Hi Marc, > On Sat, 18 Apr 2026 11:34:30 +0100, > Yeoreum Yun <[email protected]> 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.
Hmm, I also considered moving kvm_init() into finalised_pkvm() and then handling the remaining ffa_init() work after /dev/kvm is registered. However, this approach seems awkward in practice, because misc has neither a bus nor a dedicated class notifier that we can hook into. Also, the FF-A initialization is not driven by a device probe, but rather happens as part of the bus registration itself, so it does not fit well with a device_link or probe deferral based approach. Instead, perhaps we could go with the idea I mentioned previously: either introduce a notifier, or create a pseudo ffa_device once pKVM initialization has completed, and then let the ffa driver perform the additional initialization from there. Am I missing something? -- Sincerely, Yeoreum Yun
