From cd1f2528e8243fed3ce80d5170ef93928e4e7284 Mon Sep 17 00:00:00 2001
From: Arthur Hanson Rasmusson <arthur@vgpu.io>
Date: Tue, 6 Oct 2026 19:28:39 -0400
Subject: risc-v-gsp-rm-debugger: land docs 45-53 + harness/sim tool set with
 tests

rm_capture (chunked decode), launch_audit, state_seed/state_decode,
valprobe, rehost, contracts+run_contracts, host_traffic, gmmu_walk,
msgq_attach, libos_port, log_decode, server_snapshot; doc index updates
in the tool overview, operations pages and the repo README.
---
 debug/risc-v-gsp-rm-vm/tests/test_gmmu_walk.py | 243 +++++++++++++++++++++++++
 1 file changed, 243 insertions(+)
 create mode 100644 debug/risc-v-gsp-rm-vm/tests/test_gmmu_walk.py

(limited to 'debug/risc-v-gsp-rm-vm/tests/test_gmmu_walk.py')

diff --git a/debug/risc-v-gsp-rm-vm/tests/test_gmmu_walk.py b/debug/risc-v-gsp-rm-vm/tests/test_gmmu_walk.py
new file mode 100644
index 0000000..f438068
--- /dev/null
+++ b/debug/risc-v-gsp-rm-vm/tests/test_gmmu_walk.py
@@ -0,0 +1,243 @@
+"""Tests for the functional GMMU walker (sim/gmmu_walk.py, docs/48).
+
+The golden vector is a captured channel PDB (numeric entries); the synthetic
+trees are built with the module's own encoders and must round-trip.  No
+hardware, no modules, no guest, no network.
+
+Run::
+
+    python3 -m unittest tests.test_gmmu_walk -v
+"""
+from __future__ import annotations
+
+import contextlib
+import io
+import json
+import os
+import struct
+import sys
+import unittest
+
+HERE = os.path.dirname(os.path.abspath(__file__))
+TOOL_ROOT = os.path.abspath(os.path.join(HERE, ".."))
+if TOOL_ROOT not in sys.path:
+    sys.path.insert(0, TOOL_ROOT)
+
+from sim.gmmu_walk import (  # noqa: E402
+    FAULT_INVALID_APERTURE,
+    FAULT_PTE_INVALID,
+    FAULT_TABLE_MISSING,
+    FAULT_UNSUPPORTED,
+    FAULT_OUT_OF_RANGE,
+    WALK_FORMAT,
+    MemoryView,
+    WalkError,
+    channel_pdb_fixture,
+    encode_dual_slot,
+    encode_pde_pointer,
+    encode_pte,
+    main,
+    walk,
+)
+
+
+def _tree(root_pa: int, va: int, target_pa: int | None, *, base: int = 0x50000000,
+          read_only: bool = False) -> MemoryView:
+    i0 = (va >> 47) & 0x3
+    i1 = (va >> 38) & 0x1FF
+    i2 = (va >> 29) & 0x1FF
+    i3 = (va >> 21) & 0xFF
+    i4 = (va >> 12) & 0x1FF
+    pd2, pd1, pd0, pt = base + 0x1000, base + 0x2000, base + 0x3000, base + 0x4000
+    mem = MemoryView()
+    page = bytearray(0x1000)
+    struct.pack_into("<Q", page, i0 * 8, encode_pde_pointer(pd2))
+    mem.add(root_pa, bytes(page))
+    page = bytearray(0x1000)
+    struct.pack_into("<Q", page, i1 * 8, encode_pde_pointer(pd1))
+    mem.add(pd2, bytes(page))
+    page = bytearray(0x1000)
+    struct.pack_into("<Q", page, i2 * 8, encode_pde_pointer(pd0))
+    mem.add(pd1, bytes(page))
+    page = bytearray(0x1000)
+    struct.pack_into("<16s", page, i3 * 16, encode_dual_slot(None, pt))
+    mem.add(pd0, bytes(page))
+    page = bytearray(0x1000)
+    if target_pa is not None:
+        struct.pack_into("<Q", page, i4 * 8, encode_pte(target_pa, read_only=read_only))
+    mem.add(pt, bytes(page))
+    return mem
+
+
+def _run_main(argv):
+    out, err = io.StringIO(), io.StringIO()
+    with contextlib.redirect_stdout(out), contextlib.redirect_stderr(err):
+        rc = main(argv)
+    return rc, out.getvalue(), err.getvalue()
+
+
+class GoldenVectorTests(unittest.TestCase):
+    def test_captured_channel_pdb_walks_to_logged_dmas(self):
+        root_pa, mem = channel_pdb_fixture()
+        expected = {
+            0x100000: 0x2045D9000,
+            0x101000: 0x121BD9000,
+            0x102000: 0x152115000,
+            0x103000: 0x15A5F5000,
+            0x104000: 0x10CF27000,
+        }
+        for va, pa in expected.items():
+            report = walk(va, root_pa=root_pa, mem=mem)
+            self.assertEqual(report["status"], "ok", report)
+            self.assertEqual(report["format"], WALK_FORMAT)
+            self.assertEqual(int(report["pa"], 16), pa)
+            self.assertEqual(report["page_size"], "4k")
+            self.assertTrue(report["writable"])
+            self.assertEqual(report["evidence"], "validated")
+            self.assertEqual(len(report["steps"]), 5)
+
+    def test_walk_is_deterministic(self):
+        root_pa, mem = channel_pdb_fixture()
+        first = json.dumps(walk(0x100000, root_pa=root_pa, mem=mem), sort_keys=True)
+        second = json.dumps(walk(0x100000, root_pa=root_pa, mem=mem), sort_keys=True)
+        self.assertEqual(first, second)
+
+
+class SyntheticRoundTripTests(unittest.TestCase):
+    def test_encoder_round_trip_4k(self):
+        va, pa = 0x204608000, 0x15E8FA000
+        mem = _tree(0x60000000, va, pa)
+        report = walk(va, root_pa=0x60000000, mem=mem)
+        self.assertEqual(report["status"], "ok")
+        self.assertEqual(int(report["pa"], 16), pa)
+        self.assertEqual(report["page_size"], "4k")
+        self.assertTrue(report["writable"])
+
+    def test_read_only_leaf_is_reported(self):
+        va, pa = 0x204608000, 0x15E8FA000
+        mem = _tree(0x60000000, va, pa, read_only=True)
+        report = walk(va, root_pa=0x60000000, mem=mem)
+        self.assertEqual(report["status"], "ok")
+        self.assertTrue(report["read_only"])
+        self.assertFalse(report["writable"])
+
+    def test_2m_leaf(self):
+        va, base_pa = 0x40000000, 0x20000000
+        mem = MemoryView()
+        i0 = (va >> 47) & 0x3
+        i1 = (va >> 38) & 0x1FF
+        i2 = (va >> 29) & 0x1FF
+        i3 = (va >> 21) & 0xFF
+        pd2, pd1, pd0 = 0x51001000, 0x51002000, 0x51003000
+        page = bytearray(0x1000)
+        struct.pack_into("<Q", page, i0 * 8, encode_pde_pointer(pd2))
+        mem.add(0x51000000, bytes(page))
+        page = bytearray(0x1000)
+        struct.pack_into("<Q", page, i1 * 8, encode_pde_pointer(pd1))
+        mem.add(pd2, bytes(page))
+        page = bytearray(0x1000)
+        struct.pack_into("<Q", page, i2 * 8, encode_pde_pointer(pd0))
+        mem.add(pd1, bytes(page))
+        page = bytearray(0x1000)
+        struct.pack_into("<Q", page, i3 * 16, encode_pte(base_pa, page_size="2m"))
+        mem.add(pd0, bytes(page))
+        report = walk(va + 0x12345, root_pa=0x51000000, mem=mem)
+        self.assertEqual(report["status"], "ok")
+        self.assertEqual(report["page_size"], "2m")
+        self.assertEqual(int(report["pa"], 16), base_pa + 0x12345)
+
+    def test_auto_page_mode_prefers_prefers_small_when_big_invalid(self):
+        va = 0x100000  # 64K-aligned; the dual BIG half is invalid (0)
+        root_pa, mem = channel_pdb_fixture()
+        report = walk(va, root_pa=root_pa, mem=mem, page_mode="auto")
+        self.assertEqual(report["status"], "ok")
+        self.assertEqual(report["page_mode_used"], "4k")
+
+    def test_auto_page_mode_uses_big_when_valid(self):
+        va, pa = 0x100000, 0x30000000
+        # build a tree whose dual BIG half points at a 64K-granularity table
+        i0 = (va >> 47) & 0x3
+        i1 = (va >> 38) & 0x1FF
+        i2 = (va >> 29) & 0x1FF
+        i3 = (va >> 21) & 0xFF
+        pd2, pd1, pd0, pt = 0x52001000, 0x52002000, 0x52003000, 0x52004000
+        mem = MemoryView()
+        page = bytearray(0x1000)
+        struct.pack_into("<Q", page, i0 * 8, encode_pde_pointer(pd2))
+        mem.add(0x52000000, bytes(page))
+        page = bytearray(0x1000)
+        struct.pack_into("<Q", page, i1 * 8, encode_pde_pointer(pd1))
+        mem.add(pd2, bytes(page))
+        page = bytearray(0x1000)
+        struct.pack_into("<Q", page, i2 * 8, encode_pde_pointer(pd0))
+        mem.add(pd1, bytes(page))
+        page = bytearray(0x1000)
+        struct.pack_into("<16s", page, i3 * 16, encode_dual_slot(pt, pt))
+        mem.add(pd0, bytes(page))
+        page = bytearray(0x1000)
+        # BIG path indexes the 64K table by VA bits 20:16
+        struct.pack_into("<Q", page, ((va >> 16) & 0x1FF) * 8,
+                         encode_pte(pa, page_size="64k"))
+        mem.add(pt, bytes(page))
+        report = walk(va, root_pa=0x52000000, mem=mem, page_mode="auto")
+        self.assertEqual(report["status"], "ok")
+        self.assertEqual(report["page_mode_used"], "64k")
+        self.assertEqual(report["evidence"], "modeled")
+
+
+class FaultTests(unittest.TestCase):
+    def test_missing_table_page(self):
+        root_pa, mem = channel_pdb_fixture()
+        report = walk(0x100000, root_pa=root_pa, mem=MemoryView())
+        self.assertEqual(report["status"], "fault")
+        self.assertEqual(report["fault"], FAULT_TABLE_MISSING)
+
+    def test_invalid_leaf(self):
+        mem = _tree(0x60000000, 0x204608000, None)  # leaf entry stays zero
+        report = walk(0x204608000, root_pa=0x60000000, mem=mem)
+        self.assertEqual(report["status"], "fault")
+        self.assertEqual(report["fault"], FAULT_PTE_INVALID)
+
+    def test_invalid_pde_aperture(self):
+        root_pa = 0x60000000
+        mem = MemoryView()
+        page = bytearray(0x1000)
+        struct.pack_into("<Q", page, 0, 0)  # aperture 0 = invalid
+        mem.add(root_pa, bytes(page))
+        report = walk(0x100000, root_pa=root_pa, mem=mem)
+        self.assertEqual(report["status"], "fault")
+        self.assertEqual(report["fault"], FAULT_INVALID_APERTURE)
+
+    def test_unsupported_kind_fails_closed(self):
+        root_pa, mem = channel_pdb_fixture()
+        report = walk(0x100000, root_pa=root_pa, mem=mem, kind="ver9")
+        self.assertEqual(report["status"], "fault")
+        self.assertEqual(report["fault"], FAULT_UNSUPPORTED)
+
+    def test_va_out_of_range(self):
+        root_pa, mem = channel_pdb_fixture()
+        report = walk(1 << 60, root_pa=root_pa, mem=mem)
+        self.assertEqual(report["status"], "fault")
+        self.assertEqual(report["fault"], FAULT_OUT_OF_RANGE)
+
+    def test_bad_page_mode_is_clean_error(self):
+        root_pa, mem = channel_pdb_fixture()
+        with self.assertRaises(WalkError):
+            walk(0x100000, root_pa=root_pa, mem=mem, page_mode="8k")
+
+
+class CliTests(unittest.TestCase):
+    def test_demo_returns_zero(self):
+        rc, out, _ = _run_main(["demo"])
+        self.assertEqual(rc, 0)
+        self.assertIn('"ok": true', out)
+        self.assertIn("PASS", out)
+
+    def test_run_returns_three_on_fault(self):
+        rc, out, _ = _run_main(["run", "--pdb-pa", "0x60000000", "--va", "0x1000"])
+        self.assertEqual(rc, 3)
+        self.assertIn("FAULT", out)
+
+
+if __name__ == "__main__":
+    unittest.main()
-- 
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