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.
> + 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;
> +
> + 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>
