[Xen-changelog] [xen-3.2-testing] VT-d: remove Xen and tboot range from dom0's VT-d table

["Xen patchbot-3.2-testing" <patchbot-3.2-testing@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1216376969 -3600
# Node ID f3eb066168077c721d40a9d7966a8b6e74d379c1
# Parent  d6a15d8605c36d483d6a2599c899b48c9478a75a
VT-d: remove Xen and tboot range from dom0's VT-d table

This a step forward to fix the security hole introduced by dom0's 1:1
mapping VT-d table: remove the critical code and data from it. The
more flexible solution is to update dom0's VT-d table on demand as
what will be done for other PV domains. However, there could bring a
performance issue even with software optimization. Iotlb flush of some
hardware is time-consuming.

Signed-off-by: Yang, Xiaowei <xiaowei.yang@xxxxxxxxx>
xen-unstable changeset 17725:c0c0f4fa88509b6f5e4fa9bf0687c7a6df53eeb8
xen-unstable date: Mon May 26 08:24:55 2008 +0100

----------------------------------------------------------------------

Fix 17725:c0c0f4fa8850: use type paddr_t instead of unsigned long for
physcial memory address Otherwise, the address overflows on PAE system
with memory size > 4G.

Signed-off-by: Yang, Xiaowei <xiaowei.yang@xxxxxxxxx>
xen-unstable changeset 17734:e265878e8f657ca532ebe98b5bac233f395f2814
xen-unstable date: Tue May 27 10:35:10 2008 +0100
---
 xen/arch/x86/hvm/vmx/vtd/intel-iommu.c |   16 ++++++++++++++--
 xen/arch/x86/setup.c                   |    8 ++++++++
 xen/arch/x86/tboot.c                   |   12 ++++++++++++
 3 files changed, 34 insertions(+), 2 deletions(-)

diff -r d6a15d8605c3 -r f3eb06616807 xen/arch/x86/hvm/vmx/vtd/intel-iommu.c
--- a/xen/arch/x86/hvm/vmx/vtd/intel-iommu.c    Fri Jul 18 11:28:58 2008 +0100
+++ b/xen/arch/x86/hvm/vmx/vtd/intel-iommu.c    Fri Jul 18 11:29:29 2008 +0100
@@ -1788,7 +1788,7 @@ int iommu_setup(void)
     struct hvm_iommu *hd  = domain_hvm_iommu(dom0);
     struct acpi_drhd_unit *drhd;
     struct iommu *iommu;
-    unsigned long i;
+    u64 i;
 
     if ( !vtd_enabled )
         return 0;
@@ -1814,9 +1814,21 @@ int iommu_setup(void)
     memset(domid_bitmap, 0, domid_bitmap_size / 8);
     set_bit(0, domid_bitmap);
 
-    /* setup 1:1 page table for dom0 */
+    /*
+     * Set up 1:1 page table for dom0 except the critical segments
+     * like Xen and tboot.
+     */
     for ( i = 0; i < max_page; i++ )
+    {
+        extern int xen_in_range(paddr_t start, paddr_t end);
+        extern int tboot_in_range(paddr_t start, paddr_t end);
+
+        if ( xen_in_range(i << PAGE_SHIFT_4K, (i + 1) << PAGE_SHIFT_4K) ||
+            tboot_in_range(i << PAGE_SHIFT_4K, (i + 1) << PAGE_SHIFT_4K) )
+            continue;
+
         iommu_map_page(dom0, i, i);
+    }
 
     if ( init_vtd_hw() )
         goto error;
diff -r d6a15d8605c3 -r f3eb06616807 xen/arch/x86/setup.c
--- a/xen/arch/x86/setup.c      Fri Jul 18 11:28:58 2008 +0100
+++ b/xen/arch/x86/setup.c      Fri Jul 18 11:29:29 2008 +0100
@@ -1082,6 +1082,14 @@ void arch_get_xen_caps(xen_capabilities_
 #endif
 }
 
+int xen_in_range(paddr_t start, paddr_t end)
+{
+    start = max_t(paddr_t, start, xenheap_phys_start);
+    end = min_t(paddr_t, end, xenheap_phys_end);
+ 
+    return start < end; 
+}
+
 /*
  * Local variables:
  * mode: C
diff -r d6a15d8605c3 -r f3eb06616807 xen/arch/x86/tboot.c
--- a/xen/arch/x86/tboot.c      Fri Jul 18 11:28:58 2008 +0100
+++ b/xen/arch/x86/tboot.c      Fri Jul 18 11:29:29 2008 +0100
@@ -96,6 +96,18 @@ int tboot_in_measured_env(void)
     return (g_tboot_shared != NULL);
 }
 
+int tboot_in_range(paddr_t start, paddr_t end)
+{
+    if ( g_tboot_shared == NULL || g_tboot_shared->version < 0x02 )
+        return 0;
+
+    start = max_t(paddr_t, start, g_tboot_shared->tboot_base);
+    end = min_t(paddr_t, end, 
+                g_tboot_shared->tboot_base + g_tboot_shared->tboot_size);
+ 
+    return start < end; 
+}
+
 /*
  * Local variables:
  * mode: C

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