From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ian Campbell <ian.campbell@citrix.com>
Subject: Re: [RFC PATCH COLO v5 07/29] support to resume
 uncooperative HVM guests
Date: Wed, 22 Apr 2015 15:54:49 +0100
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To: Yang Hongyang <yanghy@cn.fujitsu.com>
Cc: wei.liu2@citrix.com, wency@cn.fujitsu.com, eddie.dong@intel.com, yunhong.jiang@intel.com, ian.jackson@eu.citrix.com, xen-devel@lists.xen.org, rshriram@cs.ubc.ca
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On Wed, 2015-04-01 at 14:41 +0800, Yang Hongyang wrote:
> From: Wen Congyang <wency@cn.fujitsu.com>
> 
> For PVHVM, the hypercall return code is 0, and it can be resumed
> in a new domain context.
> 
> For HVM, do nothing.
> 
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>  tools/libxc/xc_resume.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/libxc/xc_resume.c b/tools/libxc/xc_resume.c
> index e67bebd..b862ce3 100644
> --- a/tools/libxc/xc_resume.c
> +++ b/tools/libxc/xc_resume.c
> @@ -109,6 +109,21 @@ static int xc_domain_resume_cooperative(xc_interface *xch, uint32_t domid)
>      return do_domctl(xch, &domctl);
>  }
>  
> +static int xc_domain_resume_hvm(xc_interface *xch, uint32_t domid)
> +{
> +    DECLARE_DOMCTL;
> +
> +    /*
> +     * If it is PVHVM, the hypercall return code is 0, and resume
> +     * it in a new domain context.

What is a "new domain context"?

> +     *
> +     * If it is a HVM, do nothing.

If it is an HVM guest they you do something, you call a hypercall.

If that hypercall is somehow a NOP for an HVM domain then I think that
needs to be explained somewhere here.