[v2,6/7] intel-iommu: Make use of DMA quirks and ACS checks in IOMMU groups

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(+)


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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 ?

  
>   	group = iommu_group_get(&dma_pdev->dev);
>   	pci_dev_put(dma_pdev);
>   	if (!group) {
>

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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

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