From a0bf4f149bbfa2e31b5f4172c817afdb7b986733 Mon Sep 17 00:00:00 2001
From: Dominik Dingel <dingel@linux.vnet.ibm.com>
Date: Mon, 24 Mar 2014 14:27:58 +0100
Subject: [PATCH] KVM: s390/mm: new gmap_test_and_clear_dirty function
For live migration kvm needs to test and clear the dirty bit of guest pages.
That for is ptep_test_and_clear_user_dirty, to be sure we are not racing with
other code, we protect the pte. This needs to be done within
the architecture memory management code.
Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
arch/s390/include/asm/pgtable.h | 2 ++
arch/s390/mm/pgtable.c | 21 +++++++++++++++++++++
2 files changed, 23 insertions(+)
diff --git a/arch/s390/include/asm/pgtable.h b/arch/s390/include/asm/pgtable.h
index b2c630df0ca57..fcba5e03839f5 100644
--- a/arch/s390/include/asm/pgtable.h
+++ b/arch/s390/include/asm/pgtable.h
@@ -838,6 +838,8 @@ unsigned long __gmap_fault(unsigned long address, struct gmap *);
unsigned long gmap_fault(unsigned long address, struct gmap *);
void gmap_discard(unsigned long from, unsigned long to, struct gmap *);
void __gmap_zap(unsigned long address, struct gmap *);
+bool gmap_test_and_clear_dirty(unsigned long address, struct gmap *);
+
void gmap_register_ipte_notifier(struct gmap_notifier *);
void gmap_unregister_ipte_notifier(struct gmap_notifier *);
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index 1ddf975352a07..ea4a31b959900 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -1401,6 +1401,27 @@ void s390_enable_skey(void)
}
EXPORT_SYMBOL_GPL(s390_enable_skey);
+/*
+ * Test and reset if a guest page is dirty
+ */
+bool gmap_test_and_clear_dirty(unsigned long address, struct gmap *gmap)
+{
+ pte_t *pte;
+ spinlock_t *ptl;
+ bool dirty = false;
+
+ pte = get_locked_pte(gmap->mm, address, &ptl);
+ if (unlikely(!pte))
+ return false;
+
+ if (ptep_test_and_clear_user_dirty(gmap->mm, address, pte))
+ dirty = true;
+
+ spin_unlock(ptl);
+ return dirty;
+}
+EXPORT_SYMBOL_GPL(gmap_test_and_clear_dirty);
+
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
int pmdp_clear_flush_young(struct vm_area_struct *vma, unsigned long address,
pmd_t *pmdp)