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

To: Olaf Hering <olaf@xxxxxxxxx>
Subject: Re: [Xen-devel] Re: how to handle paged hypercall args?
From: Keir Fraser <keir@xxxxxxx>
Date: Thu, 18 Nov 2010 12:33:19 +0000
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, Jan Beulich <JBeulich@xxxxxxxxxx>
Delivery-date: Thu, 18 Nov 2010 04:34:14 -0800
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Thread-topic: [Xen-devel] Re: how to handle paged hypercall args?
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On 17/11/2010 16:52, "Keir Fraser" <keir@xxxxxxx> wrote:

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

I've done something along these lines now as xen-unstable:22402. It actually
seems to work okay! So you can go ahead and use waitqueues in __hvm_copy()

 -- Keir

>  -- Keir
>> Olaf

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