From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: Auger Eric <eric.auger@redhat.com>
Cc: iommu@lists.linux-foundation.org,
LKML <linux-kernel@vger.kernel.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
Joerg Roedel <joro@8bytes.org>,
David Woodhouse <dwmw2@infradead.org>,
Yi Liu <yi.l.liu@intel.com>, "Tian, Kevin" <kevin.tian@intel.com>,
Raj Ashok <ashok.raj@intel.com>,
Alex Williamson <alex.williamson@redhat.com>,
Christoph Hellwig <hch@infradead.org>,
Jean-Philippe Brucker <jean-philippe@linaro.com>,
Jonathan Cameron <jic23@kernel.org>,
jacob.jun.pan@linux.intel.com
Subject: Re: [PATCH 1/3] iommu/uapi: Define uapi version and capabilities
Date: Thu, 6 Feb 2020 10:22:47 -0800 [thread overview]
Message-ID: <20200206102247.4eeb5791@jacob-builder> (raw)
In-Reply-To: <699faadb-e714-e36d-152a-5b650c0a403f@redhat.com>
On Thu, 6 Feb 2020 11:14:27 +0100
Auger Eric <eric.auger@redhat.com> wrote:
> Hi Jacob,
> On 1/29/20 7:02 AM, Jacob Pan wrote:
> > Define a unified UAPI version to be used for compatibility
> > checks between user and kernel.
> >
> > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> > ---
> > include/uapi/linux/iommu.h | 48
> > ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 48
> > insertions(+)
> >
> > diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> > index fcafb6401430..65a26c2519ee 100644
> > --- a/include/uapi/linux/iommu.h
> > +++ b/include/uapi/linux/iommu.h
> > @@ -8,6 +8,54 @@
> >
> > #include <linux/types.h>
> >
> > +/**
> > + * Current version of the IOMMU user API. This is intended for
> > query
> > + * between user and kernel to determine compatible data structures.
> > + *
> > + * Having a single UAPI version to govern the user-kernel data
> > structures
> > + * makes compatibility check straightforward. On the contrary,
> > supporting
> > + * combinations of multiple versions of the data can be a
> > nightmare.
> I would rather put the above justification in the commit msg and not
> here.
make sense.
> > + *
> > + * UAPI version can be bumped up with the following rules:
> > + * 1. All data structures passed between user and kernel space
> > share
> > + * the same version number. i.e. any extension to to any
> > structure
> s/to to/to
will fix.
> > + * results in version bump up.
> in a version number increment?
sounds good, more specific.
> > + *
> > + * 2. Data structures are open to extension but closed to
> > modification.> + * New fields must be added at the end of each
> > data structure with
> > + * 64bit alignment. Flag bits can be added without size change
> > but
> > + * existing ones cannot be altered.
> > + *
> > + * 3. Versions are backward compatible.
> > + *
> > + * 4. Version to size lookup is supported by kernel internal API
> > for each
> > + * API function type. @version is mandatory for new data
> > structures
> > + * and must be at the beginning with type of __u32.
> > + */
> > +#define IOMMU_UAPI_VERSION 1
> > +static inline int iommu_get_uapi_version(void)
> > +{
> > + return IOMMU_UAPI_VERSION;
> > +}
> > +
> > +/*
> > + * Supported UAPI features that can be reported to user space.
> > + * These types represent the capability available in the kernel.
> > + *
> > + * REVISIT: UAPI version also implies the capabilities. Should we
> > + * report them explicitly?
> > + */
> > +enum IOMMU_UAPI_DATA_TYPES {
> > + IOMMU_UAPI_BIND_GPASID,
> > + IOMMU_UAPI_CACHE_INVAL,
> > + IOMMU_UAPI_PAGE_RESP,
> > + NR_IOMMU_UAPI_TYPE,
> > +};
> > +
> > +#define IOMMU_UAPI_CAP_MASK ((1 << IOMMU_UAPI_BIND_GPASID)
> > | \
> > + (1 << IOMMU_UAPI_CACHE_INVAL)
> > | \
> > + (1 << IOMMU_UAPI_PAGE_RESP))
> > +
> > #define IOMMU_FAULT_PERM_READ (1 << 0) /* read */
> > #define IOMMU_FAULT_PERM_WRITE (1 << 1) /* write */
> > #define IOMMU_FAULT_PERM_EXEC (1 << 2) /* exec */
> >
> Thanks
>
> Eric
>
next prev parent reply other threads:[~2020-02-06 18:17 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-29 6:02 [PATCH 0/3] IOMMU user API enhancement Jacob Pan
2020-01-29 6:02 ` [PATCH 1/3] iommu/uapi: Define uapi version and capabilities Jacob Pan
2020-02-06 10:14 ` Auger Eric
2020-02-06 18:22 ` Jacob Pan [this message]
2020-01-29 6:02 ` [PATCH 2/3] iommu/uapi: Use unified UAPI version Jacob Pan
2020-01-29 6:02 ` [PATCH 3/3] iommu/uapi: Add helper function for size lookup Jacob Pan
2020-01-29 21:40 ` Alex Williamson
2020-01-29 22:19 ` Alex Williamson
2020-01-31 19:51 ` Jacob Pan
2020-01-31 23:51 ` Jacob Pan
2020-02-03 18:27 ` Alex Williamson
2020-02-03 20:41 ` Jacob Pan
2020-02-03 21:12 ` Alex Williamson
2020-02-03 22:41 ` Jacob Pan
2020-02-06 10:14 ` Auger Eric
2020-02-07 8:47 ` Jean-Philippe Brucker
2020-01-31 17:56 ` Jacob Pan
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