Merge branch 'main' of github.com:davidharrishmc/riscv-wally into main

wally-pipelined/src/ifu/ifu.sv

@@ -98,8 +98,6 @@ module ifu (
   logic 	    reset_q; // *** look at this later.
 
   logic 	    BPPredDirWrongE, BTBPredPCWrongE, RASPredPCWrongE, BPPredClassNonCFIWrongE;
-
-  logic 	    PMPInstrAccessFaultF, PMAInstrAccessFaultF;
   
   logic [`PA_BITS-1:0] PCPFmmu, PCNextFPhys; // used to either truncate or expand PCPF and PCNextF into `PA_BITS width.
   logic [`XLEN+1:0]    PCFExt;

wally-pipelined/src/mmu/tlbcontrol.sv

@@ -78,7 +78,7 @@ module tlbcontrol #(parameter ITLB = 0) (
   endgenerate
 
   // Determine whether TLB is being used
-  assign TLBAccess = ReadAccess || WriteAccess;
+  assign TLBAccess = ReadAccess | WriteAccess;
 
   // Check whether upper bits of virtual addresss are all equal
 
@@ -120,5 +120,5 @@ module tlbcontrol #(parameter ITLB = 0) (
   endgenerate
 
   assign TLBHit = CAMHit & TLBAccess;
-  assign TLBMiss = ~CAMHit & ~TLBFlush & Translate & TLBAccess;
+  assign TLBMiss = (~CAMHit | TLBFlush) & Translate & TLBAccess;
 endmodule

wally-pipelined/src/privileged/privileged.sv

@@ -102,6 +102,7 @@ module privileged (
   logic       STATUS_MIE, STATUS_SIE;
   logic [11:0] MIP_REGW, MIE_REGW, SIP_REGW, SIE_REGW;
   logic md, sd;
+  logic       StallMQ;
 
 
   ///////////////////////////////////////////
@@ -157,8 +158,16 @@ module privileged (
 
   assign BreakpointFaultM = ebreakM; // could have other causes too
   assign EcallFaultM = ecallM;
-  assign ITLBFlushF = sfencevmaM;
+
+  flopr #(1) StallMReg(.clk, .reset, .d(StallM), .q(StallMQ));
+  assign ITLBFlushF = sfencevmaM & ~StallMQ;
   assign DTLBFlushM = sfencevmaM;
+  // sets ITLBFlush to pulse for one cycle of the sfence.vma instruction
+  // In this instr we want to flush the tlb and then do a pagetable walk to update the itlb and continue the program.
+  // But we're still in the stalled sfence instruction, so if itlbflushf == sfencevmaM, tlbflush would never drop and 
+  // the tlbwrite would never take place after the pagetable walk. by adding in ~StallMQ, we are able to drop itlbflush 
+  // after a cycle AND pulse it for another cycle on any further back-to-back sfences. 
+
 
   // A page fault might occur because of insufficient privilege during a TLB
   // lookup or a improperly formatted page table during walking