[PATCH 5.5 153/399] PCI: Add DMA alias quirk for PLX PEX NTB

From: Greg Kroah-Hartman
Date: Fri Feb 21 2020 - 02:50:29 EST

From: James Sewart <jamessewart@xxxxxxxxxx>

[ Upstream commit 7b90dfc4873b87c468cc6046538f46a531c1d785 ]

The PLX PEX NTB forwards DMA transactions using Requester IDs that don't
exist as PCI devices. The devfn for a transaction is used as an index into
a lookup table storing the origin of a transaction on the other side of the

Alias all possible devfns to the NTB device so that any transaction coming
in is governed by the mappings for the NTB.

Signed-off-by: James Sewart <jamessewart@xxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
drivers/pci/quirks.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 9aa590eb712fe..83953752337c4 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -5371,6 +5371,21 @@ SWITCHTEC_QUIRK(0x8574); /* PFXI 64XG3 */
SWITCHTEC_QUIRK(0x8575); /* PFXI 80XG3 */
SWITCHTEC_QUIRK(0x8576); /* PFXI 96XG3 */

+ * The PLX NTB uses devfn proxy IDs to move TLPs between NT endpoints.
+ * These IDs are used to forward responses to the originator on the other
+ * side of the NTB. Alias all possible IDs to the NTB to permit access when
+ * the IOMMU is turned on.
+ */
+static void quirk_plx_ntb_dma_alias(struct pci_dev *pdev)
+ pci_info(pdev, "Setting PLX NTB proxy ID aliases\n");
+ /* PLX NTB may use all 256 devfns */
+ pci_add_dma_alias(pdev, 0, 256);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_PLX, 0x87b0, quirk_plx_ntb_dma_alias);
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_PLX, 0x87b1, quirk_plx_ntb_dma_alias);
* On Lenovo Thinkpad P50 SKUs with a Nvidia Quadro M1000M, the BIOS does
* not always reset the secondary Nvidia GPU between reboots if the system