linux-kernel - Re: [PATCH V9 02/10] iommu/uapi: Define a mask for bind data

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Date:   Fri, 20 Mar 2020 14:35:55 -0700
From:   Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:     Auger Eric <eric.auger@...hat.com>
Cc:     iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Yi Liu <yi.l.liu@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Christoph Hellwig <hch@...radead.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Jonathan Cameron <jic23@...nel.org>,
        jacob.jun.pan@...ux.intel.com
Subject: Re: [PATCH V9 02/10] iommu/uapi: Define a mask for bind data

On Wed, 12 Feb 2020 13:43:43 +0100
Auger Eric <eric.auger@...hat.com> wrote:

> Hi Jacob,
> 
> On 1/29/20 7:01 AM, Jacob Pan wrote:
> > Memory type related guest PASID bind data can be grouped together
> > for one simple check.  
> Those are flags related to memory type.
right, will rephrase.
> > Link:
> > https://lore.kernel.org/linux-iommu/20200109095123.17ed5e6b@jacob-builder/  
> not sure the link is really helpful.
> > 
will delete. the patch is very simple.

> > Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> > ---
> >  include/uapi/linux/iommu.h | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> > index 4ad3496e5c43..fcafb6401430 100644
> > --- a/include/uapi/linux/iommu.h
> > +++ b/include/uapi/linux/iommu.h
> > @@ -284,7 +284,10 @@ struct iommu_gpasid_bind_data_vtd {
> >  	__u32 pat;
> >  	__u32 emt;
> >  };
> > -
> > +#define IOMMU_SVA_VTD_GPASID_EMT_MASK
> > (IOMMU_SVA_VTD_GPASID_CD | \
> > +					 IOMMU_SVA_VTD_GPASID_EMTE
> > | \
> > +					 IOMMU_SVA_VTD_GPASID_PCD
> > |  \
> > +
> > IOMMU_SVA_VTD_GPASID_PWT)  
> Why EMT rather than MT or MTS?
> the spec says:
> Those fields are treated as Reserved(0) for implementations not
> supporting Memory Type (MTS=0 in Extended Capability Register).
> 
MTS makes more sense, will change.
It was from hygiene p.o.v. checking the flag to avoid touching these
fields.

Thanks,

Jacob
> >  /**
> >   * struct iommu_gpasid_bind_data - Information about device and
> > guest PASID binding
> >   * @version:	Version of this data structure
> >   
> 
> Thanks
> 
> Eric
> 

[Jacob Pan]