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From: Ard Biesheuvel <ardb@kernel•org>
To: linux-arm-kernel@lists•infradead.org
Cc: Ard Biesheuvel <ardb@kernel•org>
Subject: [PATCH 0/2] ARM/decompressor: deal with disabled CP15 barrier instructions
Date: Wed,  6 Nov 2019 10:42:17 +0100	[thread overview]
Message-ID: <20191106094219.24365-1-ardb@kernel.org> (raw)

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 <rmk+kernel@armlinux•org.uk>
Cc: Linus Walleij <linus.walleij@linaro•org>
Cc: Marc Zyngier <maz@kernel•org>

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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             reply	other threads:[~2019-11-06  9:42 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-06  9:42 Ard Biesheuvel [this message]
2019-11-06  9:42 ` [PATCH 1/2] ARM/decompressor: avoid CP15 barrier instructions in v7 cache setup code Ard Biesheuvel
2019-11-06  9:42 ` [PATCH 2/2] Revert "ARM: 8857/1: efi: enable CP15 DMB instructions before cleaning the cache" Ard Biesheuvel
2019-11-13 13:58 ` [PATCH 0/2] ARM/decompressor: deal with disabled CP15 barrier instructions Linus Walleij
2019-11-14  9:54   ` Ard Biesheuvel

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