[RFC PATCH 1/5] vdpa: Save emulated features list in vhost_vdpa

["Eugenio Pérez" <eperezma@redhat.com>]

At this moment only _F_LOG is added there.

However future patches add features that depend on the kind of device.
In particular, only net devices can add VIRTIO_F_GUEST_ANNOUNCE. So
let's allow vhost_vdpa creator to set custom emulated device features.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 include/hw/virtio/vhost-vdpa.h | 2 ++
 hw/virtio/vhost-vdpa.c         | 8 ++++----
 net/vhost-vdpa.c               | 4 ++++
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
index 1111d85643..50083e1e3b 100644
--- a/include/hw/virtio/vhost-vdpa.h
+++ b/include/hw/virtio/vhost-vdpa.h
@@ -31,6 +31,8 @@ typedef struct vhost_vdpa {
     bool iotlb_batch_begin_sent;
     MemoryListener listener;
     struct vhost_vdpa_iova_range iova_range;
+    /* VirtIO device features that can be emulated by qemu */
+    uint64_t added_features;
     uint64_t acked_features;
     bool shadow_vqs_enabled;
     /* IOVA mapping used by the Shadow Virtqueue */
diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index 7468e44b87..ddb5e29288 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -660,8 +660,8 @@ static int vhost_vdpa_set_features(struct vhost_dev *dev,
 
         v->acked_features = features;
 
-        /* We must not ack _F_LOG if SVQ is enabled */
-        features &= ~BIT_ULL(VHOST_F_LOG_ALL);
+        /* Do not ack features emulated by qemu */
+        features &= ~v->added_features;
     }
 
     trace_vhost_vdpa_set_features(dev, features);
@@ -1244,8 +1244,8 @@ static int vhost_vdpa_get_features(struct vhost_dev *dev,
     int ret = vhost_vdpa_get_dev_features(dev, features);
 
     if (ret == 0 && v->shadow_vqs_enabled) {
-        /* Add SVQ logging capabilities */
-        *features |= BIT_ULL(VHOST_F_LOG_ALL);
+        /* Add emulated capabilities */
+        *features |= v->added_features;
     }
 
     return ret;
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 4bc3fd01a8..787e34ed99 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -600,6 +600,10 @@ static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
     s->vhost_vdpa.index = queue_pair_index;
     s->vhost_vdpa.shadow_vqs_enabled = svq;
     s->vhost_vdpa.iova_tree = iova_tree;
+    if (svq) {
+        /* Add SVQ logging capabilities */
+        s->vhost_vdpa.added_features |= BIT_ULL(VHOST_F_LOG_ALL);
+    }
     if (!is_datapath) {
         s->cvq_cmd_out_buffer = qemu_memalign(qemu_real_host_page_size(),
                                             vhost_vdpa_net_cvq_cmd_page_len());
-- 
2.31.1