virtio: allow finalize_features to fail

This will make it easy for transports to validate features and return
failure.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/lguest/lguest_device.c

@@ -126,7 +126,7 @@ static void status_notify(struct virtio_device *vdev)
  * sorted out, this routine is called so we can tell the Host which features we
  * understand and accept.
  */
-static void lg_finalize_features(struct virtio_device *vdev)
+static int lg_finalize_features(struct virtio_device *vdev)
 {
 	unsigned int i, bits;
 	struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
@@ -153,6 +153,8 @@ static void lg_finalize_features(struct virtio_device *vdev)
 
 	/* Tell Host we've finished with this device's feature negotiation */
 	status_notify(vdev);
+
+	return 0;
 }
 
 /* Once they've found a field, getting a copy of it is easy. */

drivers/misc/mic/card/mic_virtio.c

@@ -84,7 +84,7 @@ static u64 mic_get_features(struct virtio_device *vdev)
 	return features;
 }
 
-static void mic_finalize_features(struct virtio_device *vdev)
+static int mic_finalize_features(struct virtio_device *vdev)
 {
 	unsigned int i, bits;
 	struct mic_device_desc __iomem *desc = to_micvdev(vdev)->desc;
@@ -107,6 +107,8 @@ static void mic_finalize_features(struct virtio_device *vdev)
 			iowrite8(ioread8(&out_features[i / 8]) | (1 << (i % 8)),
 				 &out_features[i / 8]);
 	}
+
+	return 0;
 }
 
 /*

drivers/remoteproc/remoteproc_virtio.c

@@ -217,7 +217,7 @@ static u64 rproc_virtio_get_features(struct virtio_device *vdev)
 	return rsc->dfeatures;
 }
 
-static void rproc_virtio_finalize_features(struct virtio_device *vdev)
+static int rproc_virtio_finalize_features(struct virtio_device *vdev)
 {
 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
 	struct fw_rsc_vdev *rsc;
@@ -235,6 +235,8 @@ static void rproc_virtio_finalize_features(struct virtio_device *vdev)
 	 * to the remote processor once it is powered on.
 	 */
 	rsc->gfeatures = vdev->features;
+
+	return 0;
 }
 
 static void rproc_virtio_get(struct virtio_device *vdev, unsigned offset,

drivers/s390/kvm/kvm_virtio.c

@@ -93,7 +93,7 @@ static u64 kvm_get_features(struct virtio_device *vdev)
 	return features;
 }
 
-static void kvm_finalize_features(struct virtio_device *vdev)
+static int kvm_finalize_features(struct virtio_device *vdev)
 {
 	unsigned int i, bits;
 	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
@@ -112,6 +112,8 @@ static void kvm_finalize_features(struct virtio_device *vdev)
 		if (__virtio_test_bit(vdev, i))
 			out_features[i / 8] |= (1 << (i % 8));
 	}
+
+	return 0;
 }
 
 /*

drivers/s390/kvm/virtio_ccw.c

@@ -752,7 +752,7 @@ out_free:
 	return rc;
 }
 
-static void virtio_ccw_finalize_features(struct virtio_device *vdev)
+static int virtio_ccw_finalize_features(struct virtio_device *vdev)
 {
 	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
 	struct virtio_feature_desc *features;
@@ -760,7 +760,7 @@ static void virtio_ccw_finalize_features(struct virtio_device *vdev)
 
 	ccw = kzalloc(sizeof(*ccw), GFP_DMA | GFP_KERNEL);
 	if (!ccw)
-		return;
+		return 0;
 
 	features = kzalloc(sizeof(*features), GFP_DMA | GFP_KERNEL);
 	if (!features)
@@ -793,6 +793,8 @@ static void virtio_ccw_finalize_features(struct virtio_device *vdev)
 out_free:
 	kfree(features);
 	kfree(ccw);
+
+	return 0;
 }
 
 static void virtio_ccw_get_config(struct virtio_device *vdev,

drivers/virtio/virtio.c

@@ -212,7 +212,9 @@ static int virtio_dev_probe(struct device *_d)
 		if (device_features & (1ULL << i))
 			__virtio_set_bit(dev, i);
 
-	dev->config->finalize_features(dev);
+	err = dev->config->finalize_features(dev);
+	if (err)
+		goto err;
 
 	if (virtio_has_feature(dev, VIRTIO_F_VERSION_1)) {
 		add_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
@@ -354,6 +356,7 @@ EXPORT_SYMBOL_GPL(virtio_device_freeze);
 int virtio_device_restore(struct virtio_device *dev)
 {
 	struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+	int ret;
 
 	/* We always start by resetting the device, in case a previous
 	 * driver messed it up. */
@@ -373,14 +376,14 @@ int virtio_device_restore(struct virtio_device *dev)
 	/* We have a driver! */
 	add_status(dev, VIRTIO_CONFIG_S_DRIVER);
 
-	dev->config->finalize_features(dev);
+	ret = dev->config->finalize_features(dev);
+	if (ret)
+		goto err;
 
 	if (drv->restore) {
-		int ret = drv->restore(dev);
+		ret = drv->restore(dev);
-		if (ret) {
+		if (ret)
-			add_status(dev, VIRTIO_CONFIG_S_FAILED);
+			goto err;
-			return ret;
-		}
 	}
 
 	/* Finally, tell the device we're all set */
@@ -389,6 +392,10 @@ int virtio_device_restore(struct virtio_device *dev)
 	virtio_config_enable(dev);
 
 	return 0;
+
+err:
+	add_status(dev, VIRTIO_CONFIG_S_FAILED);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(virtio_device_restore);
 #endif

drivers/virtio/virtio_mmio.c

@@ -152,7 +152,7 @@ static u64 vm_get_features(struct virtio_device *vdev)
 	return readl(vm_dev->base + VIRTIO_MMIO_HOST_FEATURES);
 }
 
-static void vm_finalize_features(struct virtio_device *vdev)
+static int vm_finalize_features(struct virtio_device *vdev)
 {
 	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 
@@ -164,6 +164,8 @@ static void vm_finalize_features(struct virtio_device *vdev)
 
 	writel(0, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
 	writel(vdev->features, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
+
+	return 0;
 }
 
 static void vm_get(struct virtio_device *vdev, unsigned offset,

drivers/virtio/virtio_pci.c

@@ -112,7 +112,7 @@ static u64 vp_get_features(struct virtio_device *vdev)
 }
 
 /* virtio config->finalize_features() implementation */
-static void vp_finalize_features(struct virtio_device *vdev)
+static int vp_finalize_features(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 
@@ -124,6 +124,8 @@ static void vp_finalize_features(struct virtio_device *vdev)
 
 	/* We only support 32 feature bits. */
 	iowrite32(vdev->features, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);
+
+	return 0;
 }
 
 /* virtio config->get() implementation */

include/linux/virtio_config.h

@@ -47,6 +47,7 @@
  *	vdev: the virtio_device
  *	This gives the final feature bits for the device: it can change
  *	the dev->feature bits if it wants.
+ *	Returns 0 on success or error status
  * @bus_name: return the bus name associated with the device
  *	vdev: the virtio_device
  *      This returns a pointer to the bus name a la pci_name from which
@@ -68,7 +69,7 @@ struct virtio_config_ops {
 			const char *names[]);
 	void (*del_vqs)(struct virtio_device *);
 	u64 (*get_features)(struct virtio_device *vdev);
-	void (*finalize_features)(struct virtio_device *vdev);
+	int (*finalize_features)(struct virtio_device *vdev);
 	const char *(*bus_name)(struct virtio_device *vdev);
 	int (*set_vq_affinity)(struct virtqueue *vq, int cpu);
 };