[Xen-devel] [v3][PATCH 16/16] xen/vtd: prevent from assign the device with shared rmrr

[Tiejun Chen <tiejun.chen@xxxxxxxxx>]

Currently we're intending to cover this kind of devices
with shared RMRR simply since the case of shared RMRR is
a rare case according to our previous experiences. But
late we can group these devices which shared rmrr, and
then allow all devices within a group to be assigned to
same domain.

Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
---
 xen/drivers/passthrough/vtd/iommu.c | 30 +++++++++++++++++++++++++++---
 1 file changed, 27 insertions(+), 3 deletions(-)

diff --git a/xen/drivers/passthrough/vtd/iommu.c 
b/xen/drivers/passthrough/vtd/iommu.c
index d3233b8..f220081 100644
--- a/xen/drivers/passthrough/vtd/iommu.c
+++ b/xen/drivers/passthrough/vtd/iommu.c
@@ -2277,13 +2277,37 @@ static int intel_iommu_assign_device(
     if ( list_empty(&acpi_drhd_units) )
         return -ENODEV;
 
+    seg = pdev->seg;
+    bus = pdev->bus;
+    /*
+     * In rare cases one given rmrr is shared by multiple devices but
+     * obviously this would put the security of a system at risk. So
+     * we should prevent from this sort of device assignment.
+     *
+     * TODO: actually we can group these devices which shared rmrr, and
+     * then allow all devices within a group to be assigned to same domain.
+     */
+    for_each_rmrr_device( rmrr, bdf, i )
+    {
+        if ( rmrr->segment == seg &&
+             PCI_BUS(bdf) == bus &&
+             PCI_DEVFN2(bdf) == devfn )
+        {
+            if ( rmrr->scope.devices_cnt > 1 )
+            {
+                ret = -EPERM;
+                printk(XENLOG_G_ERR VTDPREFIX
+                       " cannot assign this device with shared RMRR for Dom%d 
(%d)\n",
+                       d->domain_id, ret);
+                return ret;
+            }
+        }
+    }
+
     ret = reassign_device_ownership(hardware_domain, d, devfn, pdev);
     if ( ret )
         return ret;
 
-    seg = pdev->seg;
-    bus = pdev->bus;
-
     /* Setup rmrr identity mapping */
     for_each_rmrr_device( rmrr, bdf, i )
     {
-- 
1.9.1


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel