From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.fraser@eu.citrix.com>
Subject: Re: Confusion about copy_to/from_guest
Date: Mon, 26 Apr 2010 06:33:08 +0100
Message-ID: <C7FAE424.12628%keir.fraser@eu.citrix.com>
References: <h2gf1c9d251004251932s19c2f51ofb422ee27c366fca@mail.gmail.com>
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To: Tej <bewith.tej@gmail.com>, "xen-devel@lists.xensource.com" <xen-devel@lists.xensource.com>
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On 26/04/2010 03:32, "Tej" <bewith.tej@gmail.com> wrote:

> Now passing the list_head from kernel using hypercall. Now how do I
> copy the element between kernel and hypervisor.
> 
> 1. copy_from_guest(hyp_list_head, arg, 1) or
> copy_from_guest(hyp_list_head, arg, <num_of_elements_list>)
> 2. copy_to_guest(arg, hyp_list_head, 1) or copy_to_guest(arg,
> hyp_list_head, <num of element in list>)

The first of these. Copy_{to,from}_guest can copy arrays of structures, but
since this is a linked structure you'd have to do the copy one element at a
time.

> 2nd question:
> I did first one, but first element of list was not accessible in
> hypervisor space, why?

Well, if you are really only copying the list_head, the above should work.

 -- Keir