Orange Pi5 kernel

^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   1) .. SPDX-License-Identifier: GPL-2.0+
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   2) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   3) ======================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   4) IBM Virtual Management Channel Kernel Driver (IBMVMC)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   5) ======================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   6) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   7) :Authors:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   8) 	Dave Engebretsen <engebret@us.ibm.com>,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300   9) 	Adam Reznechek <adreznec@linux.vnet.ibm.com>,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  10) 	Steven Royer <seroyer@linux.vnet.ibm.com>,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  11) 	Bryant G. Ly <bryantly@linux.vnet.ibm.com>,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  12) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  13) Introduction
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  14) ============
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  15) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  16) Note: Knowledge of virtualization technology is required to understand
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  17) this document.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  18) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  19) A good reference document would be:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  20) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  21) https://openpowerfoundation.org/wp-content/uploads/2016/05/LoPAPR_DRAFT_v11_24March2016_cmt1.pdf
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  22) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  23) The Virtual Management Channel (VMC) is a logical device which provides an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  24) interface between the hypervisor and a management partition. This interface
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  25) is like a message passing interface. This management partition is intended
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  26) to provide an alternative to systems that use a Hardware Management
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  27) Console (HMC) - based system management.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  28) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  29) The primary hardware management solution that is developed by IBM relies
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  30) on an appliance server named the Hardware Management Console (HMC),
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  31) packaged as an external tower or rack-mounted personal computer. In a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  32) Power Systems environment, a single HMC can manage multiple POWER
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  33) processor-based systems.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  34) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  35) Management Application
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  36) ----------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  37) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  38) In the management partition, a management application exists which enables
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  39) a system administrator to configure the system’s partitioning
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  40) characteristics via a command line interface (CLI) or Representational
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  41) State Transfer Application (REST API's).
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  42) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  43) The management application runs on a Linux logical partition on a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  44) POWER8 or newer processor-based server that is virtualized by PowerVM.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  45) System configuration, maintenance, and control functions which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  46) traditionally require an HMC can be implemented in the management
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  47) application using a combination of HMC to hypervisor interfaces and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  48) existing operating system methods. This tool provides a subset of the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  49) functions implemented by the HMC and enables basic partition configuration.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  50) The set of HMC to hypervisor messages supported by the management
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  51) application component are passed to the hypervisor over a VMC interface,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  52) which is defined below.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  53) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  54) The VMC enables the management partition to provide basic partitioning
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  55) functions:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  56) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  57) - Logical Partitioning Configuration
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  58) - Start, and stop actions for individual partitions
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  59) - Display of partition status
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  60) - Management of virtual Ethernet
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  61) - Management of virtual Storage
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  62) - Basic system management
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  63) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  64) Virtual Management Channel (VMC)
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  65) --------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  66) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  67) A logical device, called the Virtual Management Channel (VMC), is defined
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  68) for communicating between the management application and the hypervisor. It
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  69) basically creates the pipes that enable virtualization management
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  70) software. This device is presented to a designated management partition as
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  71) a virtual device.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  72) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  73) This communication device uses Command/Response Queue (CRQ) and the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  74) Remote Direct Memory Access (RDMA) interfaces. A three-way handshake is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  75) defined that must take place to establish that both the hypervisor and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  76) management partition sides of the channel are running prior to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  77) sending/receiving any of the protocol messages.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  78) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  79) This driver also utilizes Transport Event CRQs. CRQ messages are sent
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  80) when the hypervisor detects one of the peer partitions has abnormally
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  81) terminated, or one side has called H_FREE_CRQ to close their CRQ.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  82) Two new classes of CRQ messages are introduced for the VMC device. VMC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  83) Administrative messages are used for each partition using the VMC to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  84) communicate capabilities to their partner. HMC Interface messages are used
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  85) for the actual flow of HMC messages between the management partition and
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  86) the hypervisor. As most HMC messages far exceed the size of a CRQ buffer,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  87) a virtual DMA (RMDA) of the HMC message data is done prior to each HMC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  88) Interface CRQ message. Only the management partition drives RDMA
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  89) operations; hypervisors never directly cause the movement of message data.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  90) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  91) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  92) Terminology
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  93) -----------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  94) RDMA
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  95)         Remote Direct Memory Access is DMA transfer from the server to its
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  96)         client or from the server to its partner partition. DMA refers
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  97)         to both physical I/O to and from memory operations and to memory
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  98)         to memory move operations.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300  99) CRQ
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 100)         Command/Response Queue a facility which is used to communicate
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 101)         between partner partitions. Transport events which are signaled
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 102)         from the hypervisor to partition are also reported in this queue.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 103) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 104) Example Management Partition VMC Driver Interface
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 105) =================================================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 106) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 107) This section provides an example for the management application
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 108) implementation where a device driver is used to interface to the VMC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 109) device. This driver consists of a new device, for example /dev/ibmvmc,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 110) which provides interfaces to open, close, read, write, and perform
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 111) ioctl’s against the VMC device.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 112) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 113) VMC Interface Initialization
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 114) ----------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 115) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 116) The device driver is responsible for initializing the VMC when the driver
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 117) is loaded. It first creates and initializes the CRQ. Next, an exchange of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 118) VMC capabilities is performed to indicate the code version and number of
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 119) resources available in both the management partition and the hypervisor.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 120) Finally, the hypervisor requests that the management partition create an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 121) initial pool of VMC buffers, one buffer for each possible HMC connection,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 122) which will be used for management application  session initialization.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 123) Prior to completion of this initialization sequence, the device returns
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 124) EBUSY to open() calls. EIO is returned for all open() failures.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 125) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 126) ::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 127) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 128)         Management Partition		Hypervisor
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 129)                         CRQ INIT
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 130)         ---------------------------------------->
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 131)         	   CRQ INIT COMPLETE
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 132)         <----------------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 133)         	      CAPABILITIES
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 134)         ---------------------------------------->
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 135)         	 CAPABILITIES RESPONSE
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 136)         <----------------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 137)               ADD BUFFER (HMC IDX=0,1,..)         _
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 138)         <----------------------------------------  |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 139)         	  ADD BUFFER RESPONSE              | - Perform # HMCs Iterations
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 140)         ----------------------------------------> -
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 141) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 142) VMC Interface Open
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 143) ------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 144) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 145) After the basic VMC channel has been initialized, an HMC session level
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 146) connection can be established. The application layer performs an open() to
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 147) the VMC device and executes an ioctl() against it, indicating the HMC ID
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 148) (32 bytes of data) for this session. If the VMC device is in an invalid
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 149) state, EIO will be returned for the ioctl(). The device driver creates a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 150) new HMC session value (ranging from 1 to 255) and HMC index value (starting
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 151) at index 0 and ranging to 254) for this HMC ID. The driver then does an
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 152) RDMA of the HMC ID to the hypervisor, and then sends an Interface Open
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 153) message to the hypervisor to establish the session over the VMC. After the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 154) hypervisor receives this information, it sends Add Buffer messages to the
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 155) management partition to seed an initial pool of buffers for the new HMC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 156) connection. Finally, the hypervisor sends an Interface Open Response
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 157) message, to indicate that it is ready for normal runtime messaging. The
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 158) following illustrates this VMC flow:
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 159) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 160) ::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 161) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 162)         Management Partition             Hypervisor
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 163)         	      RDMA HMC ID
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 164)         ---------------------------------------->
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 165)         	    Interface Open
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 166)         ---------------------------------------->
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 167)         	      Add Buffer                  _
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 168)         <----------------------------------------  |
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 169)         	  Add Buffer Response              | - Perform N Iterations
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 170)         ----------------------------------------> -
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 171)         	Interface Open Response
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 172)         <----------------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 173) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 174) VMC Interface Runtime
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 175) ---------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 176) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 177) During normal runtime, the management application and the hypervisor
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 178) exchange HMC messages via the Signal VMC message and RDMA operations. When
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 179) sending data to the hypervisor, the management application performs a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 180) write() to the VMC device, and the driver RDMA’s the data to the hypervisor
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 181) and then sends a Signal Message. If a write() is attempted before VMC
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 182) device buffers have been made available by the hypervisor, or no buffers
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 183) are currently available, EBUSY is returned in response to the write(). A
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 184) write() will return EIO for all other errors, such as an invalid device
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 185) state. When the hypervisor sends a message to the management, the data is
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 186) put into a VMC buffer and an Signal Message is sent to the VMC driver in
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 187) the management partition. The driver RDMA’s the buffer into the partition
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 188) and passes the data up to the appropriate management application via a
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 189) read() to the VMC device. The read() request blocks if there is no buffer
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 190) available to read. The management application may use select() to wait for
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 191) the VMC device to become ready with data to read.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 192) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 193) ::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 194) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 195)         Management Partition             Hypervisor
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 196)         		MSG RDMA
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 197)         ---------------------------------------->
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 198)         		SIGNAL MSG
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 199)         ---------------------------------------->
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 200)         		SIGNAL MSG
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 201)         <----------------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 202)         		MSG RDMA
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 203)         <----------------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 204) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 205) VMC Interface Close
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 206) -------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 207) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 208) HMC session level connections are closed by the management partition when
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 209) the application layer performs a close() against the device. This action
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 210) results in an Interface Close message flowing to the hypervisor, which
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 211) causes the session to be terminated. The device driver must free any
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 212) storage allocated for buffers for this HMC connection.
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 213) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 214) ::
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 215) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 216)         Management Partition             Hypervisor
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 217)         	     INTERFACE CLOSE
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 218)         ---------------------------------------->
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 219)                 INTERFACE CLOSE RESPONSE
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 220)         <----------------------------------------
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 221) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 222) Additional Information
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 223) ======================
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 224) 
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 225) For more information on the documentation for CRQ Messages, VMC Messages,
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 226) HMC interface Buffers, and signal messages please refer to the Linux on
^8f3ce5b39 (kx 2023-10-28 12:00:06 +0300 227) Power Architecture Platform Reference. Section F.