Re: [PATCH 4/5] KVM: arm64: vgic-v3: Don't require IRQs be disabled for LPI xarray lock

[Oliver Upton <oliver.upton@linux.dev>]

On Fri, Sep 05, 2025 at 09:13:45AM +0100, Marc Zyngier wrote:
> > diff --git a/arch/arm64/kvm/vgic/vgic.c b/arch/arm64/kvm/vgic/vgic.c
> > index 480391a0dcad..a21b482844ce 100644
> > --- a/arch/arm64/kvm/vgic/vgic.c
> > +++ b/arch/arm64/kvm/vgic/vgic.c
> > @@ -28,7 +28,7 @@ struct vgic_global kvm_vgic_global_state __ro_after_init = {
> >   *     kvm->arch.config_lock (mutex)
> >   *       its->cmd_lock (mutex)
> >   *         its->its_lock (mutex)
> > - *           vgic_dist->lpi_xa.xa_lock		must be taken with IRQs disabled
> > + *           vgic_dist->lpi_xa.xa_lock
> 
> Doesn't this contradict the commit message statement that we always
> take this lock with interrupts disabled?

[ relaying offline conversation ]

The changelog sucks hard on this one, what I was trying to say is there
are no longer any writers that acquire the xa_lock with IRQs disabled.
What remains is readers that have interrupts disabled, although readers
are RCU-protected and don't take the lock.

Thanks,
Oliver