2014-06-10 10:02:57 +00:00
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Vhost-user Protocol
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===================
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Copyright (c) 2014 Virtual Open Systems Sarl.
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This work is licensed under the terms of the GNU GPL, version 2 or later.
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See the COPYING file in the top-level directory.
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===================
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This protocol is aiming to complement the ioctl interface used to control the
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vhost implementation in the Linux kernel. It implements the control plane needed
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to establish virtqueue sharing with a user space process on the same host. It
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uses communication over a Unix domain socket to share file descriptors in the
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ancillary data of the message.
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The protocol defines 2 sides of the communication, master and slave. Master is
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the application that shares its virtqueues, in our case QEMU. Slave is the
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consumer of the virtqueues.
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2019-03-08 14:04:44 +00:00
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In the current implementation QEMU is the Master, and the Slave is the
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external process consuming the virtio queues, for example a software
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Ethernet switch running in user space, such as Snabbswitch, or a block
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device backend processing read & write to a virtual disk. In order to
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facilitate interoperability between various backend implementations,
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it is recommended to follow the "Backend program conventions"
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described in this document.
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2014-06-10 10:02:57 +00:00
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Master and slave can be either a client (i.e. connecting) or server (listening)
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in the socket communication.
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Message Specification
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---------------------
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Note that all numbers are in the machine native byte order. A vhost-user message
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consists of 3 header fields and a payload:
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------------------------------------
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| request | flags | size | payload |
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------------------------------------
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* Request: 32-bit type of the request
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* Flags: 32-bit bit field:
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- Lower 2 bits are the version (currently 0x01)
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- Bit 2 is the reply flag - needs to be sent on each reply from the slave
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2016-08-05 10:53:50 +00:00
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- Bit 3 is the need_reply flag - see VHOST_USER_PROTOCOL_F_REPLY_ACK for
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details.
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2014-06-10 10:02:57 +00:00
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* Size - 32-bit size of the payload
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Depending on the request type, payload can be:
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* A single 64-bit integer
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-------
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| u64 |
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-------
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u64: a 64-bit unsigned integer
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* A vring state description
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---------------
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2017-12-14 20:22:19 +00:00
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| index | num |
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---------------
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2014-06-10 10:02:57 +00:00
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Index: a 32-bit index
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Num: a 32-bit number
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* A vring address description
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--------------------------------------------------------------
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| index | flags | size | descriptor | used | available | log |
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--------------------------------------------------------------
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Index: a 32-bit vring index
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Flags: a 32-bit vring flags
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2017-12-14 20:22:20 +00:00
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Descriptor: a 64-bit ring address of the vring descriptor table
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Used: a 64-bit ring address of the vring used ring
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Available: a 64-bit ring address of the vring available ring
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2014-06-10 10:02:57 +00:00
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Log: a 64-bit guest address for logging
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2017-12-14 20:22:20 +00:00
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Note that a ring address is an IOVA if VIRTIO_F_IOMMU_PLATFORM has been
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negotiated. Otherwise it is a user address.
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2014-06-10 10:02:57 +00:00
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* Memory regions description
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---------------------------------------------------
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| num regions | padding | region0 | ... | region7 |
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---------------------------------------------------
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Num regions: a 32-bit number of regions
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Padding: 32-bit
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A region is:
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2014-06-26 21:01:32 +00:00
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-----------------------------------------------------
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| guest address | size | user address | mmap offset |
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-----------------------------------------------------
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2014-06-10 10:02:57 +00:00
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Guest address: a 64-bit guest address of the region
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Size: a 64-bit size
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User address: a 64-bit user address
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2014-06-29 14:58:48 +00:00
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mmap offset: 64-bit offset where region starts in the mapped memory
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2014-06-10 10:02:57 +00:00
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2015-11-15 19:25:11 +00:00
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* Log description
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---------------------------
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| log size | log offset |
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---------------------------
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log size: size of area used for logging
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log offset: offset from start of supplied file descriptor
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where logging starts (i.e. where guest address 0 would be logged)
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2017-06-02 10:18:31 +00:00
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* An IOTLB message
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---------------------------------------------------------
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| iova | size | user address | permissions flags | type |
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---------------------------------------------------------
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IOVA: a 64-bit I/O virtual address programmed by the guest
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Size: a 64-bit size
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User address: a 64-bit user address
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2018-06-12 06:51:50 +00:00
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Permissions: an 8-bit value:
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- 0: No access
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- 1: Read access
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- 2: Write access
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- 3: Read/Write access
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2018-06-12 06:51:50 +00:00
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Type: an 8-bit IOTLB message type:
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2017-06-02 10:18:31 +00:00
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- 1: IOTLB miss
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- 2: IOTLB update
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- 3: IOTLB invalidate
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- 4: IOTLB access fail
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2018-01-04 01:53:31 +00:00
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* Virtio device config space
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-----------------------------------
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| offset | size | flags | payload |
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-----------------------------------
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Offset: a 32-bit offset of virtio device's configuration space
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Size: a 32-bit configuration space access size in bytes
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Flags: a 32-bit value:
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- 0: Vhost master messages used for writeable fields
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- 1: Vhost master messages used for live migration
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Payload: Size bytes array holding the contents of the virtio
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device's configuration space
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2018-05-24 10:33:34 +00:00
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* Vring area description
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-----------------------
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| u64 | size | offset |
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-----------------------
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u64: a 64-bit integer contains vring index and flags
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Size: a 64-bit size of this area
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Offset: a 64-bit offset of this area from the start of the
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supplied file descriptor
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2019-02-28 08:53:49 +00:00
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* Inflight description
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-----------------------------------------------------
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| mmap size | mmap offset | num queues | queue size |
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-----------------------------------------------------
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mmap size: a 64-bit size of area to track inflight I/O
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mmap offset: a 64-bit offset of this area from the start
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of the supplied file descriptor
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num queues: a 16-bit number of virtqueues
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queue size: a 16-bit size of virtqueues
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2014-06-10 10:02:57 +00:00
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In QEMU the vhost-user message is implemented with the following struct:
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typedef struct VhostUserMsg {
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VhostUserRequest request;
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uint32_t flags;
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uint32_t size;
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union {
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uint64_t u64;
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struct vhost_vring_state state;
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struct vhost_vring_addr addr;
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VhostUserMemory memory;
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2015-11-11 14:26:02 +00:00
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VhostUserLog log;
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2017-06-02 10:18:31 +00:00
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struct vhost_iotlb_msg iotlb;
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2018-01-04 01:53:31 +00:00
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VhostUserConfig config;
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2018-05-24 10:33:34 +00:00
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VhostUserVringArea area;
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2019-02-28 08:53:49 +00:00
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VhostUserInflight inflight;
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2014-06-10 10:02:57 +00:00
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};
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} QEMU_PACKED VhostUserMsg;
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Communication
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-------------
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The protocol for vhost-user is based on the existing implementation of vhost
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for the Linux Kernel. Most messages that can be sent via the Unix domain socket
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implementing vhost-user have an equivalent ioctl to the kernel implementation.
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The communication consists of master sending message requests and slave sending
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message replies. Most of the requests don't require replies. Here is a list of
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the ones that do:
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2016-11-24 03:20:56 +00:00
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* VHOST_USER_GET_FEATURES
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* VHOST_USER_GET_PROTOCOL_FEATURES
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* VHOST_USER_GET_VRING_BASE
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* VHOST_USER_SET_LOG_BASE (if VHOST_USER_PROTOCOL_F_LOG_SHMFD)
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2019-02-28 08:53:49 +00:00
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* VHOST_USER_GET_INFLIGHT_FD (if VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD)
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2014-06-10 10:02:57 +00:00
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2016-08-05 10:53:50 +00:00
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[ Also see the section on REPLY_ACK protocol extension. ]
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2014-06-10 10:02:57 +00:00
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There are several messages that the master sends with file descriptors passed
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in the ancillary data:
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2016-11-24 03:20:56 +00:00
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* VHOST_USER_SET_MEM_TABLE
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* VHOST_USER_SET_LOG_BASE (if VHOST_USER_PROTOCOL_F_LOG_SHMFD)
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* VHOST_USER_SET_LOG_FD
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* VHOST_USER_SET_VRING_KICK
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* VHOST_USER_SET_VRING_CALL
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* VHOST_USER_SET_VRING_ERR
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2017-06-02 10:18:30 +00:00
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* VHOST_USER_SET_SLAVE_REQ_FD
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2019-02-28 08:53:49 +00:00
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* VHOST_USER_SET_INFLIGHT_FD (if VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD)
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2014-06-10 10:02:57 +00:00
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If Master is unable to send the full message or receives a wrong reply it will
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close the connection. An optional reconnection mechanism can be implemented.
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2015-09-23 04:19:56 +00:00
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Any protocol extensions are gated by protocol feature bits,
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which allows full backwards compatibility on both master
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and slave.
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As older slaves don't support negotiating protocol features,
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a feature bit was dedicated for this purpose:
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#define VHOST_USER_F_PROTOCOL_FEATURES 30
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2015-11-15 19:25:11 +00:00
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Starting and stopping rings
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----------------------
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2015-11-23 10:48:52 +00:00
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Client must only process each ring when it is started.
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Client must only pass data between the ring and the
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backend, when the ring is enabled.
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If ring is started but disabled, client must process the
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ring without talking to the backend.
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For example, for a networking device, in the disabled state
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client must not supply any new RX packets, but must process
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and discard any TX packets.
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2015-11-17 11:55:48 +00:00
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If VHOST_USER_F_PROTOCOL_FEATURES has not been negotiated, the ring is initialized
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in an enabled state.
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2015-11-15 19:25:11 +00:00
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2015-11-17 11:55:48 +00:00
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If VHOST_USER_F_PROTOCOL_FEATURES has been negotiated, the ring is initialized
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2015-11-23 10:48:52 +00:00
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in a disabled state. Client must not pass data to/from the backend until ring is enabled by
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2015-11-17 11:55:48 +00:00
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VHOST_USER_SET_VRING_ENABLE with parameter 1, or after it has been disabled by
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VHOST_USER_SET_VRING_ENABLE with parameter 0.
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Each ring is initialized in a stopped state, client must not process it until
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ring is started, or after it has been stopped.
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2015-11-15 19:25:11 +00:00
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2015-11-17 11:55:48 +00:00
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Client must start ring upon receiving a kick (that is, detecting that file
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descriptor is readable) on the descriptor specified by
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VHOST_USER_SET_VRING_KICK, and stop ring upon receiving
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VHOST_USER_GET_VRING_BASE.
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2015-11-15 19:25:11 +00:00
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2015-11-23 10:48:52 +00:00
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While processing the rings (whether they are enabled or not), client must
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2015-11-17 11:55:48 +00:00
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support changing some configuration aspects on the fly.
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2015-11-15 19:25:11 +00:00
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vhost-user: add multiple queue support
This patch is initially based a patch from Nikolay Nikolaev.
This patch adds vhost-user multiple queue support, by creating a nc
and vhost_net pair for each queue.
Qemu exits if find that the backend can't support the number of requested
queues (by providing queues=# option). The max number is queried by a
new message, VHOST_USER_GET_QUEUE_NUM, and is sent only when protocol
feature VHOST_USER_PROTOCOL_F_MQ is present first.
The max queue check is done at vhost-user initiation stage. We initiate
one queue first, which, in the meantime, also gets the max_queues the
backend supports.
In older version, it was reported that some messages are sent more times
than necessary. Here we came an agreement with Michael that we could
categorize vhost user messages to 2 types: non-vring specific messages,
which should be sent only once, and vring specific messages, which should
be sent per queue.
Here I introduced a helper function vhost_user_one_time_request(), which
lists following messages as non-vring specific messages:
VHOST_USER_SET_OWNER
VHOST_USER_RESET_DEVICE
VHOST_USER_SET_MEM_TABLE
VHOST_USER_GET_QUEUE_NUM
For above messages, we simply ignore them when they are not sent the first
time.
Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
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: Jason Wang <jasowang@redhat.com>
Tested-by: Marcel Apfelbaum <marcel@redhat.com>
2015-09-23 04:20:00 +00:00
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Multiple queue support
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----------------------
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Multiple queue is treated as a protocol extension, hence the slave has to
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implement protocol features first. The multiple queues feature is supported
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2015-10-09 15:17:29 +00:00
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only when the protocol feature VHOST_USER_PROTOCOL_F_MQ (bit 0) is set.
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vhost-user: add multiple queue support
This patch is initially based a patch from Nikolay Nikolaev.
This patch adds vhost-user multiple queue support, by creating a nc
and vhost_net pair for each queue.
Qemu exits if find that the backend can't support the number of requested
queues (by providing queues=# option). The max number is queried by a
new message, VHOST_USER_GET_QUEUE_NUM, and is sent only when protocol
feature VHOST_USER_PROTOCOL_F_MQ is present first.
The max queue check is done at vhost-user initiation stage. We initiate
one queue first, which, in the meantime, also gets the max_queues the
backend supports.
In older version, it was reported that some messages are sent more times
than necessary. Here we came an agreement with Michael that we could
categorize vhost user messages to 2 types: non-vring specific messages,
which should be sent only once, and vring specific messages, which should
be sent per queue.
Here I introduced a helper function vhost_user_one_time_request(), which
lists following messages as non-vring specific messages:
VHOST_USER_SET_OWNER
VHOST_USER_RESET_DEVICE
VHOST_USER_SET_MEM_TABLE
VHOST_USER_GET_QUEUE_NUM
For above messages, we simply ignore them when they are not sent the first
time.
Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
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: Jason Wang <jasowang@redhat.com>
Tested-by: Marcel Apfelbaum <marcel@redhat.com>
2015-09-23 04:20:00 +00:00
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2018-01-12 14:56:55 +00:00
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The max number of queue pairs the slave supports can be queried with message
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VHOST_USER_GET_QUEUE_NUM. Master should stop when the number of
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vhost-user: add multiple queue support
This patch is initially based a patch from Nikolay Nikolaev.
This patch adds vhost-user multiple queue support, by creating a nc
and vhost_net pair for each queue.
Qemu exits if find that the backend can't support the number of requested
queues (by providing queues=# option). The max number is queried by a
new message, VHOST_USER_GET_QUEUE_NUM, and is sent only when protocol
feature VHOST_USER_PROTOCOL_F_MQ is present first.
The max queue check is done at vhost-user initiation stage. We initiate
one queue first, which, in the meantime, also gets the max_queues the
backend supports.
In older version, it was reported that some messages are sent more times
than necessary. Here we came an agreement with Michael that we could
categorize vhost user messages to 2 types: non-vring specific messages,
which should be sent only once, and vring specific messages, which should
be sent per queue.
Here I introduced a helper function vhost_user_one_time_request(), which
lists following messages as non-vring specific messages:
VHOST_USER_SET_OWNER
VHOST_USER_RESET_DEVICE
VHOST_USER_SET_MEM_TABLE
VHOST_USER_GET_QUEUE_NUM
For above messages, we simply ignore them when they are not sent the first
time.
Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
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: Jason Wang <jasowang@redhat.com>
Tested-by: Marcel Apfelbaum <marcel@redhat.com>
2015-09-23 04:20:00 +00:00
|
|
|
requested queues is bigger than that.
|
|
|
|
|
|
|
|
As all queues share one connection, the master uses a unique index for each
|
2015-09-23 04:20:01 +00:00
|
|
|
queue in the sent message to identify a specified queue. One queue pair
|
|
|
|
is enabled initially. More queues are enabled dynamically, by sending
|
|
|
|
message VHOST_USER_SET_VRING_ENABLE.
|
vhost-user: add multiple queue support
This patch is initially based a patch from Nikolay Nikolaev.
This patch adds vhost-user multiple queue support, by creating a nc
and vhost_net pair for each queue.
Qemu exits if find that the backend can't support the number of requested
queues (by providing queues=# option). The max number is queried by a
new message, VHOST_USER_GET_QUEUE_NUM, and is sent only when protocol
feature VHOST_USER_PROTOCOL_F_MQ is present first.
The max queue check is done at vhost-user initiation stage. We initiate
one queue first, which, in the meantime, also gets the max_queues the
backend supports.
In older version, it was reported that some messages are sent more times
than necessary. Here we came an agreement with Michael that we could
categorize vhost user messages to 2 types: non-vring specific messages,
which should be sent only once, and vring specific messages, which should
be sent per queue.
Here I introduced a helper function vhost_user_one_time_request(), which
lists following messages as non-vring specific messages:
VHOST_USER_SET_OWNER
VHOST_USER_RESET_DEVICE
VHOST_USER_SET_MEM_TABLE
VHOST_USER_GET_QUEUE_NUM
For above messages, we simply ignore them when they are not sent the first
time.
Signed-off-by: Nikolay Nikolaev <n.nikolaev@virtualopensystems.com>
Signed-off-by: Changchun Ouyang <changchun.ouyang@intel.com>
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: Jason Wang <jasowang@redhat.com>
Tested-by: Marcel Apfelbaum <marcel@redhat.com>
2015-09-23 04:20:00 +00:00
|
|
|
|
2015-10-09 15:17:29 +00:00
|
|
|
Migration
|
|
|
|
---------
|
|
|
|
|
|
|
|
During live migration, the master may need to track the modifications
|
|
|
|
the slave makes to the memory mapped regions. The client should mark
|
|
|
|
the dirty pages in a log. Once it complies to this logging, it may
|
|
|
|
declare the VHOST_F_LOG_ALL vhost feature.
|
|
|
|
|
2015-11-15 19:25:11 +00:00
|
|
|
To start/stop logging of data/used ring writes, server may send messages
|
|
|
|
VHOST_USER_SET_FEATURES with VHOST_F_LOG_ALL and VHOST_USER_SET_VRING_ADDR with
|
|
|
|
VHOST_VRING_F_LOG in ring's flags set to 1/0, respectively.
|
|
|
|
|
2015-10-09 15:17:29 +00:00
|
|
|
All the modifications to memory pointed by vring "descriptor" should
|
|
|
|
be marked. Modifications to "used" vring should be marked if
|
2015-11-15 19:25:11 +00:00
|
|
|
VHOST_VRING_F_LOG is part of ring's flags.
|
2015-10-09 15:17:29 +00:00
|
|
|
|
|
|
|
Dirty pages are of size:
|
|
|
|
#define VHOST_LOG_PAGE 0x1000
|
|
|
|
|
|
|
|
The log memory fd is provided in the ancillary data of
|
|
|
|
VHOST_USER_SET_LOG_BASE message when the slave has
|
|
|
|
VHOST_USER_PROTOCOL_F_LOG_SHMFD protocol feature.
|
|
|
|
|
2015-11-15 19:25:11 +00:00
|
|
|
The size of the log is supplied as part of VhostUserMsg
|
|
|
|
which should be large enough to cover all known guest
|
|
|
|
addresses. Log starts at the supplied offset in the
|
|
|
|
supplied file descriptor.
|
|
|
|
The log covers from address 0 to the maximum of guest
|
2015-10-09 15:17:29 +00:00
|
|
|
regions. In pseudo-code, to mark page at "addr" as dirty:
|
|
|
|
|
|
|
|
page = addr / VHOST_LOG_PAGE
|
|
|
|
log[page / 8] |= 1 << page % 8
|
|
|
|
|
2015-11-15 19:25:11 +00:00
|
|
|
Where addr is the guest physical address.
|
|
|
|
|
2015-10-09 15:17:29 +00:00
|
|
|
Use atomic operations, as the log may be concurrently manipulated.
|
|
|
|
|
2015-11-15 19:25:11 +00:00
|
|
|
Note that when logging modifications to the used ring (when VHOST_VRING_F_LOG
|
|
|
|
is set for this ring), log_guest_addr should be used to calculate the log
|
|
|
|
offset: the write to first byte of the used ring is logged at this offset from
|
|
|
|
log start. Also note that this value might be outside the legal guest physical
|
|
|
|
address range (i.e. does not have to be covered by the VhostUserMemory table),
|
|
|
|
but the bit offset of the last byte of the ring must fall within
|
|
|
|
the size supplied by VhostUserLog.
|
|
|
|
|
2015-10-09 15:17:29 +00:00
|
|
|
VHOST_USER_SET_LOG_FD is an optional message with an eventfd in
|
|
|
|
ancillary data, it may be used to inform the master that the log has
|
|
|
|
been modified.
|
|
|
|
|
2015-11-15 19:25:11 +00:00
|
|
|
Once the source has finished migration, rings will be stopped by
|
|
|
|
the source. No further update must be done before rings are
|
|
|
|
restarted.
|
2015-10-09 15:17:29 +00:00
|
|
|
|
2018-03-12 17:21:00 +00:00
|
|
|
In postcopy migration the slave is started before all the memory has been
|
|
|
|
received from the source host, and care must be taken to avoid accessing pages
|
|
|
|
that have yet to be received. The slave opens a 'userfault'-fd and registers
|
|
|
|
the memory with it; this fd is then passed back over to the master.
|
|
|
|
The master services requests on the userfaultfd for pages that are accessed
|
|
|
|
and when the page is available it performs WAKE ioctl's on the userfaultfd
|
|
|
|
to wake the stalled slave. The client indicates support for this via the
|
|
|
|
VHOST_USER_PROTOCOL_F_PAGEFAULT feature.
|
|
|
|
|
2017-12-14 20:22:20 +00:00
|
|
|
Memory access
|
|
|
|
-------------
|
|
|
|
|
|
|
|
The master sends a list of vhost memory regions to the slave using the
|
|
|
|
VHOST_USER_SET_MEM_TABLE message. Each region has two base addresses: a guest
|
|
|
|
address and a user address.
|
|
|
|
|
|
|
|
Messages contain guest addresses and/or user addresses to reference locations
|
|
|
|
within the shared memory. The mapping of these addresses works as follows.
|
|
|
|
|
|
|
|
User addresses map to the vhost memory region containing that user address.
|
|
|
|
|
|
|
|
When the VIRTIO_F_IOMMU_PLATFORM feature has not been negotiated:
|
|
|
|
|
|
|
|
* Guest addresses map to the vhost memory region containing that guest
|
|
|
|
address.
|
|
|
|
|
|
|
|
When the VIRTIO_F_IOMMU_PLATFORM feature has been negotiated:
|
|
|
|
|
|
|
|
* Guest addresses are also called I/O virtual addresses (IOVAs). They are
|
|
|
|
translated to user addresses via the IOTLB.
|
|
|
|
|
|
|
|
* The vhost memory region guest address is not used.
|
|
|
|
|
2017-06-02 10:18:31 +00:00
|
|
|
IOMMU support
|
|
|
|
-------------
|
|
|
|
|
|
|
|
When the VIRTIO_F_IOMMU_PLATFORM feature has been negotiated, the master
|
|
|
|
sends IOTLB entries update & invalidation by sending VHOST_USER_IOTLB_MSG
|
|
|
|
requests to the slave with a struct vhost_iotlb_msg as payload. For update
|
|
|
|
events, the iotlb payload has to be filled with the update message type (2),
|
|
|
|
the I/O virtual address, the size, the user virtual address, and the
|
|
|
|
permissions flags. Addresses and size must be within vhost memory regions set
|
|
|
|
via the VHOST_USER_SET_MEM_TABLE request. For invalidation events, the iotlb
|
|
|
|
payload has to be filled with the invalidation message type (3), the I/O virtual
|
|
|
|
address and the size. On success, the slave is expected to reply with a zero
|
|
|
|
payload, non-zero otherwise.
|
|
|
|
|
|
|
|
The slave relies on the slave communcation channel (see "Slave communication"
|
|
|
|
section below) to send IOTLB miss and access failure events, by sending
|
|
|
|
VHOST_USER_SLAVE_IOTLB_MSG requests to the master with a struct vhost_iotlb_msg
|
|
|
|
as payload. For miss events, the iotlb payload has to be filled with the miss
|
|
|
|
message type (1), the I/O virtual address and the permissions flags. For access
|
|
|
|
failure event, the iotlb payload has to be filled with the access failure
|
|
|
|
message type (4), the I/O virtual address and the permissions flags.
|
|
|
|
For synchronization purpose, the slave may rely on the reply-ack feature,
|
|
|
|
so the master may send a reply when operation is completed if the reply-ack
|
|
|
|
feature is negotiated and slaves requests a reply. For miss events, completed
|
|
|
|
operation means either master sent an update message containing the IOTLB entry
|
|
|
|
containing requested address and permission, or master sent nothing if the IOTLB
|
|
|
|
miss message is invalid (invalid IOVA or permission).
|
|
|
|
|
|
|
|
The master isn't expected to take the initiative to send IOTLB update messages,
|
|
|
|
as the slave sends IOTLB miss messages for the guest virtual memory areas it
|
|
|
|
needs to access.
|
|
|
|
|
2017-06-02 10:18:30 +00:00
|
|
|
Slave communication
|
|
|
|
-------------------
|
|
|
|
|
|
|
|
An optional communication channel is provided if the slave declares
|
|
|
|
VHOST_USER_PROTOCOL_F_SLAVE_REQ protocol feature, to allow the slave to make
|
|
|
|
requests to the master.
|
|
|
|
|
|
|
|
The fd is provided via VHOST_USER_SET_SLAVE_REQ_FD ancillary data.
|
|
|
|
|
|
|
|
A slave may then send VHOST_USER_SLAVE_* messages to the master
|
|
|
|
using this fd communication channel.
|
|
|
|
|
2018-05-24 10:33:32 +00:00
|
|
|
If VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD protocol feature is negotiated,
|
|
|
|
slave can send file descriptors (at most 8 descriptors in each message)
|
|
|
|
to master via ancillary data using this fd communication channel.
|
|
|
|
|
2019-02-28 08:53:49 +00:00
|
|
|
Inflight I/O tracking
|
|
|
|
---------------------
|
|
|
|
|
|
|
|
To support reconnecting after restart or crash, slave may need to resubmit
|
|
|
|
inflight I/Os. If virtqueue is processed in order, we can easily achieve
|
|
|
|
that by getting the inflight descriptors from descriptor table (split virtqueue)
|
|
|
|
or descriptor ring (packed virtqueue). However, it can't work when we process
|
|
|
|
descriptors out-of-order because some entries which store the information of
|
|
|
|
inflight descriptors in available ring (split virtqueue) or descriptor
|
|
|
|
ring (packed virtqueue) might be overrided by new entries. To solve this
|
|
|
|
problem, slave need to allocate an extra buffer to store this information of inflight
|
|
|
|
descriptors and share it with master for persistent. VHOST_USER_GET_INFLIGHT_FD and
|
|
|
|
VHOST_USER_SET_INFLIGHT_FD are used to transfer this buffer between master
|
|
|
|
and slave. And the format of this buffer is described below:
|
|
|
|
|
|
|
|
-------------------------------------------------------
|
|
|
|
| queue0 region | queue1 region | ... | queueN region |
|
|
|
|
-------------------------------------------------------
|
|
|
|
|
|
|
|
N is the number of available virtqueues. Slave could get it from num queues
|
|
|
|
field of VhostUserInflight.
|
|
|
|
|
|
|
|
For split virtqueue, queue region can be implemented as:
|
|
|
|
|
|
|
|
typedef struct DescStateSplit {
|
|
|
|
/* Indicate whether this descriptor is inflight or not.
|
|
|
|
* Only available for head-descriptor. */
|
|
|
|
uint8_t inflight;
|
|
|
|
|
|
|
|
/* Padding */
|
|
|
|
uint8_t padding[5];
|
|
|
|
|
|
|
|
/* Maintain a list for the last batch of used descriptors.
|
|
|
|
* Only available when batching is used for submitting */
|
|
|
|
uint16_t next;
|
|
|
|
|
|
|
|
/* Used to preserve the order of fetching available descriptors.
|
|
|
|
* Only available for head-descriptor. */
|
|
|
|
uint64_t counter;
|
|
|
|
} DescStateSplit;
|
|
|
|
|
|
|
|
typedef struct QueueRegionSplit {
|
|
|
|
/* The feature flags of this region. Now it's initialized to 0. */
|
|
|
|
uint64_t features;
|
|
|
|
|
|
|
|
/* The version of this region. It's 1 currently.
|
|
|
|
* Zero value indicates an uninitialized buffer */
|
|
|
|
uint16_t version;
|
|
|
|
|
|
|
|
/* The size of DescStateSplit array. It's equal to the virtqueue
|
|
|
|
* size. Slave could get it from queue size field of VhostUserInflight. */
|
|
|
|
uint16_t desc_num;
|
|
|
|
|
|
|
|
/* The head of list that track the last batch of used descriptors. */
|
|
|
|
uint16_t last_batch_head;
|
|
|
|
|
|
|
|
/* Store the idx value of used ring */
|
|
|
|
uint16_t used_idx;
|
|
|
|
|
|
|
|
/* Used to track the state of each descriptor in descriptor table */
|
|
|
|
DescStateSplit desc[0];
|
|
|
|
} QueueRegionSplit;
|
|
|
|
|
|
|
|
To track inflight I/O, the queue region should be processed as follows:
|
|
|
|
|
|
|
|
When receiving available buffers from the driver:
|
|
|
|
|
|
|
|
1. Get the next available head-descriptor index from available ring, i
|
|
|
|
|
|
|
|
2. Set desc[i].counter to the value of global counter
|
|
|
|
|
|
|
|
3. Increase global counter by 1
|
|
|
|
|
|
|
|
4. Set desc[i].inflight to 1
|
|
|
|
|
|
|
|
When supplying used buffers to the driver:
|
|
|
|
|
|
|
|
1. Get corresponding used head-descriptor index, i
|
|
|
|
|
|
|
|
2. Set desc[i].next to last_batch_head
|
|
|
|
|
|
|
|
3. Set last_batch_head to i
|
|
|
|
|
|
|
|
4. Steps 1,2,3 may be performed repeatedly if batching is possible
|
|
|
|
|
|
|
|
5. Increase the idx value of used ring by the size of the batch
|
|
|
|
|
|
|
|
6. Set the inflight field of each DescStateSplit entry in the batch to 0
|
|
|
|
|
|
|
|
7. Set used_idx to the idx value of used ring
|
|
|
|
|
|
|
|
When reconnecting:
|
|
|
|
|
|
|
|
1. If the value of used_idx does not match the idx value of used ring (means
|
|
|
|
the inflight field of DescStateSplit entries in last batch may be incorrect),
|
|
|
|
|
|
|
|
(a) Subtract the value of used_idx from the idx value of used ring to get
|
|
|
|
last batch size of DescStateSplit entries
|
|
|
|
|
|
|
|
(b) Set the inflight field of each DescStateSplit entry to 0 in last batch
|
|
|
|
list which starts from last_batch_head
|
|
|
|
|
|
|
|
(c) Set used_idx to the idx value of used ring
|
|
|
|
|
|
|
|
2. Resubmit inflight DescStateSplit entries in order of their counter value
|
|
|
|
|
|
|
|
For packed virtqueue, queue region can be implemented as:
|
|
|
|
|
|
|
|
typedef struct DescStatePacked {
|
|
|
|
/* Indicate whether this descriptor is inflight or not.
|
|
|
|
* Only available for head-descriptor. */
|
|
|
|
uint8_t inflight;
|
|
|
|
|
|
|
|
/* Padding */
|
|
|
|
uint8_t padding;
|
|
|
|
|
|
|
|
/* Link to the next free entry */
|
|
|
|
uint16_t next;
|
|
|
|
|
|
|
|
/* Link to the last entry of descriptor list.
|
|
|
|
* Only available for head-descriptor. */
|
|
|
|
uint16_t last;
|
|
|
|
|
|
|
|
/* The length of descriptor list.
|
|
|
|
* Only available for head-descriptor. */
|
|
|
|
uint16_t num;
|
|
|
|
|
|
|
|
/* Used to preserve the order of fetching available descriptors.
|
|
|
|
* Only available for head-descriptor. */
|
|
|
|
uint64_t counter;
|
|
|
|
|
|
|
|
/* The buffer id */
|
|
|
|
uint16_t id;
|
|
|
|
|
|
|
|
/* The descriptor flags */
|
|
|
|
uint16_t flags;
|
|
|
|
|
|
|
|
/* The buffer length */
|
|
|
|
uint32_t len;
|
|
|
|
|
|
|
|
/* The buffer address */
|
|
|
|
uint64_t addr;
|
|
|
|
} DescStatePacked;
|
|
|
|
|
|
|
|
typedef struct QueueRegionPacked {
|
|
|
|
/* The feature flags of this region. Now it's initialized to 0. */
|
|
|
|
uint64_t features;
|
|
|
|
|
|
|
|
/* The version of this region. It's 1 currently.
|
|
|
|
* Zero value indicates an uninitialized buffer */
|
|
|
|
uint16_t version;
|
|
|
|
|
|
|
|
/* The size of DescStatePacked array. It's equal to the virtqueue
|
|
|
|
* size. Slave could get it from queue size field of VhostUserInflight. */
|
|
|
|
uint16_t desc_num;
|
|
|
|
|
|
|
|
/* The head of free DescStatePacked entry list */
|
|
|
|
uint16_t free_head;
|
|
|
|
|
|
|
|
/* The old head of free DescStatePacked entry list */
|
|
|
|
uint16_t old_free_head;
|
|
|
|
|
|
|
|
/* The used index of descriptor ring */
|
|
|
|
uint16_t used_idx;
|
|
|
|
|
|
|
|
/* The old used index of descriptor ring */
|
|
|
|
uint16_t old_used_idx;
|
|
|
|
|
|
|
|
/* Device ring wrap counter */
|
|
|
|
uint8_t used_wrap_counter;
|
|
|
|
|
|
|
|
/* The old device ring wrap counter */
|
|
|
|
uint8_t old_used_wrap_counter;
|
|
|
|
|
|
|
|
/* Padding */
|
|
|
|
uint8_t padding[7];
|
|
|
|
|
|
|
|
/* Used to track the state of each descriptor fetched from descriptor ring */
|
|
|
|
DescStatePacked desc[0];
|
|
|
|
} QueueRegionPacked;
|
|
|
|
|
|
|
|
To track inflight I/O, the queue region should be processed as follows:
|
|
|
|
|
|
|
|
When receiving available buffers from the driver:
|
|
|
|
|
|
|
|
1. Get the next available descriptor entry from descriptor ring, d
|
|
|
|
|
|
|
|
2. If d is head descriptor,
|
|
|
|
|
|
|
|
(a) Set desc[old_free_head].num to 0
|
|
|
|
|
|
|
|
(b) Set desc[old_free_head].counter to the value of global counter
|
|
|
|
|
|
|
|
(c) Increase global counter by 1
|
|
|
|
|
|
|
|
(d) Set desc[old_free_head].inflight to 1
|
|
|
|
|
|
|
|
3. If d is last descriptor, set desc[old_free_head].last to free_head
|
|
|
|
|
|
|
|
4. Increase desc[old_free_head].num by 1
|
|
|
|
|
|
|
|
5. Set desc[free_head].addr, desc[free_head].len, desc[free_head].flags,
|
|
|
|
desc[free_head].id to d.addr, d.len, d.flags, d.id
|
|
|
|
|
|
|
|
6. Set free_head to desc[free_head].next
|
|
|
|
|
|
|
|
7. If d is last descriptor, set old_free_head to free_head
|
|
|
|
|
|
|
|
When supplying used buffers to the driver:
|
|
|
|
|
|
|
|
1. Get corresponding used head-descriptor entry from descriptor ring, d
|
|
|
|
|
|
|
|
2. Get corresponding DescStatePacked entry, e
|
|
|
|
|
|
|
|
3. Set desc[e.last].next to free_head
|
|
|
|
|
|
|
|
4. Set free_head to the index of e
|
|
|
|
|
|
|
|
5. Steps 1,2,3,4 may be performed repeatedly if batching is possible
|
|
|
|
|
|
|
|
6. Increase used_idx by the size of the batch and update used_wrap_counter if needed
|
|
|
|
|
|
|
|
7. Update d.flags
|
|
|
|
|
|
|
|
8. Set the inflight field of each head DescStatePacked entry in the batch to 0
|
|
|
|
|
|
|
|
9. Set old_free_head, old_used_idx, old_used_wrap_counter to free_head, used_idx,
|
|
|
|
used_wrap_counter
|
|
|
|
|
|
|
|
When reconnecting:
|
|
|
|
|
|
|
|
1. If used_idx does not match old_used_idx (means the inflight field of DescStatePacked
|
|
|
|
entries in last batch may be incorrect),
|
|
|
|
|
|
|
|
(a) Get the next descriptor ring entry through old_used_idx, d
|
|
|
|
|
|
|
|
(b) Use old_used_wrap_counter to calculate the available flags
|
|
|
|
|
|
|
|
(c) If d.flags is not equal to the calculated flags value (means slave has
|
|
|
|
submitted the buffer to guest driver before crash, so it has to commit the
|
|
|
|
in-progres update), set old_free_head, old_used_idx, old_used_wrap_counter
|
|
|
|
to free_head, used_idx, used_wrap_counter
|
|
|
|
|
|
|
|
2. Set free_head, used_idx, used_wrap_counter to old_free_head, old_used_idx,
|
|
|
|
old_used_wrap_counter (roll back any in-progress update)
|
|
|
|
|
|
|
|
3. Set the inflight field of each DescStatePacked entry in free list to 0
|
|
|
|
|
|
|
|
4. Resubmit inflight DescStatePacked entries in order of their counter value
|
|
|
|
|
2015-10-09 15:17:29 +00:00
|
|
|
Protocol features
|
|
|
|
-----------------
|
|
|
|
|
|
|
|
#define VHOST_USER_PROTOCOL_F_MQ 0
|
|
|
|
#define VHOST_USER_PROTOCOL_F_LOG_SHMFD 1
|
2015-10-09 15:17:32 +00:00
|
|
|
#define VHOST_USER_PROTOCOL_F_RARP 2
|
2016-08-05 10:53:50 +00:00
|
|
|
#define VHOST_USER_PROTOCOL_F_REPLY_ACK 3
|
2016-12-10 15:30:36 +00:00
|
|
|
#define VHOST_USER_PROTOCOL_F_MTU 4
|
2017-06-02 10:18:30 +00:00
|
|
|
#define VHOST_USER_PROTOCOL_F_SLAVE_REQ 5
|
2017-06-14 17:44:38 +00:00
|
|
|
#define VHOST_USER_PROTOCOL_F_CROSS_ENDIAN 6
|
2018-03-01 13:46:30 +00:00
|
|
|
#define VHOST_USER_PROTOCOL_F_CRYPTO_SESSION 7
|
2018-03-12 17:21:00 +00:00
|
|
|
#define VHOST_USER_PROTOCOL_F_PAGEFAULT 8
|
2018-03-29 07:52:33 +00:00
|
|
|
#define VHOST_USER_PROTOCOL_F_CONFIG 9
|
2018-05-24 10:33:32 +00:00
|
|
|
#define VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD 10
|
2018-05-24 10:33:34 +00:00
|
|
|
#define VHOST_USER_PROTOCOL_F_HOST_NOTIFIER 11
|
2019-02-28 08:53:49 +00:00
|
|
|
#define VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD 12
|
2015-10-09 15:17:29 +00:00
|
|
|
|
2017-06-02 10:18:30 +00:00
|
|
|
Master message types
|
|
|
|
--------------------
|
2014-06-10 10:02:57 +00:00
|
|
|
|
|
|
|
* VHOST_USER_GET_FEATURES
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 1
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_GET_FEATURES
|
|
|
|
Master payload: N/A
|
|
|
|
Slave payload: u64
|
|
|
|
|
|
|
|
Get from the underlying vhost implementation the features bitmask.
|
2015-09-23 04:19:56 +00:00
|
|
|
Feature bit VHOST_USER_F_PROTOCOL_FEATURES signals slave support for
|
|
|
|
VHOST_USER_GET_PROTOCOL_FEATURES and VHOST_USER_SET_PROTOCOL_FEATURES.
|
2014-06-10 10:02:57 +00:00
|
|
|
|
|
|
|
* VHOST_USER_SET_FEATURES
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 2
|
2014-06-10 10:02:57 +00:00
|
|
|
Ioctl: VHOST_SET_FEATURES
|
|
|
|
Master payload: u64
|
|
|
|
|
|
|
|
Enable features in the underlying vhost implementation using a bitmask.
|
2015-09-23 04:19:56 +00:00
|
|
|
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.
|
2014-06-10 10:02:57 +00:00
|
|
|
|
|
|
|
* VHOST_USER_SET_OWNER
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 3
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_SET_OWNER
|
|
|
|
Master payload: N/A
|
|
|
|
|
|
|
|
Issued when a new connection is established. It sets the current Master
|
|
|
|
as an owner of the session. This can be used on the Slave as a
|
|
|
|
"session start" flag.
|
|
|
|
|
2015-11-11 13:24:37 +00:00
|
|
|
* VHOST_USER_RESET_OWNER
|
2014-06-10 10:02:57 +00:00
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 4
|
2014-06-10 10:02:57 +00:00
|
|
|
Master payload: N/A
|
|
|
|
|
2015-11-23 10:48:52 +00:00
|
|
|
This is no longer used. Used to be sent to request disabling
|
2015-11-15 19:25:11 +00:00
|
|
|
all rings, but some clients interpreted it to also discard
|
|
|
|
connection state (this interpretation would lead to bugs).
|
|
|
|
It is recommended that clients either ignore this message,
|
2015-11-23 10:48:52 +00:00
|
|
|
or use it to disable all rings.
|
2014-06-10 10:02:57 +00:00
|
|
|
|
|
|
|
* VHOST_USER_SET_MEM_TABLE
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 5
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_SET_MEM_TABLE
|
|
|
|
Master payload: memory regions description
|
2018-03-12 17:21:10 +00:00
|
|
|
Slave payload: (postcopy only) memory regions description
|
2014-06-10 10:02:57 +00:00
|
|
|
|
|
|
|
Sets the memory map regions on the slave so it can translate the vring
|
|
|
|
addresses. In the ancillary data there is an array of file descriptors
|
|
|
|
for each memory mapped region. The size and ordering of the fds matches
|
|
|
|
the number and ordering of memory regions.
|
|
|
|
|
2018-03-12 17:21:10 +00:00
|
|
|
When VHOST_USER_POSTCOPY_LISTEN has been received, SET_MEM_TABLE replies with
|
|
|
|
the bases of the memory mapped regions to the master. The slave must
|
|
|
|
have mmap'd the regions but not yet accessed them and should not yet generate
|
|
|
|
a userfault event. Note NEED_REPLY_MASK is not set in this case.
|
|
|
|
QEMU will then reply back to the list of mappings with an empty
|
|
|
|
VHOST_USER_SET_MEM_TABLE as an acknowledgment; only upon reception of this
|
|
|
|
message may the guest start accessing the memory and generating faults.
|
|
|
|
|
2014-06-10 10:02:57 +00:00
|
|
|
* VHOST_USER_SET_LOG_BASE
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 6
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_SET_LOG_BASE
|
|
|
|
Master payload: u64
|
2015-10-09 15:17:29 +00:00
|
|
|
Slave payload: N/A
|
2014-06-10 10:02:57 +00:00
|
|
|
|
2015-11-11 14:26:02 +00:00
|
|
|
Sets logging shared memory space.
|
|
|
|
When slave has VHOST_USER_PROTOCOL_F_LOG_SHMFD protocol
|
|
|
|
feature, the log memory fd is provided in the ancillary data of
|
|
|
|
VHOST_USER_SET_LOG_BASE message, the size and offset of shared
|
|
|
|
memory area provided in the message.
|
|
|
|
|
2014-06-10 10:02:57 +00:00
|
|
|
|
|
|
|
* VHOST_USER_SET_LOG_FD
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 7
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_SET_LOG_FD
|
|
|
|
Master payload: N/A
|
|
|
|
|
|
|
|
Sets the logging file descriptor, which is passed as ancillary data.
|
|
|
|
|
|
|
|
* VHOST_USER_SET_VRING_NUM
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 8
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_SET_VRING_NUM
|
|
|
|
Master payload: vring state description
|
|
|
|
|
2016-04-09 13:50:35 +00:00
|
|
|
Set the size of the queue.
|
2014-06-10 10:02:57 +00:00
|
|
|
|
|
|
|
* VHOST_USER_SET_VRING_ADDR
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 9
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_SET_VRING_ADDR
|
|
|
|
Master payload: vring address description
|
|
|
|
Slave payload: N/A
|
|
|
|
|
|
|
|
Sets the addresses of the different aspects of the vring.
|
|
|
|
|
|
|
|
* VHOST_USER_SET_VRING_BASE
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 10
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_SET_VRING_BASE
|
|
|
|
Master payload: vring state description
|
|
|
|
|
|
|
|
Sets the base offset in the available vring.
|
|
|
|
|
|
|
|
* VHOST_USER_GET_VRING_BASE
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 11
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_USER_GET_VRING_BASE
|
|
|
|
Master payload: vring state description
|
|
|
|
Slave payload: vring state description
|
|
|
|
|
|
|
|
Get the available vring base offset.
|
|
|
|
|
|
|
|
* VHOST_USER_SET_VRING_KICK
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 12
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_SET_VRING_KICK
|
|
|
|
Master payload: u64
|
|
|
|
|
|
|
|
Set the event file descriptor for adding buffers to the vring. It
|
|
|
|
is passed in the ancillary data.
|
|
|
|
Bits (0-7) of the payload contain the vring index. Bit 8 is the
|
|
|
|
invalid FD flag. This flag is set when there is no file descriptor
|
|
|
|
in the ancillary data. This signals that polling should be used
|
|
|
|
instead of waiting for a kick.
|
|
|
|
|
|
|
|
* VHOST_USER_SET_VRING_CALL
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 13
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_SET_VRING_CALL
|
|
|
|
Master payload: u64
|
|
|
|
|
|
|
|
Set the event file descriptor to signal when buffers are used. It
|
|
|
|
is passed in the ancillary data.
|
|
|
|
Bits (0-7) of the payload contain the vring index. Bit 8 is the
|
|
|
|
invalid FD flag. This flag is set when there is no file descriptor
|
|
|
|
in the ancillary data. This signals that polling will be used
|
|
|
|
instead of waiting for the call.
|
|
|
|
|
|
|
|
* VHOST_USER_SET_VRING_ERR
|
|
|
|
|
2014-06-25 12:49:36 +00:00
|
|
|
Id: 14
|
2014-06-10 10:02:57 +00:00
|
|
|
Equivalent ioctl: VHOST_SET_VRING_ERR
|
|
|
|
Master payload: u64
|
|
|
|
|
|
|
|
Set the event file descriptor to signal when error occurs. It
|
|
|
|
is passed in the ancillary data.
|
|
|
|
Bits (0-7) of the payload contain the vring index. Bit 8 is the
|
|
|
|
invalid FD flag. This flag is set when there is no file descriptor
|
|
|
|
in the ancillary data.
|
2015-09-23 04:19:58 +00:00
|
|
|
|
|
|
|
* VHOST_USER_GET_QUEUE_NUM
|
|
|
|
|
|
|
|
Id: 17
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Master payload: N/A
|
|
|
|
Slave payload: u64
|
|
|
|
|
|
|
|
Query how many queues the backend supports. This request should be
|
2016-04-09 13:50:36 +00:00
|
|
|
sent only when VHOST_USER_PROTOCOL_F_MQ is set in queried protocol
|
2015-09-23 04:19:58 +00:00
|
|
|
features by VHOST_USER_GET_PROTOCOL_FEATURES.
|
2015-09-23 04:20:01 +00:00
|
|
|
|
|
|
|
* VHOST_USER_SET_VRING_ENABLE
|
|
|
|
|
|
|
|
Id: 18
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Master payload: vring state description
|
|
|
|
|
|
|
|
Signal slave to enable or disable corresponding vring.
|
2015-11-15 19:25:11 +00:00
|
|
|
This request should be sent only when VHOST_USER_F_PROTOCOL_FEATURES
|
|
|
|
has been negotiated.
|
2015-10-09 15:17:32 +00:00
|
|
|
|
|
|
|
* VHOST_USER_SEND_RARP
|
|
|
|
|
|
|
|
Id: 19
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Master payload: u64
|
|
|
|
|
|
|
|
Ask vhost user backend to broadcast a fake RARP to notify the migration
|
|
|
|
is terminated for guest that does not support GUEST_ANNOUNCE.
|
|
|
|
Only legal if feature bit VHOST_USER_F_PROTOCOL_FEATURES is present in
|
|
|
|
VHOST_USER_GET_FEATURES and protocol feature bit VHOST_USER_PROTOCOL_F_RARP
|
|
|
|
is present in VHOST_USER_GET_PROTOCOL_FEATURES.
|
|
|
|
The first 6 bytes of the payload contain the mac address of the guest to
|
|
|
|
allow the vhost user backend to construct and broadcast the fake RARP.
|
2016-08-05 10:53:50 +00:00
|
|
|
|
2016-12-10 15:30:36 +00:00
|
|
|
* VHOST_USER_NET_SET_MTU
|
|
|
|
|
|
|
|
Id: 20
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Master payload: u64
|
|
|
|
|
|
|
|
Set host MTU value exposed to the guest.
|
|
|
|
This request should be sent only when VIRTIO_NET_F_MTU feature has been
|
|
|
|
successfully negotiated, VHOST_USER_F_PROTOCOL_FEATURES is present in
|
|
|
|
VHOST_USER_GET_FEATURES and protocol feature bit
|
|
|
|
VHOST_USER_PROTOCOL_F_NET_MTU is present in
|
|
|
|
VHOST_USER_GET_PROTOCOL_FEATURES.
|
|
|
|
If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond
|
|
|
|
with zero in case the specified MTU is valid, or non-zero otherwise.
|
|
|
|
|
2017-06-02 10:18:30 +00:00
|
|
|
* VHOST_USER_SET_SLAVE_REQ_FD
|
|
|
|
|
|
|
|
Id: 21
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Master payload: N/A
|
|
|
|
|
|
|
|
Set the socket file descriptor for slave initiated requests. It is passed
|
|
|
|
in the ancillary data.
|
|
|
|
This request should be sent only when VHOST_USER_F_PROTOCOL_FEATURES
|
|
|
|
has been negotiated, and protocol feature bit VHOST_USER_PROTOCOL_F_SLAVE_REQ
|
|
|
|
bit is present in VHOST_USER_GET_PROTOCOL_FEATURES.
|
|
|
|
If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond
|
|
|
|
with zero for success, non-zero otherwise.
|
|
|
|
|
2017-06-02 10:18:31 +00:00
|
|
|
* VHOST_USER_IOTLB_MSG
|
|
|
|
|
|
|
|
Id: 22
|
|
|
|
Equivalent ioctl: N/A (equivalent to VHOST_IOTLB_MSG message type)
|
|
|
|
Master payload: struct vhost_iotlb_msg
|
|
|
|
Slave payload: u64
|
|
|
|
|
|
|
|
Send IOTLB messages with struct vhost_iotlb_msg as payload.
|
|
|
|
Master sends such requests to update and invalidate entries in the device
|
|
|
|
IOTLB. The slave has to acknowledge the request with sending zero as u64
|
|
|
|
payload for success, non-zero otherwise.
|
|
|
|
This request should be send only when VIRTIO_F_IOMMU_PLATFORM feature
|
|
|
|
has been successfully negotiated.
|
|
|
|
|
2017-06-14 17:44:38 +00:00
|
|
|
* VHOST_USER_SET_VRING_ENDIAN
|
|
|
|
|
|
|
|
Id: 23
|
|
|
|
Equivalent ioctl: VHOST_SET_VRING_ENDIAN
|
|
|
|
Master payload: vring state description
|
|
|
|
|
2018-07-13 12:17:27 +00:00
|
|
|
Set the endianness of a VQ for legacy devices. Little-endian is indicated
|
2017-06-14 17:44:38 +00:00
|
|
|
with state.num set to 0 and big-endian is indicated with state.num set
|
|
|
|
to 1. Other values are invalid.
|
|
|
|
This request should be sent only when VHOST_USER_PROTOCOL_F_CROSS_ENDIAN
|
|
|
|
has been negotiated.
|
2018-07-13 12:17:27 +00:00
|
|
|
Backends that negotiated this feature should handle both endiannesses
|
2017-06-14 17:44:38 +00:00
|
|
|
and expect this message once (per VQ) during device configuration
|
|
|
|
(ie. before the master starts the VQ).
|
|
|
|
|
2018-01-04 01:53:31 +00:00
|
|
|
* VHOST_USER_GET_CONFIG
|
|
|
|
|
|
|
|
Id: 24
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Master payload: virtio device config space
|
|
|
|
Slave payload: virtio device config space
|
|
|
|
|
2018-03-29 07:52:33 +00:00
|
|
|
When VHOST_USER_PROTOCOL_F_CONFIG is negotiated, this message is
|
|
|
|
submitted by the vhost-user master to fetch the contents of the virtio
|
2018-01-04 01:53:31 +00:00
|
|
|
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
|
|
|
|
|
2018-03-29 07:52:33 +00:00
|
|
|
When VHOST_USER_PROTOCOL_F_CONFIG is negotiated, this message is
|
|
|
|
submitted by the vhost-user master when the Guest changes the virtio
|
2018-01-04 01:53:31 +00:00
|
|
|
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.
|
|
|
|
|
2018-03-01 13:46:30 +00:00
|
|
|
* VHOST_USER_CREATE_CRYPTO_SESSION
|
|
|
|
|
|
|
|
Id: 26
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Master payload: crypto session description
|
|
|
|
Slave payload: crypto session description
|
|
|
|
|
|
|
|
Create a session for crypto operation. The server side must return the
|
|
|
|
session id, 0 or positive for success, negative for failure.
|
|
|
|
This request should be sent only when VHOST_USER_PROTOCOL_F_CRYPTO_SESSION
|
|
|
|
feature has been successfully negotiated.
|
|
|
|
It's a required feature for crypto devices.
|
|
|
|
|
|
|
|
* VHOST_USER_CLOSE_CRYPTO_SESSION
|
|
|
|
|
|
|
|
Id: 27
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Master payload: u64
|
|
|
|
|
|
|
|
Close a session for crypto operation which was previously
|
|
|
|
created by VHOST_USER_CREATE_CRYPTO_SESSION.
|
|
|
|
This request should be sent only when VHOST_USER_PROTOCOL_F_CRYPTO_SESSION
|
|
|
|
feature has been successfully negotiated.
|
|
|
|
It's a required feature for crypto devices.
|
|
|
|
|
2018-03-12 17:21:01 +00:00
|
|
|
* VHOST_USER_POSTCOPY_ADVISE
|
|
|
|
Id: 28
|
|
|
|
Master payload: N/A
|
|
|
|
Slave payload: userfault fd
|
|
|
|
|
|
|
|
When VHOST_USER_PROTOCOL_F_PAGEFAULT is supported, the
|
|
|
|
master advises slave that a migration with postcopy enabled is underway,
|
|
|
|
the slave must open a userfaultfd for later use.
|
|
|
|
Note that at this stage the migration is still in precopy mode.
|
|
|
|
|
2018-03-12 17:21:06 +00:00
|
|
|
* VHOST_USER_POSTCOPY_LISTEN
|
|
|
|
Id: 29
|
|
|
|
Master payload: N/A
|
|
|
|
|
|
|
|
Master advises slave that a transition to postcopy mode has happened.
|
|
|
|
The slave must ensure that shared memory is registered with userfaultfd
|
|
|
|
to cause faulting of non-present pages.
|
|
|
|
|
|
|
|
This is always sent sometime after a VHOST_USER_POSTCOPY_ADVISE, and
|
|
|
|
thus only when VHOST_USER_PROTOCOL_F_PAGEFAULT is supported.
|
|
|
|
|
2018-03-12 17:21:19 +00:00
|
|
|
* VHOST_USER_POSTCOPY_END
|
|
|
|
Id: 30
|
|
|
|
Slave payload: u64
|
|
|
|
|
|
|
|
Master advises that postcopy migration has now completed. The
|
|
|
|
slave must disable the userfaultfd. The response is an acknowledgement
|
|
|
|
only.
|
|
|
|
When VHOST_USER_PROTOCOL_F_PAGEFAULT is supported, this message
|
|
|
|
is sent at the end of the migration, after VHOST_USER_POSTCOPY_LISTEN
|
|
|
|
was previously sent.
|
|
|
|
The value returned is an error indication; 0 is success.
|
|
|
|
|
2019-02-28 08:53:49 +00:00
|
|
|
* VHOST_USER_GET_INFLIGHT_FD
|
|
|
|
Id: 31
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Master payload: inflight description
|
|
|
|
|
|
|
|
When VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD protocol feature has been
|
|
|
|
successfully negotiated, this message is submitted by master to get
|
|
|
|
a shared buffer from slave. The shared buffer will be used to track
|
|
|
|
inflight I/O by slave. QEMU should retrieve a new one when vm reset.
|
|
|
|
|
|
|
|
* VHOST_USER_SET_INFLIGHT_FD
|
|
|
|
Id: 32
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Master payload: inflight description
|
|
|
|
|
|
|
|
When VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD protocol feature has been
|
|
|
|
successfully negotiated, this message is submitted by master to send
|
|
|
|
the shared inflight buffer back to slave so that slave could get
|
|
|
|
inflight I/O after a crash or restart.
|
|
|
|
|
2017-06-02 10:18:31 +00:00
|
|
|
Slave message types
|
|
|
|
-------------------
|
|
|
|
|
|
|
|
* VHOST_USER_SLAVE_IOTLB_MSG
|
|
|
|
|
|
|
|
Id: 1
|
|
|
|
Equivalent ioctl: N/A (equivalent to VHOST_IOTLB_MSG message type)
|
|
|
|
Slave payload: struct vhost_iotlb_msg
|
|
|
|
Master payload: N/A
|
|
|
|
|
|
|
|
Send IOTLB messages with struct vhost_iotlb_msg as payload.
|
|
|
|
Slave sends such requests to notify of an IOTLB miss, or an IOTLB
|
|
|
|
access failure. 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.
|
|
|
|
This request should be send only when VIRTIO_F_IOMMU_PLATFORM feature
|
|
|
|
has been successfully negotiated.
|
|
|
|
|
2018-01-04 01:53:31 +00:00
|
|
|
* VHOST_USER_SLAVE_CONFIG_CHANGE_MSG
|
|
|
|
|
|
|
|
Id: 2
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Slave payload: N/A
|
|
|
|
Master payload: N/A
|
|
|
|
|
2018-03-29 07:52:33 +00:00
|
|
|
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.
|
2018-01-04 01:53:31 +00:00
|
|
|
|
2018-05-24 10:33:34 +00:00
|
|
|
* VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG
|
|
|
|
|
|
|
|
Id: 3
|
|
|
|
Equivalent ioctl: N/A
|
|
|
|
Slave payload: vring area description
|
|
|
|
Master payload: N/A
|
|
|
|
|
|
|
|
Sets host notifier for a specified queue. The queue index is contained
|
|
|
|
in the u64 field of the vring area description. The host notifier is
|
|
|
|
described by the file descriptor (typically it's a VFIO device fd) which
|
|
|
|
is passed as ancillary data and the size (which is mmap size and should
|
|
|
|
be the same as host page size) and offset (which is mmap offset) carried
|
|
|
|
in the vring area description. QEMU can mmap the file descriptor based
|
|
|
|
on the size and offset to get a memory range. Registering a host notifier
|
|
|
|
means mapping this memory range to the VM as the specified queue's notify
|
|
|
|
MMIO region. Slave sends this request to tell QEMU to de-register the
|
|
|
|
existing notifier if any and register the new notifier if the request is
|
|
|
|
sent with a file descriptor.
|
|
|
|
This request should be sent only when VHOST_USER_PROTOCOL_F_HOST_NOTIFIER
|
|
|
|
protocol feature has been successfully negotiated.
|
|
|
|
|
2016-08-05 10:53:50 +00:00
|
|
|
VHOST_USER_PROTOCOL_F_REPLY_ACK:
|
|
|
|
-------------------------------
|
|
|
|
The original vhost-user specification only demands replies for certain
|
|
|
|
commands. This differs from the vhost protocol implementation where commands
|
|
|
|
are sent over an ioctl() call and block until the client has completed.
|
|
|
|
|
|
|
|
With this protocol extension negotiated, the sender (QEMU) can set the
|
|
|
|
"need_reply" [Bit 3] flag to any command. This indicates that
|
|
|
|
the client MUST respond with a Payload VhostUserMsg indicating success or
|
|
|
|
failure. The payload should be set to zero on success or non-zero on failure,
|
|
|
|
unless the message already has an explicit reply body.
|
|
|
|
|
|
|
|
The response payload gives QEMU a deterministic indication of the result
|
|
|
|
of the command. Today, QEMU is expected to terminate the main vhost-user
|
|
|
|
loop upon receiving such errors. In future, qemu could be taught to be more
|
|
|
|
resilient for selective requests.
|
|
|
|
|
|
|
|
For the message types that already solicit a reply from the client, the
|
|
|
|
presence of VHOST_USER_PROTOCOL_F_REPLY_ACK or need_reply bit being set brings
|
|
|
|
no behavioural change. (See the 'Communication' section for details.)
|
2019-03-08 14:04:44 +00:00
|
|
|
|
|
|
|
Backend program conventions
|
|
|
|
---------------------------
|
|
|
|
|
|
|
|
vhost-user backends can provide various devices & services and may
|
|
|
|
need to be configured manually depending on the use case. However, it
|
|
|
|
is a good idea to follow the conventions listed here when
|
|
|
|
possible. Users, QEMU or libvirt, can then rely on some common
|
|
|
|
behaviour to avoid heterogenous configuration and management of the
|
|
|
|
backend programs and facilitate interoperability.
|
|
|
|
|
|
|
|
Each backend installed on a host system should come with at least one
|
|
|
|
JSON file that conforms to the vhost-user.json schema. Each file
|
|
|
|
informs the management applications about the backend type, and binary
|
|
|
|
location. In addition, it defines rules for management apps for
|
|
|
|
picking the highest priority backend when multiple match the search
|
|
|
|
criteria (see @VhostUserBackend documentation in the schema file).
|
|
|
|
|
|
|
|
If the backend is not capable of enabling a requested feature on the
|
|
|
|
host (such as 3D acceleration with virgl), or the initialization
|
|
|
|
failed, the backend should fail to start early and exit with a status
|
|
|
|
!= 0. It may also print a message to stderr for further details.
|
|
|
|
|
|
|
|
The backend program must not daemonize itself, but it may be
|
|
|
|
daemonized by the management layer. It may also have a restricted
|
|
|
|
access to the system.
|
|
|
|
|
|
|
|
File descriptors 0, 1 and 2 will exist, and have regular
|
|
|
|
stdin/stdout/stderr usage (they may have been redirected to /dev/null
|
|
|
|
by the management layer, or to a log handler).
|
|
|
|
|
|
|
|
The backend program must end (as quickly and cleanly as possible) when
|
|
|
|
the SIGTERM signal is received. Eventually, it may receive SIGKILL by
|
|
|
|
the management layer after a few seconds.
|
|
|
|
|
|
|
|
The following command line options have an expected behaviour. They
|
|
|
|
are mandatory, unless explicitly said differently:
|
|
|
|
|
|
|
|
* --socket-path=PATH
|
|
|
|
|
|
|
|
This option specify the location of the vhost-user Unix domain socket.
|
|
|
|
It is incompatible with --fd.
|
|
|
|
|
|
|
|
* --fd=FDNUM
|
|
|
|
|
|
|
|
When this argument is given, the backend program is started with the
|
|
|
|
vhost-user socket as file descriptor FDNUM. It is incompatible with
|
|
|
|
--socket-path.
|
|
|
|
|
|
|
|
* --print-capabilities
|
|
|
|
|
|
|
|
Output to stdout the backend capabilities in JSON format, and then
|
|
|
|
exit successfully. Other options and arguments should be ignored, and
|
|
|
|
the backend program should not perform its normal function. The
|
|
|
|
capabilities can be reported dynamically depending on the host
|
|
|
|
capabilities.
|
|
|
|
|
|
|
|
The JSON output is described in the vhost-user.json schema, by
|
|
|
|
@VHostUserBackendCapabilities. Example:
|
|
|
|
{
|
|
|
|
"type": "foo",
|
|
|
|
"features": [
|
|
|
|
"feature-a",
|
|
|
|
"feature-b"
|
|
|
|
]
|
|
|
|
}
|
|
|
|
|
|
|
|
vhost-user-input
|
|
|
|
----------------
|
|
|
|
|
|
|
|
Command line options:
|
|
|
|
|
|
|
|
* --evdev-path=PATH (optional)
|
|
|
|
|
|
|
|
Specify the linux input device.
|
|
|
|
|
|
|
|
* --no-grab (optional)
|
|
|
|
|
|
|
|
Do no request exclusive access to the input device.
|
|
|
|
|
|
|
|
vhost-user-gpu
|
|
|
|
--------------
|
|
|
|
|
|
|
|
Command line options:
|
|
|
|
|
|
|
|
* --render-node=PATH (optional)
|
|
|
|
|
|
|
|
Specify the GPU DRM render node.
|
|
|
|
|
|
|
|
* --virgl (optional)
|
|
|
|
|
|
|
|
Enable virgl rendering support.
|