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From: Laura Abbott <labbott@redhat.com>
Subject: 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 17:23:26 -0800
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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.

$ 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.

Thanks,
Laura