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));
+ }
+
+ return dma_dev;
+}
diff --git a/include/linux/pci.h b/include/linux/pci.h
index e444f5b..9910b5c 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1479,9 +1479,11 @@ enum pci_fixup_pass {
#ifdef CONFIG_PCI_QUIRKS
void pci_fixup_device(enum pci_fixup_pass pass, struct pci_dev *dev);
+struct pci_dev *pci_dma_quirk(struct pci_dev *dev);
#else
static inline void pci_fixup_device(enum pci_fixup_pass pass,
struct pci_dev *dev) {}
+struct pci_dev *pci_dma_quirk(struct pci_dev *dev) { return dev }
#endif
void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen);
--
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