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Fixed combo loop in the page table walker.

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This commit is contained in:
Ross Thompson 2021-07-05 16:37:26 -05:00
parent 2a62ee2e70
commit 530ddd667b
1 changed files with 37 additions and 17 deletions
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54
wally-pipelined/src/mmu/pagetablewalker.sv
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@ -72,6 +72,7 @@ module pagetablewalker
// Internal signals // Internal signals
// register TLBs translation miss requests // register TLBs translation miss requests
logic [`XLEN-1:0] TranslationVAdrQ;
logic ITLBMissFQ, DTLBMissMQ; logic ITLBMissFQ, DTLBMissMQ;
logic [`PPN_BITS-1:0] BasePageTablePPN; logic [`PPN_BITS-1:0] BasePageTablePPN;
@ -104,6 +105,7 @@ module pagetablewalker
LEVEL3, LEVEL3,
LEAF, LEAF,
IDLE, IDLE,
START,
FAULT} statetype; FAULT} statetype;
statetype WalkerState, NextWalkerState; statetype WalkerState, NextWalkerState;
@ -122,6 +124,13 @@ module pagetablewalker
assign TranslationVAdr = (SelDataTranslation) ? MemAdrM : PCF; // *** need to register TranslationVAdr assign TranslationVAdr = (SelDataTranslation) ? MemAdrM : PCF; // *** need to register TranslationVAdr
assign SelDataTranslation = DTLBMissMQ | DTLBMissM; assign SelDataTranslation = DTLBMissMQ | DTLBMissM;
flopenr #(`XLEN)
TranslationVAdrReg(.clk(clk),
.reset(reset),
.en(StartWalk),
.d(TranslationVAdr),
.q(TranslationVAdrQ));
flopenrc #(1) flopenrc #(1)
DTLBMissMReg(.clk(clk), DTLBMissMReg(.clk(clk),
.reset(reset), .reset(reset),
@ -193,14 +202,17 @@ module pagetablewalker
case (WalkerState) case (WalkerState)
IDLE: begin IDLE: begin
if (MMUTranslate && SvMode == `SV32) begin // *** Added SvMode if (MMUTranslate && SvMode == `SV32) begin // *** Added SvMode
NextWalkerState = LEVEL1_WDV; NextWalkerState = START;
TranslationPAdr = {BasePageTablePPN, VPN1, 2'b00};
HPTWRead = 1'b1;
end else begin end else begin
NextWalkerState = IDLE; NextWalkerState = IDLE;
TranslationPAdr = '0;
end end
end end
START: begin
NextWalkerState = LEVEL1_WDV;
TranslationPAdr = {BasePageTablePPN, VPN1, 2'b00};
HPTWRead = 1'b1;
end
LEVEL1_WDV: begin LEVEL1_WDV: begin
TranslationPAdr = {BasePageTablePPN, VPN1, 2'b00}; TranslationPAdr = {BasePageTablePPN, VPN1, 2'b00};
@ -223,7 +235,7 @@ module pagetablewalker
PageType = (WalkerState == LEVEL1) ? 2'b01 : 2'b00; // *** not sure about this mux? PageType = (WalkerState == LEVEL1) ? 2'b01 : 2'b00; // *** not sure about this mux?
DTLBWriteM = DTLBMissMQ; DTLBWriteM = DTLBMissMQ;
ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions
TranslationPAdr = {2'b00, TranslationVAdr[31:0]}; TranslationPAdr = {2'b00, TranslationVAdrQ[31:0]};
end end
// else if (ValidPTE && LeafPTE) NextWalkerState = LEAF; // *** Once the above line is properly tested, delete this line. // else if (ValidPTE && LeafPTE) NextWalkerState = LEAF; // *** Once the above line is properly tested, delete this line.
else if (ValidPTE && ~LeafPTE) begin else if (ValidPTE && ~LeafPTE) begin
@ -252,7 +264,7 @@ module pagetablewalker
PageType = (WalkerState == LEVEL1) ? 2'b01 : 2'b00; PageType = (WalkerState == LEVEL1) ? 2'b01 : 2'b00;
DTLBWriteM = DTLBMissMQ; DTLBWriteM = DTLBMissMQ;
ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions
TranslationPAdr = {2'b00, TranslationVAdr[31:0]}; TranslationPAdr = {2'b00, TranslationVAdrQ[31:0]};
end else begin end else begin
NextWalkerState = FAULT; NextWalkerState = FAULT;
end end
@ -277,8 +289,8 @@ module pagetablewalker
assign MegapageMisaligned = |(CurrentPPN[9:0]); assign MegapageMisaligned = |(CurrentPPN[9:0]);
assign BadMegapage = MegapageMisaligned || AccessAlert; // *** Implement better access/dirty scheme assign BadMegapage = MegapageMisaligned || AccessAlert; // *** Implement better access/dirty scheme
assign VPN1 = TranslationVAdr[31:22]; assign VPN1 = TranslationVAdrQ[31:22];
assign VPN0 = TranslationVAdr[21:12]; assign VPN0 = TranslationVAdrQ[21:12];
@ -331,6 +343,14 @@ module pagetablewalker
case (WalkerState) case (WalkerState)
IDLE: begin IDLE: begin
if (MMUTranslate && (SvMode == `SV48 || SvMode == `SV39)) begin
NextWalkerState = START;
end else begin
NextWalkerState = IDLE;
end
end
START: begin
if (MMUTranslate && SvMode == `SV48) begin if (MMUTranslate && SvMode == `SV48) begin
NextWalkerState = LEVEL3_WDV; NextWalkerState = LEVEL3_WDV;
TranslationPAdr = {BasePageTablePPN, VPN3, 3'b000}; TranslationPAdr = {BasePageTablePPN, VPN3, 3'b000};
@ -339,7 +359,7 @@ module pagetablewalker
NextWalkerState = LEVEL2_WDV; NextWalkerState = LEVEL2_WDV;
TranslationPAdr = {BasePageTablePPN, VPN2, 3'b000}; TranslationPAdr = {BasePageTablePPN, VPN2, 3'b000};
HPTWRead = 1'b1; HPTWRead = 1'b1;
end else begin end else begin // *** should not get here
NextWalkerState = IDLE; NextWalkerState = IDLE;
TranslationPAdr = '0; TranslationPAdr = '0;
end end
@ -368,7 +388,7 @@ module pagetablewalker
((WalkerState == LEVEL1) ? 2'b01 : 2'b00)); ((WalkerState == LEVEL1) ? 2'b01 : 2'b00));
DTLBWriteM = DTLBMissMQ; DTLBWriteM = DTLBMissMQ;
ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions
TranslationPAdr = TranslationVAdr[`PA_BITS-1:0]; TranslationPAdr = TranslationVAdrQ[`PA_BITS-1:0];
end end
// else if (ValidPTE && LeafPTE) NextWalkerState = LEAF; // *** Once the above line is properly tested, delete this line. // else if (ValidPTE && LeafPTE) NextWalkerState = LEAF; // *** Once the above line is properly tested, delete this line.
else if (ValidPTE && ~LeafPTE) begin else if (ValidPTE && ~LeafPTE) begin
@ -405,7 +425,7 @@ module pagetablewalker
((WalkerState == LEVEL1) ? 2'b01 : 2'b00)); ((WalkerState == LEVEL1) ? 2'b01 : 2'b00));
DTLBWriteM = DTLBMissMQ; DTLBWriteM = DTLBMissMQ;
ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions
TranslationPAdr = TranslationVAdr[`PA_BITS-1:0]; TranslationPAdr = TranslationVAdrQ[`PA_BITS-1:0];
end end
// else if (ValidPTE && LeafPTE) NextWalkerState = LEAF; // *** Once the above line is properly tested, delete this line. // else if (ValidPTE && LeafPTE) NextWalkerState = LEAF; // *** Once the above line is properly tested, delete this line.
else if (ValidPTE && ~LeafPTE) begin else if (ValidPTE && ~LeafPTE) begin
@ -442,7 +462,7 @@ module pagetablewalker
((WalkerState == LEVEL1) ? 2'b01 : 2'b00)); ((WalkerState == LEVEL1) ? 2'b01 : 2'b00));
DTLBWriteM = DTLBMissMQ; DTLBWriteM = DTLBMissMQ;
ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions
TranslationPAdr = TranslationVAdr[`PA_BITS-1:0]; TranslationPAdr = TranslationVAdrQ[`PA_BITS-1:0];
end end
// else if (ValidPTE && LeafPTE) NextWalkerState = LEAF; // *** Once the above line is properly tested, delete this line. // else if (ValidPTE && LeafPTE) NextWalkerState = LEAF; // *** Once the above line is properly tested, delete this line.
@ -474,7 +494,7 @@ module pagetablewalker
((WalkerState == LEVEL1) ? 2'b01 : 2'b00)); ((WalkerState == LEVEL1) ? 2'b01 : 2'b00));
DTLBWriteM = DTLBMissMQ; DTLBWriteM = DTLBMissMQ;
ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions ITLBWriteF = ~DTLBMissMQ; // Prefer data over instructions
TranslationPAdr = TranslationVAdr[`PA_BITS-1:0]; TranslationPAdr = TranslationVAdrQ[`PA_BITS-1:0];
end else begin end else begin
NextWalkerState = FAULT; NextWalkerState = FAULT;
end end
@ -512,10 +532,10 @@ module pagetablewalker
assign BadGigapage = GigapageMisaligned || AccessAlert; // *** Implement better access/dirty scheme assign BadGigapage = GigapageMisaligned || AccessAlert; // *** Implement better access/dirty scheme
assign BadMegapage = MegapageMisaligned || AccessAlert; // *** Implement better access/dirty scheme assign BadMegapage = MegapageMisaligned || AccessAlert; // *** Implement better access/dirty scheme
assign VPN3 = TranslationVAdr[47:39]; assign VPN3 = TranslationVAdrQ[47:39];
assign VPN2 = TranslationVAdr[38:30]; assign VPN2 = TranslationVAdrQ[38:30];
assign VPN1 = TranslationVAdr[29:21]; assign VPN1 = TranslationVAdrQ[29:21];
assign VPN0 = TranslationVAdr[20:12]; assign VPN0 = TranslationVAdrQ[20:12];
// Capture page table entry from ahblite // Capture page table entry from ahblite