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

From: Marc Zyngier <[email-masked]>
Date: Mon, 20 Apr 2026 13:46:47 +0100

On Mon, 20 Apr 2026 13:32:32 +0100,
Sebastian Ene <[email-masked]> wrote:
> 
> On Fri, Apr 17, 2026 at 06:57:59PM +0100, Yeoreum Yun wrote:
> 
> Hello Yeoreum,
> 
> 
> > When pKVM is enabled, the FF-A driver must be initialized after pKVM.
> > Otherwise, pKVM cannot negotiate the FF-A version or
> > obtain RX/TX buffer information, leading to failures in FF-A calls.
> 
> At the moment this already happens after you move back ffa_init() to
> device_initcall().

But relying on this sort of ordering is just making things more
fragile.

> 
> > 
> > During FF-A driver initialization, check whether pKVM has been initialized.
> > If not, defer probing of the FF-A driver.
> > 
> 
> I don't think you need to add this dependency. pKVM is
> installed through KVM's module_init() which ends up calling hyp_ffa_init() to
> do the proxy initialization. The ARM-FFA driver comes after it (since
> pKVM is arch specific code). We don't have to call finalize_pkvm(..) to
> be able to handle smc(FF-A) calls in the hyp-proxy.

You do. Without the finalisation, SMCs are not trapped by EL2.

And even if it did, relying on such hack is just wrong.

	M.

-- 
Without deviation from the norm, progress is not possible.