vt-d: for 32-bit Xen, we disable VT-d table output on DMA page faults.

This changeset is back-ported from xen-unstable.
The original description of the changeset is:

vt-d: Disable VT-d table output on DMA page faults

Printing VT-d tables requires map_domain_page() which can not be
called from interrupt context (on x86_32).

Signed-off-by: Espen Skoglund <espen.skoglund@netronome.com>
xen-unstable changeset: 18066:cec304746b360d0fccb2ab3944787bfb912902cb
xen-unstable date: Wed Jul 16 11:15:14 2008 +0100


Considering Xen 3.2, for 32-bit Xen, maddr_to_virt() can not be used
in print_vtd_entries() since the pages (except the pgd) are allocated
from domheap.

Signed-off-by: Dexuan Cui <dexuan.cui@intel.com>

diff -r 9ed6fe0070ce -r 6d920337b363 xen/arch/x86/hvm/vmx/vtd/intel-iommu.c
--- a/xen/arch/x86/hvm/vmx/vtd/intel-iommu.c	Fri Jul 18 11:30:29 2008 +0100
+++ b/xen/arch/x86/hvm/vmx/vtd/intel-iommu.c	Fri Jul 25 19:12:36 2008 +0800
@@ -758,8 +758,13 @@ static int iommu_page_fault_do_one(struc
             (source_id >> 8), PCI_SLOT(source_id & 0xFF),
             PCI_FUNC(source_id & 0xFF), addr, fault_reason);
 
+ /* For 32-bit Xen, maddr_to_virt() can not be used in print_vtd_entries()
+  * since the pages (except the pgd) are allocated from domheap.
+  */
+#ifndef __i386__
     print_vtd_entries(current->domain, (source_id >> 8),(source_id & 0xff),
                       (addr >> PAGE_SHIFT)); 
+#endif
     return 0;
 }