Re: [Xen-devel] [PATCH v5 09/15] vtd: add lookup_page method to iommu_ops

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.08.18 at 10:21, <Paul.Durrant@xxxxxxxxxx> wrote:
>> From: Tian, Kevin [mailto:kevin.tian@xxxxxxxxx]
>> Sent: 07 August 2018 04:25
>> 
>> > From: Paul Durrant [mailto:paul.durrant@xxxxxxxxxx]
>> > Sent: Saturday, August 4, 2018 1:22 AM
>> >
>> > --- a/xen/drivers/passthrough/vtd/iommu.c
>> > +++ b/xen/drivers/passthrough/vtd/iommu.c
>> > @@ -1830,6 +1830,39 @@ static int __must_check
>> > intel_iommu_unmap_page(struct domain *d,
>> >      return dma_pte_clear_one(d, bfn_to_baddr(bfn));
>> >  }
>> >
>> > +static int intel_iommu_lookup_page(struct domain *d, bfn_t bfn, mfn_t
>> > *mfn,
>> > +                                   unsigned int *flags)
>> 
>> Not looking at later patches yet... but in concept bfn address
>> space is per device instead of per domain.
> 
> Not in this case. Xen has always maintained a single IOMMU address per 
> virtual machine. That is what BFN refers to.

Nut is that a model we can maintain mid and long term? In particular
on ARM, where Julien has told me a single system could have multiple
_different_ IOMMUs, I could easily see the address spaces diverging.

Jan



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