Re: [PATCH RESEND 1/2] KVM: Prevent module exit until all VMs are freed

[Paolo Bonzini <pbonzini@xxxxxxxxxx>]

On 3/15/22 16:43, Murilo Opsfelder Araújo wrote:
> > +    if (!try_module_get(kvm_chardev_ops.owner)) {
> > +        r = -ENODEV;
> > +        goto out_err;
> > +    }
> > +
>
> Doesn't this problem also affects the other functions called from
> kvm_dev_ioctl()?
>
> Is it possible that the module is removed while other ioctl's are
> still running, e.g. KVM_GET_API_VERSION and KVM_CHECK_EXTENSION, even
> though they don't use struct kvm?

No, because opening /dev/kvm also adds a reference to the module.  The 
problem is that create_vm creates another source of references to the 
module that can survive after /dev/kvm is closed.

Paolo