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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Message-ID: <CAEJqkgjwD+Ucj+J7taBuQm+qMbOXCccgHBsfnutEa=jcPBYAbw@mail.gmail.com>
Date:   Sat, 20 Jan 2018 06:25:48 +0100
From:   Gabriel C <nix.or.die@...il.com>
To:     Laura Abbott <labbott@...hat.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

2018-01-20 5:02 GMT+01:00 Laura Abbott <labbott@...hat.com>:
> 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.

Ok . I did an build ( v4.15-rc8-225-g8dd903d2cf7b ) on my AMD
Workstation  ( EPYC CPU )
 with your 64bit config and one on the Ideapad ( Intel i7-6498DU ) ..
I disabled Selinux since I don't use it here and module  signing.

Also with your config my serial setup won't work and the kernel hangs
but mem_encrypt=on/off works just fine.

Also I notice on the Workstation it takes forever to boot untill
'DMA-API' reports out-of-memory
( dunno how much memory it need but the box has 128GB of RAM )..


Can you tell us your Lenovo models  please  ?

Reagrds,

Gabriel C