Re: [XEN PATCH v4 5/5] xen/arm: ffa: support notification

[Julien Grall <julien@xxxxxxx>]

Hi Jens,

On 03/05/2024 14:54, Jens Wiklander wrote:
> > > +static int ffa_setup_irq_callback(struct notifier_block *nfb,
> > > +                                  unsigned long action, void *hcpu)
> > > +{
> > > +    unsigned int cpu = (unsigned long)hcpu;
> > > +    struct notif_irq_info irq_info = { };
> > > +
> > > +    switch ( action )
> > > +    {
> > > +    case CPU_ONLINE:
> > Can't you execute the notifier in CPU_STARTING? This will be called on
> > the CPU directly, so you should be able to use request_irq(...).
> I tried that first but it failed with the ASSERT_ALLOC_CONTEXT() in _xmalloc().
>
> I've also tested a three-step solution with CPU_UP_PREPARE,
> CPU_STARTING, and CPU_UP_CANCELED.
> My approach here is more direct, but it still suffers from a weakness
> in error handling even if it seems quite unlikely to run out of heap
> or for setup_irq() to fail at this stage.
Ah I didn't notice that notify_cpu_starting() is called with IRQ 
disabled. I assumed they would be enabled.
Then I would consider to do:

diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
index 6efed876782e..db322672e508 100644
--- a/xen/arch/arm/smpboot.c
+++ b/xen/arch/arm/smpboot.c
@@ -389,6 +389,7 @@ void asmlinkage start_secondary(void)
      */
     init_maintenance_interrupt();
     init_timer_interrupt();
+    init_tee_interrupt();

     local_abort_enable();

And plumb through the TEE subsystem.

Cheers,

--
Julien Grall