linux-kernel - Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when mapping memory

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Message-ID: <7199e366-f56a-acc8-ffa5-0c85d6975049@oracle.com>
Date:   Wed, 31 May 2017 09:54:43 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Julien Grall <julien.grall@....com>, xen-devel@...ts.xen.org
Cc:     sstabellini@...nel.org, jgross@...e.com,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Feng Kan <fkan@....com>
Subject: Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when
 mapping memory

On 05/31/2017 09:03 AM, Julien Grall wrote:
> Commit 5995a68 "xen/privcmd: Add support for Linux 64KB page granularity" did
> not go far enough to support 64KB in mmap_batch_fn.
>
> The variable 'nr' is the number of 4KB chunk to map. However, when Linux
> is using 64KB page granularity the array of pages (vma->vm_private_data)
> contain one page per 64KB. Fix it by incrementing st->index correctly.
>
> Furthermore, st->va is not correctly incremented as PAGE_SIZE !=
> XEN_PAGE_SIZE.
>
> Fixes: 5995a68 ("xen/privcmd: Add support for Linux 64KB page granularity")
> CC: stable@...r.kernel.org
> Reported-by: Feng Kan <fkan@....com>
> Signed-off-by: Julien Grall <julien.grall@....com>
> ---
>  drivers/xen/privcmd.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 7a92a5e1d40c..feca75b07fdd 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -362,8 +362,8 @@ static int mmap_batch_fn(void *data, int nr, void *state)
>  				st->global_error = 1;
>  		}
>  	}
> -	st->va += PAGE_SIZE * nr;
> -	st->index += nr;
> +	st->va += XEN_PAGE_SIZE * nr;
> +	st->index += nr / XEN_PFN_PER_PAGE;
>  
>  	return 0;
>  }


Are we still using PAGE_MASK for xen_remap_domain_gfn_array()?

-boris