Comment 2 for bug 1284874

Comments from Alex Williamson :
> The sequence leading up to this is quite short. We do standard PCI BAR
> sizing and setup, read the ROM, then do:
>
> vfio: vfio_pci_write_config(0000:03:00.0, @0x78, 0x1, len=0x4)
> vfio: vfio_pci_write_config(0000:03:00.0, @0x80, 0x9430, len=0x4)
> vfio: vfio_pci_write_config(0000:03:00.0, @0x78, 0xa30c, len=0x4)
> vfio: vfio_pci_write_config(0000:03:00.0, @0x80, 0x7fffffff, len=0x4)
> vfio: vfio_pci_write_config(0000:03:00.0, @0x78, 0xa5dc, len=0x4)
> vfio: vfio_pci_write_config(0000:03:00.0, @0x80, 0x0, len=0x4)
> vfio: vfio_pci_write_config(0000:03:00.0, @0x78, 0xa2ec, len=0x4)
> vfio: vfio_pci_write_config(0000:03:00.0, @0x80, 0x3, len=0x4)
> vfio: vfio_pci_read_config(0000:03:00.0, @0x98, len=0x4) 200
> vfio: vfio_pci_write_config(0000:03:00.0, @0x78, 0xa408, len=0x4)
> vfio: vfio_pci_read_config(0000:03:00.0, @0x80, len=0x4) 8
>
> vfio: vfio_pci_write_config(0000:03:00.0, @0x78, 0x86420, len=0x4)
> vfio: vfio_pci_write_config(0000:03:00.0, @0x80, 0x4, len=0x4)
> vfio: vfio_pci_write_config(0000:03:00.0, @0x78, 0x86420, len=0x4)
> vfio: vfio_pci_read_config(0000:03:00.0, @0x80, len=0x4) 8
>
> The last 4 operations are repeated forever.

Based on the Linux driver we can see that 0x86420 is MCP_REG_MCPR_NVM_SW_ARB which arbitrates software locking of the nvram on the device. A write of 4 seems to indicate that we want to lock port 1 for nvram access. A successful lock would set bit 2 (0x4). The value 0x8 is read back, so the lock was not successful and the ROM repeats this forever.

Perhaps there's a problem with how the port number is selected? It seems suspicious that we're using port 1 here.