Commit 12748007 authored by Christian Borntraeger's avatar Christian Borntraeger
Browse files

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



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: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: default avatarThomas Huth <thuth@redhat.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Reviewed-by: default avatarDavid Hildenbrand <david@redhat.com>
parent fa0c5eab

arch/s390/include/asm/gmap.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

arch/s390/kvm/pv.c

+3 −0
Original line number Diff line number Diff line
@@ -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);

arch/s390/mm/gmap.c

+35 −0
Original line number Diff line number Diff line
@@ -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);

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