PCI: Introduce pci_real_dma_dev()
The current DMA alias implementation requires the aliased device be on the
same PCI bus as the requester ID. Add an arch-specific mechanism to point
to another PCI device when doing mapping and PCI DMA alias search. The
default case returns the actual device.
Link: https://lore.kernel.org/r/1579613871-301529-4-git-send-email-jonathan.derrick@intel.com
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Christoph Hellwig <hch@lst.de>
diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index bade140..efdb8b5 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -32,6 +32,12 @@ int pci_for_each_dma_alias(struct pci_dev *pdev,
struct pci_bus *bus;
int ret;
+ /*
+ * The device may have an explicit alias requester ID for DMA where the
+ * requester is on another PCI bus.
+ */
+ pdev = pci_real_dma_dev(pdev);
+
ret = fn(pdev, pci_dev_id(pdev), data);
if (ret)
return ret;