[Xen-devel] [PATCH v2 2/3] VT-d: suppress UR signaling for desktop chipsets

["Jan Beulich" <JBeulich@xxxxxxxx>]

Unsupported Requests can be signaled for malformed writes to the MSI
address region, e.g. due to buggy or malicious DMA set up to that
region. These should normally result in IOMMU faults, but don't on
the desktop chipsets dealt with here.

This is CVE-2013-3495 / XSA-59.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

--- a/xen/drivers/passthrough/vtd/quirks.c
+++ b/xen/drivers/passthrough/vtd/quirks.c
@@ -393,6 +393,8 @@ void __init pci_vtd_quirk(struct pci_dev
     int func = PCI_FUNC(pdev->devfn);
     int pos;
     u32 val;
+    u64 bar;
+    paddr_t pa;
 
     if ( pci_conf_read16(seg, bus, dev, func, PCI_VENDOR_ID) !=
          PCI_VENDOR_ID_INTEL )
@@ -454,5 +456,33 @@ void __init pci_vtd_quirk(struct pci_dev
         printk(XENLOG_INFO "Masked UR signaling on %04x:%02x:%02x.%u\n",
                seg, bus, dev, func);
         break;
+
+    case 0x100: case 0x104: case 0x108: /* Sandybridge */
+    case 0x150: case 0x154: case 0x158: /* Ivybridge */
+    case 0xa04: /* Haswell ULT */
+    case 0xc00: case 0xc04: case 0xc08: /* Haswell */
+        bar = pci_conf_read32(seg, bus, dev, func, 0x6c);
+        bar = (bar << 32) | pci_conf_read32(seg, bus, dev, func, 0x68);
+        pa = bar & 0x7fffff000; /* bits 12...38 */
+        if ( (bar & 1) && pa &&
+             page_is_ram_type(paddr_to_pfn(pa), RAM_TYPE_RESERVED) )
+        {
+            u32 __iomem *va = ioremap(pa, PAGE_SIZE);
+
+            if ( va )
+            {
+                __set_bit(0x1c8 * 8 + 20, va);
+                iounmap(va);
+                printk(XENLOG_INFO "Masked UR signaling on 
%04x:%02x:%02x.%u\n",
+                       seg, bus, dev, func);
+            }
+            else
+                printk(XENLOG_ERR "Could not map %"PRIpaddr" for 
%04x:%02x:%02x.%u\n",
+                       pa, seg, bus, dev, func);
+        }
+        else
+            printk(XENLOG_WARNING "Bogus DMIBAR %#"PRIx64" on 
%04x:%02x:%02x.%u\n",
+                   bar, seg, bus, dev, func);
+        break;
     }
 }

Attachment: VT-d-mask-UR-host-bridge-desktop.patch
Description: Text document

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