Re: [PATCH v3 10/10] irqchip/riscv-imsic: Use IRQCHIP_MOVE_DEFERRED flag for PCI devices

[Thomas Gleixner]

On Tue, Feb 04 2025 at 20:19, Anup Patel wrote:
> On Tue, Feb 4, 2025 at 2:26 PM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
>> The same could be achieved by executing that intermediate transition on
>> CPU0 with interrupts disabled by affining the calling context (thread)
>> to CPU0 or by issuing an IPI on CPU0 and doing it in that context. I
>> looked into that, but that has it's own pile of issues. So at the end
>> moving it in the context of the interrupt on the original CPU/vector
>> turned out to be the simplest way to achieve it.
>
> I got confused because IRQCHIP_MOVE_DEFERRED updates affinity
> with the interrupt masked which I interpreted as masked at the device
> level. Also, PCI MSI mask/unmask is an optional feature of PCI devices
> which I totally missed.

That's the problem this actually handles. If PCI mask/unmask would be
mandatory the problem would not exist in the first place :)