[ibex,dv] Add new test for memory integrity errors

This test picks between inserting an integrity error or a bus error
to the response in the case of a memory request from Ibex. Introduces
a control knob `enable_mem_intg_err` which can control the rate of
having integrity errors per request.

This commit also disables checking for double fault alerts in the
scoreboard because they're expected to be seen while simulating and
they don't cause infinite loop problems because every time a memory
response is requested the error causing part is just randomized.
That means Ibex trying to execute same instruction again would have
a chance to succeed this time.

Signed-off-by: Canberk Topal <ctopal@lowrisc.org>

Author: ctopal

dv/uvm/core_ibex/common/ibex_mem_intf_agent/ibex_mem_intf_response_seq_lib.sv

@@ -10,6 +10,7 @@ class ibex_mem_intf_response_seq extends uvm_sequence #(ibex_mem_intf_seq_item);
 
   ibex_mem_intf_seq_item item;
   mem_model              m_mem;
+  bit                    enable_intg_error = 1'b0;
   bit                    enable_error = 1'b0;
   // Used to ensure that whenever inject_error() is called, the very next transaction will inject an
   // error, and that enable_error will not be flipped back to 0 immediately
@@ -64,6 +65,7 @@ class ibex_mem_intf_response_seq extends uvm_sequence #(ibex_mem_intf_seq_item);
       // TODO: Parametrize this. Until then, this needs to be changed manually.
       if (aligned_addr == 32'h8ffffff8) begin
         req.error = 1'b0;
+        enable_intg_error = 1'b0;
       end
       if (req.error) begin
         `DV_CHECK_STD_RANDOMIZE_FATAL(rand_data)
@@ -90,7 +92,10 @@ class ibex_mem_intf_response_seq extends uvm_sequence #(ibex_mem_intf_seq_item);
 
       // If data_was_uninitialized is true then we want to force bad integrity bits: invert the
       // correct ones, which we know will break things for the codes we use.
-      if (data_was_uninitialized) req.intg = ~req.intg;
+      if (data_was_uninitialized || enable_intg_error) begin
+        req.intg = ~req.intg;
+        enable_intg_error = 1'b0;
+      end
 
       `uvm_info(get_full_name(), $sformatf("Response transfer:\n%0s", req.sprint()), UVM_HIGH)
       start_item(req);
@@ -111,6 +116,10 @@ class ibex_mem_intf_response_seq extends uvm_sequence #(ibex_mem_intf_seq_item);
     this.enable_error = 1'b1;
   endfunction
 
+  virtual function void inject_intg_error();
+    this.enable_intg_error = 1'b1;
+  endfunction
+
   virtual function bit get_error_synch();
     return this.error_synch;
   endfunction

dv/uvm/core_ibex/env/core_ibex_env_cfg.sv

@@ -7,6 +7,7 @@ class core_ibex_env_cfg extends uvm_object;
   virtual clk_rst_if              ibex_clk_vif;
   virtual core_ibex_dut_probe_if  ibex_dut_vif;
 
+  bit                           enable_mem_intg_err;
   bit                           enable_irq_single_seq;
   bit                           enable_irq_multiple_seq;
   bit                           enable_irq_nmi_seq;
@@ -31,6 +32,7 @@ class core_ibex_env_cfg extends uvm_object;
   `uvm_object_utils_begin(core_ibex_env_cfg)
     `uvm_field_int(enable_double_fault_detector, UVM_DEFAULT)
     `uvm_field_int(is_double_fault_detected_fatal, UVM_DEFAULT)
+    `uvm_field_int(enable_mem_intg_err,   UVM_DEFAULT)
     `uvm_field_int(enable_irq_single_seq,   UVM_DEFAULT)
     `uvm_field_int(enable_irq_multiple_seq,   UVM_DEFAULT)
     `uvm_field_int(enable_irq_nmi_seq,   UVM_DEFAULT)
@@ -48,6 +50,7 @@ class core_ibex_env_cfg extends uvm_object;
     super.new(name);
     void'($value$plusargs("enable_double_fault_detector=%0d", enable_double_fault_detector));
     void'($value$plusargs("is_double_fault_detected_fatal=%0d", is_double_fault_detected_fatal));
+    void'($value$plusargs("enable_mem_intg_err=%0d", enable_mem_intg_err));
     void'($value$plusargs("enable_irq_single_seq=%0d", enable_irq_single_seq));
     void'($value$plusargs("enable_irq_multiple_seq=%0d", enable_irq_multiple_seq));
     void'($value$plusargs("enable_irq_nmi_seq=%0d", enable_irq_nmi_seq));

dv/uvm/core_ibex/riscv_dv_extension/testlist.yaml

@@ -549,6 +549,27 @@
     +suppress_pmp_setup=1
   rtl_test: core_ibex_mem_error_test
   sim_opts: >
+    +enable_mem_intg_err=0
+    +enable_double_fault_detector=0
+    +require_signature_addr=1
+  compare_opts:
+    compare_final_value_only: 1
+
+- test: riscv_mem_intg_error_test
+  description: >
+    Normal random instruction test, but randomly insert memory load/store integrity errors
+  iterations: 15
+  gen_test: riscv_rand_instr_test
+  gen_opts: >
+    +require_signature_addr=1
+    +instr_cnt=10000
+    +randomize_csr=1
+    +enable_unaligned_load_store=1
+    +suppress_pmp_setup=1
+  rtl_test: core_ibex_mem_error_test
+  sim_opts: >
+    +enable_mem_intg_err=1
+    +enable_double_fault_detector=0
     +require_signature_addr=1
   compare_opts:
     compare_final_value_only: 1

dv/uvm/core_ibex/tb/core_ibex_tb_top.sv

@@ -158,8 +158,9 @@ module core_ibex_tb_top;
   );
 
   // We should never see any alerts triggered in normal testing
-  `ASSERT(NoAlertsTriggered,
+  `ASSERT(NoAlertsTriggered_A,
     !dut_if.alert_minor && !dut_if.alert_major_internal && !dut_if.alert_major_bus, clk, !rst_n)
+  `DV_ASSERT_CTRL("NoAlertsTriggered", core_ibex_tb_top.NoAlertsTriggered_A)
 
   // Data load/store vif connection
   assign data_mem_vif.reset = ~rst_n;

dv/uvm/core_ibex/tests/core_ibex_new_seq_lib.sv

@@ -205,6 +205,13 @@ class memory_error_seq extends core_base_new_seq#(ibex_mem_intf_seq_item);
   bit                          start_seq = 0; // Use this bit to start any unique sequence once
 
   rand error_type_e            err_type = PickErr;
+  rand bit                     inject_intg_err;
+  // CONTROL_KNOB: Configure the rate between seeing an integrity error versus seeing a bus error.
+  int unsigned                 intg_err_pct = 50;
+  constraint inject_intg_err_c {
+     inject_intg_err dist {1 :/ intg_err_pct,
+                           0 :/ 100 - intg_err_pct};
+  }
 
   `uvm_object_utils(memory_error_seq)
   `uvm_declare_p_sequencer(core_ibex_vseqr)
@@ -214,21 +221,39 @@ class memory_error_seq extends core_base_new_seq#(ibex_mem_intf_seq_item);
   endfunction
 
   virtual task send_req();
-    case (err_type)
-      IsideErr: begin
+    `DV_CHECK_MEMBER_RANDOMIZE_FATAL(inject_intg_err)
+    // If we expect to see only bus errors, we can enable this assertion. Otherwise
+    // integrity errors would cause alerts to trigger.
+    `DV_ASSERT_CTRL_REQ("NoAlertsTriggered", intg_err_pct == 0)
+    case ({err_type, inject_intg_err})
+      {IsideErr, 1'b0}: begin
         vseq.instr_intf_seq.inject_error();
       end
-      DsideErr: begin
+      {DsideErr, 1'b0}: begin
         vseq.data_intf_seq.inject_error();
       end
-      PickErr: begin
+      {PickErr, 1'b0}: begin
         `DV_CHECK_STD_RANDOMIZE_FATAL(choose_side)
         if (choose_side) begin
           vseq.instr_intf_seq.inject_error();
         end else begin
           vseq.data_intf_seq.inject_error();
         end
       end
+      {IsideErr, 1'b1}: begin
+        vseq.instr_intf_seq.inject_intg_error();
+      end
+      {DsideErr, 1'b1}: begin
+        vseq.data_intf_seq.inject_intg_error();
+      end
+      {PickErr, 1'b1}: begin
+        `DV_CHECK_STD_RANDOMIZE_FATAL(choose_side)
+        if (choose_side) begin
+          vseq.instr_intf_seq.inject_intg_error();
+        end else begin
+          vseq.data_intf_seq.inject_intg_error();
+        end
+      end
       default: begin
         // DO nothing
       end

dv/uvm/core_ibex/tests/core_ibex_test_lib.sv

@@ -1174,6 +1174,8 @@ class core_ibex_mem_error_test extends core_ibex_directed_test;
     memory_error_seq_h = memory_error_seq::type_id::create("memory_error_seq_h", this);
     `uvm_info(`gfn, "Running core_ibex_mem_error_test", UVM_LOW)
     memory_error_seq_h.vseq = vseq;
+    memory_error_seq_h.iteration_modes = InfiniteRuns;
+    memory_error_seq_h.intg_err_pct = cfg.enable_mem_intg_err ? 75 : 0;
     fork
       begin
         // Wait for the hart to initialize