Commit fa0c5eab authored by Janosch Frank's avatar Janosch Frank Committed by Christian Borntraeger
Browse files

KVM: s390: protvirt: Secure memory is not mergeable 



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: default avatarJanosch Frank <frankja@linux.ibm.com>
Reviewed-by: default avatarThomas Huth <thuth@redhat.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
[borntraeger@de.ibm.com: patch merging, splitting, fixing]
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent 29b40f10

arch/s390/include/asm/gmap.h

+1 −0
Original line number Diff line number Diff line
@@ -148,4 +148,5 @@ int gmap_mprotect_notify(struct gmap *, unsigned long start, 


void gmap_sync_dirty_log_pmd(struct gmap *gmap, unsigned long dirty_bitmap[4],

			     unsigned long gaddr, unsigned long vmaddr);

int gmap_mark_unmergeable(void);

#endif /* _ASM_S390_GMAP_H */

arch/s390/kvm/kvm-s390.c

+6 −0
Original line number Diff line number Diff line
@@ -2234,6 +2234,12 @@ static int kvm_s390_handle_pv(struct kvm *kvm, struct kvm_pv_cmd *cmd) 
		if (r)

			break;



		down_write(&current->mm->mmap_sem);

		r = gmap_mark_unmergeable();

		up_write(&current->mm->mmap_sem);

		if (r)

			break;



		r = kvm_s390_pv_init_vm(kvm, &cmd->rc, &cmd->rrc);

		if (r)

			break;

arch/s390/mm/gmap.c

+20 −10
Original line number Diff line number Diff line
@@ -2548,6 +2548,22 @@ 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;



	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);



/*

 * Enable storage key handling from now on and initialize the storage

 * keys with the default key.
@@ -2593,7 +2609,6 @@ static const struct mm_walk_ops enable_skey_walk_ops = { 
int s390_enable_skey(void)

{

	struct mm_struct *mm = current->mm;

	struct vm_area_struct *vma;

	int rc = 0;



	down_write(&mm->mmap_sem);
@@ -2601,16 +2616,11 @@ int s390_enable_skey(void) 
		goto out_up;



	mm->context.uses_skeys = 1;

	for (vma = mm->mmap; vma; vma = vma->vm_next) {

		if (ksm_madvise(vma, vma->vm_start, vma->vm_end,

				MADV_UNMERGEABLE, &vma->vm_flags)) {

	rc = gmap_mark_unmergeable();

	if (rc) {

		mm->context.uses_skeys = 0;

			rc = -ENOMEM;

		goto out_up;

	}

	}

	mm->def_flags &= ~VM_MERGEABLE;



	walk_page_range(mm, 0, TASK_SIZE, &enable_skey_walk_ops, NULL);



out_up:

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