Re: [PATCH for-4.14 2/2] x86/passthrough: introduce a flag for GSIs not requiring an EOI or unmask

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 10/06/2020 12:51, Roger Pau Monne wrote:
> @@ -920,6 +927,11 @@ static void hvm_dirq_assist(struct domain *d, struct hvm_pirq_dpci *pirq_dpci)
>          if ( pirq_dpci->flags & HVM_IRQ_DPCI_IDENTITY_GSI )
>          {
>              hvm_gsi_assert(d, pirq->pirq);
> +            if ( pirq_dpci->flags & HVM_IRQ_DPCI_NO_EOI )
> +            {
> +                spin_unlock(&d->event_lock);
> +                return;
> +            }

Urgh.  Could I possibly talk you into fixing hvm_dirq_assist() to have a
"goto out;" and a single unlock path ?  (How far are you expecting this
to be backported?)

I'm also totally unconvinced that the atomic test_and_clear() needs to
be done with the event lock held (it should either be non-atomic, or the
locking should be inside the if() condition), but that is probably not a
can of worms wanting opening right now...

~Andrew