[Xen-changelog] [xen-unstable] x86: Fix fatal page fault when vram dirty logic handles MMIO of passthrough devices.

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

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1210582861 -3600
# Node ID 14d362d5fa5913a2e917cdd0ca90cf3b898a45d7
# Parent  810d8c3ac992e8979abb2e60cac5cef5ed6ccb36
x86: Fix fatal page fault when vram dirty logic handles MMIO of passthrough 
devices.

Signed-off-by: Qing He <qing.he@xxxxxxxxx>
---
 xen/arch/x86/mm/shadow/multi.c |    6 ++++++
 1 files changed, 6 insertions(+)

diff -r 810d8c3ac992 -r 14d362d5fa59 xen/arch/x86/mm/shadow/multi.c
--- a/xen/arch/x86/mm/shadow/multi.c    Thu May 08 16:58:33 2008 +0100
+++ b/xen/arch/x86/mm/shadow/multi.c    Mon May 12 10:01:01 2008 +0100
@@ -1268,6 +1268,9 @@ static inline void shadow_vram_get_l1e(s
     if ( !d->dirty_vram ) return;
 
     mfn = shadow_l1e_get_mfn(new_sl1e);
+
+    if ( !mfn_valid(mfn) ) return; /* m2p for mmio_direct may not exist */
+
     gfn = mfn_to_gfn(d, mfn);
 
     if ( (gfn >= d->dirty_vram->begin_pfn) && (gfn < d->dirty_vram->end_pfn) ) 
{
@@ -1293,6 +1296,9 @@ static inline void shadow_vram_put_l1e(s
     if ( !d->dirty_vram ) return;
 
     mfn = shadow_l1e_get_mfn(old_sl1e);
+
+    if ( !mfn_valid(mfn) ) return;
+
     gfn = mfn_to_gfn(d, mfn);
 
     if ( (gfn >= d->dirty_vram->begin_pfn) && (gfn < d->dirty_vram->end_pfn) ) 
{

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