On Sat, Nov 11 2023 at 20:16, Jacob Pan wrote:
> With posted MSIs, end of interrupt is handled by the notification
> handler. Each MSI handler does not go through local APIC IRR, ISR
> processing. There's no need to do apic_eoi() in those handlers.
>
> Add a new acpi_ack_irq_no_eoi() for the posted MSI IR chip. At runtime
> the call trace looks like:
>
> __sysvec_posted_msi_notification() {
> irq_chip_ack_parent() {
> apic_ack_irq_no_eoi();
> }
Huch? There is something missing here to make sense.
> handle_irq_event() {
> handle_irq_event_percpu() {
> driver_handler()
> }
> }
>
> IO-APIC IR is excluded the from posted MSI, we need to make sure it
> still performs EOI.
We need to make the code correct and write changelogs which make
sense. This sentence makes no sense whatsoever.
What has the IO-APIC to do with posted MSIs?
It's a different interrupt chip hierarchy, no?
> diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
> index 00da6cf6b07d..ca398ee9075b 100644
> --- a/arch/x86/kernel/apic/io_apic.c
> +++ b/arch/x86/kernel/apic/io_apic.c
> @@ -1993,7 +1993,7 @@ static struct irq_chip ioapic_ir_chip __read_mostly = {
> .irq_startup = startup_ioapic_irq,
> .irq_mask = mask_ioapic_irq,
> .irq_unmask = unmask_ioapic_irq,
> - .irq_ack = irq_chip_ack_parent,
> + .irq_ack = apic_ack_irq,
Why?
> .irq_eoi = ioapic_ir_ack_level,
> .irq_set_affinity = ioapic_set_affinity,
> .irq_retrigger = irq_chip_retrigger_hierarchy,
> diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c
> index 14fc33cfdb37..01223ac4f57a 100644
> --- a/arch/x86/kernel/apic/vector.c
> +++ b/arch/x86/kernel/apic/vector.c
> @@ -911,6 +911,11 @@ void apic_ack_irq(struct irq_data *irqd)
> apic_eoi();
> }
>
> +void apic_ack_irq_no_eoi(struct irq_data *irqd)
> +{
> + irq_move_irq(irqd);
> +}
> +
The exact purpose of that function is to invoke irq_move_irq() which is
a completely pointless exercise for interrupts which are remapped.
