Re: [PATCH v4 4/7] KVM: mmu: Add slots_arch_lock for memslot arch fields

[Paolo Bonzini]

On 11/05/21 21:21, Sean Christopherson wrote:
> > +	/* Released in install_new_memslots. */
>
> This needs a much more comprehensive comment, either here or above the declaration
> of slots_arch_lock.  I can't find anything that explicitly states the the lock
> must be held from the time the previous memslots are duplicated/copied until the
> new memslots are set.  Without that information, the rules/expecations are not
> clear.

Indeed, this needs basically a description of the races that can happen, 
as you explained them in the v1 review.

> Unfortunately I'm just whining at this point since I
> don't have a better idea 

Yeah, the synchronize_srcu call in install_new_memslots throws a wrench 
in most alternatives.

Paolo