[Xen-changelog] [xen-unstable] Handle PoD case in hvm_hap_nested_page_fault()

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1262781923 0
# Node ID cba56c13ca3eba67a3b56e78256418fd62445a95
# Parent  a1d0a575b4bace0a79ecfb48704b24fc9ae7866b
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@xxxxxxxxxxxxx>
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c |   19 +++++++++----------
 1 files changed, 9 insertions(+), 10 deletions(-)

diff -r a1d0a575b4ba -r cba56c13ca3e xen/arch/x86/hvm/hvm.c
--- a/xen/arch/x86/hvm/hvm.c    Wed Jan 06 10:13:55 2010 +0000
+++ b/xen/arch/x86/hvm/hvm.c    Wed Jan 06 12:45:23 2010 +0000
@@ -951,22 +951,21 @@ bool_t hvm_hap_nested_page_fault(unsigne
     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) )
+    /* Mem sharing: unshare the page and try again */
+    if ( p2mt == p2m_ram_shared )
+    {
+        mem_sharing_unshare_page(current->domain, gfn, 0);
+        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;
     }
 
-    /* Mem sharing: unshare the page and try again */
-    if ( p2mt == p2m_ram_shared )
-    {
-        mem_sharing_unshare_page(current->domain, gfn, 0);
-        return 1;
-    }
- 
     /* Shouldn't happen: Maybe the guest was writing to a r/o grant mapping? */
     if ( p2mt == p2m_grant_map_ro )
     {

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