1 files changed, 39 insertions, 0 deletions
diff --git a/hw/block/virtio-blk-common.c b/hw/block/virtio-blk-common.c
new file mode 100644
index 0000000000..ac52d7c176
--- /dev/null
+++ b/hw/block/virtio-blk-common.c
@@ -0,0 +1,39 @@
+/*
+ * Virtio Block Device common helpers
+ *
+ * Copyright IBM, Corp. 2007
+ *
+ * Authors:
+ *  Anthony Liguori   <aliguori@us.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+
+#include "standard-headers/linux/virtio_blk.h"
+#include "hw/virtio/virtio.h"
+#include "hw/virtio/virtio-blk-common.h"
+
+/* Config size before the discard support (hide associated config fields) */
+#define VIRTIO_BLK_CFG_SIZE offsetof(struct virtio_blk_config, \
+                                     max_discard_sectors)
+
+/*
+ * Starting from the discard feature, we can use this array to properly
+ * set the config size depending on the features enabled.
+ */
+static const VirtIOFeature feature_sizes[] = {
+    {.flags = 1ULL << VIRTIO_BLK_F_DISCARD,
+     .end = endof(struct virtio_blk_config, discard_sector_alignment)},
+    {.flags = 1ULL << VIRTIO_BLK_F_WRITE_ZEROES,
+     .end = endof(struct virtio_blk_config, write_zeroes_may_unmap)},
+    {}
+};
+
+const VirtIOConfigSizeParams virtio_blk_cfg_size_params = {
+    .min_size = VIRTIO_BLK_CFG_SIZE,
+    .max_size = sizeof(struct virtio_blk_config),
+    .feature_sizes = feature_sizes
+};