tree 025eb64abd9eee4a82f5c6004d30b9c393f588ff
parent 01ab9886ea7815d41a4ee435524c3fce127e7290
author Matthew Garrett <mjg59@google.com> 1516093802 +0000
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1517675965 +0100

x86/efi: Clarify that reset attack mitigation needs appropriate userspace

commit a5c03c31af2291f13689d11760c0b59fb70c9a5a upstream.

Some distributions have turned on the reset attack mitigation feature,
which is designed to force the platform to clear the contents of RAM if
the machine is shut down uncleanly. However, in order for the platform
to be able to determine whether the shutdown was clean or not, userspace
has to be configured to clear the MemoryOverwriteRequest flag on
shutdown - otherwise the firmware will end up clearing RAM on every
reboot, which is unnecessarily time consuming. Add some additional
clarity to the kconfig text to reduce the risk of systems being
configured this way.

Signed-off-by: Matthew Garrett <mjg59@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>