[PATCH v7 18/31] arm64: smp: Support non-SGIs for IPIs

[Catalin Marinas]

On Thu, Jul 03, 2025 at 12:25:08PM +0200, Lorenzo Pieralisi wrote:
> From: Marc Zyngier <maz at kernel.org>
> 
> The arm64 arch has relied so far on GIC architectural software
> generated interrupt (SGIs) to handle IPIs. Those are per-cpu
> software generated interrupts.
> 
> arm64 architecture code that allocates the IPIs virtual IRQs and
> IRQ descriptors was written accordingly.
> 
> On GICv5 systems, IPIs are implemented using LPIs that are not
> per-cpu interrupts - they are just normal routable IRQs.
> 
> Add arch code to set-up IPIs on systems where they are handled
> using normal routable IRQs.
> 
> For those systems, force the IRQ affinity (and make it immutable)
> to the cpu a given IRQ was assigned to.
> 
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> [timothy.hayes at arm.com: fixed ipi/irq conversion, irq flags]
> Signed-off-by: Timothy Hayes <timothy.hayes at arm.com>
> [lpieralisi: changed affinity set-up, log]
> Signed-off-by: Lorenzo Pieralisi <lpieralisi at kernel.org>
> Cc: Will Deacon <will at kernel.org>
> Cc: Catalin Marinas <catalin.marinas at arm.com>

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