Re: [PATCH v2 24/28] KVM: x86/mmu: Allow zap gfn range to operate under the mmu read lock

[Paolo Bonzini]

On 03/02/21 19:31, Ben Gardon wrote:
> On Wed, Feb 3, 2021 at 3:26 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
> > On 02/02/21 19:57, Ben Gardon wrote:
> > > +#ifdef CONFIG_LOCKDEP
> > > +     if (shared)
> > > +             lockdep_assert_held_read(&kvm->mmu_lock);
> > > +     else
> > > +             lockdep_assert_held_write(&kvm->mmu_lock);
> > > +#endif /* CONFIG_LOCKDEP */
> >
> > Also, there's no need for the #ifdef here.
>
> I agree, I must have misinterpreted some feedback on a previous commit
> and gone overboard with it.
>
>
> > Do we want a helper
> > kvm_lockdep_assert_mmu_lock_held(struct kvm *kvm, bool shared)?
>
> There are only two places that try to assert both ways as far as I can
> see on a cursory check, but it couldn't hurt.

I think there's a couple more after patches 25/26.  But there's no issue 
in having them in too (and therefore having a more complete picture) 
before figuring out what the locking API could look like.

Paolo