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Don't cache TL error responses; report access exceptions

This commit is contained in:
Andrew Waterman 2017-09-20 17:01:08 -07:00
parent 9b828a2640
commit 6bc20942b5
1 changed files with 17 additions and 6 deletions
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23
src/main/scala/rocket/DCache.scala
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@ -203,7 +203,8 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
val s1_all_data_ways = Vec(data.io.resp :+ dummyEncodeData(tl_out.d.bits.data))
val s1_mask = Mux(s1_req.cmd === M_PWR, io.cpu.s1_data.mask, new StoreGen(s1_req.typ, s1_req.addr, UInt(0), wordBytes).mask)
val s2_valid = Reg(next=s1_valid_masked && !s1_sfence, init=Bool(false)) && !io.cpu.s2_xcpt.asUInt.orR
val s2_valid_pre_xcpt = Reg(next=s1_valid_masked && !s1_sfence, init=Bool(false))
val s2_valid = s2_valid_pre_xcpt && !io.cpu.s2_xcpt.asUInt.orR
val s2_probe = Reg(next=s1_probe, init=Bool(false))
val releaseInFlight = s1_probe || s2_probe || release_state =/= s_ready
val s2_valid_masked = s2_valid && Reg(next = !s1_nack)
@ -286,15 +287,19 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
metaArb.io.in(2).bits.data.coh := Mux(s2_valid_hit, s2_new_hit_state, ClientMetadata.onReset)
metaArb.io.in(2).bits.data.tag := s2_req.addr >> untagBits
// load reservations
// load reservations and TL error reporting
val s2_lr = Bool(usingAtomics && !usingDataScratchpad) && s2_req.cmd === M_XLR
val s2_sc = Bool(usingAtomics && !usingDataScratchpad) && s2_req.cmd === M_XSC
val lrscCount = Reg(init=UInt(0))
val tl_error_valid = RegInit(false.B)
val lrscValid = lrscCount > lrscBackoff
val lrscAddr = Reg(UInt())
val s2_sc_fail = s2_sc && !(lrscValid && lrscAddr === (s2_req.addr >> blockOffBits))
when (s2_valid_hit && s2_lr) {
lrscCount := lrscCycles - 1
val lrscAddrMatch = lrscAddr === (s2_req.addr >> blockOffBits)
val s2_sc_fail = s2_sc && !(lrscValid && lrscAddrMatch)
val s2_tl_error = tl_error_valid && lrscAddrMatch
when (s2_valid_hit && s2_lr && !cached_grant_wait || s2_valid_cached_miss) {
tl_error_valid := false
lrscCount := Mux(s2_hit, lrscCycles - 1, 0.U)
lrscAddr := s2_req.addr >> blockOffBits
}
when (lrscCount > 0) { lrscCount := lrscCount - 1 }
@ -436,6 +441,7 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
grantInProgress := true
assert(cached_grant_wait, "A GrantData was unexpected by the dcache.")
when(d_last) {
tl_error_valid := tl_out.d.bits.error
cached_grant_wait := false
grantInProgress := false
blockProbeAfterGrantCount := blockProbeAfterGrantCycles - 1
@ -487,7 +493,7 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
// ignore backpressure from metaArb, which can only be caused by tag ECC
// errors on hit-under-miss. failing to write the new tag will leave the
// line invalid, so we'll simply request the line again later.
metaArb.io.in(3).valid := grantIsCached && d_done
metaArb.io.in(3).valid := grantIsCached && d_done && !tl_out.d.bits.error
metaArb.io.in(3).bits.write := true
metaArb.io.in(3).bits.way_en := s2_victim_way
metaArb.io.in(3).bits.addr := Cat(io.cpu.req.bits.addr >> untagBits, s2_req.addr(idxMSB, 0))
@ -614,6 +620,11 @@ class DCacheModule(outer: DCache) extends HellaCacheModule(outer) {
val s1_xcpt_valid = tlb.io.req.valid && !s1_nack
val s1_xcpt = tlb.io.resp
io.cpu.s2_xcpt := Mux(RegNext(s1_xcpt_valid), RegEnable(s1_xcpt, s1_valid_not_nacked), 0.U.asTypeOf(s1_xcpt))
when (s2_valid_pre_xcpt && s2_tl_error) {
assert(!s2_valid_hit && !s2_uncached)
when (s2_write) { io.cpu.s2_xcpt.ae.st := true }
when (s2_read) { io.cpu.s2_xcpt.ae.ld := true }
}
if (usingDataScratchpad) {
require(!usingVM) // therefore, req.phys means this is a slave-port access