Subject: Re: [RFC PATCH 4/4] firmware: arm_ffa: check pkvm initailised when initailise ffa driver

From: Marc Zyngier <[email-masked]>
Date: Sun, 19 Apr 2026 11:41:17 +0100

On Sat, 18 Apr 2026 11:34:30 +0100,
Yeoreum Yun <[email-masked]> wrote:
> 
> > > @@ -2035,6 +2037,16 @@ static int __init ffa_init(void)
> > >  	u32 buf_sz;
> > >  	size_t rxtx_bufsz = SZ_4K;
> > >
> > > +	/*
> > > +	 * When pKVM is enabled, the FF-A driver must be initialized
> > > +	 * after pKVM initialization. Otherwise, pKVM cannot negotiate
> > > +	 * the FF-A version or obtain RX/TX buffer information,
> > > +	 * which leads to failures in FF-A calls.
> > > +	 */
> > > +	if (IS_ENABLED(CONFIG_KVM) && is_protected_kvm_enabled() &&
> > > +	    !is_kvm_arm_initialised())
> > > +		return -EPROBE_DEFER;
> > > +
> >
> > That's still fundamentally wrong: pkvm is not ready until
> > finalize_pkvm() has finished, and that's not indicated by
> > is_kvm_arm_initialised().
> 
> Thanks. I miss the TSC bit set in here.

That's the least of the problems. None of the infrastructure is in
place at this stage...

> IMHO, I'd like to make an new state check function --
> is_pkvm_arm_initialised() so that ff-a driver to know whether
> pkvm is initialised.

Doesn't sound great, TBH.

> or any other suggestion?

Instead of adding more esoteric predicates, I'd rather you build on an
existing infrastructure. You have a dependency on KVM, use something
that is designed to enforce dependencies. Device links spring to mind
as something designed for that.

Can you look into enabling this for KVM? If that's possible, then it
should be easy enough to delay the actual KVM registration after pKVM
is finalised.

Thanks,

	M.

-- 
Jazz isn't dead. It just smells funny.