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

Jacob Pan
2020-03-20T21:30:23Z

On Wed, 12 Feb 2020 13:43:43 +0100
Auger Eric <eric.auger@redhat.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@linux.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]