Handle PoD case in hvm_hap_nested_page_fault()

The new combined nested page fault handling doesn't consider the case
where the gfn_to_mfn() translation caused the page to be transparently
populated.

Signed-off-by: George Dunlap <george.dunlap@eu.citrix.com>
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 3109a6df03256c24bdf0c905ede07f19a475c5e6..3bfe57cec40e873246a1c47d3f70852dfe6abe70 100644 (file)
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -951,15 +951,6 @@ bool_t hvm_hap_nested_page_fault(unsigned long gfn)
     if ( p2m_is_paged(p2mt) || (p2mt == p2m_ram_paging_out) )
         p2m_mem_paging_populate(current->domain, gfn);
 
-    /* Log-dirty: mark the page dirty and let the guest write it again */
-    if ( paging_mode_log_dirty(current->domain)
-         && p2m_is_ram(p2mt) && (p2mt != p2m_ram_ro) )
-    {
-        paging_mark_dirty(current->domain, mfn_x(mfn));
-        p2m_change_type(current->domain, gfn, p2m_ram_logdirty, p2m_ram_rw);
-        return 1;
-    }
-
     /* Mem sharing: unshare the page and try again */
     if ( p2mt == p2m_ram_shared )
     {
@@ -967,6 +958,14 @@ bool_t hvm_hap_nested_page_fault(unsigned long gfn)
         return 1;
     }
  
+    /* Spurious fault? PoD and log-dirty also take this path. */
+    if ( p2m_is_ram(p2mt) )
+    {
+        paging_mark_dirty(current->domain, mfn_x(mfn));
+        p2m_change_type(current->domain, gfn, p2m_ram_logdirty, p2m_ram_rw);
+        return 1;
+    }
+
     /* Shouldn't happen: Maybe the guest was writing to a r/o grant mapping? */
     if ( p2mt == p2m_grant_map_ro )
     {