diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 2fcad18622eb..e0b014157288 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -5369,6 +5369,21 @@ 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