linux-kernel - Re: [linus:master] [x86/sme] 48204aba80: BUG:kernel_failed_in_early-boot_stage,last_printk:Booting_the_kernel(entry

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Message-ID: <CAMj1kXG2D8cwtXTqjepm30B9X9KQD_q2XMDAA522mv9z-5_-ug@mail.gmail.com>
Date: Tue, 26 Mar 2024 10:59:04 +0200
From: Ard Biesheuvel <ardb@...nel.org>
To: Oliver Sang <oliver.sang@...el.com>
Cc: Borislav Petkov <bp@...en8.de>, oe-lkp@...ts.linux.dev, lkp@...el.com, 
	linux-kernel@...r.kernel.org, Tom Lendacky <thomas.lendacky@....com>
Subject: Re: [linus:master] [x86/sme] 48204aba80: BUG:kernel_failed_in_early-boot_stage,last_printk:Booting_the_kernel(entry_offset:#)

On Tue, 26 Mar 2024 at 10:31, Oliver Sang <oliver.sang@...el.com> wrote:
>
> hi, Ard Biesheuvel,
>
> On Mon, Mar 25, 2024 at 04:39:26PM +0200, Ard Biesheuvel wrote:
> > On Sun, 24 Mar 2024 at 16:26, Borislav Petkov <bp@...en8.de> wrote:
> > >
> > > On Fri, Mar 22, 2024 at 05:03:18PM +0800, kernel test robot wrote:
> > > >
> > > >
> > > > Hello,
> > > >
> > > > kernel test robot noticed "BUG:kernel_failed_in_early-boot_stage,last_printk:Booting_the_kernel(entry_offset:#)" on:
> > > >
> > > > commit: 48204aba801f1b512b3abed10b8e1a63e03f3dd1 ("x86/sme: Move early SME kernel encryption handling into .head.text")
> > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git master
> > > >
> > > > [test failed on linus/master 741e9d668aa50c91e4f681511ce0e408d55dd7ce]
> > > > [test failed on linux-next/master a1e7655b77e3391b58ac28256789ea45b1685abb]
> > > >
> > > > in testcase: boot
> > > >
> > > > compiler: gcc-12
> > > > test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G
> > >
> > > My guest boots with your .config and SNB as CPU model:
> > >
> > > ...
> > > [    0.373770][    T1] smpboot: CPU0: Intel Xeon E312xx (Sandy Bridge) (family: 0x6, model: 0x2a, stepping: 0x1)
> > >
> > > Artefacts like:
> > >
> > > -initrd initrd-vm-meta-180.cgz
> > >
> > > or
> > >
> > > RESULT_ROOT=/result/boot/1/vm-snb/quantal-x86_64-core-20190426.cgz/x86_64-rhel-8.3-bpf/gcc-12/48204aba801f1b512b3abed10b8e1a63e03f3dd1/3
> > >
> > > I don't have and don't know how to generate here so I can't run your
> > > exact reproducer.
> > >
> >
> > I ran the reproducer using the instructions, and things seem to work fine.
> >
> > https://paste.debian.net/1311951/
> >
> > Could you provide any information regarding the QEMU version and its
> > BIOS implementation?
>
> for QEMU version:
>
> $ qemu-system-x86_64 --version
> QEMU emulator version 7.2.9 (Debian 1:7.2+dfsg-7+deb12u5)
> Copyright (c) 2003-2022 Fabrice Bellard and the QEMU Project developers
>

I tested the exact same version.

Does it reproduce with -cpu host instead of -cpu SandyBridge? When
running under KVM, I suspect emulating the actual host uarch rather
than setting a different one is a more reliable strategy. What CPU
type does the host have?

>
> for BIOS:
>
> We don't specify bios option for qemu, my understanding is we just run with
> default bios for qemu (the seabios). Extra info of seabios
>

Today, legacy BIOS boot is only used by a minority of x86 systems in
the field, so for better coverage, it would make sense to at least
start testing UEFI as well.

On debian, just install the ovmf package, and pass -bios
/usr/share/ovmf/OVMF.fd on the QEMU command line.

And given that you are doing virt based boot testing, another very
important use case is TDX boot (as well as SEV-SNP, but that may be
more difficult for you to organize). But please explore internally at
Intel whether TDX can be added to your test matrix as well.