diff --git a/iommu_ref_model/libiommu/src/iommu_ats.c b/iommu_ref_model/libiommu/src/iommu_ats.c
index 5669bf3b..2e20c4ef 100644
--- a/iommu_ref_model/libiommu/src/iommu_ats.c
+++ b/iommu_ref_model/libiommu/src/iommu_ats.c
@@ -102,27 +102,43 @@ handle_page_request(
     page_rec_t prec;
     uint8_t L;
     uint16_t PRGI;
-    uint32_t device_id, cause, status, response_code;
+    uint32_t device_id, cause, status, response_code, PRPR;
     uint64_t prec_addr;
     uint64_t pqb;
     uint32_t pqh;
     uint32_t pqt;
 
+    PRPR = 0;
+    device_id =  ( pr->DSV == 1 ) ? (pr->RID | (pr->DSEG << 16)) : pr->RID;
+    if ( g_reg_file.ddtp.iommu_mode == Off ) {
+        cause = 256; // "All inbound transactions disallowed"
+        report_fault(cause, PAGE_REQ_MSG_CODE, 0, PCIE_MESSAGE_REQUEST, 0,
+                     device_id, pr->PV, pr->PID, pr->PRIV);
+        response_code = RESPONSE_FAILURE;
+        goto send_prgr;
+    }
+    if ( g_reg_file.ddtp.iommu_mode == DDT_Bare ) {
+        cause = 260; // "Transaction type disallowed"
+        report_fault(cause, PAGE_REQ_MSG_CODE, 0, PCIE_MESSAGE_REQUEST, 0,
+                     device_id, pr->PV, pr->PID, pr->PRIV);
+        response_code = INVALID_REQUEST;
+        goto send_prgr;
+    }
     // To process a "Page Request" or "Stop Marker" message, the IOMMU first
     // locates the device-context to determine if ATS and PRI are enabled for
     // the requestor. 
-    device_id =  ( pr->DSV == 1 ) ? (pr->RID | (pr->DSEG << 16)) : pr->RID;
     if ( locate_device_context(&DC, device_id, pr->PV, pr->PID, &cause) ) {
         report_fault(cause, PAGE_REQ_MSG_CODE, 0, PCIE_MESSAGE_REQUEST, 0, 
                      device_id, pr->PV, pr->PID, pr->PRIV);
         response_code = RESPONSE_FAILURE;
         goto send_prgr;
     }
+    PRPR = DC.tc.PRPR;
     if ( DC.tc.EN_PRI == 0 ) {
         // 7. if any of the following conditions hold then stop and report
         //    "Transaction type disallowed" (cause = 260).
         //   * Transaction type is a PCIe "Page Request" Message and `DC.tc.EN_PRI` is 0.
-        report_fault(260, PAGE_REQ_MSG_CODE, 0, PCIE_MESSAGE_REQUEST, 0, 
+        report_fault(260, PAGE_REQ_MSG_CODE, 0, PCIE_MESSAGE_REQUEST, DC.tc.DTF,
                      device_id, pr->PV, pr->PID, pr->PRIV);
         response_code = INVALID_REQUEST;
         goto send_prgr;
@@ -286,17 +302,12 @@ handle_page_request(
     // the associated "Page Request" had a PASID.  For IOMMU generated "Page Request 
     // Group Response" with response code set to Response Failure, if the "Page Request" 
     // had a PASID then response is generated with a PASID.
-    if ( response_code == INVALID_REQUEST || response_code == SUCCESS ) {
-        if ( DC.tc.PRPR == 1 ) {
-            prgr.PV = pr->PV;
-            prgr.PID = pr->PID;
-        } else {
-            prgr.PV = 0;
-            prgr.PID = 0;
-        }
-    } else {
+    if ( PRPR == 1 ) {
         prgr.PV = pr->PV;
         prgr.PID = pr->PID;
+    } else {
+        prgr.PV = 0;
+        prgr.PID = 0;
     }
     // PAYLOAD encoding of PRGR is as follows
     //           +0         |      +1         |      +2         |      +3        |
diff --git a/iommu_ref_model/test/test_app.c b/iommu_ref_model/test/test_app.c
index a1bc9a57..860e4876 100644
--- a/iommu_ref_model/test/test_app.c
+++ b/iommu_ref_model/test/test_app.c
@@ -112,6 +112,29 @@ main(void) {
             fail_if( ( check_rsp_and_faults(&req, &rsp, UNSUPPORTED_REQUEST, 256, 0) < 0 ) );
         }
     });
+    pr.MSGCODE = PAGE_REQ_MSG_CODE;
+    pr.TAG = 0;
+    pr.RID = 0x1234;
+    pr.PV = 1;
+    pr.PID = 0xbabec;
+    pr.PRIV = 1;
+    pr.EXEC_REQ = 0;
+    pr.DSV = 1;
+    pr.DSEG = 0x43;
+    pr.PAYLOAD = 0xdeadbeef00000007; // Set last, PRG index = 0
+    exp_msg.MSGCODE = PRGR_MSG_CODE;
+    exp_msg.TAG = 0;
+    exp_msg.RID = 0x1234;
+    exp_msg.PV = 0;
+    exp_msg.PID = 0;
+    exp_msg.PRIV = 0;
+    exp_msg.EXEC_REQ = 0;
+    exp_msg.DSV = 1;
+    exp_msg.DSEG = 0x43;
+    exp_msg.PAYLOAD = (0x1234UL << 48UL) | (RESPONSE_FAILURE << 44UL);
+    handle_page_request(&pr);
+    fail_if( ( exp_msg_received == 0 ) );
+    fail_if( ( check_msg_faults(256, pr.PV, pr.PID, pr.PRIV, 0x431234, PAGE_REQ_MSG_CODE) < 0 ) );
     END_TEST();
 
     START_TEST("Bare mode tests");
@@ -130,6 +153,29 @@ main(void) {
                 fail_if( ( check_rsp_and_faults(&req, &rsp, SUCCESS, 0, 0) < 0 ) );
         }
     });
+    pr.MSGCODE = PAGE_REQ_MSG_CODE;
+    pr.TAG = 0;
+    pr.RID = 0x1234;
+    pr.PV = 0;
+    pr.PID = 0;
+    pr.PRIV = 0;
+    pr.EXEC_REQ = 0;
+    pr.DSV = 1;
+    pr.DSEG = 0x43;
+    pr.PAYLOAD = 0xdeadbeef00000007; // Set last, PRG index = 0
+    exp_msg.MSGCODE = PRGR_MSG_CODE;
+    exp_msg.TAG = 0;
+    exp_msg.RID = 0x1234;
+    exp_msg.PV = 0;
+    exp_msg.PID = 0;
+    exp_msg.PRIV = 0;
+    exp_msg.EXEC_REQ = 0;
+    exp_msg.DSV = 1;
+    exp_msg.DSEG = 0x43;
+    exp_msg.PAYLOAD = (0x1234UL << 48UL) | (INVALID_REQUEST << 44UL);
+    handle_page_request(&pr);
+    fail_if( ( exp_msg_received == 0 ) );
+    fail_if( ( check_msg_faults(260, pr.PV, pr.PID, pr.PRIV, 0x431234, PAGE_REQ_MSG_CODE) < 0 ) );
     // Turn it off
     fail_if( ( enable_iommu(Off) < 0 ) );
     END_TEST();
@@ -2847,8 +2893,8 @@ main(void) {
     exp_msg.MSGCODE = PRGR_MSG_CODE;
     exp_msg.TAG = 0;
     exp_msg.RID = 0x1234;
-    exp_msg.PV = 1;
-    exp_msg.PID = 0xbabec;
+    exp_msg.PV = 0;
+    exp_msg.PID = 0;
     exp_msg.PRIV = 0;
     exp_msg.EXEC_REQ = 0;
     exp_msg.DSV = 1;
@@ -2895,6 +2941,7 @@ main(void) {
     fail_if( ( enable_disable_pq(4, 0) < 0 ) );
     DC.tc.EN_ATS = 1;
     DC.tc.EN_PRI = 1;
+    DC.tc.PRPR = 1;
     write_memory((char *)&DC, DC_addr, 64);
     iodir(INVAL_DDT, 1, 0x112233, 0);
     exp_msg.RID = 0x2233;
@@ -2927,6 +2974,7 @@ main(void) {
     pr.DSEG = 0x11;
     DC.tc.EN_ATS = 1;
     DC.tc.EN_PRI = 1;
+    DC.tc.PRPR = 0;
     write_memory((char *)&DC, DC_addr, 64);
     iodir(INVAL_DDT, 1, 0x112233, 0);
     message_received = 0;