[Xen-changelog] Fix cleanup path if an HVM guest fails very early, before direct map is built.

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

# HG changeset patch
# User kaf24@xxxxxxxxxxxxxxxxxxxx
# Node ID 1fd6e9c32b034126128ff4fcd2bb6d209446d146
# Parent  e8d04411931640322013a1f97726ce64137e94ce
Fix cleanup path if an HVM guest fails very early, before direct map is built.

Signed-off-by: Xin Li <xin.b.li@xxxxxxxxx>

diff -r e8d044119316 -r 1fd6e9c32b03 xen/arch/x86/shadow32.c
--- a/xen/arch/x86/shadow32.c   Tue Feb 21 17:19:16 2006
+++ b/xen/arch/x86/shadow32.c   Tue Feb 21 17:21:13 2006
@@ -1110,22 +1110,30 @@
 void shadow_direct_map_clean(struct vcpu *v)
 {
     int i;
+    unsigned long mfn;
+    struct domain *d = v->domain;
     l2_pgentry_t *l2e;
 
-    l2e = map_domain_page(
-      pagetable_get_pfn(v->domain->arch.phys_table));
+    mfn =  pagetable_get_pfn(d->arch.phys_table);
+
+    /*
+     * We may fail very early before direct map is built.
+     */
+    if ( !mfn )
+        return;
+
+    l2e = map_domain_page(mfn);
 
     for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
     {
         if ( l2e_get_flags(l2e[i]) & _PAGE_PRESENT )
             free_domheap_page(mfn_to_page(l2e_get_pfn(l2e[i])));
     }
-
-    free_domheap_page(
-            mfn_to_page(pagetable_get_pfn(v->domain->arch.phys_table)));
+    free_domheap_page(mfn_to_page(mfn));
 
     unmap_domain_page(l2e);
-    v->domain->arch.phys_table = mk_pagetable(0);
+
+    d->arch.phys_table = mk_pagetable(0);
 }
 
 int __shadow_mode_enable(struct domain *d, unsigned int mode)
diff -r e8d044119316 -r 1fd6e9c32b03 xen/arch/x86/shadow_public.c
--- a/xen/arch/x86/shadow_public.c      Tue Feb 21 17:19:16 2006
+++ b/xen/arch/x86/shadow_public.c      Tue Feb 21 17:21:13 2006
@@ -59,12 +59,21 @@
 
 void shadow_direct_map_clean(struct vcpu *v)
 {
+    unsigned long mfn;
+    struct domain *d = v->domain;
     l2_pgentry_t *l2e;
     l3_pgentry_t *l3e;
     int i, j;
 
-    l3e = (l3_pgentry_t *)map_domain_page(
-        pagetable_get_pfn(v->domain->arch.phys_table));
+    mfn = pagetable_get_pfn(d->arch.phys_table);
+
+    /*
+     * We may fail very early before direct map is built.
+     */
+    if ( !mfn )
+        return;
+
+    l3e = (l3_pgentry_t *)map_domain_page(mfn);
 
     for ( i = 0; i < PAE_L3_PAGETABLE_ENTRIES; i++ )
     {
@@ -81,12 +90,11 @@
             free_domheap_page(mfn_to_page(l3e_get_pfn(l3e[i])));
         }
     }
-
-    free_domheap_page(
-        mfn_to_page(pagetable_get_pfn(v->domain->arch.phys_table)));
+    free_domheap_page(mfn_to_page(mfn));
 
     unmap_domain_page(l3e);
-    v->domain->arch.phys_table = mk_pagetable(0);
+
+    d->arch.phys_table = mk_pagetable(0);
 }
 
 /****************************************************************************/

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