Add a test that ensures correct BDF assignment #68

scholzp · 2025-11-27T15:41:39Z

This test adds checks for verifying correct BDF assignment through libvirt and that CHV respects those assignments, even after live migration. Moreover, this test ensures that BDFs can be freed and reused when de-/attaching devices (might be more of a theoretical feature?).

For further details, see the test description.

Related to https://github.com/cobaltcore-dev/cobaltcore/issues/287.

tests/common.nix

phip1611

Generally great work! Left a few remarks

tests/common.nix

tests/testscript.py

tpressure · 2025-11-27T19:38:58Z

This is great work, can we also add 2 hotplug devices:

1 network dev with specific bdf
1 disk with dev specific bdf?

tests/testscript.py

hertrste

We well written test case 👍

tests/testscript.py

phip1611

I like the direction into that we are going here - good work! I left a few remarks

tests/common.nix

tests/testscript.py

phip1611

LGTM but I left a few remarks. I'm already approving.

tests/testscript.py

tests/common.nix

tests/testscript.py

phip1611 · 2025-12-05T12:47:13Z

You need to rebase your PR.

phip1611 · 2025-12-05T14:11:25Z

tests/common.nix

+        <target dev='tap0'/>
+        <model type='virtio'/>
+        <driver queues='1'/>
+        all_static_bdf ? false


all_static_bdf ? false

this looks lile a oopsie and will land as is in the XML string.

It surprises me that libvirt doesnt fail

Good Catch! Fixed.

tpressure · 2025-12-05T15:31:56Z

@scholzp please resolve conflicts

We don't use the DHCP anymore, so we can deactivate it. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

We need to specify slot IDs in the XML from which the VM config for CHV is created. This is in preparation for testing BDF fixing. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

When evaluating PCI BDF assignment we need a way to query these information from a test VM. This commit adds a handy way to obtain all BDFs with their assigned devices. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

Some test, as the anticipated tests for BDF assignment might need to do some additional cleanup after terminating that is specific for this test only. This also needs to work reliably in case of tests failing. This commit therefore introduces infrastructure that allows to define some 'guard', that once garbage collected, executes the cleanup routines. Signed-off-by: Pascal Scholz pascal.scholz@cyberus-technology.de On-behalf-of: SAP pascal.scholz@sap.com

phip1611 · 2025-12-10T05:16:12Z

Please fix the ci.

Are all issues in the corresponding libvirt pr now resolved?

scholzp · 2025-12-10T10:28:46Z

Please fix the ci.

Are all issues in the corresponding libvirt pr now resolved?

Yes, they are.
The CI should now be fixed for all commits that I intent to keep.

The added tests checks that libvirt and CHV assigned and propagate PCI BDF correctly to the guest's PCI devices. It furthermore ensures, that these assignment stay valid even after live migration. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

We test that the persistent config stores the correct BDF. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

This test ensures that BDFs stored in the live and the persistent config don't go out of sync when transiently removing a device. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

We need to test that an invalid BDF results in an error from libvirt and does not crash CHV. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

We need a negative test that shows, that adding a function ID when entering a BDF result in libvirt generating a failure and CHV not crashing. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

scholzp · 2025-12-12T10:20:06Z

I just added negative tests for:

libvirt receives an invalid device ID in a BDF
libvirt receives a function ID in a BDF

Both are expected to be blocked and errrored upon by libvirt.

phip1611 · 2025-12-12T10:29:54Z

Great work!

phip1611 · 2025-12-15T09:54:25Z

tests/testscript.py

+        Test that a BDFs containing a function ID leads to errors.
+        """
+        # We don't support multi function devices currently
+        controllerVM.fail("virsh define /etc/domain-chv-static-bdf-with-function.xml")


this file doesn't exist?!

scholzp requested review from hertrste, phip1611 and tpressure November 27, 2025 15:41

scholzp self-assigned this Nov 27, 2025

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scholzp force-pushed the bdf_tests branch 3 times, most recently from b23fb51 to 4aac2f1 Compare November 27, 2025 17:17

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scholzp force-pushed the bdf_tests branch 3 times, most recently from 240f603 to 8654c40 Compare December 5, 2025 14:07

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scholzp force-pushed the bdf_tests branch from c48baf7 to a9dfe3f Compare December 9, 2025 15:01

scholzp added 4 commits December 9, 2025 16:23

nix: Disable DHCP

462f4bd

We don't use the DHCP anymore, so we can deactivate it. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

nix: Add PCI slot IDs to testvm XML

f551f4d

We need to specify slot IDs in the XML from which the VM config for CHV is created. This is in preparation for testing BDF fixing. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

scholzp force-pushed the bdf_tests branch from a9dfe3f to 541454a Compare December 9, 2025 15:24

scholzp force-pushed the bdf_tests branch 2 times, most recently from c038d6b to 68b98a1 Compare December 10, 2025 10:25

scholzp added 3 commits December 10, 2025 12:47

testscript: Add test for checking BDFs after VM restart

083abdc

We test that the persistent config stores the correct BDF. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

scholzp force-pushed the bdf_tests branch from 68b98a1 to 2ba7d05 Compare December 10, 2025 11:47

scholzp added 2 commits December 12, 2025 11:10

testscript: Test case that the given BDF device ID is invalid

105a932

We need to test that an invalid BDF results in an error from libvirt and does not crash CHV. Signed-off-by: Pascal Scholz <pascal.scholz@cyberus-technology.de> On-behalf-of: SAP pascal.scholz@sap.com

phip1611 requested changes Dec 15, 2025

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scholzp commented Nov 27, 2025 •

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