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@xxxxxxxxxxxxx>
>> ---
> [...]
>> 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@xxxxxxxxxx>
>
Thanks!
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