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vhost-user: add new vhost user messages to support virtio config space

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Add VHOST_USER_GET_CONFIG/VHOST_USER_SET_CONFIG messages which can be
used for live migration of vhost user devices, also vhost user devices
can benefit from the messages to get/set virtio config space from/to the
I/O target. For the purpose to support virtio config space change,
VHOST_USER_SLAVE_CONFIG_CHANGE_MSG message is added as the event notifier
in case virtio config space change in the slave I/O target.

Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Changpeng Liu 2018-01-04 09:53:31 +08:00 • committed by Michael S. Tsirkin
parent 1bcf209154
commit 4c3e257b5e
5 changed files with 232 additions and 0 deletions
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55
docs/interop/vhost-user.txt
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@ -119,6 +119,19 @@ Depending on the request type, payload can be:
- 3: IOTLB invalidate
- 4: IOTLB access fail
* Virtio device config space
-----------------------------------
| offset | size | flags | payload |
-----------------------------------
Offset: a 32-bit offset of virtio device's configuration space
Size: a 32-bit configuration space access size in bytes
Flags: a 32-bit value:
- 0: Vhost master messages used for writeable fields
- 1: Vhost master messages used for live migration
Payload: Size bytes array holding the contents of the virtio
device's configuration space
In QEMU the vhost-user message is implemented with the following struct:
typedef struct VhostUserMsg {
@ -132,6 +145,7 @@ typedef struct VhostUserMsg {
VhostUserMemory memory;
VhostUserLog log;
struct vhost_iotlb_msg iotlb;
VhostUserConfig config;
};
} QEMU_PACKED VhostUserMsg;
@ -623,6 +637,32 @@ Master message types
and expect this message once (per VQ) during device configuration
(ie. before the master starts the VQ).
* VHOST_USER_GET_CONFIG
Id: 24
Equivalent ioctl: N/A
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
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
cache the contents to avoid repeated VHOST_USER_GET_CONFIG calls.
* VHOST_USER_SET_CONFIG
Id: 25
Equivalent ioctl: N/A
Master payload: virtio device config space
Slave payload: N/A
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
configuration space fields unless the live migration bit is set.
Slave message types
-------------------
@ -641,6 +681,21 @@ Slave message types
This request should be send only when VIRTIO_F_IOMMU_PLATFORM feature
has been successfully negotiated.
* VHOST_USER_SLAVE_CONFIG_CHANGE_MSG
Id: 2
Equivalent ioctl: N/A
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.
VHOST_USER_PROTOCOL_F_REPLY_ACK:
-------------------------------
The original vhost-user specification only demands replies for certain