[PATCH RFC 4/4] NOT FOR MERGE: script for CPU model stuff related to x86-64 ABI levels

["Daniel P. Berrangé" <berrange@redhat.com>]

This script is something that I wrote in order to help with creation of
the first two patches. Since those patches are essentially static data
once created, I don't intend for this script to be called repeatedly
in future. I've just included here as a reference to show how I came
up with content.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
---
 scripts/cpu-x86-uarch-abi.py | 194 +++++++++++++++++++++++++++++++++++
 1 file changed, 194 insertions(+)
 create mode 100644 scripts/cpu-x86-uarch-abi.py

diff --git a/scripts/cpu-x86-uarch-abi.py b/scripts/cpu-x86-uarch-abi.py
new file mode 100644
index 0000000000..8ef6d3ea08
--- /dev/null
+++ b/scripts/cpu-x86-uarch-abi.py
@@ -0,0 +1,194 @@
+#!/usr/bin/python3
+
+from qemu import qmp
+import sys
+
+# Mandatory CPUID features for each microarch ABI level
+levels = [
+    [ # x86-64 baseline
+        "cmov",
+        "cx8",
+        "fpu",
+        "fxsr",
+        "mmx",
+        "syscall",
+        "sse",
+        "sse2",
+    ],
+    [ # x86-64-v2
+        "cx16",
+        "lahf-lm",
+        "popcnt",
+        "pni",
+        "sse4.1",
+        "sse4.2",
+        "ssse3",
+    ],
+    [ # x86-64-v3
+        "avx",
+        "avx2",
+        "bmi1",
+        "bmi2",
+        "f16c",
+        "fma",
+        "abm",
+        "movbe",
+    ],
+    [ # x86-64-v4
+        "avx512f",
+        "avx512bw",
+        "avx512cd",
+        "avx512dq",
+        "avx512vl",
+    ],
+]
+
+# Assumes externally launched process such as
+#
+#   qemu-system-x86_64 -qmp unix:/tmp/qmp,server,nowait -display none -accel kvm
+#
+# Note different results will be obtained with TCG, as
+# TCG masks out certain features otherwise present in
+# the CPU model definitions, as does KVM.
+
+
+sock = sys.argv[1]
+cmd = sys.argv[2]
+shell = qmp.QEMUMonitorProtocol(sock)
+shell.connect()
+
+models = shell.cmd("query-cpu-definitions")
+
+# These QMP props don't correspond to CPUID fatures
+# so ignore them
+skip = [
+    "family",
+    "min-level",
+    "min-xlevel",
+    "vendor",
+    "model",
+    "model-id",
+    "stepping",
+]
+
+names = [model["name"] for model in models["return"]]
+
+models = {}
+
+for name in sorted(names):
+    cpu = shell.cmd("query-cpu-model-expansion",
+                     { "type": "static",
+                       "model": { "name": name }})
+
+    got = {}
+    for (feature, present) in cpu["return"]["model"]["props"].items():
+        if present and feature not in skip:
+            got[feature] = True
+
+    if name in ["host", "max", "base"]:
+        continue
+
+    models[name] = {
+        # Dict of all present features in this CPU model
+        "features": got,
+
+        # Whether each x86-64 ABI level is satisfied
+        "levels": [False, False, False, False],
+
+        # Number of extra CPUID features compared to the x86-64 ABI level
+        "distance":[-1, -1, -1, -1],
+
+        # CPUID features present in model, but not in ABI level
+        "delta":[[], [], [], []],
+    }
+
+
+# Calculate whether the CPU models satisfy each ABI level
+for name in models.keys():
+    for level in range(len(levels)):
+        match = True
+        for feat in levels[level]:
+            if feat not in models[name]["features"]:
+                match = False
+        models[name]["levels"][level] = match
+
+# Cache list of CPU models satisfying each ABI level
+abi_models = [
+    [],
+    [],
+    [],
+    [],
+]
+
+for name in models.keys():
+    for level in range(len(levels)):
+        if models[name]["levels"][level]:
+            abi_models[level].append(name)
+
+
+for level in range(len(abi_models)):
+    # Find the union of features in all CPU models satisfying this ABI
+    allfeatures = {}
+    for name in abi_models[level]:
+        for feat in models[name]["features"]:
+            allfeatures[feat] = True
+
+    # Find the intersection of features in all CPU models satisfying this ABI
+    commonfeatures = []
+    for feat in allfeatures:
+        present = True
+        for name in models.keys():
+            if not models[name]["levels"][level]:
+                continue
+            if feat not in models[name]["features"]:
+                present = False
+        if present:
+            commonfeatures.append(feat)
+
+    # Determine how many extra features are present compared to the lowest
+    # common denominator
+    for name in models.keys():
+        if not models[name]["levels"][level]:
+            continue
+
+        delta = set(models[name]["features"].keys()) - set(commonfeatures)
+        models[name]["distance"][level] = len(delta)
+        models[name]["delta"][level] = delta
+
+def print_uarch_abi_csv():
+    print("Model,baseline,v2,v3,v4")
+    for name in models.keys():
+        print(name, end="")
+        for level in range(len(levels)):
+            if models[name]["levels"][level]:
+                print(",✅", end="")
+            else:
+                print(",", end="")
+        print()
+
+def find_closest_abi_models():
+    for level in range(len(abi_models)):
+        # Determine which CPU model(s) are the "best" match for the lowest
+        # common denominator. One of these will be used as the basis for
+        # defining the generic CPU model for this ABI level
+        distance = -1
+        for name in models.keys():
+            if not models[name]["levels"][level]:
+                continue
+
+            this = models[name]["distance"][level]
+            if distance == -1 or this < distance:
+                distance = this
+                best = name
+
+        for name in models:
+            if models[name]["distance"][level] == distance:
+                print("  >> Level %d match %s (distance %d)" % (
+                    level, name, models[name]["distance"][level]))
+                print("     Remove features: %s" %
+                      " ".join(models[name]["delta"][level]))
+
+if cmd == "abi-table":
+    print_uarch_abi_csv()
+elif cmd == "abi-model":
+    find_closest_abi_models()
-- 
2.29.2