Re: [Xen-devel] [PATCH v6 08/14] vtd: add lookup_page method to iommu_ops

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: 07 September 2018 15:56
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: George Dunlap <George.Dunlap@xxxxxxxxxx>; Kevin Tian
> <kevin.tian@xxxxxxxxx>; xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
> Subject: RE: [PATCH v6 08/14] vtd: add lookup_page method to iommu_ops
> 
> >>> On 07.09.18 at 14:36, <Paul.Durrant@xxxxxxxxxx> wrote:
> >>  -----Original Message-----
> >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> >> Sent: 07 September 2018 12:11
> >> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> >> Cc: George Dunlap <George.Dunlap@xxxxxxxxxx>; Kevin Tian
> >> <kevin.tian@xxxxxxxxx>; xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
> >> Subject: Re: [PATCH v6 08/14] vtd: add lookup_page method to
> iommu_ops
> >>
> >> >>> On 23.08.18 at 11:47, <paul.durrant@xxxxxxxxxx> wrote:
> >> > This patch adds a new method to the VT-d IOMMU implementation to
> find
> >> the
> >> > MFN currently mapped by the specified BFN along with a wrapper
> function
> >> in
> >> > generic IOMMU code to call the implementation if it exists.
> >>
> >> For this to go in, I think the AMD side of it wants to also be implemented.
> >
> > Why? It can be done later. Nothing existing is going to break if it is not
> > implemented.
> 
> If it was something that's terribly difficult to implement, I'd
> probably agree. But introducing PV IOMMU for Intel only (and
> hence once again making AMD a second class citizen) I don't
> really like. Another thing would be if you had the implementation
> ready, but the maintainer(s) don't respond...
> 

It's all time though. The fact is that, in XenServer, we've never had PV-IOMMU 
for AMD. It would be wonderful to have it for AMD too and indeed I may find the 
time to do it, but is that really a reason to block integration of these 
patches when no actual regression will be caused by of the lack of AMD support?

  Paul

> Jan
> 


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