vhost: add support for negotiating extended features

Similar to virtio infra, vhost core maintains the features status
in the full extended format and allows the devices to implement
extended version of the getter/setter.

Note that 'protocol_features' are not extended: they are only
used by vhost-user, and the latter device is not going to implement
extended features soon.

Reviewed-by: Akihiko Odaki <odaki@rsg.ci.i.u-tokyo.ac.jp>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <a0062c3b1847fb2baedd6cd8f6ef13b051d6beb2.1758549625.git.pabeni@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 48 insertions, 20 deletions

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 6557c58d12..5f485ad6cb 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -972,20 +972,34 @@ static int vhost_virtqueue_set_addr(struct vhost_dev *dev,
 static int vhost_dev_set_features(struct vhost_dev *dev,
                                   bool enable_log)
 {
-    uint64_t features = dev->acked_features;
+    uint64_t features[VIRTIO_FEATURES_NU64S];
     int r;
+
+    virtio_features_copy(features, dev->acked_features_ex);
     if (enable_log) {
-        features |= 0x1ULL << VHOST_F_LOG_ALL;
+        virtio_add_feature_ex(features, VHOST_F_LOG_ALL);
     }
     if (!vhost_dev_has_iommu(dev)) {
-        features &= ~(0x1ULL << VIRTIO_F_IOMMU_PLATFORM);
+        virtio_clear_feature_ex(features, VIRTIO_F_IOMMU_PLATFORM);
     }
     if (dev->vhost_ops->vhost_force_iommu) {
         if (dev->vhost_ops->vhost_force_iommu(dev) == true) {
-            features |= 0x1ULL << VIRTIO_F_IOMMU_PLATFORM;
+            virtio_add_feature_ex(features, VIRTIO_F_IOMMU_PLATFORM);
        }
     }
-    r = dev->vhost_ops->vhost_set_features(dev, features);
+
+    if (virtio_features_use_ex(features) &&
+        !dev->vhost_ops->vhost_set_features_ex) {
+        r = -EINVAL;
+        VHOST_OPS_DEBUG(r, "extended features without device support");
+        goto out;
+    }
+
+    if (dev->vhost_ops->vhost_set_features_ex) {
+        r = dev->vhost_ops->vhost_set_features_ex(dev, features);
+    } else {
+        r = dev->vhost_ops->vhost_set_features(dev, features[0]);
+    }
     if (r < 0) {
         VHOST_OPS_DEBUG(r, "vhost_set_features failed");
         goto out;
@@ -1508,12 +1522,27 @@ static void vhost_virtqueue_cleanup(struct vhost_virtqueue *vq)
     }
 }
 
+static int vhost_dev_get_features(struct vhost_dev *hdev,
+                                  uint64_t *features)
+{
+    uint64_t features64;
+    int r;
+
+    if (hdev->vhost_ops->vhost_get_features_ex) {
+        return hdev->vhost_ops->vhost_get_features_ex(hdev, features);
+    }
+
+    r = hdev->vhost_ops->vhost_get_features(hdev, &features64);
+    virtio_features_from_u64(features, features64);
+    return r;
+}
+
 int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
                    VhostBackendType backend_type, uint32_t busyloop_timeout,
                    Error **errp)
 {
+    uint64_t features[VIRTIO_FEATURES_NU64S];
     unsigned int used, reserved, limit;
-    uint64_t features;
     int i, r, n_initialized_vqs = 0;
 
     hdev->vdev = NULL;
@@ -1533,7 +1562,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
         goto fail;
     }
 
-    r = hdev->vhost_ops->vhost_get_features(hdev, &features);
+    r = vhost_dev_get_features(hdev, features);
     if (r < 0) {
         error_setg_errno(errp, -r, "vhost_get_features failed");
         goto fail;
@@ -1571,7 +1600,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
         }
     }
 
-    hdev->features = features;
+    virtio_features_copy(hdev->features_ex, features);
 
     hdev->memory_listener = (MemoryListener) {
         .name = "vhost",
@@ -1594,7 +1623,7 @@ int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
     };
 
     if (hdev->migration_blocker == NULL) {
-        if (!(hdev->features & (0x1ULL << VHOST_F_LOG_ALL))) {
+        if (!virtio_has_feature_ex(hdev->features_ex, VHOST_F_LOG_ALL)) {
             error_setg(&hdev->migration_blocker,
                        "Migration disabled: vhost lacks VHOST_F_LOG_ALL feature.");
         } else if (vhost_dev_log_is_shared(hdev) && !qemu_memfd_alloc_check()) {
@@ -1859,28 +1888,27 @@ static void vhost_start_config_intr(struct vhost_dev *dev)
     }
 }
 
-uint64_t vhost_get_features(struct vhost_dev *hdev, const int *feature_bits,
-                            uint64_t features)
+void vhost_get_features_ex(struct vhost_dev *hdev,
+                           const int *feature_bits,
+                           uint64_t *features)
 {
     const int *bit = feature_bits;
+
     while (*bit != VHOST_INVALID_FEATURE_BIT) {
-        uint64_t bit_mask = (1ULL << *bit);
-        if (!(hdev->features & bit_mask)) {
-            features &= ~bit_mask;
+        if (!virtio_has_feature_ex(hdev->features_ex, *bit)) {
+            virtio_clear_feature_ex(features, *bit);
         }
         bit++;
     }
-    return features;
 }
 
-void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits,
-                        uint64_t features)
+void vhost_ack_features_ex(struct vhost_dev *hdev, const int *feature_bits,
+                           const uint64_t *features)
 {
     const int *bit = feature_bits;
     while (*bit != VHOST_INVALID_FEATURE_BIT) {
-        uint64_t bit_mask = (1ULL << *bit);
-        if (features & bit_mask) {
-            hdev->acked_features |= bit_mask;
+        if (virtio_has_feature_ex(features, *bit)) {
+            virtio_add_feature_ex(hdev->acked_features_ex, *bit);
         }
         bit++;
     }