[PATCH for-next v2 01/10] x86/mm: make free_perdomain_mappings idempotent

[Wei Liu <wei.liu2@citrix.com>]

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
Cc: Tim Deegan <tim@xen.org>
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
---
 xen/arch/x86/mm.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index bd68e56dc7..cdef5c49c4 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -6503,9 +6503,14 @@ void destroy_perdomain_mapping(struct domain *d, unsigned long va,
 
 void free_perdomain_mappings(struct domain *d)
 {
-    l3_pgentry_t *l3tab = __map_domain_page(d->arch.perdomain_l3_pg);
+    l3_pgentry_t *l3tab;
     unsigned int i;
 
+    if ( !d->arch.perdomain_l3_pg )
+        return;
+
+    l3tab = __map_domain_page(d->arch.perdomain_l3_pg);
+
     for ( i = 0; i < PERDOMAIN_SLOTS; ++i)
         if ( l3e_get_flags(l3tab[i]) & _PAGE_PRESENT )
         {
@@ -6544,6 +6549,7 @@ void free_perdomain_mappings(struct domain *d)
 
     unmap_domain_page(l3tab);
     free_domheap_page(d->arch.perdomain_l3_pg);
+    d->arch.perdomain_l3_pg = NULL;
 }
 
 #ifdef MEMORY_GUARD
-- 
2.11.0


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