On 11/13/19 1:23 PM, Thomas Huth wrote:
> On 25/10/2019 10.24, Janosch Frank wrote:
>> KSM will not work on secure pages, because when the kernel reads a
>> secure page, it will be encrypted and hence no two pages will look the
>> same.
>>
>> Let's mark the guest pages as unmergeable when we transition to secure
>> mode.
>>
>> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
> [...]
>> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
>> index edcdca97e85e..faecdf81abdb 100644
>> --- a/arch/s390/mm/gmap.c
>> +++ b/arch/s390/mm/gmap.c
>> @@ -2548,6 +2548,23 @@ int s390_enable_sie(void)
>>  }
>>  EXPORT_SYMBOL_GPL(s390_enable_sie);
>>  
>> +int gmap_mark_unmergeable(void)
>> +{
>> +	struct mm_struct *mm = current->mm;
>> +	struct vm_area_struct *vma;
>> +
>> +
> 
> Please remove one of the two empty lines.

Already gone

> 
>> +	for (vma = mm->mmap; vma; vma = vma->vm_next) {
>> +		if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
>> +				MADV_UNMERGEABLE, &vma->vm_flags))
>> +			return -ENOMEM;
>> +	}
>> +	mm->def_flags &= ~VM_MERGEABLE;
>> +

Also this one was removed

>> +	return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(gmap_mark_unmergeable);
>> +
> [...]
> 
> Apart from the cosmetic nit, the patch looks fine to me.
> 
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> 
Thanks!