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arm64: ssbd: Restore mitigation status on CPU resume

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On a system where firmware can dynamically change the state of the
mitigation, the CPU will always come up with the mitigation enabled,
including when coming back from suspend.

If the user has requested "no mitigation" via a command line option,
let's enforce it by calling into the firmware again to disable it.

Similarily, for a resume from hibernate, the mitigation could have
been disabled by the boot kernel. Let's ensure that it is set
back on in that case.

Acked-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Marc Zyngier 2018-05-29 13:11:12 +01:00 • committed by Catalin Marinas
parent 986372c436
commit 647d0519b5
4 changed files with 26 additions and 1 deletions
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11
arch/arm64/kernel/hibernate.c
View file

@ -313,6 +313,17 @@ int swsusp_arch_suspend(void)
sleep_cpu = -EINVAL;
__cpu_suspend_exit();
/*
* Just in case the boot kernel did turn the SSBD
* mitigation off behind our back, let's set the state
* to what we expect it to be.
*/
switch (arm64_get_ssbd_state()) {
case ARM64_SSBD_FORCE_ENABLE:
case ARM64_SSBD_KERNEL:
arm64_set_ssbd_mitigation(true);
}
}
local_daif_restore(flags);