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

From	Julien Grall <julien.grall@arm.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when mapping memory
Date	2017-06-01 15:00 +0200
Message-ID	<tNxRM-2EE-1@gated-at.bofh.it> (permalink)
References	<tNbxT-5ao-7@gated-at.bofh.it> <tNcki-5yl-11@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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Hi Boris,

On 31/05/17 14:54, Boris Ostrovsky wrote:
> 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@vger.kernel.org
>> Reported-by: Feng Kan <fkan@apm.com>
>> Signed-off-by: Julien Grall <julien.grall@arm.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()?

Do you mean in the xen_xlate_remap_gfn_array implementation? If so there 
are no use of PAGE_MASK as the code has been converted to support 64K 
page granularity.

If you mean the x86 version of xen_remap_domain_gfn_array, then we don't 
really care as x86 only use 4KB page granularity.

Cheers,

-- 
Julien Grall

Thread

[PATCH] xen/privcmd: Support correctly 64KB page granularity when mapping memory Julien Grall <julien.grall@arm.com> - 2017-05-31 15:10 +0200
  Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when  mapping memory Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-05-31 16:00 +0200
    Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when  mapping memory Julien Grall <julien.grall@arm.com> - 2017-06-01 15:00 +0200
      Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when  mapping memory Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-06-01 15:40 +0200
        Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when  mapping memory Julien Grall <julien.grall@arm.com> - 2017-06-01 16:10 +0200
          Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when  mapping memory Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-06-01 17:20 +0200
            Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when  mapping memory Julien Grall <julien.grall@arm.com> - 2017-06-01 17:40 +0200
              Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when  mapping memory Boris Ostrovsky <boris.ostrovsky@oracle.com> - 2017-06-01 22:50 +0200
                Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when  mapping memory Julien Grall <julien.grall@arm.com> - 2017-06-06 18:20 +0200
  Re: [PATCH] xen/privcmd: Support correctly 64KB page granularity when  mapping memory Juergen Gross <jgross@suse.com> - 2017-06-07 11:30 +0200

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