linux-kernel - Re: [Xen-devel] [PATCH 6/8] xen/pvh: Initialize grant table for PVH guests

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Date:   Fri, 14 Oct 2016 15:19:23 -0400
From:   Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     david.vrabel@...rix.com, JGross@...e.com,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        roger.pau@...rix.com
Subject: Re: [Xen-devel] [PATCH 6/8] xen/pvh: Initialize grant table for PVH
 guests

On Fri, Oct 14, 2016 at 02:05:16PM -0400, Boris Ostrovsky wrote:

Perhaps add in here:

PVH is like PV in that there are no PCI devices - which HVM
code would piggyback on to find the Xen PCI platform device and
use its MMIO space to stash the grants in.

For PVH we balloon out memory and stash the grants in there.

(Which begs the next question - where and when do we balloon out the
normal memory back in?)

> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
> ---
>  drivers/xen/grant-table.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
> index bb36b1e..d6786b8 100644
> --- a/drivers/xen/grant-table.c
> +++ b/drivers/xen/grant-table.c
> @@ -1146,13 +1146,13 @@ int gnttab_init(void)
>  
>  static int __gnttab_init(void)
>  {
> +	if (!xen_domain())
> +		return -ENODEV;
> +
>  	/* Delay grant-table initialization in the PV on HVM case */
> -	if (xen_hvm_domain())
> +	if (xen_hvm_domain() && !xen_pvh_domain())
>  		return 0;
>  
> -	if (!xen_pv_domain())
> -		return -ENODEV;
> -
>  	return gnttab_init();
>  }
>  /* Starts after core_initcall so that xen_pvh_gnttab_setup can be called
> -- 
> 1.8.3.1
> 
> 
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