Re: [Xen-devel] Xen crash on HVM shutdown [PATCH]

[Gianluca Guida <gianluca.guida@xxxxxxxxxxxxx>]

Hello,

Sorry for the late reply. Sending emails is sometimes more  
complicated than what you expect.
On Jun 25, 2008, at 3:17 PM, Christoph Egger wrote:


> It looks to me, the recent L1 shadow changesets introduced a bug.
Yes. This bug is triggered when the guest shuts down with pages still  
OOS (e.g., paging still enabled and  recently touched L1s pagetables,  
or supposedly so). I unfortunately could not reproduce it, but the  
inline patch should fix this.
Thanks!
Gianluca

Signed-off-by: Gianluca Guida <gianluca.guida@xxxxxxxxxxxxx>

diff -r 2be3c309e446 xen/arch/x86/mm/shadow/common.c
--- a/xen/arch/x86/mm/shadow/common.c   Wed Jun 25 13:39:14 2008 -0400
+++ b/xen/arch/x86/mm/shadow/common.c   Wed Jun 25 14:54:34 2008 -0400
@@ -630,6 +630,11 @@
     struct domain *d = v->domain;

     perfc_incr(shadow_oos_fixup_remove);
+
+    /* If the domain is dying we might get called when deallocating
+     * the shadows. Fixup tables are already freed so exit now. */
+    if (d->is_dying)
+        return;

     idx = mfn_x(gmfn) % SHADOW_OOS_FT_HASH;
     for_each_vcpu(d, v)
@@ -3168,6 +3173,7 @@
         {
             free_xenheap_pages(v->arch.paging.shadow.oos_fixups,
                                SHADOW_OOS_FT_ORDER);
+            v->arch.paging.shadow.oos_fixups = NULL;
         }

         {


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