fix(test): Add invpcid_single to guest-host feature diff on ubuntu

Linux kernel v6.6+ drops the synthetic feature flag. While our ubuntu
host kernel is v6.8 that has the change, Amazon Linux kernels and our
guest kernel doesn't.

Fixes: 4e014a1 ("test(x86_64): add host vs guest cpu feature test")
Signed-off-by: Takahiro Itazuri <[email protected]>

Author: zulinx86

tests/integration_tests/functional/test_cpu_features_x86_64.py

@@ -401,11 +401,18 @@ def test_host_vs_guest_cpu_features_x86_64(uvm_nano):
                 expected -= {"flush_l1d"}
             assert host_feats - guest_feats == expected
 
-            assert guest_feats - host_feats == {
+            expected = {
                 "hypervisor",
                 "tsc_known_freq",
                 "umip",
             }
+            # TODO: Remove the below ubuntu exception once our guest kernel and Amazon Linux host
+            # kernels pick the following kernel commit and remove the synthetic feature flag.
+            # https://github.com/torvalds/linux/commit/54e3d9434ef61b97fd3263c141b928dc5635e50d
+            # See also https://github.com/firecracker-microvm/firecracker/issues/4901
+            if "Ubuntu" in global_props.os:
+                expected += {"invpcid_single"}
+            assert guest_feats - host_feats == expected
         case CpuModel.INTEL_ICELAKE:
             host_guest_diff_5_10 = {
                 "dtes64",