ACS fc27 4.15.0

From wendell Fri Mar  10 15:23:02 2017
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Subject: [PATCH] ACS-patch
From: level1techs <queries@level1techs.com>
Date: Fri,  10 Mar 2017 18:22:12 +0300

This is imperfect and no one should use this. I was able to apply this on
fedora 25/26 kernels "the fedora way" by copying it into the kernel
dir and doing
## scripts/newpatch.sh acs.patch
then
# fedpkg local

It masks (but not fixes) the iommu groups. you will need to add
a line to your /etc/default/grub kernel line something like
pcie_acs_override=downstream pci-stub.ids="1003:1f1f,1003:1f1c"

where the pci-stub.ids are the PCIe IDs you intend to pass through to
your virtual machine.

Fixed for fc27 4.15.0 by Dryparn
---

--- a/drivers/pci/quirks.c	2018-02-01 22:56:44.044737101 +0100
+++ b/drivers/pci/quirks.c	2018-02-01 23:00:37.598646953 +0100
@@ -3394,6 +3394,108 @@
 DECLARE_PCI_FIXUP_CLASS_HEADER(PCI_VENDOR_ID_ATI, PCI_ANY_ID,
 			       PCI_CLASS_DISPLAY_VGA, 8, quirk_no_pm_reset);

+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;
+}
+
+
 /*
  * Thunderbolt controllers with broken MSI hotplug signaling:
  * Entire 1st generation (Light Ridge, Eagle Ridge, Light Peak) and part
@@ -4512,6 +4614,7 @@
 	{ PCI_VENDOR_ID_CAVIUM, PCI_ANY_ID, pci_quirk_cavium_acs },
 	/* APM X-Gene */
 	{ PCI_VENDOR_ID_AMCC, 0xE004, pci_quirk_xgene_acs },
+	{ PCI_ANY_ID, PCI_ANY_ID, pcie_acs_overrides },
 	{ 0 }
 };