On Thu, 2012-05-17 at 13:39 +1000, David Gibson wrote:
> On Fri, May 11, 2012 at 04:55:55PM -0600, Alex Williamson wrote:
> > Integrating IOMMU groups more closely into the driver core allows
> > us to more easily work around DMA quirks. The Ricoh multifunction
> > controller is a favorite example of devices that are currently
> > incompatible with IOMMU isolation as all the functions use the
> > requestor ID of function 0 for DMA. Passing this device into
> > pci_dma_quirk returns the PCI device to use for DMA. The IOMMU
> > driver can then construct an IOMMU group including both devices.
> >
> > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> > ---
> >
> > drivers/pci/quirks.c | 22 ++++++++++++++++++++++
> > include/linux/pci.h | 2 ++
> > 2 files changed, 24 insertions(+), 0 deletions(-)
> >
> > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> > index 4bf7102..6f9f7f9 100644
> > --- a/drivers/pci/quirks.c
> > +++ b/drivers/pci/quirks.c
> > @@ -3109,3 +3109,25 @@ int pci_dev_specific_reset(struct pci_dev *dev, int probe)
> >
> > return -ENOTTY;
> > }
> > +
> > +struct pci_dev *pci_dma_quirk(struct pci_dev *dev)
> > +{
> > + struct pci_dev *dma_dev = dev;
> > +
> > + /*
> > + * https://bugzilla.redhat.com/show_bug.cgi?id=605888
> > + *
> > + * Some Ricoh devices use the function 0 source ID for DMA on
> > + * other functions of a multifunction device. The DMA devices
> > + * is therefore function 0, which will have implications of the
> > + * iommu grouping of these devices.
> > + */
> > + if (dev->vendor == PCI_VENDOR_ID_RICOH &&
> > + (dev->device == 0xe822 || dev->device == 0xe230 ||
> > + dev->device == 0xe832 || dev->device == 0xe476)) {
> > + dma_dev = pci_get_slot(dev->bus,
> > + PCI_DEVFN(PCI_SLOT(dev->devfn), 0));
> > + }
>
> Hrm. This seems like a very generic name for a function performing a
> very specific test. We could well have devices with the same problem
> in future, so shouldn't this be set up so the same quirk can be easily
> added to new device ids without changing the function code itself.
I've since added a USB quirk here to group all the USB functions in a
slot. I'll take a closer look at the quirk helpers to see if anything
makes this easier, but I didn't see much point in spending a lot of time
over-optimizing this for 1 or 2 quirks that we can just step through in
a monolithic function. Thanks,
Alex
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