diff --git a/src/arch/arm/tlb.cc b/src/arch/arm/tlb.cc
index a8216204f8..74624e31ea 100644
--- a/src/arch/arm/tlb.cc
+++ b/src/arch/arm/tlb.cc
@@ -264,6 +264,7 @@ TLB::insert(TlbEntry &entry)
         table[i] = table[i-1];
     table[0] = entry;
 
+    observedPageSizes.insert(entry.N);
     stats.inserts++;
     ppRefills->notify(1);
 }
@@ -314,12 +315,14 @@ TLB::flushAll()
     }
 
     stats.flushTlb++;
+    observedPageSizes.clear();
 }
 
 void
 TLB::flush(const TLBIOp& tlbi_op)
 {
     int x = 0;
+    bool valid_entry = false;
     TlbEntry *te;
     while (x < size) {
         te = &table[x];
@@ -328,10 +331,13 @@ TLB::flush(const TLBIOp& tlbi_op)
             te->valid = false;
             stats.flushedEntries++;
         }
+        valid_entry = valid_entry || te->valid;
         ++x;
     }
 
     stats.flushTlb++;
+    if (!valid_entry)
+        observedPageSizes.clear();
 }
 
 void
diff --git a/src/arch/arm/tlb.hh b/src/arch/arm/tlb.hh
index e42c06d58d..8ede9a331a 100644
--- a/src/arch/arm/tlb.hh
+++ b/src/arch/arm/tlb.hh
@@ -156,6 +156,16 @@ class TLB : public BaseTLB
     int rangeMRU; //On lookup, only move entries ahead when outside rangeMRU
     vmid_t vmid;
 
+    /** Set of observed page sizes in the TLB
+     * We update the set conservatively, therefore allowing
+     * false positives but not false negatives.
+     * This means there could be a stored page size with
+     * no matching TLB entry (e.g. it has been invalidated),
+     * but if the page size is not in the set, we are certain
+     * there is no associated TLB with that size
+     */
+    std::set<Addr> observedPageSizes;
+
   public:
     using Params = ArmTLBParams;
     using Lookup = TlbEntry::Lookup;