Re: [PATCH v3 22/28] KVM: x86/mmu: Zap defunct roots via asynchronous worker

David Matlack
2022-03-02T18:33:57Z

On Wed, Mar 2, 2022 at 9:35 AM Sean Christopherson <seanjc@google.com> wrote:
>
> On Wed, Mar 02, 2022, Paolo Bonzini wrote:
> > However, I think we now need a module_get/module_put when creating/destroying
> > a VM; the workers can outlive kvm_vm_release and therefore any reference
> > automatically taken by VFS's fops_get/fops_put.
>
> Haven't read the rest of the patch, but this caught my eye. We _already_ need
> to handle this scenario. As you noted, any worker, i.e. anything that takes a
> reference via kvm_get_kvm() without any additional guarantee that the module can't
> be unloaded is suspect. x86 is mostly fine, though kvm_setup_async_pf() is likely
> affected, and other architectures seem to have bugs.
>
> Google has an internal patch that addresses this. I believe David is going to post
> the fix... David?

This was towards the back of my queue but I can bump it to the front.
I'll have the patches out this week.