Re: [Xen-devel] [PATCH for 4.6] VT-d: Create IOMMU mappings for RMRR regions if shared EPT is not being used

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Chen, Tiejun
> Sent: Thursday, August 27, 2015 5:05 PM
> 
> On 8/27/2015 4:40 PM, Malcolm Crossley wrote:
> > On 27/08/15 03:59, Chen, Tiejun wrote:
> >> This kind of issue is already gone.
> >>
> >> https://www.mail-archive.com/xen-devel@xxxxxxxxxxxxx/msg32464.html
> >
> > There is a bug in the code you refer to above which results in no IOMMU 
> > page table
> > mappings being created if the guest domain is not sharing it's EPT page 
> > tables with
> > the IOMMU.
> >
> > set_identity_p2m_entry only configures the EPT page tables and does not 
> > configure
> > the IOMMU page tables.
> 
> Okay, I got what you mean.
> 
> Instead, could you insert iommu_{map,unmap_page() into
> {set,clear}_identity_p2m_entry()? I think this can make
> {set,clear}_identity_p2m_entry approachable in all circumstances.
> 
> Kevin and Jan,
> 
> Is this fine?
> 

Yes that is the right thing to do. It's a bit surprise to me that it's
not there yet. :-)

Thanks
Kevin

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