Re: [PATCH v6 01/10] iommu/vt-d: Enlightened PASID allocation

[Lu Baolu]

Hi,

On 10/24/19 5:11 AM, Jacob Pan wrote:
> On Wed, 23 Oct 2019 10:55:23 -0700
> Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> wrote:
>
> > > > Do you have to check this everytime? every dmar_readq is going to
> > > > trap to the other side ...
> > >
> > > Yes. We don't need to check it every time. Check once and save the
> > > result during boot is enough.
> > >
> > > How about below incremental change?
> > >    
> > Below is good but I was thinking to include vccap in struct
> > intel_iommu{} where cap and ecaps reside. i.e.
> > diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> > index 14b87ae2916a..e2cf25c9c956 100644
> > --- a/include/linux/intel-iommu.h
> > +++ b/include/linux/intel-iommu.h
> > @@ -528,6 +528,7 @@ struct intel_iommu {
> >          u64             reg_size; /* size of hw register set */
> >          u64             cap;
> >          u64             ecap;
> > +       u64             vccap;
> >
> > Also, we can use a static branch here.
> On a second thought, we cannot use static(branch) here in that we
> cannot assume there is only one vIOMMU all the time. Have to cache the
> vccap per iommu.

intel_iommu is a per iommu structure, right? Or I missed anything?

> > > diff --git a/drivers/iommu/intel-pasid.c
> > > b/drivers/iommu/intel-pasid.c index ff7e877b7a4d..c15d9d7e1e73
> > > 100644 --- a/drivers/iommu/intel-pasid.c
> > > +++ b/drivers/iommu/intel-pasid.c
> > > @@ -29,22 +29,29 @@ u32 intel_pasid_max_id = PASID_MAX;
> [Jacob Pan]

Best regards,
baolu