IOMMU: only try to share IOMMU and HAP tables for domains with P2M.
This makes the check more precise, and brings VTd in line with AMD code.

Signed-off-by: Tim Deegan <tim@xxxxxxx>

diff -r e856f75d327c xen/include/xen/iommu.h
--- a/xen/include/xen/iommu.h	Mon Aug 15 11:22:52 2011 +0100
+++ b/xen/include/xen/iommu.h	Mon Aug 15 11:24:18 2011 +0100
@@ -33,6 +33,9 @@ extern bool_t iommu_snoop, iommu_qinval,
 extern bool_t iommu_hap_pt_share;
 extern bool_t iommu_debug;
 
+/* Does this domain have a P2M table we can use as its IOMMU pagetable? */
+#define iommu_use_hap_pt(d) (paging_mode_hap(d) && iommu_hap_pt_share)
+
 extern struct rangeset *mmio_ro_ranges;
 
 #define domain_hvm_iommu(d)     (&d->arch.hvm_domain.hvm_iommu)
diff -r e856f75d327c xen/drivers/passthrough/amd/iommu_map.c
--- a/xen/drivers/passthrough/amd/iommu_map.c	Mon Aug 15 11:22:52 2011 +0100
+++ b/xen/drivers/passthrough/amd/iommu_map.c	Mon Aug 15 11:24:18 2011 +0100
@@ -581,7 +581,7 @@ int amd_iommu_map_page(struct domain *d,
 
     BUG_ON( !hd->root_table );
 
-    if ( iommu_hap_pt_share && is_hvm_domain(d) )
+    if ( iommu_use_hap_pt(d) )
         return 0;
 
     spin_lock(&hd->mapping_lock);
@@ -624,7 +624,7 @@ int amd_iommu_unmap_page(struct domain *
 
     BUG_ON( !hd->root_table );
 
-    if ( iommu_hap_pt_share && is_hvm_domain(d) )
+    if ( iommu_use_hap_pt(d) )
         return 0;
 
     spin_lock(&hd->mapping_lock);
@@ -723,7 +723,7 @@ void amd_iommu_share_p2m(struct domain *
 
     ASSERT( is_hvm_domain(d) && d->arch.hvm_domain.hap_enabled );
 
-    if ( !iommu_hap_pt_share )
+    if ( !iommu_use_hap_pt(d) )
         return;
 
     pgd_mfn = pagetable_get_mfn(p2m_get_pagetable(p2m_get_hostp2m(d)));
diff -r e856f75d327c xen/drivers/passthrough/amd/pci_amd_iommu.c
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c	Mon Aug 15 11:22:52 2011 +0100
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c	Mon Aug 15 11:24:18 2011 +0100
@@ -21,6 +21,7 @@
 #include <xen/sched.h>
 #include <xen/pci.h>
 #include <xen/pci_regs.h>
+#include <xen/paging.h>
 #include <asm/hvm/iommu.h>
 #include <asm/amd-iommu.h>
 #include <asm/hvm/svm/amd-iommu-proto.h>
@@ -359,7 +360,7 @@ static void deallocate_iommu_page_tables
 {
     struct hvm_iommu *hd  = domain_hvm_iommu(d);
 
-    if ( iommu_hap_pt_share )
+    if ( iommu_use_hap_pt(d) )
         return;
 
     spin_lock(&hd->mapping_lock);
diff -r e856f75d327c xen/drivers/passthrough/iommu.c
--- a/xen/drivers/passthrough/iommu.c	Mon Aug 15 11:22:52 2011 +0100
+++ b/xen/drivers/passthrough/iommu.c	Mon Aug 15 11:24:18 2011 +0100
@@ -177,7 +177,7 @@ int assign_device(struct domain *d, u8 b
     if ( has_arch_pdevs(d) && !need_iommu(d) )
     {
         d->need_iommu = 1;
-        if ( !iommu_hap_pt_share )
+        if ( !iommu_use_hap_pt(d) )
             rc = iommu_populate_page_table(d);
         goto done;
     }
diff -r e856f75d327c xen/drivers/passthrough/vtd/iommu.c
--- a/xen/drivers/passthrough/vtd/iommu.c	Mon Aug 15 11:22:52 2011 +0100
+++ b/xen/drivers/passthrough/vtd/iommu.c	Mon Aug 15 11:24:18 2011 +0100
@@ -1613,7 +1613,7 @@ void iommu_domain_teardown(struct domain
     if ( list_empty(&acpi_drhd_units) )
         return;
 
-    if ( iommu_hap_pt_share )
+    if ( iommu_use_hap_pt(d) )
         return;
 
     spin_lock(&hd->mapping_lock);
@@ -1635,7 +1635,7 @@ static int intel_iommu_map_page(
     int iommu_domid;
 
     /* Do nothing if VT-d shares EPT page table */
-    if ( iommu_hap_pt_share )
+    if ( iommu_use_hap_pt(d) )
         return 0;
 
     /* do nothing if dom0 and iommu supports pass thru */
@@ -1760,7 +1760,7 @@ void iommu_set_pgd(struct domain *d)
 
     ASSERT( is_hvm_domain(d) && d->arch.hvm_domain.hap_enabled );
 
-    if ( !iommu_hap_pt_share )
+    if ( !iommu_use_hap_pt(d) )
         return;
 
     pgd_mfn = pagetable_get_mfn(p2m_get_pagetable(p2m_get_hostp2m(d)));