Re: [RFC PATCH 04/36] arm64: suspend: rely on daif helpers to handle PMR
From: Jinjie Ruan <hidden>
Date: 2026-07-10 03:41:44
On 7/9/2026 8:13 PM, Vladimir Murzin wrote:
From: Ada Couprie Diaz <redacted>
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.local_daif_save()/local_daif_restore() has done all relevant PMR and DAIF save and restore tasks. LGTM Reviewed-by: Jinjie Ruan <redacted>
quoted hunk ↗ jump to hunk
Signed-off-by: Ada Couprie Diaz <redacted> Signed-off-by: Vladimir Murzin <redacted> --- arch/arm64/kernel/suspend.c | 12 +++--------- 1 file changed, 3 insertions(+), 9 deletions(-)diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c index eaaff94329cd..c41724a40b75 100644 --- a/arch/arm64/kernel/suspend.c +++ b/arch/arm64/kernel/suspend.c@@ -99,7 +99,6 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) int ret = 0; unsigned long flags; struct sleep_stack_data state; - struct arm_cpuidle_irq_context context; /* * Some portions of CPU state (e.g. PSTATE.{PAN,DIT}) are initialized@@ -121,6 +120,9 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) * Strictly speaking the trace_hardirqs_off() here is superfluous, * hardirqs should be firmly off by now. This really ought to use * something like raw_local_daif_save(). + * + * This also unmasks interrupts in PMR in order to reliably + * resume if we're using pseudo-NMIs. */ flags = local_daif_save();@@ -131,12 +133,6 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) */ pause_graph_tracing(); - /* - * Switch to using DAIF.IF instead of PMR in order to reliably - * resume if we're using pseudo-NMIs. - */ - arm_cpuidle_save_irq_context(&context); - ct_cpuidle_enter(); if (__cpu_suspend_enter(&state)) {@@ -159,8 +155,6 @@ int cpu_suspend(unsigned long arg, int (*fn)(unsigned long)) __cpu_suspend_exit(); } - arm_cpuidle_restore_irq_context(&context); - unpause_graph_tracing(); /*