Re: [PATCH 0/5] KVM paravirt_ops implementation

Jeremy Fitzhardinge
2007-06-20T20:53:05Z

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