virtio: use u32, not bitmap for features

It seemed like a good idea to use bitmap for features
in struct virtio_device, but it's actually a pain,
and seems to become even more painful when we get more
than 32 feature bits.  Just change it to a u32 for now.

Based on patch by Rusty.

Suggested-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>

4 files changed, 9 insertions, 14 deletions

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index df598dd..2b9aafb 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -49,9 +49,9 @@ static ssize_t features_show(struct device *_d,
 
 	/* We actually represent this as a bitstring, as it could be
 	 * arbitrary length in future. */
-	for (i = 0; i < ARRAY_SIZE(dev->features)*BITS_PER_LONG; i++)
+	for (i = 0; i < sizeof(dev->features)*8; i++)
 		len += sprintf(buf+len, "%c",
-			       test_bit(i, dev->features) ? '1' : '0');
+			       __virtio_test_bit(dev, i) ? '1' : '0');
 	len += sprintf(buf+len, "\n");
 	return len;
 }
@@ -168,18 +168,18 @@ static int virtio_dev_probe(struct device *_d)
 	device_features = dev->config->get_features(dev);
 
 	/* Features supported by both device and driver into dev->features. */
-	memset(dev->features, 0, sizeof(dev->features));
+	dev->features = 0;
 	for (i = 0; i < drv->feature_table_size; i++) {
 		unsigned int f = drv->feature_table[i];
 		BUG_ON(f >= 32);
 		if (device_features & (1 << f))
-			set_bit(f, dev->features);
+			__virtio_set_bit(dev, f);
 	}
 
 	/* 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);
+			__virtio_set_bit(dev, i);
 
 	dev->config->finalize_features(dev);
 
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index ef9a165..eb5b0e2 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -155,16 +155,12 @@ static u32 vm_get_features(struct virtio_device *vdev)
 static void vm_finalize_features(struct virtio_device *vdev)
 {
 	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
-	int i;
 
 	/* Give virtio_ring a chance to accept features. */
 	vring_transport_features(vdev);
 
-	for (i = 0; i < ARRAY_SIZE(vdev->features); i++) {
-		writel(i, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
-		writel(vdev->features[i],
-				vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
-	}
+	writel(0, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
+	writel(vdev->features, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
 }
 
 static void vm_get(struct virtio_device *vdev, unsigned offset,
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index d34ebfa..4e112c1 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -120,8 +120,7 @@ static void vp_finalize_features(struct virtio_device *vdev)
 	vring_transport_features(vdev);
 
 	/* 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);
+	iowrite32(vdev->features, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);
 }
 
 /* virtio config->get() implementation */
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 3b1f89b..839247c 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -781,7 +781,7 @@ void vring_transport_features(struct virtio_device *vdev)
 			break;
 		default:
 			/* We don't understand this bit. */
-			clear_bit(i, vdev->features);
+			__virtio_clear_bit(vdev, i);
 		}
 	}
 }