diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 6366b5fbb3a4..cdc1f4736a11 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5962,6 +5962,23 @@ static bool intel_iommu_is_attach_deferred(struct iommu_domain *domain,
 	return dev->archdata.iommu == DEFER_DEVICE_DOMAIN_INFO;
 }
 
+/*
+ * Check that the device does not live on an external facing PCI port that is
+ * marked as untrusted. Such devices should not be able to apply quirks and
+ * thus not be able to bypass the IOMMU restrictions.
+ */
+static bool risky_device(struct pci_dev *pdev)
+{
+	if (pdev->untrusted) {
+		pci_info(pdev,
+			 "Skipping IOMMU quirk for dev [%04X:%04X] on untrusted PCI link\n",
+			 pdev->vendor, pdev->device);
+		pci_info(pdev, "Please check with your BIOS/Platform vendor about this\n");
+		return true;
+	}
+	return false;
+}
+
 const struct iommu_ops intel_iommu_ops = {
 	.capable		= intel_iommu_capable,
 	.domain_alloc		= intel_iommu_domain_alloc,
@@ -5990,6 +6007,9 @@ const struct iommu_ops intel_iommu_ops = {
 
 static void quirk_iommu_igfx(struct pci_dev *dev)
 {
+	if (risky_device(dev))
+		return;
+
 	pci_info(dev, "Disabling IOMMU for graphics on this chipset\n");
 	dmar_map_gfx = 0;
 }
@@ -6031,6 +6051,9 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x163D, quirk_iommu_igfx);
 
 static void quirk_iommu_rwbf(struct pci_dev *dev)
 {
+	if (risky_device(dev))
+		return;
+
 	/*
 	 * Mobile 4 Series Chipset neglects to set RWBF capability,
 	 * but needs it. Same seems to hold for the desktop versions.
@@ -6061,6 +6084,9 @@ static void quirk_calpella_no_shadow_gtt(struct pci_dev *dev)
 {
 	unsigned short ggc;
 
+	if (risky_device(dev))
+		return;
+
 	if (pci_read_config_word(dev, GGC, &ggc))
 		return;
 
@@ -6094,6 +6120,12 @@ static void __init check_tylersburg_isoch(void)
 	pdev = pci_get_device(PCI_VENDOR_ID_INTEL, 0x3a3e, NULL);
 	if (!pdev)
 		return;
+
+	if (risky_device(pdev)) {
+		pci_dev_put(pdev);
+		return;
+	}
+
 	pci_dev_put(pdev);
 
 	/* System Management Registers. Might be hidden, in which case
@@ -6103,6 +6135,11 @@ static void __init check_tylersburg_isoch(void)
 	if (!pdev)
 		return;
 
+	if (risky_device(pdev)) {
+		pci_dev_put(pdev);
+		return;
+	}
+
 	if (pci_read_config_dword(pdev, 0x188, &vtisochctrl)) {
 		pci_dev_put(pdev);
 		return;