arm64: suspend: rely on daif helpers to handle PMR

Commit 77345ef70445 ("arm64: suspend: Use cpuidle context helpers
in cpu_suspend()") added cpuidle helpers to handle PMR manipulation
and restoration to ensure that the CPU receives interrupts when suspended
and pseudo-NMIs are enabled.

However, those helpers are called in between a pair of `local_daif_save()`
and `local_daif_restore()`, which already configure the PMR as expected.
Effectively, `arm_cpuidle_save_irq_context()` is a no-op here,
even when using pseudo-NMIs, and `arm_cpuidle_restore_irq_context()`
would not restore proper interrupt masking configuration early enough
if there were unexpected changes during suspend or resume.
(This can be observed with Trusted Firmware A (TF-A) at EL3 handling
suspend through PSCI. Even though it should not be the case, TF-A can
reset `ICC_PMR_EL1` during CPU_SUSPEND, thus resuming the kernel
with an inconsistent priority mask value on hardware implementing
more than the minimum number of priority levels, such as Morello.)

Thus : remove the cpuidle context helpers as they do not do anything,
but keep the comment mentioning the need for interrupts to reach the CPU
if we are using pseudo-NMIs.

Signed-off-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Signed-off-by: Will Deacon <will@kernel.org>

0 files changed, 0 insertions, 0 deletions