[ipxe-devel] [PATCH 2/2] virtio-net: reset virtio NICs when booting under UEFI

[Laszlo Ersek]

On 04/10/15 22:45, Laszlo Ersek wrote:
> On 04/10/15 22:16, Michael Brown wrote:
>> On 10/04/15 20:53, Laszlo Ersek wrote:
>>> In efi_init() [src/interface/efi/efi_init.c], iPXE registers the
>>> efi_shutdown_hook() function as a callback for the
>>> EVT_SIGNAL_EXIT_BOOT_SERVICES event. This event is emitted under UEFI
>>> when
>>> the OS loader (including the Linux EFI stub) calls ExitBootServices().
>>>
>>> Currently, that event results in the following call chain:
>>>
>>> efi_shutdown_hook()                        
>>> [src/interface/efi/efi_init.c]
>>>    shutdown_boot()                           [src/include/ipxe/init.h]
>>>      shutdown(1)                             [src/core/init.c]
>>>        /* Call registered shutdown functions (in reverse order) */
>>>        forall startup_fn:
>>>          startup_fn->shutdown(1)
>>>
>>> This infrastructure is fine. However, the virtio-net driver does not
>>> register such a shutdown function at the moment.
>>>
>>> Consequently, virtio-net devices remain configured (active) after
>>> ExitBootServices().
>>
>> Individual iPXE drivers are not expected to have to register shutdown
>> functions.  All drivers should have their remove() method called for all
>> open devices already.  Registering custom shutdown functions is intended
>> for code which needs to do something unusual at shutdown time (e.g. the
>> EHCI/xHCI USB bus drivers, which need to decide whether or not to
>> attempt to hand control back to the BIOS).
>>
>> Looking at the code, I think there might be a missing piece:
>>
>> - Under our (very) old EFI driver model, we enumerated the PCI bus
>> directly and basically ignored EFI's concept of devices.  The
>> efi_shutdown_hook() would therefore result in devices being closed via
>> remove_devices() in core/device.c.  This no longer happens, because we
>> now attach to devices only as requested by EFI.
>>
>> - When built as an EFI application, the efi_root_device in efiprefix.c
>> means that the call to remove_devices() will end up calling efi_remove()
>> and hence efi_driver_disconnect_all().
>>
>> - From a quick look, there seems to be no equivalent functionality for
>> when built as an EFI driver.
>>
>> I don't have time to look at it properly right now, but could you try
>> the attached (totally untested) patch?

> I'll test your patch next week. Many thanks!

Couldn't wait that long. Your patch works fine.

Thanks!
Laszlo