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KVM: s390/mm: Make pages accessible before destroying the guest

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Before we destroy the secure configuration, we better make all
pages accessible again. This also happens during reboot, where we reboot
into a non-secure guest that then can go again into secure mode. As
this "new" secure guest will have a new ID we cannot reuse the old page
state.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
This commit is contained in:
Christian Borntraeger 2019-12-16 10:48:11 -05:00
parent fa0c5eabbd
commit 1274800792
3 changed files with 39 additions and 0 deletions
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1
arch/s390/include/asm/gmap.h
View file

@ -149,4 +149,5 @@ 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);
void s390_reset_acc(struct mm_struct *mm);
#endif /* _ASM_S390_GMAP_H */

3
arch/s390/kvm/pv.c
View file

@ -140,6 +140,9 @@ int kvm_s390_pv_deinit_vm(struct kvm *kvm, u16 *rc, u16 *rrc)
{
int cc;
/* make all pages accessible before destroying the guest */
s390_reset_acc(kvm->mm);
cc = uv_cmd_nodata(kvm_s390_pv_get_handle(kvm),
UVC_CMD_DESTROY_SEC_CONF, rc, rrc);
WRITE_ONCE(kvm->arch.gmap->guest_handle, 0);

35
arch/s390/mm/gmap.c
View file

@ -2650,3 +2650,38 @@ void s390_reset_cmma(struct mm_struct *mm)
up_write(&mm->mmap_sem);
}
EXPORT_SYMBOL_GPL(s390_reset_cmma);
/*
* make inaccessible pages accessible again
*/
static int __s390_reset_acc(pte_t *ptep, unsigned long addr,
unsigned long next, struct mm_walk *walk)
{
pte_t pte = READ_ONCE(*ptep);
if (pte_present(pte))
WARN_ON_ONCE(uv_convert_from_secure(pte_val(pte) & PAGE_MASK));
return 0;
}
static const struct mm_walk_ops reset_acc_walk_ops = {
.pte_entry = __s390_reset_acc,
};
#include <linux/sched/mm.h>
void s390_reset_acc(struct mm_struct *mm)
{
/*
* we might be called during
* reset: we walk the pages and clear
* close of all kvm file descriptors: we walk the pages and clear
* exit of process on fd closure: vma already gone, do nothing
*/
if (!mmget_not_zero(mm))
return;
down_read(&mm->mmap_sem);
walk_page_range(mm, 0, TASK_SIZE, &reset_acc_walk_ops, NULL);
up_read(&mm->mmap_sem);
mmput(mm);
}
EXPORT_SYMBOL_GPL(s390_reset_acc);