linux-kernel - RE: [PATCH 1/9 v2] pci:msi: add weak function for returning msi region info

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Message-ID: <6A3DF150A5B70D4F9B66A25E3F7C888D072363E5@039-SN2MPN1-012.039d.mgd.msft.net>
Date:	Thu, 28 Nov 2013 10:08:16 +0000
From:	Bharat Bhushan <Bharat.Bhushan@...escale.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
CC:	"alex.williamson@...hat.com" <alex.williamson@...hat.com>,
	"joro@...tes.org" <joro@...tes.org>,
	"agraf@...e.de" <agraf@...e.de>,
	Scott Wood <scottwood@...escale.com>,
	Stuart Yoder <stuart.yoder@...escale.com>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 1/9 v2] pci:msi: add weak function for returning msi
 region info



> -----Original Message-----
> From: linux-pci-owner@...r.kernel.org [mailto:linux-pci-owner@...r.kernel.org]
> On Behalf Of Bjorn Helgaas
> Sent: Tuesday, November 26, 2013 5:06 AM
> To: Bhushan Bharat-R65777
> Cc: alex.williamson@...hat.com; joro@...tes.org; agraf@...e.de; Wood Scott-
> B07421; Yoder Stuart-B08248; iommu@...ts.linux-foundation.org; linux-
> pci@...r.kernel.org; linuxppc-dev@...ts.ozlabs.org; linux-
> kernel@...r.kernel.org; Bhushan Bharat-R65777
> Subject: Re: [PATCH 1/9 v2] pci:msi: add weak function for returning msi region
> info
> 
> On Tue, Nov 19, 2013 at 10:47:05AM +0530, Bharat Bhushan wrote:
> > In Aperture type of IOMMU (like FSL PAMU), VFIO-iommu system need to
> > know the MSI region to map its window in h/w. This patch just defines
> > the required weak functions only and will be used by followup patches.
> >
> > Signed-off-by: Bharat Bhushan <bharat.bhushan@...escale.com>
> > ---
> > v1->v2
> >  - Added description on "struct msi_region"
> >
> >  drivers/pci/msi.c   |   22 ++++++++++++++++++++++
> >  include/linux/msi.h |   14 ++++++++++++++
> >  2 files changed, 36 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index
> > d5f90d6..2643a29 100644
> > --- a/drivers/pci/msi.c
> > +++ b/drivers/pci/msi.c
> > @@ -67,6 +67,28 @@ int __weak arch_msi_check_device(struct pci_dev *dev, int
> nvec, int type)
> >  	return chip->check_device(chip, dev, nvec, type);  }
> >
> > +int __weak arch_msi_get_region_count(void) {
> > +	return 0;
> > +}
> > +
> > +int __weak arch_msi_get_region(int region_num, struct msi_region
> > +*region) {
> > +	return 0;
> > +}
> > +
> > +int msi_get_region_count(void)
> > +{
> > +	return arch_msi_get_region_count();
> > +}
> > +EXPORT_SYMBOL(msi_get_region_count);
> > +
> > +int msi_get_region(int region_num, struct msi_region *region) {
> > +	return arch_msi_get_region(region_num, region); }
> > +EXPORT_SYMBOL(msi_get_region);
> > +
> >  int __weak arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int
> > type)  {
> >  	struct msi_desc *entry;
> > diff --git a/include/linux/msi.h b/include/linux/msi.h index
> > b17ead8..ade1480 100644
> > --- a/include/linux/msi.h
> > +++ b/include/linux/msi.h
> > @@ -51,6 +51,18 @@ struct msi_desc {
> >  };
> >
> >  /*
> > + * This structure is used to get
> > + * - physical address
> > + * - size
> > + * of a msi region
> > + */
> > +struct msi_region {
> > +	int region_num; /* MSI region number */
> > +	dma_addr_t addr; /* Address of MSI region */
> > +	size_t size; /* Size of MSI region */ };
> > +
> > +/*
> >   * The arch hooks to setup up msi irqs. Those functions are
> >   * implemented as weak symbols so that they /can/ be overriden by
> >   * architecture specific code if needed.
> > @@ -64,6 +76,8 @@ void arch_restore_msi_irqs(struct pci_dev *dev, int
> > irq);
> >
> >  void default_teardown_msi_irqs(struct pci_dev *dev);  void
> > default_restore_msi_irqs(struct pci_dev *dev, int irq);
> > +int arch_msi_get_region_count(void);
> > +int arch_msi_get_region(int region_num, struct msi_region *region);
> 
> It doesn't look like any of this (struct msi_region, msi_get_region(),
> msi_get_region_count()) is actually used by drivers/pci/msi.c, so I don't think
> it needs to be declared in generic code.  It looks like it's only used in
> drivers/vfio/vfio_iommu_fsl_pamu.c, where you already know you have an FSL
> IOMMU, and you can just call FSL-specific interfaces directly.

Thanks Bjorn,

Want to be sure of what you are suggesting.

What I understood is that we define these (struct msi_region, msi_get_region(), msi_get_region_count()) in arch/powerpc/include/fsl_msi.h (a new file). Include this header file directly in driver/vfio/vfio_iommu_fsl_pamu.c

Same also applies for msi_set_iova() in patch-5 ?

-Bharat

> 
> Bjorn
> 
> >
> >  struct msi_chip {
> >  	struct module *owner;
> > --
> > 1.7.0.4
> >
> >
> --
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