virtio-blk: use VIRTIO_BLK_F_WCE and VIRTIO_BLK_F_CONFIG_WCE in virtio1

VIRTIO_BLK_F_CONFIG_WCE is important in order to achieve good performance
(up to 2x, though more realistically +30-40%) in latency-bound workloads.
However, it was removed by mistake together with VIRTIO_BLK_F_FLUSH.

It will be restored in the next revision of the virtio 1.0 standard, so
do the same in Linux.

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

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index d4d05f0..ea2c17c 100644 (file)
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -478,8 +478,7 @@ static int virtblk_get_cache_mode(struct virtio_device *vdev)
                                   struct virtio_blk_config, wce,
                                   &writeback);
        if (err)
-               writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE) ||
-                           virtio_has_feature(vdev, VIRTIO_F_VERSION_1);
+               writeback = virtio_has_feature(vdev, VIRTIO_BLK_F_WCE);
 
        return writeback;
 }
@@ -840,7 +839,7 @@ static unsigned int features_legacy[] = {
 static unsigned int features[] = {
        VIRTIO_BLK_F_SEG_MAX, VIRTIO_BLK_F_SIZE_MAX, VIRTIO_BLK_F_GEOMETRY,
        VIRTIO_BLK_F_RO, VIRTIO_BLK_F_BLK_SIZE,
-       VIRTIO_BLK_F_TOPOLOGY,
+       VIRTIO_BLK_F_WCE, VIRTIO_BLK_F_TOPOLOGY, VIRTIO_BLK_F_CONFIG_WCE,
        VIRTIO_BLK_F_MQ,
 };