[PATCH v2 1/2] KVM: s390x: some utility functions for migration

[Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>]

These are some utilty functions that will be used later on for storage
attributes migration.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
---
 arch/s390/kvm/kvm-s390.c | 32 ++++++++++++++++++++++++++++++++
 arch/s390/kvm/kvm-s390.h |  6 ++++++
 2 files changed, 38 insertions(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 6f17031..5a69334 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1512,6 +1512,38 @@ static long kvm_s390_set_skeys(struct kvm *kvm, struct kvm_s390_skeys *args)
 #define KVM_S390_CMMA_SIZE_MAX ((u32)KVM_S390_SKEYS_MAX)
 
 /*
+ * Similar to gfn_to_memslot, but returns a memslot also when the address falls
+ * in a hole. In that case a memslot near the hole is returned.
+ */
+static int gfn_to_memslot_approx(struct kvm *kvm, gfn_t gfn)
+{
+	struct kvm_memslots *slots = kvm_memslots(kvm);
+	int start = 0, end = slots->used_slots;
+	int slot = atomic_read(&slots->lru_slot);
+	struct kvm_memory_slot *memslots = slots->memslots;
+
+	if (gfn >= memslots[slot].base_gfn &&
+	    gfn < memslots[slot].base_gfn + memslots[slot].npages)
+		return slot;
+
+	while (start < end) {
+		slot = start + (end - start) / 2;
+
+		if (gfn >= memslots[slot].base_gfn)
+			end = slot;
+		else
+			start = slot + 1;
+	}
+
+	if (gfn >= memslots[start].base_gfn &&
+	    gfn < memslots[start].base_gfn + memslots[start].npages) {
+		atomic_set(&slots->lru_slot, start);
+	}
+
+	return start;
+}
+
+/*
  * This function searches for the next page with dirty CMMA attributes, and
  * saves the attributes in the buffer up to either the end of the buffer or
  * until a block of at least KVM_S390_MAX_BIT_DISTANCE clean bits is found;
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 04a3e91..b86c1ad 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -183,6 +183,12 @@ static inline int kvm_s390_user_cpu_state_ctrl(struct kvm *kvm)
 	return kvm->arch.user_cpu_state_ctrl != 0;
 }
 
+static inline unsigned long *cmma_bitmap(struct kvm_memory_slot *slot)
+{
+	return slot->dirty_bitmap +
+	       kvm_dirty_bitmap_bytes(slot) / sizeof(*slot->dirty_bitmap);
+}
+
 /* implemented in interrupt.c */
 int kvm_s390_handle_wait(struct kvm_vcpu *vcpu);
 void kvm_s390_vcpu_wakeup(struct kvm_vcpu *vcpu);
-- 
2.7.4