Let's return the number of free slots instead of only checking if there
is a free slot. Required to support memory devices that consume multiple
memslots.

This is a preparation for memory devices that consume multiple memslots.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
 hw/mem/memory-device.c    | 2 +-
 hw/virtio/vhost-stub.c    | 4 ++--
 hw/virtio/vhost.c         | 4 ++--
 include/hw/virtio/vhost.h | 2 +-
 4 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/hw/mem/memory-device.c b/hw/mem/memory-device.c
index cee90d5182..2f19183a25 100644
--- a/hw/mem/memory-device.c
+++ b/hw/mem/memory-device.c
@@ -137,7 +137,7 @@ static void memory_device_check_addable(MachineState *ms, MemoryRegion *mr,
         error_setg(errp, "hypervisor has no free memory slots left");
         return;
     }
-    if (!vhost_has_free_slot()) {
+    if (!vhost_get_free_memslots()) {
         error_setg(errp, "a used vhost backend has no free memory slots left");
         return;
     }
diff --git a/hw/virtio/vhost-stub.c b/hw/virtio/vhost-stub.c
index 2722af5580..d77b944cda 100644
--- a/hw/virtio/vhost-stub.c
+++ b/hw/virtio/vhost-stub.c
@@ -7,9 +7,9 @@ unsigned int vhost_get_max_memslots(void)
     return UINT_MAX;
 }
 
-bool vhost_has_free_slot(void)
+unsigned int vhost_get_free_memslots(void)
 {
-    return true;
+    return UINT_MAX;
 }
 
 bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error **errp)
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 5865049484..472ccba4ab 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -67,7 +67,7 @@ unsigned int vhost_get_max_memslots(void)
     return max;
 }
 
-bool vhost_has_free_slot(void)
+unsigned int vhost_get_free_memslots(void)
 {
     unsigned int free = UINT_MAX;
     struct vhost_dev *hdev;
@@ -84,7 +84,7 @@ bool vhost_has_free_slot(void)
         }
         free = MIN(free, cur_free);
     }
-    return free > 0;
+    return free;
 }
 
 static void vhost_dev_sync_region(struct vhost_dev *dev,
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index fb8fdf07f9..7f87fa2661 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -316,7 +316,7 @@ uint64_t vhost_get_features(struct vhost_dev *hdev, const int *feature_bits,
 void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits,
                         uint64_t features);
 unsigned int vhost_get_max_memslots(void);
-bool vhost_has_free_slot(void);
+unsigned int vhost_get_free_memslots(void);
 
 int vhost_net_set_backend(struct vhost_dev *hdev,
                           struct vhost_vring_file *file);
-- 
2.40.1