linux-kernel - Re: [BUG][SEVERE] Enabling EFI runtime services causes panics in the T2 security chip on Macs equipped with it.

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Date:   Mon, 10 Jan 2022 18:45:35 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Aditya Garg <gargaditya08@...e.com>
Cc:     "jk@...abs.org" <jk@...abs.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        "linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Orlando Chamberlain <redecorating@...tonmail.com>,
        Aun-Ali Zaidi <admin@...eit.net>
Subject: Re: [BUG][SEVERE] Enabling EFI runtime services causes panics in the
 T2 security chip on Macs equipped with it.

On Mon, 10 Jan 2022 at 17:37, Ard Biesheuvel <ardb@...nel.org> wrote:
>
> On Mon, 10 Jan 2022 at 17:28, Aditya Garg <gargaditya08@...e.com> wrote:
...
> > >>
> > >> This seems to be triggered by EFI_QUERY_VARIABLE_INFO here
> > >>
> > >
> > > This is interesting. QueryVariableInfo() was introduced in EFI 2.00,
> > > and for a very long time, Intel MACs would claim to implement EFI 1.10
> > > only. This means Linux would never attempt to use QueryVariableInfo()
> > > on such platforms.
> > >
> > > Can you please check your boot log which revision it claims to implement now?
> > >
> > > Mine says
> > >
> > > efi: EFI v1.10 by Apple
> >
> > Mine says
> >
> > efi: EFI v2.40 by Apple
> >

Can you check whether things work as before after applying the change below?

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 147c30a81f15..d7203355cc69 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -399,7 +399,7 @@ static int __init efi_systab_init(unsigned long phys)
                efi_nr_tables           = systab32->nr_tables;
        }

-       efi.runtime_version = hdr->revision;
+       efi.runtime_version = EFI_1_10_SYSTEM_TABLE_REVISION;

        efi_systab_report_header(hdr, efi_fw_vendor);
        early_memunmap(p, size);