linux-kernel - Re: [PATCH 0/2] Fix boot hang issue on Ampere Emag server

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Date:   Tue, 31 Jan 2023 19:03:12 +0100
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     Jia He <justin.he@....com>, Huacai Chen <chenhuacai@...nel.org>,
        linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Alexandru Elisei <alexandru.elisei@....com>
Subject: Re: [PATCH 0/2] Fix boot hang issue on Ampere Emag server

On Tue, Jan 31, 2023 at 08:18:49AM +0100, Ard Biesheuvel wrote:
> (cc Jason for awareness)
> 
> On Tue, 31 Jan 2023 at 05:04, Jia He <justin.he@....com> wrote:
> >
> > I met a hung task warning and then kernel was hung forever with latest
> > kernel on an Ampere Emag server.
> >
> > The root cause is kernel was hung  when invoking an efi rts call to set
> > the RandomSeed variable during the booting stage. The arch_efi_call_virt
> > call (set_variable) was never returned and then caused the hung task error.
> >
> 
> Given that EFI variables work on this platform (as far as I know), the
> problem may be that we are calling SetVariable() too early.
> 

On my phone and with very limited connectivity for another 10 days, but
I wonder if there's a later place we could move this block:

    if (efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE))
        execute_with_initialized_rng(&refresh_nv_rng_seed_nb);

Is there any additional initialization that happens after
efisubsys_init() that we're maybe missing out on there?

Jason