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

[Laura Abbott]

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