Re: [PATCH 0/5] KVM paravirt_ops implementation

[Jeremy Fitzhardinge <jeremy-TSDbQ3PG+2Y@public.gmane.org>]

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

-------------------------------------------------------------------------
This SF.net email is sponsored by DB2 Express
Download DB2 Express C - the FREE version of DB2 express and take
control of your XML. No limits. Just data. Click to get it now.
http://sourceforge.net/powerbar/db2/