[PATCH v3 03/16] arm64: Allow IPIs to be handled as normal interrupts

[Catalin Marinas]

On Tue, Sep 01, 2020 at 03:43:11PM +0100, Marc Zyngier wrote:
> In order to deal with IPIs as normal interrupts, let's add
> a new way to register them with the architecture code.
> 
> set_smp_ipi_range() takes a range of interrupts, and allows
> the arch code to request them as if the were normal interrupts.
> A standard handler is then called by the core IRQ code to deal
> with the IPI.
> 
> This means that we don't need to call irq_enter/irq_exit, and
> that we don't need to deal with set_irq_regs either. So let's
> move the dispatcher into its own function, and leave handle_IPI()
> as a compatibility function.
> 
> On the sending side, let's make use of ipi_send_mask, which
> already exists for this purpose.
> 
> One of the major difference is that we end up, in some cases
> (such as when performing IRQ time accounting on the scheduler
> IPI), end up with nested irq_enter()/irq_exit() pairs.
> Other than the (relatively small) overhead, there should be
> no consequences to it (these pairs are designed to nest
> correctly, and the accounting shouldn't be off).
> 
> Reviewed-by: Valentin Schneider <valentin.schneider at arm.com>
> Signed-off-by: Marc Zyngier <maz at kernel.org>

In case you need an ack for the arm64 part:

Acked-by: Catalin Marinas <catalin.marinas at arm.com>