Re: [edk2-devel] OVMF Issue with Netboot, VirtioRng, and both COM1/COM2 configured

["Gerd Hoffmann" <kraxel@redhat.com>]

On Mon, Nov 04, 2024 at 10:14:47AM +0100, Stefano Garzarella wrote:
> Hi Gerd,
> 
> On Fri, Nov 1, 2024 at 10:31 AM Gerd Hoffmann <kraxel@redhat.com> wrote:
> >
> >   Hi,
> >
> > > By analyzing the calls to the dispatcher (`gDS->Dispatch ()`) I found
> > > that when we only have COM1, EfiBootManagerConnectDevicePath() at some
> > > point invokes `gDS->Dispatch ()` after VirtioRng has started. This call
> > > will then get DxeNetLib loaded.
> >
> > Ok, so it is probably a good idea to explicitly request a dispatch after
> > activating virtio-rng, so we do not depend on this happening by pure
> > luck for other reasons:
> >
> > --- a/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c
> > +++ b/OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c
> > @@ -670,6 +670,7 @@ ConnectVirtioPciRng (
> >      if (EFI_ERROR (Status)) {
> >        goto Error;
> >      }
> > +    gDS->Dispatch ();
> >    }
> >
> >    return EFI_SUCCESS;
> >
> > [ untested patch, and we probably should do something similar for ArmVirt,
> >   /me goes continue walking through my email backlog now ]
> >
> 
> Yep, that should work.
> 
> Last week I went a little deeper into the problem and basically
> starting with commit 4c4ceb2ceb ("NetworkPkg: SECURITY PATCH
> CVE-2023-45237") the network stack is no longer initialized during
> DXE, but in BDS (see
> https://issues.redhat.com/browse/RHEL-58631?focusedId=25981655&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-25981655).
> 
> Is this intentional? Could there be other problems besides this one we just had?

A lot of the more important stuff for network booting happens in the
BDS phase anyway, i.e. OVMF checking the qemu boot order, connecting
the devices configured as bootable devices (including the NICs),
creating (if needed) and sorting the BootNNNN entries.

So I don't expect any bad side effects from initializing the core
network modules in the (early) BDS phase.

take care,
  Gerd



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