Message-ID: <1338496905.2788.63.camel@ul30vt>
Subject: Re: [PATCH v2 6/7] intel-iommu: Make use of DMA quirks and ACS
 checks in IOMMU groups
From: Alex Williamson <alex.williamson@redhat.com>
To: Don Dutile <ddutile@redhat.com>
Cc: joerg.roedel@amd.com, dwmw2@infradead.org,
        iommu@lists.linux-foundation.org, bhelgaas@google.com,
        benh@kernel.crashing.org, aik@ozlabs.ru, david@gibson.dropbear.id.au,
        konrad.wilk@oracle.com, linux-kernel@vger.kernel.org,
        linux-pci@vger.kernel.org, gregkh@linuxfoundation.org,
        liuj97@gmail.com
Date: Thu, 31 May 2012 14:41:45 -0600
In-Reply-To: <4FC7CAE5.7020306@redhat.com>
References: <20120530201424.31527.33142.stgit@bling.home>
	 <20120530201942.31527.51604.stgit@bling.home> <4FC7CAE5.7020306@redhat.com>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
Mime-Version: 1.0
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2547
Lines: 69

On Thu, 2012-05-31 at 15:47 -0400, Don Dutile wrote:
> On 05/30/2012 04:19 PM, Alex Williamson wrote:
> > Work around broken devices and adhere to ACS support when determining
> > IOMMU grouping.
> >
> > Signed-off-by: Alex Williamson<alex.williamson@redhat.com>
> > ---
> >
> >   drivers/iommu/intel-iommu.c |   25 +++++++++++++++++++++++++
> >   1 file changed, 25 insertions(+)
> >
> > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> > index 4a43452..ebf2b31 100644
> > --- a/drivers/iommu/intel-iommu.c
> > +++ b/drivers/iommu/intel-iommu.c
> > @@ -4090,6 +4090,14 @@ static int intel_iommu_domain_has_cap(struct iommu_domain *domain,
> >   	return 0;
> >   }
> >
> > +static void swap_pci_ref(struct pci_dev **from, struct pci_dev *to)
> > +{
> > +	pci_dev_put(*from);
> > +	*from = to;
> > +}
> > +
> > +#define REQ_ACS_FLAGS	(PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF)
> > +
> >   static int intel_iommu_add_device(struct device *dev)
> >   {
> >   	struct pci_dev *pdev = to_pci_dev(dev);
> > @@ -4112,6 +4120,23 @@ static int intel_iommu_add_device(struct device *dev)
> >   	} else
> >   		dma_pdev = pci_dev_get(pdev);
> >
> > +	swap_pci_ref(&dma_pdev, pci_get_dma_source(dma_pdev));
> > +
> > +	if (dma_pdev->multifunction&&
> > +	    !pci_acs_enabled(dma_pdev, REQ_ACS_FLAGS))
> > +		swap_pci_ref(&dma_pdev,
> > +			     pci_get_slot(dma_pdev->bus,
> > +					  PCI_DEVFN(PCI_SLOT(dma_pdev->devfn),
> > +					  0)));
> > +
> > +	while (!pci_is_root_bus(dma_pdev->bus)) {
> > +		if (pci_acs_path_enabled(dma_pdev->bus->self,
> > +					 NULL, REQ_ACS_FLAGS))
> > +			break;
> > +
> > +		swap_pci_ref(&dma_pdev, pci_dev_get(dma_pdev->bus->self));
> > +	}
> > +
> I'm having deja-vu on this patch....
> .... why not just make the above two patches as two functions in drivers/iommu/iommu.c,
> one exported for these two modules (and maybe others someday...), e.g., iommu_pdev_put())
> which [intel-,amd-]iommu.c call ?

Do we want to put PCI specific code in the IOMMU base code?  I think
we'd want to avoid that.  I have no objection to reducing the
duplication, but I'm not sure who else is going to use this, where to
put it and what to call it.  So, I left the duplication here so it might
get more review from the IOMMU driver maintainers.  Thanks,

Alex

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/