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hptw: renamed DTLBMissQ to DTLBWalk

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This commit is contained in:
David Harris 2021-07-17 14:13:00 -04:00
parent 8e966b37f2
commit af02437c3a
1 changed files with 12 additions and 11 deletions
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23
wally-pipelined/src/mmu/pagetablewalker.sv
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@ -68,7 +68,7 @@ module pagetablewalker
if (`MEM_VIRTMEM) begin if (`MEM_VIRTMEM) begin
// Internal signals // Internal signals
// register TLBs translation miss requests // register TLBs translation miss requests
logic DTLBMissMQ; logic DTLBWalk;
logic [`PPN_BITS-1:0] BasePageTablePPN; logic [`PPN_BITS-1:0] BasePageTablePPN;
logic [`XLEN-1:0] TranslationVAdr; logic [`XLEN-1:0] TranslationVAdr;
@ -100,11 +100,11 @@ module pagetablewalker
assign MemWrite = MemRWM[0]; assign MemWrite = MemRWM[0];
// Prefer data address translations over instruction address translations // Prefer data address translations over instruction address translations
assign TranslationVAdr = (SelDataTranslation) ? MemAdrM : PCF; assign SelDataTranslation = DTLBWalk | DTLBMissM; // *** missM is probably unnecessary
assign SelDataTranslation = DTLBMissMQ | DTLBMissM; assign TranslationVAdr = (SelDataTranslation) ? MemAdrM : PCF;
flop #(`XLEN) HPTWPAdrMReg(clk, HPTWPAdrE, HPTWPAdrM); flop #(`XLEN) HPTWPAdrMReg(clk, HPTWPAdrE, HPTWPAdrM);
flopenrc #(1) TLBMissMReg(clk, reset, EndWalk, StartWalk | EndWalk, DTLBMissM, DTLBMissMQ); flopenrc #(1) TLBMissMReg(clk, reset, EndWalk, StartWalk | EndWalk, DTLBMissM, DTLBWalk);
flopenl #(.TYPE(statetype)) WalkerStateReg(clk, reset, 1'b1, NextWalkerState, IDLE, WalkerState); flopenl #(.TYPE(statetype)) WalkerStateReg(clk, reset, 1'b1, NextWalkerState, IDLE, WalkerState);
flopenr #(`XLEN) PTEReg(clk, reset, PRegEn, HPTWReadPTE, CurrentPTE); // Capture page table entry from data cache flopenr #(`XLEN) PTEReg(clk, reset, PRegEn, HPTWReadPTE, CurrentPTE); // Capture page table entry from data cache
assign CurrentPPN = CurrentPTE[`PPN_BITS+9:10]; assign CurrentPPN = CurrentPTE[`PPN_BITS+9:10];
@ -124,16 +124,16 @@ module pagetablewalker
assign PageTableEntryM = CurrentPTE; assign PageTableEntryM = CurrentPTE;
assign SelPTW = (WalkerState != IDLE) & (WalkerState != FAULT); assign SelPTW = (WalkerState != IDLE) & (WalkerState != FAULT);
assign DTLBWriteM = (WalkerState == LEAF) & DTLBMissMQ; assign DTLBWriteM = (WalkerState == LEAF) & DTLBWalk;
assign ITLBWriteF = (WalkerState == LEAF) & ~DTLBMissMQ; assign ITLBWriteF = (WalkerState == LEAF) & ~DTLBWalk;
assign WalkerInstrPageFaultF = (WalkerState == FAULT) & ~DTLBMissMQ; //*** why do these only get raised on TLB misses? Should they always fault even for ADpagefaults, invalid addresses,etc?? // Raise faults. DTLBMiss
assign WalkerLoadPageFaultM = (WalkerState == FAULT) & DTLBMissMQ & ~MemWrite; assign WalkerInstrPageFaultF = (WalkerState == FAULT) & ~DTLBWalk;
assign WalkerStorePageFaultM = (WalkerState == FAULT) & DTLBMissMQ & MemWrite; assign WalkerLoadPageFaultM = (WalkerState == FAULT) & DTLBWalk & ~MemWrite;
assign WalkerStorePageFaultM = (WalkerState == FAULT) & DTLBWalk & MemWrite;
assign PRegEn = (NextWalkerState == LEVEL3) | (NextWalkerState == LEVEL2) | (NextWalkerState == LEVEL1) | (NextWalkerState == LEVEL0); assign PRegEn = (NextWalkerState == LEVEL3) | (NextWalkerState == LEVEL2) | (NextWalkerState == LEVEL1) | (NextWalkerState == LEVEL0);
assign HPTWRead = (WalkerState == LEVEL3_WDV) | (WalkerState == LEVEL2_WDV) | (WalkerState == LEVEL1_WDV) | (WalkerState == LEVEL0_WDV); assign HPTWRead = (WalkerState == LEVEL3_WDV) | (WalkerState == LEVEL2_WDV) | (WalkerState == LEVEL1_WDV) | (WalkerState == LEVEL0_WDV);
// *** is there a way to speed up HPTW?
// FSM to track PageType based on the levels of the page table traversed // FSM to track PageType based on the levels of the page table traversed
flopr #(2) PageTypeReg(clk, reset, NextPageType, PageType); flopr #(2) PageTypeReg(clk, reset, NextPageType, PageType);
@ -206,6 +206,7 @@ module pagetablewalker
end end
// Page Table Walker FSM // Page Table Walker FSM
// ***Is there a w ay to reduce the number of cycles needed to do the walk?
always_comb always_comb
case (WalkerState) case (WalkerState)
IDLE: if (StartWalk) NextWalkerState = InitialWalkerState; IDLE: if (StartWalk) NextWalkerState = InitialWalkerState;