On 08/27/2012 11:17 AM, Jan Kiszka wrote: > On 2012-08-27 20:09, Avi Kivity wrote: > > On 08/27/2012 10:14 AM, Jan Kiszka wrote: > >>> > >>> Deregistration is fine, the problem is destruction. > >>> > >> > >> It isn't as you access memory region states that can change after > >> deregistration. Devices can remove memory regions from the mapping, > >> alter and then reinsert them. The last to steps must not happen while > >> anyone is still using a reference to that region. > >> > > > > Why not? If the guest is accessing an mmio region while reconfiguring > > it in a way that changes its meaning, either the previous or the next > > meaning is valid. > > If the memory region owner sets the content to zero or even releases it > (nothing states a memory region can only live inside a device > structure), we will crash. Restricting how a memory region can be > created and handled after it was once registered somewhere is an > unnatural interface, waiting to cause subtle bugs.
Using an Object * allows the simple case to be really simple (object == device) and the hard cases to be doable. What would you suggest as a better interface? -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.
