QEMU Guest Agent Protocol Reference

Table of Contents

QEMU Guest Agent protocol reference


1 API Reference

General note concerning the use of guest agent interfaces:

"unsupported" is a higher-level error than the errors that individual commands might document. The caller should always be prepared to receive QERR_UNSUPPORTED, even if the given command doesn’t specify it, or doesn’t document any failure mode at all.

Command: guest-sync-delimited

Echo back a unique integer value, and prepend to response a leading sentinel byte (0xFF) the client can check scan for.

This is used by clients talking to the guest agent over the wire to ensure the stream is in sync and doesn’t contain stale data from previous client. It must be issued upon initial connection, and after any client-side timeouts (including timeouts on receiving a response to this command).

After issuing this request, all guest agent responses should be ignored until the response containing the unique integer value the client passed in is returned. Receival of the 0xFF sentinel byte must be handled as an indication that the client’s lexer/tokenizer/parser state should be flushed/reset in preparation for reliably receiving the subsequent response. As an optimization, clients may opt to ignore all data until a sentinel value is receiving to avoid unnecessary processing of stale data.

Similarly, clients should also precede this request with a 0xFF byte to make sure the guest agent flushes any partially read JSON data from a previous client connection.

'id'

randomly generated 64-bit integer

Returns: The unique integer id passed in by the client

Since: 1.1

Command: guest-sync

Echo back a unique integer value

This is used by clients talking to the guest agent over the wire to ensure the stream is in sync and doesn’t contain stale data from previous client. All guest agent responses should be ignored until the provided unique integer value is returned, and it is up to the client to handle stale whole or partially-delivered JSON text in such a way that this response can be obtained.

In cases where a partial stale response was previously received by the client, this cannot always be done reliably. One particular scenario being if qemu-ga responses are fed character-by-character into a JSON parser. In these situations, using guest-sync-delimited may be optimal.

For clients that fetch responses line by line and convert them to JSON objects, guest-sync should be sufficient, but note that in cases where the channel is dirty some attempts at parsing the response may result in a parser error.

Such clients should also precede this command with a 0xFF byte to make sure the guest agent flushes any partially read JSON data from a previous session.

'id'

randomly generated 64-bit integer

Returns: The unique integer id passed in by the client

Since: 0.15.0

Command: guest-ping

Ping the guest agent, a non-error return implies success

Since: 0.15.0

Command: guest-get-time

Get the information about guest’s System Time relative to the Epoch of 1970-01-01 in UTC.

Returns: Time in nanoseconds.

Since: 1.5

Command: guest-set-time

Set guest time.

When a guest is paused or migrated to a file then loaded from that file, the guest OS has no idea that there was a big gap in the time. Depending on how long the gap was, NTP might not be able to resynchronize the guest.

This command tries to set guest’s System Time to the given value, then sets the Hardware Clock (RTC) to the current System Time. This will make it easier for a guest to resynchronize without waiting for NTP. If no time is specified, then the time to set is read from RTC. However, this may not be supported on all platforms (i.e. Windows). If that’s the case users are advised to always pass a value.

'time' (optional)

time of nanoseconds, relative to the Epoch of 1970-01-01 in UTC.

Returns: Nothing on success.

Since: 1.5

Struct: GuestAgentCommandInfo

Information about guest agent commands.

'name'

name of the command

'enabled'

whether command is currently enabled by guest admin

'success-response'

whether command returns a response on success (since 1.7)

Since: 1.1.0

Struct: GuestAgentInfo

Information about guest agent.

'version'

guest agent version

'supported_commands'

Information about guest agent commands

Since: 0.15.0

Command: guest-info

Get some information about the guest agent.

Returns: GuestAgentInfo

Since: 0.15.0

Command: guest-shutdown

Initiate guest-activated shutdown. Note: this is an asynchronous shutdown request, with no guarantee of successful shutdown.

'mode' (optional)

"halt", "powerdown" (default), or "reboot"

This command does NOT return a response on success. Success condition is indicated by the VM exiting with a zero exit status or, when running with –no-shutdown, by issuing the query-status QMP command to confirm the VM status is "shutdown".

Since: 0.15.0

Command: guest-file-open

Open a file in the guest and retrieve a file handle for it

'path'

Full path to the file in the guest to open.

'mode' (optional)

open mode, as per fopen(), "r" is the default.

Returns: Guest file handle on success.

Since: 0.15.0

Command: guest-file-close

Close an open file in the guest

'handle'

filehandle returned by guest-file-open

Returns: Nothing on success.

Since: 0.15.0

Struct: GuestFileRead

Result of guest agent file-read operation

'count'

number of bytes read (note: count is before base64-encoding is applied)

'buf-b64'

base64-encoded bytes read

'eof'

whether EOF was encountered during read operation.

Since: 0.15.0

Command: guest-file-read

Read from an open file in the guest. Data will be base64-encoded

'handle'

filehandle returned by guest-file-open

'count' (optional)

maximum number of bytes to read (default is 4KB)

Returns: GuestFileRead on success.

Since: 0.15.0

Struct: GuestFileWrite

Result of guest agent file-write operation

'count'

number of bytes written (note: count is actual bytes written, after base64-decoding of provided buffer)

'eof'

whether EOF was encountered during write operation.

Since: 0.15.0

Command: guest-file-write

Write to an open file in the guest.

'handle'

filehandle returned by guest-file-open

'buf-b64'

base64-encoded string representing data to be written

'count' (optional)

bytes to write (actual bytes, after base64-decode), default is all content in buf-b64 buffer after base64 decoding

Returns: GuestFileWrite on success.

Since: 0.15.0

Struct: GuestFileSeek

Result of guest agent file-seek operation

'position'

current file position

'eof'

whether EOF was encountered during file seek

Since: 0.15.0

Enum: QGASeek

Symbolic names for use in guest-file-seek

'set'

Set to the specified offset (same effect as ’whence’:0)

'cur'

Add offset to the current location (same effect as ’whence’:1)

'end'

Add offset to the end of the file (same effect as ’whence’:2)

Since: 2.6

Alternate: GuestFileWhence

Controls the meaning of offset to guest-file-seek.

'value'

Integral value (0 for set, 1 for cur, 2 for end), available for historical reasons, and might differ from the host’s or guest’s SEEK_* values (since: 0.15)

'name'

Symbolic name, and preferred interface

Since: 2.6

Command: guest-file-seek

Seek to a position in the file, as with fseek(), and return the current file position afterward. Also encapsulates ftell()’s functionality, with offset=0 and whence=1.

'handle'

filehandle returned by guest-file-open

'offset'

bytes to skip over in the file stream

'whence'

Symbolic or numeric code for interpreting offset

Returns: GuestFileSeek on success.

Since: 0.15.0

Command: guest-file-flush

Write file changes bufferred in userspace to disk/kernel buffers

'handle'

filehandle returned by guest-file-open

Returns: Nothing on success.

Since: 0.15.0

Enum: GuestFsfreezeStatus

An enumeration of filesystem freeze states

'thawed'

filesystems thawed/unfrozen

'frozen'

all non-network guest filesystems frozen

Since: 0.15.0

Command: guest-fsfreeze-status

Get guest fsfreeze state. error state indicates

Returns: GuestFsfreezeStatus ("thawed", "frozen", etc., as defined below)

Note: This may fail to properly report the current state as a result of some other guest processes having issued an fs freeze/thaw.

Since: 0.15.0

Command: guest-fsfreeze-freeze

Sync and freeze all freezable, local guest filesystems

Returns: Number of file systems currently frozen. On error, all filesystems will be thawed.

Since: 0.15.0

Command: guest-fsfreeze-freeze-list

Sync and freeze specified guest filesystems

'mountpoints' (optional)

an array of mountpoints of filesystems to be frozen. If omitted, every mounted filesystem is frozen.

Returns: Number of file systems currently frozen. On error, all filesystems will be thawed.

Since: 2.2

Command: guest-fsfreeze-thaw

Unfreeze all frozen guest filesystems

Returns: Number of file systems thawed by this call

Note: if return value does not match the previous call to guest-fsfreeze-freeze, this likely means some freezable filesystems were unfrozen before this call, and that the filesystem state may have changed before issuing this command.

Since: 0.15.0

Struct: GuestFilesystemTrimResult
'path'

path that was trimmed

'error' (optional)

an error message when trim failed

'trimmed' (optional)

bytes trimmed for this path

'minimum' (optional)

reported effective minimum for this path

Since: 2.4

Struct: GuestFilesystemTrimResponse
'paths'

list of GuestFilesystemTrimResult per path that was trimmed

Since: 2.4

Command: guest-fstrim

Discard (or "trim") blocks which are not in use by the filesystem.

'minimum' (optional)

Minimum contiguous free range to discard, in bytes. Free ranges smaller than this may be ignored (this is a hint and the guest may not respect it). By increasing this value, the fstrim operation will complete more quickly for filesystems with badly fragmented free space, although not all blocks will be discarded. The default value is zero, meaning "discard every free block".

Returns: A GuestFilesystemTrimResponse which contains the status of all trimmed paths. (since 2.4)

Since: 1.2

Command: guest-suspend-disk

Suspend guest to disk.

This command tries to execute the scripts provided by the pm-utils package. If it’s not available, the suspend operation will be performed by manually writing to a sysfs file.

For the best results it’s strongly recommended to have the pm-utils package installed in the guest.

This command does NOT return a response on success. There is a high chance the command succeeded if the VM exits with a zero exit status or, when running with –no-shutdown, by issuing the query-status QMP command to to confirm the VM status is "shutdown". However, the VM could also exit (or set its status to "shutdown") due to other reasons.

The following errors may be returned: If suspend to disk is not supported, Unsupported

Notes: It’s strongly recommended to issue the guest-sync command before sending commands when the guest resumes

Since: 1.1

Command: guest-suspend-ram

Suspend guest to ram.

This command tries to execute the scripts provided by the pm-utils package. If it’s not available, the suspend operation will be performed by manually writing to a sysfs file.

For the best results it’s strongly recommended to have the pm-utils package installed in the guest.

IMPORTANT: guest-suspend-ram requires QEMU to support the ’system_wakeup’ command. Thus, it’s required to query QEMU for the presence of the ’system_wakeup’ command before issuing guest-suspend-ram.

This command does NOT return a response on success. There are two options to check for success:

  1. Wait for the SUSPEND QMP event from QEMU
  2. Issue the query-status QMP command to confirm the VM status is "suspended"

The following errors may be returned: If suspend to ram is not supported, Unsupported

Notes: It’s strongly recommended to issue the guest-sync command before sending commands when the guest resumes

Since: 1.1

Command: guest-suspend-hybrid

Save guest state to disk and suspend to ram.

This command requires the pm-utils package to be installed in the guest.

IMPORTANT: guest-suspend-hybrid requires QEMU to support the ’system_wakeup’ command. Thus, it’s required to query QEMU for the presence of the ’system_wakeup’ command before issuing guest-suspend-hybrid.

This command does NOT return a response on success. There are two options to check for success:

  1. Wait for the SUSPEND QMP event from QEMU
  2. Issue the query-status QMP command to confirm the VM status is "suspended"

The following errors may be returned: If hybrid suspend is not supported, Unsupported

Notes: It’s strongly recommended to issue the guest-sync command before sending commands when the guest resumes

Since: 1.1

Enum: GuestIpAddressType

An enumeration of supported IP address types

'ipv4'

IP version 4

'ipv6'

IP version 6

Since: 1.1

Struct: GuestIpAddress
'ip-address'

IP address

'ip-address-type'

Type of ip-address (e.g. ipv4, ipv6)

'prefix'

Network prefix length of ip-address

Since: 1.1

Struct: GuestNetworkInterface
'name'

The name of interface for which info are being delivered

'hardware-address' (optional)

Hardware address of name

'ip-addresses' (optional)

List of addresses assigned to name

Since: 1.1

Command: guest-network-get-interfaces

Get list of guest IP addresses, MAC addresses and netmasks.

Returns: List of GuestNetworkInfo on success.

Since: 1.1

Struct: GuestLogicalProcessor
'logical-id'

Arbitrary guest-specific unique identifier of the VCPU.

'online'

Whether the VCPU is enabled.

'can-offline' (optional)

Whether offlining the VCPU is possible. This member is always filled in by the guest agent when the structure is returned, and always ignored on input (hence it can be omitted then).

Since: 1.5

Command: guest-get-vcpus

Retrieve the list of the guest’s logical processors.

This is a read-only operation.

Returns: The list of all VCPUs the guest knows about. Each VCPU is put on the list exactly once, but their order is unspecified.

Since: 1.5

Command: guest-set-vcpus

Attempt to reconfigure (currently: enable/disable) logical processors inside the guest.

The input list is processed node by node in order. In each node logical-id is used to look up the guest VCPU, for which online specifies the requested state. The set of distinct logical-id’s is only required to be a subset of the guest-supported identifiers. There’s no restriction on list length or on repeating the same logical-id (with possibly different online field). Preferably the input list should describe a modified subset of guest-get-vcpus’ return value.

Returns: The length of the initial sublist that has been successfully processed. The guest agent maximizes this value. Possible cases:

  • - 0: if the vcpus list was empty on input. Guest state has not been changed. Otherwise,
  • - Error: processing the first node of vcpus failed for the reason returned. Guest state has not been changed. Otherwise,
  • - < length(vcpus): more than zero initial nodes have been processed, but not the entire vcpus list. Guest state has changed accordingly. To retrieve the error (assuming it persists), repeat the call with the successfully processed initial sublist removed. Otherwise,
  • - length(vcpus): call successful.

Since: 1.5

Enum: GuestDiskBusType

An enumeration of bus type of disks

'ide'

IDE disks

'fdc'

floppy disks

'scsi'

SCSI disks

'virtio'

virtio disks

'xen'

Xen disks

'usb'

USB disks

'uml'

UML disks

'sata'

SATA disks

'sd'

SD cards

'unknown'

Unknown bus type

'ieee1394'

Win IEEE 1394 bus type

'ssa'

Win SSA bus type

'fibre'

Win fiber channel bus type

'raid'

Win RAID bus type

'iscsi'

Win iScsi bus type

'sas'

Win serial-attaches SCSI bus type

'mmc'

Win multimedia card (MMC) bus type

'virtual'

Win virtual bus type file-backed virtual: Win file-backed bus type

'file-backed-virtual'

Since: 2.2; ’Unknown’ and all entries below since 2.4

Struct: GuestPCIAddress
'domain'

domain id

'bus'

bus id

'slot'

slot id

'function'

function id

Since: 2.2

Struct: GuestDiskAddress
'pci-controller'

controller’s PCI address

'bus-type'

bus type

'bus'

bus id

'target'

target id

'unit'

unit id

Since: 2.2

Struct: GuestFilesystemInfo
'name'

disk name

'mountpoint'

mount point path

'type'

file system type string

'disk'

an array of disk hardware information that the volume lies on, which may be empty if the disk type is not supported

Since: 2.2

Command: guest-get-fsinfo

Returns: The list of filesystems information mounted in the guest. The returned mountpoints may be specified to guest-fsfreeze-freeze-list. Network filesystems (such as CIFS and NFS) are not listed.

Since: 2.2

Command: guest-set-user-password
'username'

the user account whose password to change

'password'

the new password entry string, base64 encoded

'crypted'

true if password is already crypt()d, false if raw

If the crypted flag is true, it is the caller’s responsibility to ensure the correct crypt() encryption scheme is used. This command does not attempt to interpret or report on the encryption scheme. Refer to the documentation of the guest operating system in question to determine what is supported.

Not all guest operating systems will support use of the crypted flag, as they may require the clear-text password

The password parameter must always be base64 encoded before transmission, even if already crypt()d, to ensure it is 8-bit safe when passed as JSON.

Returns: Nothing on success.

Since: 2.3

Struct: GuestMemoryBlock
'phys-index'

Arbitrary guest-specific unique identifier of the MEMORY BLOCK.

'online'

Whether the MEMORY BLOCK is enabled in guest.

'can-offline' (optional)

Whether offlining the MEMORY BLOCK is possible. This member is always filled in by the guest agent when the structure is returned, and always ignored on input (hence it can be omitted then).

Since: 2.3

Command: guest-get-memory-blocks

Retrieve the list of the guest’s memory blocks.

This is a read-only operation.

Returns: The list of all memory blocks the guest knows about. Each memory block is put on the list exactly once, but their order is unspecified.

Since: 2.3

Enum: GuestMemoryBlockResponseType

An enumeration of memory block operation result.

'success'

the operation of online/offline memory block is successful.

'not-found'

can’t find the corresponding memoryXXX directory in sysfs.

'operation-not-supported'

for some old kernels, it does not support online or offline memory block.

'operation-failed'

the operation of online/offline memory block fails, because of some errors happen.

Since: 2.3

Struct: GuestMemoryBlockResponse
'phys-index'

same with the ’phys-index’ member of GuestMemoryBlock.

'response'

the result of memory block operation.

'error-code' (optional)

the error number. When memory block operation fails, we assign the value of ’errno’ to this member, it indicates what goes wrong. When the operation succeeds, it will be omitted.

Since: 2.3

Command: guest-set-memory-blocks

Attempt to reconfigure (currently: enable/disable) state of memory blocks inside the guest.

The input list is processed node by node in order. In each node phys-index is used to look up the guest MEMORY BLOCK, for which online specifies the requested state. The set of distinct phys-index’s is only required to be a subset of the guest-supported identifiers. There’s no restriction on list length or on repeating the same phys-index (with possibly different online field). Preferably the input list should describe a modified subset of guest-get-memory-blocks’ return value.

Returns: The operation results, it is a list of GuestMemoryBlockResponse, which is corresponding to the input list.

Note: it will return NULL if the mem-blks list was empty on input, or there is an error, and in this case, guest state will not be changed.

Since: 2.3

Struct: GuestMemoryBlockInfo
'size'

the size (in bytes) of the guest memory blocks, which are the minimal units of memory block online/offline operations (also called Logical Memory Hotplug).

Since: 2.3

Command: guest-get-memory-block-info

Get information relating to guest memory blocks.

Returns: GuestMemoryBlockInfo

Since: 2.3

Struct: GuestExecStatus
'exited'

true if process has already terminated.

'exitcode' (optional)

process exit code if it was normally terminated.

'signal' (optional)

signal number (linux) or unhandled exception code (windows) if the process was abnormally terminated.

'out-data' (optional)

base64-encoded stdout of the process

'err-data' (optional)

base64-encoded stderr of the process Note: out-data and err-data are present only if ’capture-output’ was specified for ’guest-exec’

'out-truncated' (optional)

true if stdout was not fully captured due to size limitation.

'err-truncated' (optional)

true if stderr was not fully captured due to size limitation.

Since: 2.5

Command: guest-exec-status

Check status of process associated with PID retrieved via guest-exec. Reap the process and associated metadata if it has exited.

'pid'

pid returned from guest-exec

Returns: GuestExecStatus on success.

Since: 2.5

Struct: GuestExec
'pid'

pid of child process in guest OS

Since: 2.5

Command: guest-exec

Execute a command in the guest

'path'

path or executable name to execute

'arg' (optional)

argument list to pass to executable

'env' (optional)

environment variables to pass to executable

'input-data' (optional)

data to be passed to process stdin (base64 encoded)

'capture-output' (optional)

bool flag to enable capture of stdout/stderr of running process. defaults to false.

Returns: PID on success.

Since: 2.5


Commands and Events Index

Jump to:   G  
Index Entry  Section

G
guest-exec: API Reference
guest-exec-status: API Reference
guest-file-close: API Reference
guest-file-flush: API Reference
guest-file-open: API Reference
guest-file-read: API Reference
guest-file-seek: API Reference
guest-file-write: API Reference
guest-fsfreeze-freeze: API Reference
guest-fsfreeze-freeze-list: API Reference
guest-fsfreeze-status: API Reference
guest-fsfreeze-thaw: API Reference
guest-fstrim: API Reference
guest-get-fsinfo: API Reference
guest-get-memory-block-info: API Reference
guest-get-memory-blocks: API Reference
guest-get-time: API Reference
guest-get-vcpus: API Reference
guest-info: API Reference
guest-network-get-interfaces: API Reference
guest-ping: API Reference
guest-set-memory-blocks: API Reference
guest-set-time: API Reference
guest-set-user-password: API Reference
guest-set-vcpus: API Reference
guest-shutdown: API Reference
guest-suspend-disk: API Reference
guest-suspend-hybrid: API Reference
guest-suspend-ram: API Reference
guest-sync: API Reference
guest-sync-delimited: API Reference

Jump to:   G  

Data Types Index

Jump to:   G   Q  
Index Entry  Section

G
GuestAgentCommandInfo: API Reference
GuestAgentInfo: API Reference
GuestDiskAddress: API Reference
GuestDiskBusType: API Reference
GuestExec: API Reference
GuestExecStatus: API Reference
GuestFileRead: API Reference
GuestFileSeek: API Reference
GuestFilesystemInfo: API Reference
GuestFilesystemTrimResponse: API Reference
GuestFilesystemTrimResult: API Reference
GuestFileWhence: API Reference
GuestFileWrite: API Reference
GuestFsfreezeStatus: API Reference
GuestIpAddress: API Reference
GuestIpAddressType: API Reference
GuestLogicalProcessor: API Reference
GuestMemoryBlock: API Reference
GuestMemoryBlockInfo: API Reference
GuestMemoryBlockResponse: API Reference
GuestMemoryBlockResponseType: API Reference
GuestNetworkInterface: API Reference
GuestPCIAddress: API Reference

Q
QGASeek: API Reference

Jump to:   G   Q