kernel: validate learned semaphore maps and post guest GPU events

- admit {GPU VA -> PA} pairs only when the preceding bytes form a valid
  client memory descriptor header (type 0/1, CPU+GPU mapped bits), prefer
  validated pairs over headerless candidates under first-wins dedup, and
  invalidate the translation cache on every rebuild; fixes stale identity
  entries shadowing live pool pages and lets the guest UVM channel
  bring-up complete on its own
- capture OS event allocations (class 0x79) and post event records
  (function 0x1003) into the guest status queue when a channel's busy
  notification is consumed, with a broadcast fallback, serialized with
  replies via a queue lock
- add BAR0 shadow introspection (dump_bar0/scan_bar0) and guest-side
  diagnostic scripts for the VM cycle

1 files changed, 37 insertions, 0 deletions

diff --git a/tools/guest-diag/guest_pmap.py b/tools/guest-diag/guest_pmap.py
new file mode 100644
index 0000000..96b7ddc
--- /dev/null
+++ b/tools/guest-diag/guest_pmap.py
@@ -0,0 +1,37 @@
+#!/usr/bin/env python3
+# guest-side helper: translate GPU/user VAs of a process through its pagemap.
+# Usage: sudo python3 guest_pmap.py <pid> <hex-va> [hex-va ...]
+import os
+import sys
+
+pid = int(sys.argv[1])
+vas = [int(x, 16) for x in sys.argv[2:]]
+
+maps = []
+try:
+    with open('/proc/%d/maps' % pid) as f:
+        for line in f:
+            parts = line.split()
+            a, b = parts[0].split('-')
+            maps.append((int(a, 16), int(b, 16), line.strip()))
+except OSError as e:
+    print('MAPS_ERROR: %s' % e)
+
+def in_maps(va):
+    for a, b, line in maps:
+        if a <= va < b:
+            return line
+    return None
+
+fd = os.open('/proc/%d/pagemap' % pid, os.O_RDONLY)
+try:
+    for va in vas:
+        os.lseek(fd, (va // 4096) * 8, 0)
+        e = int.from_bytes(os.read(fd, 8), 'little')
+        present = (e >> 63) & 1
+        pfn = e & ((1 << 55) - 1)
+        pa = (pfn << 12) | (va & 0xfff)
+        line = in_maps(va)
+        print('VA=0x%x present=%d PA=0x%x map=%s' % (va, present, pa, line if line else '-'))
+finally:
+    os.close(fd)