On 02/02/19 07:57, Peter Xu wrote:
> 
> I'm thinking whether it's legal for multiple VMs to run on a single mm
> address space.  I don't see a limitation so far but it's very possible
> I am just missing something there (if there is, IMHO they might be
> something nice to put into the commit message?).  Thanks,

Yes, it certainly is legal, and even useful in fact.

For example there are people running WebAssembly in a KVM sandbox.  In
that case you can have multiple KVM instances in a single process.

It seems to me that there is already a perfect way to link an mm to its
users, which is the MMU notifier.  Why do you need a separate
proc_ept_idle_operations?  You could change ept_idle_read into an MMU
notifier callback, and have core mm/ core combine the output of
mm_idle_read and all the MMU notifiers?  Basically, ept_idle_ctrl
becomes an argument to the new MMU notifier callback, or something like
that.

Paolo