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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: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
[borntraeger@de.ibm.com: patch merging, splitting, fixing]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Janosch Frank 2019-07-16 13:08:37 +02:00 committed by Christian Borntraeger
parent 29b40f105e
commit fa0c5eabbd
3 changed files with 27 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/s390/include/asm/gmap.h
View File

@ -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 */

6
arch/s390/kvm/kvm-s390.c
View File

@ -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;

30
arch/s390/mm/gmap.c
View File

@ -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)) {
mm->context.uses_skeys = 0;
rc = -ENOMEM;
goto out_up;
}
rc = gmap_mark_unmergeable();
if (rc) {
mm->context.uses_skeys = 0;
goto out_up;
}
mm->def_flags &= ~VM_MERGEABLE;
walk_page_range(mm, 0, TASK_SIZE, &enable_skey_walk_ops, NULL);
out_up: