tools: transport-proof demand writes + tolerant demand parsing (the pool-pin latency root cause)

The r581 boot's guest scanner died mid-boot with ValueError in main():
"invalid literal for int() with base 16:
'0x20400f000\\n0x121000000\\n0x12000ab4c'". A guest-agent transport-escaped
append merged demand VAs onto one line with literal backslash-n, and the
old parser crashed on it. The crash stopped ALL new pins; the host only
re-asserted known pairs, so the UVM pool VA 0x121000000 never arrived
while 185 other injections flowed - the pool-pin latency that blocked
every validation boot.

* pin_gr_stream._demand_send/_demand_loop now write one "echo <va> >>"
  per VA (no newlines, no backslashes in the transported command; immune
  to transport escaping).
* guest_pin_stream's demand parser extracts every 0x token with re and
  skips malformed ones instead of raising out of main().

1 files changed, 15 insertions, 2 deletions

diff --git a/tools/guest-diag/guest_pin_stream.py b/tools/guest-diag/guest_pin_stream.py
index aa21655..b56f79d 100644
--- a/tools/guest-diag/guest_pin_stream.py
+++ b/tools/guest-diag/guest_pin_stream.py
@@ -1772,8 +1772,21 @@ def main():
                 st_d = os.stat("/tmp/guest_want_vas.txt")
                 if st_d.st_mtime != _want_state.get("mtime"):
                     with open("/tmp/guest_want_vas.txt") as fw:
-                        wvas = [int(t, 16) for t in fw.read().split()
-                                if t.startswith("0x")]
+                        # r582: tolerate malformed historical lines. The
+                        # r581 boot's scanner died here: a transport-escaped
+                        # append merged VAs into one token containing
+                        # literal backslash-n ('0x20400f000\\n0x121000000\\n
+                        # ...') and int(t, 16) raised ValueError out of
+                        # main(), stopping ALL new pins (the observed
+                        # pool-pin latency). Extract every 0x token instead;
+                        # a bad token is skipped, never fatal.
+                        wvas = []
+                        for t in re.findall(r"0x[0-9a-fA-F]+",
+                                            fw.read()):
+                            try:
+                                wvas.append(int(t, 16))
+                            except ValueError:
+                                pass
                     _want_state["mtime"] = st_d.st_mtime
                     for wv in wvas[-64:]:
                         if wv in _want_state["done"]: