Virtualization - Sep 2009 - [Lguest] [PATCH 3/5] lguest: use PGDIR_SHIFT for PAE code to allow different PAGE_OFFSET

On Mon, Sep 21, 2009 at 04:52:21PM +0930, Rusty Russell
wrote:
> 
> We still assume the Guest and Host have the same PAGE_OFFSET settings,
> but now we don't assume 0xC0000000.
> 
> Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
> Cc: Matias Zabaljauregui <zabaljauregui at gmail.com>
> ---
>  drivers/lguest/page_tables.c |    6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c
> --- a/drivers/lguest/page_tables.c
> +++ b/drivers/lguest/page_tables.c
> @@ -996,11 +996,9 @@ static unsigned long setup_pagetables(st
>  	if (copy_to_user(&pgdir[0], &pgd, sizeof(pgd)) != 0)
>  		return -EFAULT;
>  	/*
> -	 * And the third PGD entry (ie. addresses 3G-4G).
> -	 *
> -	 * FIXME: This assumes that PAGE_OFFSET for the Guest is 0xC0000000.
> +	 * And the other PGD entry to make the linear mapping at PAGE_OFFSET
>  	 */
> -	if (copy_to_user(&pgdir[3], &pgd, sizeof(pgd)) != 0)
> +	if (copy_to_user(&pgdir[KERNEL_PGD_BOUNDARY], &pgd, sizeof(pgd)))
How about this:

+	if (!!copy_to_user(&pgdir[KERNEL_PGD_BOUNDARY], &pgd, sizeof(pgd)))

:)

Thanks,
-L
>  		return -EFAULT;
>  #else
>  	/*
> 
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