Re: [PATCH v6 12/12] KVM: indicate readonly access fault

[Marcelo Tosatti]

On Tue, Sep 11, 2012 at 12:18:22PM +0300, Avi Kivity wrote:
> > The same can happen with slot deletion, for example. 
> > 
> > Userspace (which performed the modification which can result in faults
> > to non-existant/read-only/.../new-tag memslot), must handle the faults 
> > properly or avoid the possibility for reference to memslot information 
> > from the past.
> > 
> > I think its worthwhile to add a note about this in the API
> > documentation: "The user of this interface is responsible for handling 
> > references to stale memslot information, either by handling
> > exit notifications which reference stale memslot information or not
> > allowing these notifications to exist by stopping all vcpus in userspace
> > before performing modifications to the memslots map".
> 
> Or we can drop the new interface and rely on userspace to perform the
> lookup under its own locking rules.
> 
> It's slow, but writes to ROM or ROM/device are rare anyway.

Lookup what information? 

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