linux-kernel - Re: Boot regression with bacf6b499e11 ("x86/mm: Use a struct to reduce parameters for SME PGD mapping") on top of -rc8

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Date:   Fri, 19 Jan 2018 20:02:40 -0800
From:   Laura Abbott <labbott@...hat.com>
To:     Gabriel C <nix.or.die@...il.com>
Cc:     Tom Lendacky <thomas.lendacky@....com>,
        Borislav Petkov <bp@...e.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Brijesh Singh <brijesh.singh@....com>, X86 ML <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Boot regression with bacf6b499e11 ("x86/mm: Use a struct to
 reduce parameters for SME PGD mapping") on top of -rc8

On 01/19/2018 06:23 PM, Gabriel C wrote:
> 2018-01-20 2:23 GMT+01:00 Laura Abbott <labbott@...hat.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 ?
> 

The bisect was a vanilla kernel without Fedora patches.

>>
>> Thanks,
>> Laura
> 
> Regards,
> 
> Gabriel C
>