diff options
| author | Michael S. Tsirkin <mst@redhat.com> | 2015-09-23 12:19:56 +0800 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2015-09-24 16:27:52 +0300 |
| commit | dcb10c000cdd4d14f5ac4f07b04fb666494ef4a8 (patch) | |
| tree | 125005c6c7d27f69771f8e1b0d20b0c0d4eebc85 /docs | |
| parent | 7305483a3d113456681ba6c6e8dd41513decd5f6 (diff) | |
| download | qemu-dcb10c000cdd4d14f5ac4f07b04fb666494ef4a8.zip qemu-dcb10c000cdd4d14f5ac4f07b04fb666494ef4a8.tar.gz qemu-dcb10c000cdd4d14f5ac4f07b04fb666494ef4a8.tar.bz2 | |
vhost-user: add protocol feature negotiation
Support a separate bitmask for vhost-user protocol features,
and messages to get/set protocol features.
Invoke them at init.
No features are defined yet.
[ leverage vhost_user_call for request handling -- Yuanhan Liu ]
Signed-off-by: Michael S. Tsirkin <address@hidden>
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Marcel Apfelbaum <marcel@redhat.com>
Tested-by: Marcel Apfelbaum <marcel@redhat.com>
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/specs/vhost-user.txt | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt index 650bb18..70da3b1 100644 --- a/docs/specs/vhost-user.txt +++ b/docs/specs/vhost-user.txt @@ -113,6 +113,7 @@ message replies. Most of the requests don't require replies. Here is a list of the ones that do: * VHOST_GET_FEATURES + * VHOST_GET_PROTOCOL_FEATURES * VHOST_GET_VRING_BASE There are several messages that the master sends with file descriptors passed @@ -127,6 +128,13 @@ in the ancillary data: If Master is unable to send the full message or receives a wrong reply it will close the connection. An optional reconnection mechanism can be implemented. +Any protocol extensions are gated by protocol feature bits, +which allows full backwards compatibility on both master +and slave. +As older slaves don't support negotiating protocol features, +a feature bit was dedicated for this purpose: +#define VHOST_USER_F_PROTOCOL_FEATURES 30 + Message types ------------- @@ -138,6 +146,8 @@ Message types Slave payload: u64 Get from the underlying vhost implementation the features bitmask. + Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals slave support for + VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES. * VHOST_USER_SET_FEATURES @@ -146,6 +156,33 @@ Message types Master payload: u64 Enable features in the underlying vhost implementation using a bitmask. + Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals slave support for + VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES. + + * VHOST_USER_GET_PROTOCOL_FEATURES + + Id: 15 + Equivalent ioctl: VHOST_GET_FEATURES + Master payload: N/A + Slave payload: u64 + + Get the protocol feature bitmask from the underlying vhost implementation. + Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in + VHOST_USER_GET_FEATURES. + Note: slave that reported VHOST_USER_F_PROTOCOL_FEATURES must support + this message even before VHOST_USER_SET_FEATURES was called. + + * VHOST_USER_SET_PROTOCOL_FEATURES + + Id: 16 + Ioctl: VHOST_SET_FEATURES + Master payload: u64 + + Enable protocol features in the underlying vhost implementation. + Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in + VHOST_USER_GET_FEATURES. + Note: slave that reported VHOST_USER_F_PROTOCOL_FEATURES must support + this message even before VHOST_USER_SET_FEATURES was called. * VHOST_USER_SET_OWNER |