override_for_missing_acs_capabilities.patch

## override_for_missing_acs_capabilities.patch
diff -uNr linux-4.2.5/Documentation/kernel-parameters.txt linux-4.2.5-acs/Documentation/kernel-parameters.txt
--- linux-4.2.5/Documentation/kernel-parameters.txt	2015-10-26 17:53:59.000000000 -0700
+++ linux-4.2.5-acs/Documentation/kernel-parameters.txt	2015-11-02 18:02:28.643526086 -0800
@@ -2850,6 +2850,16 @@
 		nomsi	Do not use MSI for native PCIe PME signaling (this makes
 			all PCIe root ports use INTx for all services).

+	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
+
 	pcmv=		[HW,PCMCIA] BadgePAD 4

 	pd_ignore_unused
diff -uNr linux-4.2.5/drivers/pci/quirks.c linux-4.2.5-acs/drivers/pci/quirks.c
--- linux-4.2.5/drivers/pci/quirks.c	2015-10-26 17:53:59.000000000 -0700
+++ linux-4.2.5-acs/drivers/pci/quirks.c	2015-11-02 18:02:28.643526086 -0800
@@ -3361,6 +3361,107 @@

 fs_initcall_sync(pci_apply_final_quirks);

+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_overrides(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;
+}
+
 /*
  * Followings are device-specific reset methods which can be used to
  * reset a single function if other methods (e.g. FLR, PM D0->D3) are
@@ -3822,6 +3923,7 @@
 	return acs_flags ? 0 : 1;
 }

+
 static const struct pci_dev_acs_enabled {
 	u16 vendor;
 	u16 device;
@@ -3890,6 +3992,7 @@
 	{ PCI_VENDOR_ID_INTEL, 0x10D9, pci_quirk_mf_endpoint_acs },
 	/* Intel PCH root ports */
 	{ PCI_VENDOR_ID_INTEL, PCI_ANY_ID, pci_quirk_intel_pch_acs },
+	{ PCI_ANY_ID, PCI_ANY_ID, pcie_acs_overrides },
 	{ 0x19a2, 0x710, pci_quirk_mf_endpoint_acs }, /* Emulex BE3-R */
 	{ 0x10df, 0x720, pci_quirk_mf_endpoint_acs }, /* Emulex Skyhawk-R */
 	{ 0 }