5 files changed, 24 insertions, 20 deletions

diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 1a8de57289eb..54fdc2aa4806 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -98,16 +98,17 @@ static u32 lg_get_features(struct virtio_device *vdev)
         return features;
 }
 
-static void lg_set_features(struct virtio_device *vdev, u32 features)
+static void lg_finalize_features(struct virtio_device *vdev)
 {
-        unsigned int i;
+        unsigned int i, bits;
         struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
         /* Second half of bitmap is features we accept. */
         u8 *out_features = lg_features(desc) + desc->feature_len;
 
         memset(out_features, 0, desc->feature_len);
-        for (i = 0; i < min(desc->feature_len * 8, 32); i++) {
-                if (features & (1 << i))
+        bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
+        for (i = 0; i < bits; i++) {
+                if (test_bit(i, vdev->features))
                         out_features[i / 8] |= (1 << (i % 8));
         }
 }
@@ -297,7 +298,7 @@ static void lg_del_vq(struct virtqueue *vq)
 /* The ops structure which hooks everything together. */
 static struct virtio_config_ops lguest_config_ops = {
         .get_features = lg_get_features,
-        .set_features = lg_set_features,
+        .finalize_features = lg_finalize_features,
         .get = lg_get,
         .set = lg_set,
         .get_status = lg_get_status,
diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index d41f234bb2c2..5953510e7d5f 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -88,16 +88,17 @@ static u32 kvm_get_features(struct virtio_device *vdev)
         return features;
 }
 
-static void kvm_set_features(struct virtio_device *vdev, u32 features)
+static void kvm_finalize_features(struct virtio_device *vdev)
 {
-        unsigned int i;
+        unsigned int i, bits;
         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
         /* Second half of bitmap is features we accept. */
         u8 *out_features = kvm_vq_features(desc) + desc->feature_len;
 
         memset(out_features, 0, desc->feature_len);
-        for (i = 0; i < min(desc->feature_len * 8, 32); i++) {
-                if (features & (1 << i))
+        bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
+        for (i = 0; i < bits; i++) {
+                if (test_bit(i, vdev->features))
                         out_features[i / 8] |= (1 << (i % 8));
         }
 }
@@ -223,7 +224,7 @@ static void kvm_del_vq(struct virtqueue *vq)
  */
 static struct virtio_config_ops kvm_vq_configspace_ops = {
         .get_features = kvm_get_features,
-        .set_features = kvm_set_features,
+        .finalize_features = kvm_finalize_features,
         .get = kvm_get,
         .set = kvm_set,
         .get_status = kvm_get_status,
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index baf103361e3a..5b78fd0aff0a 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -113,7 +113,7 @@ static int virtio_dev_probe(struct device *_d)
                         set_bit(f, dev->features);
         }
 
-        /* Transport features are always preserved to pass to set_features. */
+        /* Transport features always preserved to pass to finalize_features. */
         for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
                 if (device_features & (1 << i))
                         set_bit(i, dev->features);
@@ -122,8 +122,7 @@ static int virtio_dev_probe(struct device *_d)
         if (err)
                 add_status(dev, VIRTIO_CONFIG_S_FAILED);
         else {
-                /* They should never have set feature bits beyond 32 */
-                dev->config->set_features(dev, dev->features[0]);
+                dev->config->finalize_features(dev);
                 add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
         }
         return err;
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index eae7236310e4..9855975a72a3 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -94,12 +94,14 @@ static u32 vp_get_features(struct virtio_device *vdev)
         return ioread32(vp_dev->ioaddr + VIRTIO_PCI_HOST_FEATURES);
 }
 
-/* virtio config->set_features() implementation */
-static void vp_set_features(struct virtio_device *vdev, u32 features)
+/* virtio config->finalize_features() implementation */
+static void vp_finalize_features(struct virtio_device *vdev)
 {
         struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 
-        iowrite32(features, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);
+        /* We only support 32 feature bits. */
+        BUILD_BUG_ON(ARRAY_SIZE(vdev->features) != 1);
+        iowrite32(vdev->features[0], vp_dev->ioaddr+VIRTIO_PCI_GUEST_FEATURES);
 }
 
 /* virtio config->get() implementation */
@@ -297,7 +299,7 @@ static struct virtio_config_ops virtio_pci_config_ops = {
         .find_vq        = vp_find_vq,
         .del_vq         = vp_del_vq,
         .get_features   = vp_get_features,
-        .set_features   = vp_set_features,
+        .finalize_features = vp_finalize_features,
 };
 
 /* the PCI probing function */
diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h
index 5a30cfb7934b..bf8ec283b232 100644
--- a/include/linux/virtio_config.h
+++ b/include/linux/virtio_config.h
@@ -61,9 +61,10 @@
  * @get_features: get the array of feature bits for this device.
  *      vdev: the virtio_device
  *      Returns the first 32 feature bits (all we currently need).
- * @set_features: confirm what device features we'll be using.
+ * @finalize_features: confirm what device features we'll be using.
  *      vdev: the virtio_device
- *      feature: the first 32 feature bits
+ *      This gives the final feature bits for the device: it can change
+ *      the dev->feature bits if it wants.
  */
 struct virtio_config_ops
 {
@@ -79,7 +80,7 @@ struct virtio_config_ops
                                      void (*callback)(struct virtqueue *));
         void (*del_vq)(struct virtqueue *vq);
         u32 (*get_features)(struct virtio_device *vdev);
-        void (*set_features)(struct virtio_device *vdev, u32 features);
+        void (*finalize_features)(struct virtio_device *vdev);
 };
 
 /* If driver didn't advertise the feature, it will never appear. */