Re: [PATCH 0/5] KVM paravirt_ops implementation

Zachary Amsden wrote:

Unless you also migrate the hypercall page itself and impose migration 
restrictions on compatible hypercall pages.

Seems unreasonable, especially if you support migration between VT and 
SVM machines.  The whole point of a hypercall page is to give you a 
point of indirection in order to hide these kinds of hardware 
differences; migrating it would defeat the purpose.

Although I favor the guarantee that execution within the hypercall 
page is finished - it is important for protecting against 
non-reentrancy as well.  Think about interrupts during batching / 
queueing operations.

Not quite sure that's specifically relevant to migration, but yes, its 
important to disable interrupts while doing the setup for a batch of 
stuff unless you want to see some surprises in your queue (and not "Oh, 
yay, a puppy!" kind of surprises).

    J

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