tree 9584862eef22a09b0299a3e5e4a975ddc67e1de9
parent 0dce3771fdd1db03c6f498594a34bba5a6d1f870
author Michael S. Tsirkin <mst@redhat.com> 1418568944 +0200
committer Michael S. Tsirkin <mst@redhat.com> 1418574091 +0200

virtio: core support for config generation

virtio 1.0 spec says:

Drivers MUST NOT assume reads from fields greater than 32 bits wide are
atomic, nor are reads from multiple fields: drivers SHOULD read device
configuration space fields like so:
	u32 before, after;
	do {
		before = get_config_generation(device);
		// read config entry/entries.
		after = get_config_generation(device);
	} while (after != before);

Do exactly this, for transports that support it.

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