Subject: [PATCH resend 0/2] ARM/decompressor: deal with disabled CP15 barrier instructions

From: Ard Biesheuvel <[email-masked]>
Date: Wed, 6 Nov 2019 11:49:16 +0100

[ Resending because --cc-cover didn't take ]

While trying to test my v4.4 backport of the firmware/hypervisor based spectre
v1/v2 mitigations for 32-bit ARM, I noticed that KVM/qemu failed to boot my
kernel while it booted fine under TCG emulation.

As it turns out, KVM/qemu may instantiate the VCPU with support for CP15
barrier instructions disabled, causing them to UNDEF and crash the
decompressor.

I already fixed the same issue for UEFI boot, but since v4.4 does not support
that, I only noticed now that this is an issue for bare metal as well.

Cc: Russell King <[email-masked]>
Cc: Linus Walleij <[email-masked]>
Cc: Marc Zyngier <[email-masked]>

Ard Biesheuvel (2):
  ARM/decompressor: avoid CP15 barrier instructions in v7 cache setup
    code
  Revert "ARM: 8857/1: efi: enable CP15 DMB instructions before cleaning
    the cache"

 arch/arm/boot/compressed/head.S | 51 ++++++++++----------
 1 file changed, 26 insertions(+), 25 deletions(-)

-- 
2.17.1

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