diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index d1b3da2960ab65aed69f2427f4f731fde34f242f..b456b048eca9b86467b2069f03e22b7db05c3bfb 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -532,12 +532,13 @@ static bool alloc_p2m(unsigned long pfn)
 	unsigned topidx, mididx;
 	unsigned long ***top_p, **mid;
 	unsigned long *top_mfn_p, *mid_mfn;
+	unsigned long *p2m_orig;
 
 	topidx = p2m_top_index(pfn);
 	mididx = p2m_mid_index(pfn);
 
 	top_p = &p2m_top[topidx];
-	mid = *top_p;
+	mid = ACCESS_ONCE(*top_p);
 
 	if (mid == p2m_mid_missing) {
 		/* Mid level is missing, allocate a new one */
@@ -552,7 +553,7 @@ static bool alloc_p2m(unsigned long pfn)
 	}
 
 	top_mfn_p = &p2m_top_mfn[topidx];
-	mid_mfn = p2m_top_mfn_p[topidx];
+	mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
 
 	BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
 
@@ -579,11 +580,10 @@ static bool alloc_p2m(unsigned long pfn)
 		}
 	}
 
-	if (p2m_top[topidx][mididx] == p2m_identity ||
-	    p2m_top[topidx][mididx] == p2m_missing) {
+	p2m_orig = ACCESS_ONCE(p2m_top[topidx][mididx]);
+	if (p2m_orig == p2m_identity || p2m_orig == p2m_missing) {
 		/* p2m leaf page is missing */
 		unsigned long *p2m;
-		unsigned long *p2m_orig = p2m_top[topidx][mididx];
 
 		p2m = alloc_p2m_page();
 		if (!p2m)