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| author | Maxime Coquelin <maxime.coquelin@redhat.com> | 2018-03-29 09:52:33 +0200 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2018-04-09 17:35:46 +0300 |
| commit | 1c3e5a261709daee4a01f30b1534329b2eea386e (patch) | |
| tree | 89519017ce06eb0f639886a884a99735420bc2d7 /docs/interop | |
| parent | bc6abcff7c608dba27962efa75f234c5dd10e290 (diff) | |
vhost-user: back SET/GET_CONFIG requests with a protocol feature
Without a dedicated protocol feature, QEMU cannot know whether
the backend can handle VHOST_USER_SET_CONFIG and
VHOST_USER_GET_CONFIG messages.
This patch adds a protocol feature that is only advertised by
QEMU if the device implements the config ops. Vhost user init
fails if the device support the feature but the backend doesn't.
The backend should only send VHOST_USER_SLAVE_CONFIG_CHANGE_MSG
requests if the protocol feature has been negotiated.
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Changpeng Liu <changpeng.liu@intel.com>
Diffstat (limited to 'docs/interop')
| -rw-r--r-- | docs/interop/vhost-user.txt | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt index c058c407df..534caab18a 100644 --- a/docs/interop/vhost-user.txt +++ b/docs/interop/vhost-user.txt @@ -379,6 +379,7 @@ Protocol features #define VHOST_USER_PROTOCOL_F_CROSS_ENDIAN 6 #define VHOST_USER_PROTOCOL_F_CRYPTO_SESSION 7 #define VHOST_USER_PROTOCOL_F_PAGEFAULT 8 +#define VHOST_USER_PROTOCOL_F_CONFIG 9 Master message types -------------------- @@ -664,7 +665,8 @@ Master message types Master payload: virtio device config space Slave payload: virtio device config space - Submitted by the vhost-user master to fetch the contents of the virtio + When VHOST_USER_PROTOCOL_F_CONFIG is negotiated, this message is + submitted by the vhost-user master to fetch the contents of the virtio device configuration space, vhost-user slave's payload size MUST match master's request, vhost-user slave uses zero length of payload to indicate an error to vhost-user master. The vhost-user master may @@ -677,7 +679,8 @@ Master message types Master payload: virtio device config space Slave payload: N/A - Submitted by the vhost-user master when the Guest changes the virtio + When VHOST_USER_PROTOCOL_F_CONFIG is negotiated, this message is + submitted by the vhost-user master when the Guest changes the virtio device configuration space and also can be used for live migration on the destination host. The vhost-user slave must check the flags field, and slaves MUST NOT accept SET_CONFIG for read-only @@ -766,13 +769,13 @@ Slave message types Slave payload: N/A Master payload: N/A - Vhost-user slave sends such messages to notify that the virtio device's - configuration space has changed, for those host devices which can support - such feature, host driver can send VHOST_USER_GET_CONFIG message to slave - to get the latest content. If VHOST_USER_PROTOCOL_F_REPLY_ACK is - negotiated, and slave set the VHOST_USER_NEED_REPLY flag, master must - respond with zero when operation is successfully completed, or non-zero - otherwise. + When VHOST_USER_PROTOCOL_F_CONFIG is negotiated, vhost-user slave sends + such messages to notify that the virtio device's configuration space has + changed, for those host devices which can support such feature, host + driver can send VHOST_USER_GET_CONFIG message to slave to get the latest + content. If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, and slave set + the VHOST_USER_NEED_REPLY flag, master must respond with zero when + operation is successfully completed, or non-zero otherwise. VHOST_USER_PROTOCOL_F_REPLY_ACK: ------------------------------- |