Re: [RFC PATCH v2 33/45] arm64: irq: Report FEAT_NMI masking local IRQs

[Jinjie Ruan <ruanjinjie@huawei.com>]

在 2026/7/28 0:34, Vladimir Murzin 写道:
> From: Ada Couprie Diaz <ada.coupriediaz@arm.com>
> 
> As we clear SCTLR_EL1.SPINTMASK when enabling FEAT_NMI, ALLINT masks
> IRQs and FIQs regardless of superpriority.
> Update irqflags.h and `regs_irqs_disabled()` to take it into account,
> so we properly keep track of the local IRQ masking state.
> 
> We have documentation at the top of irqflags.h which explains the DAIF
> masking. Since the additional masking with NMIs is related and also
> covers the IF in DAIF, extend the comment to note what's going on
> with NMIs.
> 
> Co-developed-by: Mark Brown <broonie@kernel.org>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> Signed-off-by: Ada Couprie Diaz <ada.coupriediaz@arm.com>
> Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
> ---
>  arch/arm64/include/asm/irqflags.h | 17 +++++++++++++++++
>  arch/arm64/include/asm/ptrace.h   |  3 +++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/irqflags.h b/arch/arm64/include/asm/irqflags.h
> index c719b7e2912e..9115cdc9d517 100644
> --- a/arch/arm64/include/asm/irqflags.h
> +++ b/arch/arm64/include/asm/irqflags.h
> @@ -20,6 +20,16 @@
>   * always masked and unmasked together, and have no side effects for other
>   * flags. Keeping to this order makes it easier for entry.S to know which
>   * exceptions should be unmasked.
> + *
> + * With the addition of the FEAT_NMI extension we gain an additional
> + * class of superpriority IRQ/FIQ which is separately masked with a
> + * choice of modes controlled by SCTLR_ELn.{SPINTMASK,NMI}.
> + * Linux sets SPINTMASK to 0 and NMI to 1 which results in ALLINT.ALLINT
> + * masking both superpriority interrupts and IRQ/FIQ regardless of the
> + * I and F settings. Since these superpriority interrupts are being
> + * used as NMIs we do not include them in the interrupt masking here,
> + * anything that requires that NMIs be masked needs to explicitly do so,
> + * but we do check for ALLINT masking IRQs/FIQs.
>   */
>  
>   /*
> @@ -104,6 +114,9 @@ static __always_inline unsigned long arch_local_save_flags(void)
>  {
>  	arm64_exc_hwstate_t hwstate = { .daif = read_sysreg(daif) };
>  
> +	if (system_uses_nmi())
> +		hwstate.allint = read_sysreg_s(SYS_ALLINT);
> +
>  	if (system_uses_irq_prio_masking())
>  		hwstate.pmr = read_sysreg_s(SYS_ICC_PMR_EL1);
>  
> @@ -117,6 +130,10 @@ static __always_inline bool arch_irqs_disabled_flags(unsigned long flags)
>  	if (hwstate.daif & PSR_I_BIT)
>  		return true;
>  
> +	/* SCTLR_EL1.SPINTMASK is clear, so ALLINT masks *all* IRQs/FIQs. */
> +	if (system_uses_nmi())
> +		return !!(hwstate.allint & ALLINT_ALLINT);
> +
>  	if (system_uses_irq_prio_masking()) {
>  		WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_IRQFLAGS) &&
>  			     hwstate.pmr != GIC_PRIO_IRQOFF &&
> diff --git a/arch/arm64/include/asm/ptrace.h b/arch/arm64/include/asm/ptrace.h
> index cf7e51b8ef0b..16ba164b890e 100644
> --- a/arch/arm64/include/asm/ptrace.h
> +++ b/arch/arm64/include/asm/ptrace.h
> @@ -206,6 +206,9 @@ static __always_inline bool regs_irqs_disabled(const struct pt_regs *regs)
>  	if (regs->pstate & PSR_I_BIT)
>  		return true;
>  
> +	if (system_uses_nmi())
> +		return !!(regs->pstate & PSR_ALLINT_BIT);

Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>

> +
>  	if (system_uses_irq_prio_masking()) {
>  		WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_IRQFLAGS) &&
>  			     regs->pmr != GIC_PRIO_IRQOFF &&