sema-svc: apply releases promptly and decode compute-push releases

The content sweep now:
- decodes a release whose method stream continues with any INC_METHOD,
  not only the CE LAUNCH_DMA group, so the releases at the head of a
  compute/GR channel's first push are applied too;
- remembers releases whose target VA had no translation (deferred list)
  and retries them every service pass, so a VA->PA injection lands them
  immediately instead of after the next full sweep;
- re-arms the fast sliced sweep for a few seconds after an injection;
- treats a channel whose USERD/ring cannot be resolved as stalled, so the
  sweep keeps looking for the releases its unreadable pushes carry.

tools: add per-cdt client-pin helper (sem pages + /dev/nvidia0 windows),
sem-page scanner and memprobe fixes (short-read guard, --brief).
Live-verified: injecting a client sem page applied 12 deferred releases
within a second; the service kept applying (89 -> 202) while cdt ran.

1 files changed, 37 insertions, 0 deletions

diff --git a/tools/guest-diag/sempages.py b/tools/guest-diag/sempages.py
new file mode 100755
index 0000000..ad4dae6
--- /dev/null
+++ b/tools/guest-diag/sempages.py
@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+# Print the distinct pages of the semaphore VAs a process references
+# (reuses memprobe.py's scanner; run in the guest as root). The VA window is
+# derived from the process's /dev/nvidia* mappings unless lo/hi are given.
+# usage: sudo python3 sempages.py <pid> [lo] [hi]
+import os
+import sys
+
+sys.path.insert(0, '/tmp')
+import memprobe as m
+
+pid = int(sys.argv[1])
+if len(sys.argv) > 3:
+    lo = int(sys.argv[2], 16)
+    hi = int(sys.argv[3], 16)
+else:
+    lo = 1 << 64
+    hi = 0
+    with open('/proc/%d/maps' % pid) as f:
+        for line in f:
+            parts = line.split()
+            if len(parts) < 6 or not parts[5].startswith('/dev/nvidia'):
+                continue
+            a, b = parts[0].split('-')
+            lo = min(lo, int(a, 16))
+            hi = max(hi, int(b, 16))
+    if hi == 0:
+        print('no /dev/nvidia mappings')
+        raise SystemExit(1)
+
+fd = os.open('/proc/%d/mem' % pid, os.O_RDONLY)
+sems = m.sem_objs(pid, fd, lo, hi)
+os.close(fd)
+pages = sorted({va & ~0xfff for va in sems})
+print('sem VAs: %d pages: %d (window 0x%x..0x%x)' % (len(sems), len(pages), lo, hi))
+for pg in pages:
+    print('0x%x' % pg)