[Xen-changelog] [xen-unstable] VT-d: improve RMRR validity checking

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1264235004 0
# Node ID 7d65247d5f067ac745a73f62696408ad2589fecf
# Parent  4978b4a4bbb69171abc9e92fddaa2b61189a177f
VT-d: improve RMRR validity checking

In order to make Xen more defensive to VT-d related BIOS issue, this
patch ignores a DRHD if all devices under its scope are not pci
discoverable, and regards a DRHD as invalid and then disable whole
VT-d if some devices under its scope are not pci discoverable. But if
iommu=force is set, it will enable all DRHDs reported by BIOS, to
avoid any security vulnerability with malicious s/s re-enabling
"supposed disabled" devices.  Pls note that we don't know the devices
under the "Include_all" DRHD are existent or not, because the scope of
"Include_all" DRHD won't enumerate common pci device, it only
enumerates I/OxAPIC and HPET devices.

Signed-off-by: Noboru Iwamatsu <n_iwamatsu@xxxxxxxxxxxxxx>
Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
---
 xen/drivers/passthrough/vtd/dmar.c |   43 ++++++++++++++++++++++++++++++++++++-
 1 files changed, 42 insertions(+), 1 deletion(-)

diff -r 4978b4a4bbb6 -r 7d65247d5f06 xen/drivers/passthrough/vtd/dmar.c
--- a/xen/drivers/passthrough/vtd/dmar.c        Fri Jan 22 13:32:26 2010 +0000
+++ b/xen/drivers/passthrough/vtd/dmar.c        Sat Jan 23 08:23:24 2010 +0000
@@ -396,8 +396,49 @@ acpi_parse_one_drhd(struct acpi_dmar_ent
 
     if ( ret )
         xfree(dmaru);
+    else if ( force_iommu || dmaru->include_all )
+        acpi_register_drhd_unit(dmaru);
     else
-        acpi_register_drhd_unit(dmaru);
+    {
+        u8 b, d, f;
+        int i, invalid_cnt = 0;
+
+        for ( i = 0; i < dmaru->scope.devices_cnt; i++ )
+        {
+            b = PCI_BUS(dmaru->scope.devices[i]);
+            d = PCI_SLOT(dmaru->scope.devices[i]);
+            f = PCI_FUNC(dmaru->scope.devices[i]);
+
+            if ( pci_device_detect(b, d, f) == 0 )
+            {
+                dprintk(XENLOG_WARNING VTDPREFIX,
+                    "  Non-existent device (%x:%x.%x) is reported "
+                    "in this DRHD's scope!\n", b, d, f);
+                invalid_cnt++;
+            }
+        }
+
+        if ( invalid_cnt )
+        {
+            xfree(dmaru);
+            if ( invalid_cnt == dmaru->scope.devices_cnt )
+            {
+                dprintk(XENLOG_WARNING VTDPREFIX,
+                    "  Ignore the DRHD due to all devices under "
+                    "its scope are not PCI discoverable!\n");
+            }
+            else
+            {
+                dprintk(XENLOG_WARNING VTDPREFIX,
+                    "  The DRHD is invalid due to some devices under "
+                    "its scope are not PCI discoverable!\n");
+                ret = -EINVAL;
+            }
+        }
+        else
+            acpi_register_drhd_unit(dmaru);
+    }
+
     return ret;
 }
 

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