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

[Michael Brown]

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?

Thanks,

Michael
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