From 6dbbd053e6aea827abde89ac9b9d6855dab1a66b Mon Sep 17 00:00:00 2001 From: Logan Gunthorpe Date: Wed, 19 Jun 2019 12:56:26 -0600 Subject: [PATCH] PCI/P2PDMA: Ignore root complex whitelist when an IOMMU is present MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Presently, there is no path to DMA map P2PDMA memory, so if a TLP targeting this memory hits the root complex and an IOMMU is present, the IOMMU will reject the transaction, even if the RC would support P2PDMA. So until the kernel knows to map these DMA addresses in the IOMMU, we should not enable the whitelist when an IOMMU is present. Link: https://lore.kernel.org/linux-pci/20190522201252.2997-1-logang@deltatee.com/ Fixes: 0f97da831026 ("PCI/P2PDMA: Allow P2P DMA between any devices under AMD ZEN Root Complex") Signed-off-by: Logan Gunthorpe Reviewed-by: Christian König Signed-off-by: Bjorn Helgaas Cc: Christoph Hellwig --- drivers/pci/p2pdma.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c index 742928d0053e..84ba3058eada 100644 --- a/drivers/pci/p2pdma.c +++ b/drivers/pci/p2pdma.c @@ -18,6 +18,7 @@ #include #include #include +#include struct pci_p2pdma { struct percpu_ref devmap_ref; @@ -284,6 +285,9 @@ static bool root_complex_whitelist(struct pci_dev *dev) struct pci_dev *root = pci_get_slot(host->bus, PCI_DEVFN(0, 0)); unsigned short vendor, device; + if (iommu_present(dev->dev.bus)) + return false; + if (!root) return false;