fix(test): Fix io_engine related tests

Ensure all io_engine related tests run with both the sync and the async
io_engine.

Prior to 4.14 deprecation, some tests used the following logic to
determine whether the Async engine or the Sync engine should be tested:

If io_uring is supported (e.g. host_kernel != 4.14) then use Async
Else use Sync

This meant we were running with the Async engine on 5.10 and 6.1, and
with the Sync engine on 4.14. However, once 4.14 went out of support,
this meant that tests employing this logic only ever tested the Async
engine anymore. Fix this by having all these tests always run with both
Sync and Async engines, independently of host kernel version.

Also remove all logic around checking whether io_uring is supported,
because it definitely is supported on all currently supported host
kernels.

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

tests/conftest.py

@@ -373,8 +373,6 @@ def cpu_template_any(request, record_property):
 @pytest.fixture(params=["Sync", "Async"])
 def io_engine(request):
     """All supported io_engines"""
-    if request.param == "Async" and not utils.is_io_uring_supported():
-        pytest.skip("io_uring not supported in this kernel")
     return request.param
 
 

tests/framework/defs.py

@@ -33,10 +33,6 @@
     / "release"
 )
 
-# The minimum required host kernel version for which io_uring is supported in
-# Firecracker.
-MIN_KERNEL_VERSION_FOR_IO_URING = "5.10.51"
-
 SUPPORTED_HOST_KERNELS = ["5.10", "6.1"]
 
 IMG_DIR = Path(DEFAULT_TEST_SESSION_ROOT_PATH) / "img"

tests/framework/utils.py

@@ -28,8 +28,6 @@
     wait_fixed,
 )
 
-from framework.defs import MIN_KERNEL_VERSION_FOR_IO_URING
-
 FLUSH_CMD = 'screen -S {session} -X colon "logfile flush 0^M"'
 CommandReturn = namedtuple("CommandReturn", "returncode stdout stderr")
 CMDLOG = logging.getLogger("commands")
@@ -455,17 +453,6 @@ def get_kernel_version(level=2):
     return linux_version
 
 
-def is_io_uring_supported():
-    """
-    Return whether Firecracker supports io_uring for the running kernel ...
-
-    ...version.
-    """
-    kv = packaging.version.parse(get_kernel_version())
-    min_kv = packaging.version.parse(MIN_KERNEL_VERSION_FOR_IO_URING)
-    return kv >= min_kv
-
-
 def generate_mmds_session_token(ssh_connection, ipv4_address, token_ttl):
     """Generate session token used for MMDS V2 requests."""
     cmd = "curl -m 2 -s"

tests/integration_tests/functional/test_api.py

@@ -17,7 +17,7 @@
 import host_tools.drive as drive_tools
 import host_tools.network as net_tools
 from framework import utils, utils_cpuid
-from framework.utils import get_firecracker_version_from_toml, is_io_uring_supported
+from framework.utils import get_firecracker_version_from_toml
 
 MEM_LIMIT = 1000000000
 
@@ -46,7 +46,7 @@ def test_api_happy_start(uvm_plain):
         assert "Kernel loaded using PVH boot protocol" in test_microvm.log_data
 
 
-def test_drive_io_engine(uvm_plain):
+def test_drive_io_engine(uvm_plain, io_engine):
     """
     Test io_engine configuration.
 
@@ -59,35 +59,20 @@ def test_drive_io_engine(uvm_plain):
     test_microvm.basic_config(add_root_device=False)
     test_microvm.add_net_iface()
 
-    supports_io_uring = is_io_uring_supported()
-
     kwargs = {
         "drive_id": "rootfs",
         "path_on_host": test_microvm.create_jailed_resource(test_microvm.rootfs_file),
         "is_root_device": True,
         "is_read_only": True,
     }
 
-    # Test the opposite of the default backend type.
-    if supports_io_uring:
-        test_microvm.api.drive.put(io_engine="Sync", **kwargs)
-
-    if not supports_io_uring:
-        with pytest.raises(RuntimeError):
-            test_microvm.api.drive.put(io_engine="Async", **kwargs)
-        # The Async engine is not supported for older kernels.
-        test_microvm.check_log_message(
-            "Received Error. Status code: 400 Bad Request. Message: Drive config error: "
-            "Unable to create the virtio block device: Virtio backend error: "
-            "Error coming from the IO engine: Unsupported engine type: Async"
-        )
-
-        # Now configure the default engine type and check that it works.
-        test_microvm.api.drive.put(**kwargs)
+    test_microvm.api.drive.put(io_engine=io_engine, **kwargs)
 
     test_microvm.start()
 
-    assert test_microvm.api.vm_config.get().json()["drives"][0]["io_engine"] == "Sync"
+    assert (
+        test_microvm.api.vm_config.get().json()["drives"][0]["io_engine"] == io_engine
+    )
 
 
 def test_api_put_update_pre_boot(uvm_plain, io_engine):
@@ -735,7 +720,7 @@ def test_negative_api_patch_post_boot(uvm_plain, io_engine):
         test_microvm.api.logger.patch(level="Error")
 
 
-def test_drive_patch(uvm_plain):
+def test_drive_patch(uvm_plain, io_engine):
     """
     Extensively test drive PATCH scenarios before and after boot.
     """
@@ -752,7 +737,7 @@ def test_drive_patch(uvm_plain):
         path_on_host=fs.path,
         is_root_device=False,
         is_read_only=False,
-        io_engine="Async" if is_io_uring_supported() else "Sync",
+        io_engine=io_engine,
     )
 
     fs_vub = drive_tools.FilesystemFile(
@@ -766,7 +751,7 @@ def test_drive_patch(uvm_plain):
 
     test_microvm.start()
 
-    _drive_patch(test_microvm)
+    _drive_patch(test_microvm, io_engine)
 
 
 @pytest.mark.skipif(
@@ -802,7 +787,7 @@ def test_send_ctrl_alt_del(uvm_plain):
         pass
 
 
-def _drive_patch(test_microvm):
+def _drive_patch(test_microvm, io_engine):
     """Exercise drive patch test scenarios."""
     # Patches without mandatory fields for virtio block are not allowed.
     expected_msg = "Unable to patch the block device: Device manager error: Running method expected different backend. Please verify the request arguments"
@@ -912,7 +897,7 @@ def _drive_patch(test_microvm):
                 "bandwidth": {"size": 5000, "one_time_burst": None, "refill_time": 100},
                 "ops": {"size": 500, "one_time_burst": None, "refill_time": 100},
             },
-            "io_engine": "Async" if is_io_uring_supported() else "Sync",
+            "io_engine": io_engine,
             "socket": None,
         },
         {