Re: [Xen-devel] Re: how to handle paged hypercall args?

[Keir Fraser <keir@xxxxxxx>]

On 15/11/2010 13:12, "Olaf Hering" <olaf@xxxxxxxxx> wrote:

> On Fri, Nov 12, Keir Fraser wrote:
> 
>> On 12/11/2010 10:47, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:
>>> Sounds good, and you helping with this will be much appreciated
>>> (Olaf - unless you had plans doing this yourself). Whether it's going
>>> to be widely used I can't tell immediately - for the moment,
>>> overcoming the paging problems seems like the only application.
>> 
>> Yeah, I'll get on this.
> 
> Sorry for being late here.
> 
> I'm glad you volunteer for this task.

The basis of what you need is checked in as xen-unstable:22396. You can
include <xen/wait.h> and you get an interface like a very simplified version
of Linux waitqueues. There are still some details to be worked out but it
basically works as-is and you can start using it now.

The one big cleanup/audit we will need is that all callers of __hvm_copy()
(which ends up being all HVM guest callers of the copy_to/from_guest*
macros) must not hold any locks. This is because you are going to modify
__hvm_copy() such that it may sleep. Probably you should
ASSERT(!in_atomic()) at the top of __hvm_copy(), and go from there. :-)

 -- Keir

> 
> Olaf
> 



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