PCI/P2PDMA: Allow P2P DMA between any devices under AMD ZEN Root Complex

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The PCI specs say that peer-to-peer DMA should be supported between any two
devices that have a common upstream PCI-to-PCI bridge.  But devices under
different Root Ports don't share a common upstream bridge, and PCIe r4.0,
sec 1.3.1, says routing peer-to-peer transactions between Root Ports in the
same Root Complex is optional.

Many Root Complexes, including AMD ZEN, *do* support peer-to-peer DMA even
between Root Ports.  Add a whitelist and allow peer-to-peer DMA if both
participants are attached to a Root Complex known to support it.

Link: https://lore.kernel.org/linux-pci/20190418115859.2394-1-christian.koenig@amd.com
Signed-off-by: Christian König <christian.koenig@amd.com>
[bhelgaas: changelog]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Logan Gunthorpe <logang@deltatee.com>

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Christian König 2019-04-18 13:58:59 +02:00 • committed by Bjorn Helgaas

parent 9e98c678c2

commit 0f97da8310

1 changed files with 35 additions and 3 deletions

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drivers/pci/p2pdma.c

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