Re: [PATCH 10/15] irq: arm64: perform irqentry in entry code

[Catalin Marinas]

On Thu, Oct 21, 2021 at 07:02:31PM +0100, Mark Rutland wrote:
> In preparation for removing HANDLE_DOMAIN_IRQ_IRQENTRY, have arch/arm64
> perform all the irqentry accounting in its entry code.
> 
> As arch/arm64 already performs portions of the irqentry logic in
> enter_from_kernel_mode() and exit_to_kernel_mode(), including
> rcu_irq_{enter,exit}(), the only additional calls that need to be made
> are to irq_{enter,exit}_rcu(). Removing the calls to
> rcu_irq_{enter,exit}() from handle_domain_irq() ensures that we inform
> RCU once per IRQ entry and will correctly identify quiescent periods.
> 
> Since we should not call irq_{enter,exit}_rcu() when entering a
> pseudo-NMI, el1_interrupt() is reworked to have separate __el1_irq() and
> __el1_pnmi() paths for regular IRQ and psuedo-NMI entry, with
> irq_{enter,exit}_irq() only called for the former.
> 
> In preparation for removing HANDLE_DOMAIN_IRQ, the irq regs are managed
> in do_interrupt_handler() for both regular IRQ and pseudo-NMI. This is
> currently redundant, but not harmful.
> 
> For clarity the preemption logic is moved into __el1_irq(). We should
> never preempt within a pseudo-NMI, and arm64_enter_nmi() already
> enforces this by incrementing the preempt_count, but it's clearer if we
> never invoke the preemption logic when entering a pseudo-NMI.
> 
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
> Cc: Marc Zyngier <maz@xxxxxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>

Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>