gwj / at91sam9263 · Commits

Commit ee4d919f30f1378cda697dd94d5a21b2a7f4d90d

Authored by aliguori
1 parent 72ecb8d9

LSI SCSI: raise UDC on infinite loop (Marcelo Tosatti) 

Raise UDC (Unexpected Disconnect) when a large enough number of
instructions has been executed by the SCRIPTS processor. This "solution"
is much simpler than temporarily interrupting execution.

This remedies the situation with Windows which downloads SCRIPTS code
that busy loops on guest main memory. Their drivers _do_ handle UDC 
appropriately (at least XP and 2003).

It would be nicer to actually detect infinite loops, but until then,
this bandaid seems acceptable.

Since the situation seems to be rare enough, raise the number 
of instructions to 10000 (previously 1000).

Three people other than myself had success with this patch.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5293 c046a42c-6fe2-441c-8c8c-71466251a162
Inline Side-by-side
Showing 1 changed file with 8 additions and 2 deletions
hw/lsi53c895a.c
  View file @ee4d919
... ... @@ -839,9 +839,11 @@ static void lsi_execute_script(LSIState *s)
839 839 uint32_t insn;
840 840 uint32_t addr;
841 841 int opcode;
  842 + int insn_processed = 0;
842 843  
843 844 s->istat1 |= LSI_ISTAT1_SRUN;
844 845 again:
  846 + insn_processed++;
845 847 insn = read_dword(s, s->dsp);
846 848 addr = read_dword(s, s->dsp + 4);
847 849 DPRINTF("SCRIPTS dsp=%08x opcode %08x arg %08x\n", s->dsp, insn, addr);
... ... @@ -1196,8 +1198,12 @@ again:
1196 1198 }
1197 1199 }
1198 1200 }
1199   - /* ??? Need to avoid infinite loops. */
1200   - if (s->istat1 & LSI_ISTAT1_SRUN && !s->waiting) {
  1201 + if (insn_processed > 10000 && !s->waiting) {
  1202 + if (!(s->sien0 & LSI_SIST0_UDC))
  1203 + fprintf(stderr, "inf. loop with UDC masked\n");
  1204 + lsi_script_scsi_interrupt(s, LSI_SIST0_UDC, 0);
  1205 + lsi_disconnect(s);
  1206 + } else if (s->istat1 & LSI_ISTAT1_SRUN && !s->waiting) {
1201 1207 if (s->dcntl & LSI_DCNTL_SSM) {
1202 1208 lsi_script_dma_interrupt(s, LSI_DSTAT_SSI);
1203 1209 } else {
... ...