** Description changed:
- Description will follow
+ Today, the enumeration of PCI functions on s390x does not reflect which
+ functions belongs to which physical adapter.
+
+ Layout of a PCI function address on Linux:
+ 0000:00:00.0
+ <root complex>:<bus>:<device>.<function>
+
+ On s390x, each function is presented as individual root complex today,
+ e.g.:
+
+ PCHID 0100 VF1 0000:00:00.0
+ PCHID 0100 VF23 0001:00:00.0
+ PCHID 0200 VF1 0002:00:00.0
+ OCHID 0100 VF17 0003:00:00.0
+
+ On other platforms, the addresses correctly reflect the actual HW
+ configuration. Some device drivers (mlx5 for Mellanox adapters) group
+ functions of one physical adapter by checking which PCI functions have
+ identical values for <root complex>:<bus>:<device>. We need to use the
+ same enumeration scheme to achieve this functionality on s390x.
+
+ In this case, the two physical functions of a Mellanox adapter need to
+ get function number 0 and 1, and all virtual functions need to use the
+ same <root complex>:<bus> numbers with function/device numbers counting
+ up.
+
+ Required result (example with 4 VFs per PF):
+
+ PCHID 0100 PF 0 0000:00:00.0
+ PCHID 0100 PF 1 0000:00:00.1
+ PCHID 0100 PF 0 VF 0 0000:00:00.2
+ PCHID 0100 PF 0 VF 1 0000:00:00.3
+ PCHID 0100 PF 0 VF 2 0000:00:00.4
+ PCHID 0100 PF 0 VF 3 0000:00:00.5
+ PCHID 0100 PF 1 VF 0 0000:00:00.6
+ PCHID 0100 PF 1 VF 1 0000:00:00.7
+ PCHID 0100 PF 1 VF 2 0000:00:00.8
+ PCHID 0100 PF 1 VF 3 0000:00:00.9
+
+ PCHID 0200 PF 0 0001:00:00.0
** Also affects: ubuntu-z-systems
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/1874056
Title:
[UBUNTU 20.04] s390x/pci: enumerate pci functions per physical adapter
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