test: Check all vCPUs have the same features inside guest

The test ensures Firecracker or CPU templates don't configure CPU
features differently between vCPUs.

Note that whether the printed CPU features are expected or not should be
tested in (arch-specific) test_cpu_features_*.py only for vCPU 0. Thus,
we only test the equivalence of all CPUs in the same guest.

Signed-off-by: Takahiro Itazuri <[email protected]>

Author: zulinx86

tests/integration_tests/functional/test_cpu_multiple.py

@@ -16,3 +16,21 @@ def test_all_vcpus_online(uvm_any):
         uvm_any.ssh.check_output("cat /sys/devices/system/cpu/online").stdout.strip()
         == f"0-{uvm_any.vcpus_count - 1}"
     )
+
+
+def test_all_vcpus_have_same_features(uvm_any):
+    """
+    Check all vCPUs have the same features inside guest.
+
+    This test ensures Firecracker or CPU templates don't configure CPU features
+    differently between vCPUs.
+
+    Note that whether the shown CPU features are expected or not should be
+    tested in (arch-specific) test_cpu_features_*.py only for vCPU 0. Thus, we
+    only test the equivalence of all CPUs in the same guest.
+    """
+    # Get a feature set for each CPU and deduplicate them.
+    unique_feature_lists = uvm_any.ssh.check_output(
+        'grep -E "^(flags|Features)" /proc/cpuinfo | uniq'
+    ).stdout.splitlines()
+    assert len(unique_feature_lists) == 1