From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir@xen.org>
Subject: Re: Re: how to handle paged hypercall args?
Date: Thu, 11 Nov 2010 20:08:59 +0000
Message-ID: <C901FDDB.999A%keir@xen.org>
References: <20101111143338.GA27721@aepfle.de>
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To: Olaf Hering <olaf@aepfle.de>, xen-devel@lists.xensource.com
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On 11/11/2010 14:33, "Olaf Hering" <olaf@aepfle.de> wrote:

> So is that an acceptable way to deal with the HVMCOPY_gfn_paged_out
> return codes from __hvm_copy?
> Or should I explore some different way, like spinning there and possible
> let other threads-of-execution make progress while waiting for the gfns
> to come back?

You can't just spin because Xen is not preemptible. If it were a single CPU
system for example, no other thread would ever run again. You have to 'spin'
via a preemptible loop that returns to guest context and then back into the
hypercall. Which appears to be what you're doing.

 -- Keir