Distinguish between page faults from MMU and access faults from PMP

src/main/scala/vexriscv/Services.scala

@@ -71,6 +71,7 @@ case class MemoryTranslatorCmd() extends Bundle{
 case class MemoryTranslatorRsp() extends Bundle{
   val physicalAddress = UInt(32 bits)
   val isIoAccess = Bool
+  val isPaging = Bool
   val allowRead, allowWrite, allowExecute = Bool
   val exception = Bool
   val refilling = Bool

src/main/scala/vexriscv/ip/DataCache.scala

@@ -551,9 +551,20 @@ class DataCache(p : DataCacheConfig) extends Component{
 
 
     val memCmdSent = RegInit(False) setWhen (io.mem.cmd.ready) clearWhen (!io.cpu.writeBack.isStuck)
-    io.cpu.redo := False
+    val badPermissions = (!mmuRsp.allowWrite && request.wr) || (!mmuRsp.allowRead && (!request.wr || isAmo))
+    val loadStoreFault = io.cpu.writeBack.isValid && (mmuRsp.exception || badPermissions)
+
     io.cpu.writeBack.accessError := False
-    io.cpu.writeBack.mmuException := io.cpu.writeBack.isValid && (if(catchIllegal) mmuRsp.exception || (!mmuRsp.allowWrite && request.wr) || (!mmuRsp.allowRead && (!request.wr || isAmo)) else False)
+    when(mmuRsp.isIoAccess) {
+      io.cpu.writeBack.data := io.mem.rsp.data
+      if (catchAccessError) io.cpu.writeBack.accessError := io.mem.rsp.valid && io.mem.rsp.error
+    } otherwise {
+      io.cpu.writeBack.data := dataMux
+      if (catchAccessError) io.cpu.writeBack.accessError := (waysHits & B(tagsReadRsp.map(_.error))) =/= 0 || (loadStoreFault && !mmuRsp.isPaging)
+    }
+
+    io.cpu.redo := False
+    io.cpu.writeBack.mmuException := loadStoreFault && (if(catchIllegal) mmuRsp.isPaging else False)
     io.cpu.writeBack.unalignedAccess := io.cpu.writeBack.isValid && (if(catchUnaligned) ((request.size === 2 && mmuRsp.physicalAddress(1 downto 0) =/= 0) || (request.size === 1 && mmuRsp.physicalAddress(0 downto 0) =/= 0)) else False)
     io.cpu.writeBack.isWrite := request.wr
 
@@ -626,14 +637,6 @@ class DataCache(p : DataCacheConfig) extends Component{
       }
     }
 
-    when(mmuRsp.isIoAccess){
-      io.cpu.writeBack.data :=  io.mem.rsp.data
-      if(catchAccessError) io.cpu.writeBack.accessError := io.mem.rsp.valid && io.mem.rsp.error
-    } otherwise {
-      io.cpu.writeBack.data :=  dataMux
-      if(catchAccessError) io.cpu.writeBack.accessError := (waysHits & B(tagsReadRsp.map(_.error))) =/= 0
-    }
-
     //remove side effects on exceptions
     when(mmuRsp.refilling || io.cpu.writeBack.accessError || io.cpu.writeBack.mmuException || io.cpu.writeBack.unalignedAccess){
       io.mem.cmd.valid := False

src/main/scala/vexriscv/ip/InstructionCache.scala

@@ -438,9 +438,9 @@ class InstructionCache(p : InstructionCacheConfig) extends Component{
       val mmuRsp = io.cpu.fetch.mmuBus.rsp
 
       io.cpu.fetch.cacheMiss := !hit.valid
-      io.cpu.fetch.error := hit.error
+      io.cpu.fetch.error := hit.error || (!mmuRsp.isPaging && (mmuRsp.exception || !mmuRsp.allowExecute))
       io.cpu.fetch.mmuRefilling := mmuRsp.refilling
-      io.cpu.fetch.mmuException := !mmuRsp.refilling && (mmuRsp.exception || !mmuRsp.allowExecute)
+      io.cpu.fetch.mmuException := !mmuRsp.refilling && mmuRsp.isPaging && (mmuRsp.exception || !mmuRsp.allowExecute)
     })
   }
 
@@ -468,9 +468,9 @@ class InstructionCache(p : InstructionCacheConfig) extends Component{
     }
 
     io.cpu.decode.cacheMiss := !hit.valid
-    io.cpu.decode.error := hit.error
+    io.cpu.decode.error := hit.error || (!mmuRsp.isPaging && (mmuRsp.exception || !mmuRsp.allowExecute))
     io.cpu.decode.mmuRefilling := mmuRsp.refilling
-    io.cpu.decode.mmuException := !mmuRsp.refilling && (mmuRsp.exception || !mmuRsp.allowExecute)
+    io.cpu.decode.mmuException := !mmuRsp.refilling && mmuRsp.isPaging && (mmuRsp.exception || !mmuRsp.allowExecute)
     io.cpu.decode.physicalAddress := mmuRsp.physicalAddress
   })
 }

src/main/scala/vexriscv/plugin/DBusCachedPlugin.scala

@@ -273,15 +273,14 @@ class DBusCachedPlugin(val config : DataCacheConfig,
           exceptionBus.valid := True
           exceptionBus.code := (input(MEMORY_WR) ? U(7) | U(5)).resized
         }
-
-        if (catchUnaligned) when(cache.io.cpu.writeBack.unalignedAccess) {
-          exceptionBus.valid := True
-          exceptionBus.code := (input(MEMORY_WR) ? U(6) | U(4)).resized
-        }
         if(catchIllegal) when (cache.io.cpu.writeBack.mmuException) {
           exceptionBus.valid := True
           exceptionBus.code := (input(MEMORY_WR) ? U(15) | U(13)).resized
         }
+        if (catchUnaligned) when(cache.io.cpu.writeBack.unalignedAccess) {
+          exceptionBus.valid := True
+          exceptionBus.code := (input(MEMORY_WR) ? U(6) | U(4)).resized
+        }
 
         when(cache.io.cpu.redo) {
           redoBranch.valid := True

src/main/scala/vexriscv/plugin/MmuPlugin.scala

@@ -127,6 +127,7 @@ class MmuPlugin(ioRange : UInt => Bool,
           port.bus.rsp.allowExecute := cacheLine.allowExecute
           port.bus.rsp.exception := cacheHit && (cacheLine.exception || cacheLine.allowUser && privilegeService.isSupervisor() && !csr.status.sum || !cacheLine.allowUser && privilegeService.isUser())
           port.bus.rsp.refilling := !cacheHit
+          port.bus.rsp.isPaging := True
         } otherwise {
           port.bus.rsp.physicalAddress := port.bus.cmd.virtualAddress
           port.bus.rsp.allowRead := True
@@ -134,6 +135,7 @@ class MmuPlugin(ioRange : UInt => Bool,
           port.bus.rsp.allowExecute := True
           port.bus.rsp.exception := False
           port.bus.rsp.refilling := False
+          port.bus.rsp.isPaging := False
         }
         port.bus.rsp.isIoAccess := ioRange(port.bus.rsp.physicalAddress)
 

src/main/scala/vexriscv/plugin/PmpPlugin.scala

@@ -205,6 +205,7 @@ class PmpPlugin(regions : Int, ioRange : UInt => Bool) extends Plugin[VexRiscv]
         }
 
         port.bus.rsp.isIoAccess := ioRange(port.bus.rsp.physicalAddress)
+        port.bus.rsp.isPaging := False
         port.bus.rsp.exception := False
         port.bus.rsp.refilling := False
         port.bus.busy := False

src/main/scala/vexriscv/plugin/StaticMemoryTranslatorPlugin.scala

@@ -32,6 +32,7 @@ class StaticMemoryTranslatorPlugin(ioRange : UInt => Bool) extends Plugin[VexRis
         port.bus.rsp.allowWrite := True
         port.bus.rsp.allowExecute := True
         port.bus.rsp.isIoAccess := ioRange(port.bus.rsp.physicalAddress)
+        port.bus.rsp.isPaging := False
         port.bus.rsp.exception := False
         port.bus.rsp.refilling := False
         port.bus.busy := False