Re: [PATCH kernel v10 14/34] powerpc/iommu: Move tce_xxx callbacks from ppc_md to iommu_table

[Alexey Kardashevskiy]

On 05/14/2015 10:23 AM, Gavin Shan wrote:
> On Tue, May 12, 2015 at 01:39:03AM +1000, Alexey Kardashevskiy wrote:
> > This adds a iommu_table_ops struct and puts pointer to it into
> > the iommu_table struct. This moves tce_build/tce_free/tce_get/tce_flush
> > callbacks from ppc_md to the new struct where they really belong to.
> >
> > This adds the requirement for @it_ops to be initialized before calling
> > iommu_init_table() to make sure that we do not leave any IOMMU table
> > with iommu_table_ops uninitialized. This is not a parameter of
> > iommu_init_table() though as there will be cases when iommu_init_table()
> > will not be called on TCE tables, for example - VFIO.
> >
> > This does s/tce_build/set/, s/tce_free/clear/ and removes "tce_"
> > redundand prefixes.
>
> s/redundand/redundant  I might be wrong because of my bad English.

No, you're right ;)

> > This removes tce_xxx_rm handlers from ppc_md but does not add
> > them to iommu_table_ops as this will be done later if we decide to
> > support TCE hypercalls in real mode. This removes _vm callbacks as
> > only virtual mode is supported by now so this also removes @rm parameter.
> >
> > For pSeries, this always uses tce_buildmulti_pSeriesLP/
> > tce_buildmulti_pSeriesLP. This changes multi callback to fall back to
> > tce_build_pSeriesLP/tce_free_pSeriesLP if FW_FEATURE_MULTITCE is not
> > present. The reason for this is we still have to support "multitce=off"
> > boot parameter in disable_multitce() and we do not want to walk through
> > all IOMMU tables in the system and replace "multi" callbacks with single
> > ones.
> >
> > For powernv, this defines _ops per PHB type which are P5IOC2/IODA1/IODA2.
> > This makes the callbacks for them public. Later patches will extend
> > callbacks for IODA1/2.
> >
> > No change in behaviour is expected.
> >
> > Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
> > Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
>
> Reviewed-by: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx>
>
> > ---
> > Changes:
> > v9:
> > * pnv_tce_build/pnv_tce_free/pnv_tce_get have been made public and lost
> > "rm" parameters to make following patches simpler (realmode is not
> > supported here anyway)
> > * got rid of _vm versions of callbacks
> > ---
> > arch/powerpc/include/asm/iommu.h            | 17 +++++++++++
> > arch/powerpc/include/asm/machdep.h          | 25 ---------------
> > arch/powerpc/kernel/iommu.c                 | 46 ++++++++++++++--------------
> > arch/powerpc/kernel/vio.c                   |  5 +++
> > arch/powerpc/platforms/cell/iommu.c         |  8 +++--
> > arch/powerpc/platforms/pasemi/iommu.c       |  7 +++--
> > arch/powerpc/platforms/powernv/pci-ioda.c   | 14 +++++++++
> > arch/powerpc/platforms/powernv/pci-p5ioc2.c |  7 +++++
> > arch/powerpc/platforms/powernv/pci.c        | 47 +++++------------------------
> > arch/powerpc/platforms/powernv/pci.h        |  5 +++
> > arch/powerpc/platforms/pseries/iommu.c      | 34 ++++++++++++---------
> > arch/powerpc/sysdev/dart_iommu.c            | 12 +++++---
> > 12 files changed, 116 insertions(+), 111 deletions(-)
> >
> > diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
> > index d91bd69..e2a45c3 100644
> > --- a/arch/powerpc/include/asm/iommu.h
> > +++ b/arch/powerpc/include/asm/iommu.h
> > @@ -44,6 +44,22 @@
> > extern int iommu_is_off;
> > extern int iommu_force_on;
> >
> > +struct iommu_table_ops {
> > +	int (*set)(struct iommu_table *tbl,
> > +			long index, long npages,
> > +			unsigned long uaddr,
> > +			enum dma_data_direction direction,
> > +			struct dma_attrs *attrs);
> > +	void (*clear)(struct iommu_table *tbl,
> > +			long index, long npages);
> > +	unsigned long (*get)(struct iommu_table *tbl, long index);
> > +	void (*flush)(struct iommu_table *tbl);
>
> Currently, there isn't flush backend on PowerNV platform. I'm not sure
> if we have to implement it for PowerNV if we really need it. Maybe you
> will have it to support DDW in subsequent patches which I didn't look
> into it, but I will :-)


I am not adding new callbacks here, I am moving them. DART uses flush() so 
it has to be here.


> > +};
> > +
> > +/* These are used by VIO */
> > +extern struct iommu_table_ops iommu_table_lpar_multi_ops;
> > +extern struct iommu_table_ops iommu_table_pseries_ops;
> > +
>
> It might be reasonable to add "struct iommu_table_ops *ops" to function
> vio_register_device_node() where the specified "ops" can be hooked to
> the newly created IOMMU table. In that way, the platform (pSeries) specific
> IOMMU table operations doesn't have to be exposed to PowerPC subsystem.

I am not exposing anything new here - I am just replacing references to 
ppc_md with references to iommu_table_ops.

vio_register_device_node() is called from VIO code. So I'll have to have a 
copy of iommu_table_pseries_ops and iommu_table_lpar_multi_ops in VIO code. 
If I do this, I'll have to export 
tce_build_pSeries()/tce_free_pSeries()/tce_get_pseries() to initialize 
those structs. Either way I need to expose some symbols and do deeper 
rework but not in this patchset.



--
Alexey
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