Re: [Xen-devel] Requesting a freeze exception for vm_event memory introspection helpers

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Jul 13, 2015 at 10:35:44AM +0300, Razvan Cojocaru wrote:
> Hello,
> 
> I'd like to ask for a freeze exception for the "vm_event memory
> introspection helpers" series.
> 
> [PATCH 1/3] xen/mem_access: Support for memory-content hiding
> [PATCH 2/3] xen/vm_event: Support for guest-requested events
> [PATCH 3/3] xen/vm_event: Deny register writes if refused by
> vm_event reply
> 
> All patches have been acked by at least one person (though patch 1 is
> still under some discussion).
> 
> 1. Benefits of the series making it in this release:
> 
> * Probably the most important benefit is that 4.6 development has been
> very open to refactoring vm_events, and patch 3/3 makes vm_events behave
> in a consistent manner (all register-write vm_events are pre-write events).
> 
> * There are 3rd parties interested in these features (Tamas, for
> example, has already expressed interest in uses of patch 1/1).
> 

These aren't really good arguments for getting this in for 4.6. It would
be easy for you and Tamas to carry three patches for a while.

What are the impact to end users (end users -- meaning either system
administrator that sets up Xen and other developers who want to use the
new interface you introduce)?  Does this series consist of the last
missing pieces of a feature?

Wei.

> 2. Risks of including the series:
> 
> * Since two of the three patches have already received acks from 3+
> people, I would assume that the risks for those are minimal. As for the
> first patch, unless a vm_event consumer uses the new
> VM_EVENT_FLAG_SET_EMUL_READ_DATA vm_event response flag in conjunction
> with VM_EVENT_FLAG_EMULATE, the impact should be close to 0 (only a few
> "if ( unlikely(set_context_enabled) )" extra statements).
> 
> A new series will follow as soon as possible, addressing Jan's comments
> on the first patch and cleaning up patch 3 a little more.
> 
> 
> Thank you in advance for considering this,
> Razvan

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel