guest-diag: drop the fixed +1 vmap pairing (allocation-dependent)

The +1 vmap pairing was content-validated on one boot's CE push-buffer
allocation (4097-page vmap: five rescue anchors at k+1), but r116/r117
show the leading header page is not universal: with the shift applied
client #1 stalls mid-run (rescues resume) where it was green without it.
Reverting the shift restores the previous behaviour; the kernel-side
repair from 16124929 stays (a content-validated rescue replaces the
injected pair, so a wrong pin is corrected once per page instead of
being re-rescued on every pass).

1 files changed, 7 insertions, 33 deletions

diff --git a/tools/guest-diag/guest_pin_stream.py b/tools/guest-diag/guest_pin_stream.py
index 2c1a1a3..35cbfb9 100644
--- a/tools/guest-diag/guest_pin_stream.py
+++ b/tools/guest-diag/guest_pin_stream.py
@@ -266,17 +266,11 @@ def _vmalloc_pages_for(kc, va):
     return 0
 
 
-def resolve_mem_pins(kc, mem, out, default_pages=16, va_lo=0, va_hi=0,
-                     page_off=0):
+def resolve_mem_pins(kc, mem, out, default_pages=16, va_lo=0, va_hi=0):
     """uvm_rm_mem kptr -> GPU-VA/GPA runs (direct map or page-table walk).
 
     va_lo/va_hi optionally restrict the emitted GPU VA range; the kcore
-    chain resolver targets the CE push-buffer window only. page_off shifts
-    the vmap page paired with GPU data page k (the CE push-buffer vmap is
-    a 4097-page area = 1 header page + 4096 data pages, so data page k
-    lives at vmap page k+1; pairing k with k pinned the previous page and
-    every entry read returned the adjacent push - the second-session
-    content-rescue crawl).
+    chain resolver targets the CE push-buffer window only.
     """
     if not is_kern_ptr(mem):
         return 0
@@ -303,7 +297,7 @@ def resolve_mem_pins(kc, mem, out, default_pages=16, va_lo=0, va_hi=0,
     runs = []
     cur = None
     for k in range(npages):
-        pa = kc.va_to_pa(cpu + (k + page_off) * 0x1000)
+        pa = kc.va_to_pa(cpu + k * 0x1000)
         if pa is None:
             if cur:
                 runs.append(cur)
@@ -324,23 +318,6 @@ def resolve_mem_pins(kc, mem, out, default_pages=16, va_lo=0, va_hi=0,
     return emitted
 
 
-def mem_page_off(kc, mem):
-    """vmap-page offset for a uvm_rm_mem's GPU data pages.
-
-    The CE push-buffer allocation's vmap is one page longer than its GPU
-    data window (16 MB of data + one leading page), so GPU data page k is
-    vmap page k+1. Content-validated against the host's rescue anchors
-    (five independent (va,pa) pairs, k=20..28, all delta +1).
-    """
-    vas = [kc.read64(mem + 0x10 + i * 8) for i in range(16)]
-    cpu = next((v for v in vas if is_kern_ptr(v)), None)
-    if not cpu:
-        return 0
-    if _direct_map_pa(kc, cpu) is not None:
-        return 0
-    return 1 if _vmalloc_pages_for(kc, cpu) == 4097 else 0
-
-
 def _emit_ring_pins(kc, gpu_va, entries_cpu, entries, out):
     """Pin the GPFIFO ring pages (and the pages after it, where the GPPUT
     buffer usually sits) from the ring's CPU mapping."""
@@ -467,8 +444,7 @@ def resolve_pb_pins(kc, pb, out):
     mem = kc.read64(pb + 8)
     if not mem:
         return 0
-    return resolve_mem_pins(kc, mem, out, default_pages=64,
-                            page_off=mem_page_off(kc, mem))
+    return resolve_mem_pins(kc, mem, out, default_pages=64)
 
 
 # The CE push-buffer window is the one UVM region the client never maps into
@@ -534,14 +510,12 @@ def resolve_pb_chain(kc, sem, out):
                 continue
             RESOLVED_KC_PB.add(mem)
             n = resolve_mem_pins(kc, mem, out, default_pages=64,
-                                 va_lo=PB_CE_LO, va_hi=PB_CE_HI,
-                                 page_off=mem_page_off(kc, mem))
+                                 va_lo=PB_CE_LO, va_hi=PB_CE_HI)
             try:
                 with open('/tmp/guest_pin_stream.log', 'a') as f:
                     f.write('%s kc-chain CE push-buffer mem=0x%x sem=0x%x '
-                            'pin-runs=%d off=%d\n'
-                            % (time.strftime('%T'), mem, sem, n,
-                               mem_page_off(kc, mem)))
+                            'pin-runs=%d\n'
+                            % (time.strftime('%T'), mem, sem, n))
             except OSError:
                 pass
     return found