Re: [RFC PATCH v5 3/4] x86/acrn: Use HYPERVISOR_CALLBACK_VECTOR for ACRN guest upcall vector

From: Ingo Molnar
Date: Thu Apr 25 2019 - 15:45:34 EST



* Zhao, Yakui <yakui.zhao@xxxxxxxxx> wrote:

> > > + alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR,
> > > + acrn_hv_callback_vector);
> >
> > Why is this on two lines, not a single line?
>
> At first it used the long function name for acrn_hv_callback_vector.
> As it exceeds 80 columns, it is split into two lines.

No, it doesn't exceed 80 columns - the last character of that line is on
column 71.

> > Does the hypervisor model the APIC EOI command, i.e. does it require the
> > APIC to be acked? I.e. would not acking the APIC create an IRQ storm?
>
> The hypervisor requires that the APIC EOI should be acked. If the EOI APIC
> is not acked, the APIC ISR bit for the HYPERVISOR_CALLBACK_VECTOR will not
> be cleared and then it will block the interrupt whose vector is lower than
> HYPERVISOR_CALLBACK_VECTOR.

Ok!

Thanks,

Ingo