ACS_Override.patch

diff -rupN linux-3.12-rc6.orig/Documentation/kernel-parameters.txt linux-3.12-rc6/Documentation/kernel-parameters.txt
--- linux-3.12-rc6.orig/Documentation/kernel-parameters.txt 2013-10-19 19:28:15.000000000 +0000
+++ linux-3.12-rc6/Documentation/kernel-parameters.txt  2013-10-23 18:06:02.963749702 +0000
@@ -2454,6 +2454,16 @@ bytes respectively. Such letter suffixes
        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.     [PARIDE]
--- a/drivers/pci/quirks.c  2014-05-30 16:08:19.561232936 +0000
+++ b/drivers/pci/quirks.c  2014-05-30 16:18:44.745241038 +0000
@@ -3423,6 +3423,107 @@
 #endif
 }

+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;
+}
+
 static const struct pci_dev_acs_enabled {
    u16 vendor;
    u16 device;
@@ -3434,6 +3535,7 @@
    { PCI_VENDOR_ID_ATI, 0x439d, pci_quirk_amd_sb_acs },
    { PCI_VENDOR_ID_ATI, 0x4384, pci_quirk_amd_sb_acs },
    { PCI_VENDOR_ID_ATI, 0x4399, pci_quirk_amd_sb_acs },
+   { PCI_ANY_ID, PCI_ANY_ID, pcie_acs_overrides },
    { 0 }
 };