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From:   Gabriel C <nix.or.die@gmail.com>
Date:   Sat, 20 Jan 2018 03:23:11 +0100
Message-ID: <CAEJqkggBANYY98EFxWFDtuh1q3Ov7=UGnn2GYo_T661=LnVNPA@mail.gmail.com>
Subject: Re: Boot regression with bacf6b499e11 ("x86/mm: Use a struct to
 reduce parameters for SME PGD mapping") on top of -rc8
To:     Laura Abbott <labbott@redhat.com>
Cc:     Tom Lendacky <thomas.lendacky@amd.com>,
        Borislav Petkov <bp@suse.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        Brijesh Singh <brijesh.singh@amd.com>, X86 ML <x86@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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2018-01-20 2:23 GMT+01:00 Laura Abbott <labbott@redhat.com>:
> Hi,

Hi ,

>
> Fedora got multiple reports of an early bootup crash post -rc8.
> Bisection showed bacf6b499e11 ("x86/mm: Use a struct to reduce
> parameters for SME PGD mapping") . It doesn't revert cleanly
> but if I revert the few other changes in arch/x86/mm/mem_encrypt.c
> as well it boots up fine.
>
> Annoyingly, I can't seem to get any actual kernel logs even with
> earlyprintk. It just reboots immediately (triple fault?). This
> happens on both of my Lenovo machines and I can ask other reporters
> for details as well.
>

I tested these patches on 2 Lenovo Ideapad both with Skylake CPUs
on a older dual Xeon box , on 2 Toshibas with AMD APUs , on a RYZEN box ,
on dual EPYC box .. ofc on EPYC with mem_encrypt=on on the Intel CPUs disabled.

Also tested on top 4.14.13 , 4.14.14 as well on top 4.15.0-rc7 and on
current master/rc8++ without to see something like this.

Also we pushed these patches on 4.14.13/14 and didn't got any reports about
something like this.

What Lenovo boxes are these ? maybe I find one to reproduce.


> $ git bisect log
> # bad: [ec835f8104a21f4d4eeb9d316ee71d2b4a7f00de] Merge tag
> 'trace-v4.15-rc4-3' of
> git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
> # good: [a8750ddca918032d6349adbf9a4b6555e7db20da] Linux 4.15-rc8
> git bisect start 'origin/master' 'v4.15-rc8'
> # bad: [79683f80e4f07dba13cc08d0ebcf5c7b0aa1bf68] Merge tag
> 'mmc-v4.15-rc2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc
> git bisect bad 79683f80e4f07dba13cc08d0ebcf5c7b0aa1bf68
> # good: [161f72ed6dbe7fb176585091d3b797125d310399] Merge tag
> 'mac80211-for-davem-2018-01-15' of
> git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211
> git bisect good 161f72ed6dbe7fb176585091d3b797125d310399
> # good: [88dc7fca18001fd883e5ace775afa316b68c8f2c] Merge branch
> 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
> git bisect good 88dc7fca18001fd883e5ace775afa316b68c8f2c
> # bad: [d47924417319e3b6a728c0b690f183e75bc2a702] x86/intel_rdt/cqm: Prevent
> use after free
> git bisect bad d47924417319e3b6a728c0b690f183e75bc2a702
> # good: [fc90ccfd286eabb05ec54521367df8663cf0bbbf] Revert "x86/apic: Remove
> init_bsp_APIC()"
> git bisect good fc90ccfd286eabb05ec54521367df8663cf0bbbf
> # bad: [bacf6b499e11760aef73a3bb5ce4e5eea74a3fd4] x86/mm: Use a struct to
> reduce parameters for SME PGD mapping
> git bisect bad bacf6b499e11760aef73a3bb5ce4e5eea74a3fd4
> # good: [1303880179e67c59e801429b7e5d0f6b21137d99] x86/mm: Clean up register
> saving in the __enc_copy() assembly code
> git bisect good 1303880179e67c59e801429b7e5d0f6b21137d99
> # first bad commit: [bacf6b499e11760aef73a3bb5ce4e5eea74a3fd4] x86/mm: Use a
> struct to reduce parameters for SME PGD mapping
>
>
> Configuration is at
> https://git.kernel.org/pub/scm/linux/kernel/git/jwboyer/fedora.git/commit/?h=rawhide
> Note that I do think this is something in the Fedora configuration
> because a generic "make defconfig" booted just fine.

But maybe some of the Fedora patches ?

Can you try an kernel with the config but without any patches ?
Or a defconfig and just enable  CONFIG_AMD_MEM_ENCRYPT ?

>
> Thanks,
> Laura

Regards,

Gabriel C