalidation of IOMMU side paging structure
>>caches, i.e. further changes may be needed. Am I overlooking something?

as it may require the patch to be extended (and hence the ack to
be dropped again).

Thanks, Jan


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