override_for_missing_acs_capabilities.patch

PCIe ACS Override
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3238,6 +3238,16 @@
 				conflict with unreported devices), so this
 				taints the kernel.
 
+        pcie_acs_override=
+                        [PCIE] Override missing PCIe ACS support for:
+                downstream
+                        All downstream ports - full ACS capabilties
+                multifunction
+                        All multifunction devices - multifunction ACS subset
+                id:nnnn:nnnn
+                        Specfic device - full ACS capabilities
+                        Specified as vid:did (vendor/device ID) in hex
+
 	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
 			Management.
 		off	Disable ASPM.
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3534,6 +3534,111 @@
 fs_initcall_sync(pci_apply_final_quirks);
 
 /*
+ * PCIe ACS Override
+ */
+static bool acs_on_downstream;
+static bool acs_on_multifunction;
+
+#define NUM_ACS_IDS 16
+struct acs_on_id {
+	unsigned short vendor;
+	unsigned short device;
+};
+static struct acs_on_id acs_on_ids[NUM_ACS_IDS];
+static u8 max_acs_id;
+
+static __init int pcie_acs_override_setup(char *p)
+{
+	if (!p)
+		return -EINVAL;
+
+	while (*p) {
+		if (!strncmp(p, "downstream", 10))
+			acs_on_downstream = true;
+		if (!strncmp(p, "multifunction", 13))
+			acs_on_multifunction = true;
+		if (!strncmp(p, "id:", 3)) {
+			char opt[5];
+			int ret;
+			long val;
+
+			if (max_acs_id >= NUM_ACS_IDS - 1) {
+				pr_warn("Out of PCIe ACS override slots (%d)\n",
+					NUM_ACS_IDS);
+				goto next;
+			}
+
+			p += 3;
+			snprintf(opt, 5, "%s", p);
+			ret = kstrtol(opt, 16, &val);
+			if (ret) {
+				pr_warn("PCIe ACS ID parse error %d\n", ret);
+				goto next;
+			}
+			acs_on_ids[max_acs_id].vendor = val;
+
+			p += strcspn(p, ":");
+			if (*p != ':') {
+				pr_warn("PCIe ACS invalid ID\n");
+				goto next;
+			}
+
+			p++;
+			snprintf(opt, 5, "%s", p);
+			ret = kstrtol(opt, 16, &val);
+			if (ret) {
+				pr_warn("PCIe ACS ID parse error %d\n", ret);
+				goto next;
+			}
+			acs_on_ids[max_acs_id].device = val;
+			max_acs_id++;
+		}
+next:
+		p += strcspn(p, ",");
+		if (*p == ',')
+			p++;
+	}
+
+	if (acs_on_downstream || acs_on_multifunction || max_acs_id)
+		pr_warn("Warning: PCIe ACS overrides enabled; This may allow non-IOMMU protected peer-to-peer DMA\n");
+
+	return 0;
+}
+
+early_param("pcie_acs_override", pcie_acs_override_setup);
+
+static int pcie_acs_override_enabled(struct pci_dev *dev, u16 acs_flags)
+{
+	int i;
+
+	/* Never override ACS for legacy devices or devices with ACS caps */
+	if (!pci_is_pcie(dev) ||
+	    pci_find_ext_capability(dev, PCI_EXT_CAP_ID_ACS))
+		return -ENOTTY;
+
+	for (i = 0; i < max_acs_id; i++)
+		if (acs_on_ids[i].vendor == dev->vendor &&
+		    acs_on_ids[i].device == dev->device)
+			return 1;
+
+	switch (pci_pcie_type(dev)) {
+	case PCI_EXP_TYPE_DOWNSTREAM:
+	case PCI_EXP_TYPE_ROOT_PORT:
+		if (acs_on_downstream)
+			return 1;
+		break;
+	case PCI_EXP_TYPE_ENDPOINT:
+	case PCI_EXP_TYPE_UPSTREAM:
+	case PCI_EXP_TYPE_LEG_END:
+	case PCI_EXP_TYPE_RC_END:
+		if (acs_on_multifunction && dev->multifunction)
+			return 1;
+	}
+
+	return -ENOTTY;
+}
+
+/*
  * Following are device-specific reset methods which can be used to
  * reset a single function if other methods (e.g. FLR, PM D0->D3) are
  * not available.
@@ -4426,6 +4531,11 @@
 		}
 	}
 
+	/* ACS Override */
+	ret = pcie_acs_override_enabled(dev, acs_flags);
+	if (ret >= 0)
+		return ret;
+
 	return -ENOTTY;
 }