Re: [PATCH v6 12/12] KVM: indicate readonly access fault
From: Marcelo Tosatti
Date: Wed Sep 12 2012 - 11:28:04 EST
On Tue, Sep 11, 2012 at 11:39:01AM -0300, Marcelo Tosatti wrote:
> 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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