diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
index 53ebc526ae..b538297bb5 100644
--- a/hw/cxl/cxl-mailbox-utils.c
+++ b/hw/cxl/cxl-mailbox-utils.c
@@ -1606,6 +1606,7 @@ static CXLRetCode cmd_dcd_add_dyn_cap_rsp(const struct cxl_cmd *cmd,
 
         cxl_insert_extent_to_extent_list(extent_list, dpa, len, NULL, 0);
         ct3d->dc.total_extent_count += 1;
+        ct3_set_region_block_backed(ct3d, dpa, len);
     }
 
     /*
@@ -1681,17 +1682,20 @@ static CXLRetCode cmd_dcd_release_dyn_cap(const struct cxl_cmd *cmd,
                     found = true;
                     cxl_remove_extent_from_extent_list(extent_list, ent);
                     ct3d->dc.total_extent_count -= 1;
+                    ct3_clear_region_block_backed(ct3d, ent_start_dpa, ent_len);
 
                     if (len1) {
                         cxl_insert_extent_to_extent_list(extent_list,
                                                          ent_start_dpa, len1,
                                                          NULL, 0);
                         ct3d->dc.total_extent_count += 1;
+                        ct3_set_region_block_backed(ct3d, ent_start_dpa, len1);
                     }
                     if (len2) {
                         cxl_insert_extent_to_extent_list(extent_list, dpa + len,
                                                          len2, NULL, 0);
                         ct3d->dc.total_extent_count += 1;
+                        ct3_set_region_block_backed(ct3d, dpa + len, len2);
                     }
                     break;
                 } else {
diff --git a/hw/mem/cxl_type3.c b/hw/mem/cxl_type3.c
index e9c8994cdb..c164cf4580 100644
--- a/hw/mem/cxl_type3.c
+++ b/hw/mem/cxl_type3.c
@@ -672,6 +672,7 @@ static bool cxl_create_dc_regions(CXLType3Dev *ct3d, Error **errp)
 
         region_base += region->len;
         ct3d->dc.total_capacity += region->len;
+        region->blk_bitmap = bitmap_new(region->len / region->block_size);
     }
     QTAILQ_INIT(&ct3d->dc.extents);
     QTAILQ_INIT(&ct3d->dc.extents_pending_to_add);
@@ -682,6 +683,8 @@ static bool cxl_create_dc_regions(CXLType3Dev *ct3d, Error **errp)
 static void cxl_destroy_dc_regions(CXLType3Dev *ct3d)
 {
     CXLDCExtent *ent;
+    int i;
+    CXLDCRegion *region;
 
     while (!QTAILQ_EMPTY(&ct3d->dc.extents)) {
         ent = QTAILQ_FIRST(&ct3d->dc.extents);
@@ -693,6 +696,11 @@ static void cxl_destroy_dc_regions(CXLType3Dev *ct3d)
         cxl_remove_extent_from_extent_list(&ct3d->dc.extents_pending_to_add,
                                            ent);
     }
+
+    for (i = 0; i < ct3d->dc.num_regions; i++) {
+        region = &ct3d->dc.regions[i];
+        g_free(region->blk_bitmap);
+    }
 }
 
 static bool cxl_setup_memory(CXLType3Dev *ct3d, Error **errp)
@@ -924,6 +932,70 @@ static void ct3_exit(PCIDevice *pci_dev)
     }
 }
 
+/*
+ * Mark the DPA range [dpa, dap + len) to be backed and accessible. This
+ * happens when a DC extent is added and accepted by the host.
+ */
+void ct3_set_region_block_backed(CXLType3Dev *ct3d, uint64_t dpa,
+                                 uint64_t len)
+{
+    CXLDCRegion *region;
+
+    region = cxl_find_dc_region(ct3d, dpa, len);
+    if (!region) {
+        return;
+    }
+
+    bitmap_set(region->blk_bitmap, (dpa - region->base) / region->block_size,
+               len / region->block_size);
+}
+
+/*
+ * Check whether the DPA range [dpa, dpa + len) is backed with DC extents.
+ * Used when validating read/write to dc regions
+ */
+bool ct3_test_region_block_backed(CXLType3Dev *ct3d, uint64_t dpa,
+                                  uint64_t len)
+{
+    CXLDCRegion *region;
+    uint64_t nbits;
+    long nr;
+
+    region = cxl_find_dc_region(ct3d, dpa, len);
+    if (!region) {
+        return false;
+    }
+
+    nr = (dpa - region->base) / region->block_size;
+    nbits = DIV_ROUND_UP(len, region->block_size);
+    /*
+     * if bits between [dpa, dpa + len) are all 1s, meaning the DPA range is
+     * backed with DC extents, return true; else return false.
+     */
+    return find_next_zero_bit(region->blk_bitmap, nr + nbits, nr) == nr + nbits;
+}
+
+/*
+ * Mark the DPA range [dpa, dap + len) to be unbacked and inaccessible. This
+ * happens when a dc extent is released by the host.
+ */
+void ct3_clear_region_block_backed(CXLType3Dev *ct3d, uint64_t dpa,
+                                   uint64_t len)
+{
+    CXLDCRegion *region;
+    uint64_t nbits;
+    long nr;
+
+    region = cxl_find_dc_region(ct3d, dpa, len);
+    if (!region) {
+        return;
+    }
+
+    nr = (dpa - region->base) / region->block_size;
+    nbits = len / region->block_size;
+    bitmap_clear(region->blk_bitmap, nr, nbits);
+}
+
 static bool cxl_type3_dpa(CXLType3Dev *ct3d, hwaddr host_addr, uint64_t *dpa)
 {
     int hdm_inc = R_CXL_HDM_DECODER1_BASE_LO - R_CXL_HDM_DECODER0_BASE_LO;
@@ -1029,6 +1101,10 @@ static int cxl_type3_hpa_to_as_and_dpa(CXLType3Dev *ct3d,
         *as = &ct3d->hostpmem_as;
         *dpa_offset -= vmr_size;
     } else {
+        if (!ct3_test_region_block_backed(ct3d, *dpa_offset, size)) {
+            return -ENODEV;
+        }
+
         *as = &ct3d->dc.host_dc_as;
         *dpa_offset -= (vmr_size + pmr_size);
     }
diff --git a/include/hw/cxl/cxl_device.h b/include/hw/cxl/cxl_device.h
index b524c5e699..b213149de2 100644
--- a/include/hw/cxl/cxl_device.h
+++ b/include/hw/cxl/cxl_device.h
@@ -450,6 +450,7 @@ typedef struct CXLDCRegion {
     uint64_t block_size;
     uint32_t dsmadhandle;
     uint8_t flags;
+    unsigned long *blk_bitmap;
 } CXLDCRegion;
 
 struct CXLType3Dev {
@@ -557,4 +558,10 @@ void cxl_insert_extent_to_extent_list(CXLDCExtentList *list, uint64_t dpa,
                                       uint16_t shared_seq);
 bool test_any_bits_set(const unsigned long *addr, unsigned long nr,
                        unsigned long size);
+void ct3_set_region_block_backed(CXLType3Dev *ct3d, uint64_t dpa,
+                                 uint64_t len);
+void ct3_clear_region_block_backed(CXLType3Dev *ct3d, uint64_t dpa,
+                                   uint64_t len);
+bool ct3_test_region_block_backed(CXLType3Dev *ct3d, uint64_t dpa,
+                                  uint64_t len);
 #endif
