[PATCH v1 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 | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 6f17031..100ea15 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -764,6 +764,14 @@ static void kvm_s390_sync_request_broadcast(struct kvm *kvm, int req)
 		kvm_s390_sync_request(req, vcpu);
 }
 
+static inline unsigned long *_cmma_bitmap(struct kvm_memory_slot *ms)
+{
+	unsigned long long len;
+
+	len = kvm_dirty_bitmap_bytes(ms) / sizeof(*ms->dirty_bitmap);
+	return ms->dirty_bitmap + len;
+}
+
 /*
  * Must be called with kvm->srcu held to avoid races on memslots, and with
  * kvm->lock to avoid races with ourselves and kvm_s390_vm_stop_migration.
@@ -1512,6 +1520,38 @@ 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;
-- 
2.7.4