misc: IBM Virtual Management Channel Driver (VMC)

This driver is a logical device which provides an
interface between the hypervisor and a management
partition. This interface is like a message
passing interface. This management partition
is intended to provide an alternative to HMC-based
system management.

VMC enables the Management LPAR to provide basic
logical partition functions:
- Logical Partition Configuration
- Boot, start, and stop actions for individual
  partitions
- Display of partition status
- Management of virtual Ethernet
- Management of virtual Storage
- Basic system management

This driver is to be used for the POWER Virtual
Management Channel Virtual Adapter on the PowerPC
platform. It provides a character device which
allows for both request/response and async message
support through the /dev/ibmvmc node.
Signed-off-by: NBryant G. Ly <bryantly@linux.vnet.ibm.com>
Reviewed-by: NSteven Royer <seroyer@linux.vnet.ibm.com>
Reviewed-by: NAdam Reznechek <adreznec@linux.vnet.ibm.com>
Reviewed-by: NRandy Dunlap <rdunlap@infradead.org>
Tested-by: NTaylor Jakobson <tjakobs@us.ibm.com>
Tested-by: NBrad Warrum <bwarrum@us.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ioctl/ioctl-number.txt

@@ -327,6 +327,7 @@ Code  Seq#(hex)	Include File		Comments
 0xCA	80-BF	uapi/scsi/cxlflash_ioctl.h
 0xCB	00-1F	CBM serial IEC bus	in development:
 					<mailto:michael.klein@puffin.lb.shuttle.de>
+0xCC	00-0F	drivers/misc/ibmvmc.h    pseries VMC driver
 0xCD	01	linux/reiserfs_fs.h
 0xCF	02	fs/cifs/ioctl.c
 0xDB	00-0F	drivers/char/mwave/mwavepub.h

Documentation/misc-devices/ibmvmc.rst

+.. SPDX-License-Identifier: GPL-2.0+
+======================================================
+IBM Virtual Management Channel Kernel Driver (IBMVMC)
+======================================================
+
+:Authors:
+	Dave Engebretsen <engebret@us.ibm.com>,
+	Adam Reznechek <adreznec@linux.vnet.ibm.com>,
+	Steven Royer <seroyer@linux.vnet.ibm.com>,
+	Bryant G. Ly <bryantly@linux.vnet.ibm.com>,
+
+Introduction
+============
+
+Note: Knowledge of virtualization technology is required to understand
+this document.
+
+A good reference document would be:
+
+https://openpowerfoundation.org/wp-content/uploads/2016/05/LoPAPR_DRAFT_v11_24March2016_cmt1.pdf
+
+The Virtual Management Channel (VMC) is a logical device which provides an
+interface between the hypervisor and a management partition. This interface
+is like a message passing interface. This management partition is intended
+to provide an alternative to systems that use a Hardware Management
+Console (HMC) - based system management.
+
+The primary hardware management solution that is developed by IBM relies
+on an appliance server named the Hardware Management Console (HMC),
+packaged as an external tower or rack-mounted personal computer. In a
+Power Systems environment, a single HMC can manage multiple POWER
+processor-based systems.
+
+Management Application
+----------------------
+
+In the management partition, a management application exists which enables
+a system administrator to configure the system’s partitioning
+characteristics via a command line interface (CLI) or Representational
+State Transfer Application (REST API's).
+
+The management application runs on a Linux logical partition on a
+POWER8 or newer processor-based server that is virtualized by PowerVM.
+System configuration, maintenance, and control functions which
+traditionally require an HMC can be implemented in the management
+application using a combination of HMC to hypervisor interfaces and
+existing operating system methods. This tool provides a subset of the
+functions implemented by the HMC and enables basic partition configuration.
+The set of HMC to hypervisor messages supported by the management
+application component are passed to the hypervisor over a VMC interface,
+which is defined below.
+
+The VMC enables the management partition to provide basic partitioning
+functions:
+
+- Logical Partitioning Configuration
+- Start, and stop actions for individual partitions
+- Display of partition status
+- Management of virtual Ethernet
+- Management of virtual Storage
+- Basic system management
+
+Virtual Management Channel (VMC)
+--------------------------------
+
+A logical device, called the Virtual Management Channel (VMC), is defined
+for communicating between the management application and the hypervisor. It
+basically creates the pipes that enable virtualization management
+software. This device is presented to a designated management partition as
+a virtual device.
+
+This communication device uses Command/Response Queue (CRQ) and the
+Remote Direct Memory Access (RDMA) interfaces. A three-way handshake is
+defined that must take place to establish that both the hypervisor and
+management partition sides of the channel are running prior to
+sending/receiving any of the protocol messages.
+
+This driver also utilizes Transport Event CRQs. CRQ messages are sent
+when the hypervisor detects one of the peer partitions has abnormally
+terminated, or one side has called H_FREE_CRQ to close their CRQ.
+Two new classes of CRQ messages are introduced for the VMC device. VMC
+Administrative messages are used for each partition using the VMC to
+communicate capabilities to their partner. HMC Interface messages are used
+for the actual flow of HMC messages between the management partition and
+the hypervisor. As most HMC messages far exceed the size of a CRQ buffer,
+a virtual DMA (RMDA) of the HMC message data is done prior to each HMC
+Interface CRQ message. Only the management partition drives RDMA
+operations; hypervisors never directly cause the movement of message data.
+
+
+Terminology
+-----------
+RDMA
+        Remote Direct Memory Access is DMA transfer from the server to its
+        client or from the server to its partner partition. DMA refers
+        to both physical I/O to and from memory operations and to memory
+        to memory move operations.
+CRQ
+        Command/Response Queue a facility which is used to communicate
+        between partner partitions. Transport events which are signaled
+        from the hypervisor to partition are also reported in this queue.
+
+Example Management Partition VMC Driver Interface
+=================================================
+
+This section provides an example for the management application
+implementation where a device driver is used to interface to the VMC
+device. This driver consists of a new device, for example /dev/ibmvmc,
+which provides interfaces to open, close, read, write, and perform
+ioctl’s against the VMC device.
+
+VMC Interface Initialization
+----------------------------
+
+The device driver is responsible for initializing the VMC when the driver
+is loaded. It first creates and initializes the CRQ. Next, an exchange of
+VMC capabilities is performed to indicate the code version and number of
+resources available in both the management partition and the hypervisor.
+Finally, the hypervisor requests that the management partition create an
+initial pool of VMC buffers, one buffer for each possible HMC connection,
+which will be used for management application  session initialization.
+Prior to completion of this initialization sequence, the device returns
+EBUSY to open() calls. EIO is returned for all open() failures.
+
+::
+
+        Management Partition		Hypervisor
+                        CRQ INIT
+        ---------------------------------------->
+        	   CRQ INIT COMPLETE
+        <----------------------------------------
+        	      CAPABILITIES
+        ---------------------------------------->
+        	 CAPABILITIES RESPONSE
+        <----------------------------------------
+              ADD BUFFER (HMC IDX=0,1,..)         _
+        <----------------------------------------  |
+        	  ADD BUFFER RESPONSE              | - Perform # HMCs Iterations
+        ----------------------------------------> -
+
+VMC Interface Open
+------------------
+
+After the basic VMC channel has been initialized, an HMC session level
+connection can be established. The application layer performs an open() to
+the VMC device and executes an ioctl() against it, indicating the HMC ID
+(32 bytes of data) for this session. If the VMC device is in an invalid
+state, EIO will be returned for the ioctl(). The device driver creates a
+new HMC session value (ranging from 1 to 255) and HMC index value (starting
+at index 0 and ranging to 254) for this HMC ID. The driver then does an
+RDMA of the HMC ID to the hypervisor, and then sends an Interface Open
+message to the hypervisor to establish the session over the VMC. After the
+hypervisor receives this information, it sends Add Buffer messages to the
+management partition to seed an initial pool of buffers for the new HMC
+connection. Finally, the hypervisor sends an Interface Open Response
+message, to indicate that it is ready for normal runtime messaging. The
+following illustrates this VMC flow:
+
+::
+
+        Management Partition             Hypervisor
+        	      RDMA HMC ID
+        ---------------------------------------->
+        	    Interface Open
+        ---------------------------------------->
+        	      Add Buffer                  _
+        <----------------------------------------  |
+        	  Add Buffer Response              | - Perform N Iterations
+        ----------------------------------------> -
+        	Interface Open Response
+        <----------------------------------------
+
+VMC Interface Runtime
+---------------------
+
+During normal runtime, the management application and the hypervisor
+exchange HMC messages via the Signal VMC message and RDMA operations. When
+sending data to the hypervisor, the management application performs a
+write() to the VMC device, and the driver RDMA’s the data to the hypervisor
+and then sends a Signal Message. If a write() is attempted before VMC
+device buffers have been made available by the hypervisor, or no buffers
+are currently available, EBUSY is returned in response to the write(). A
+write() will return EIO for all other errors, such as an invalid device
+state. When the hypervisor sends a message to the management, the data is
+put into a VMC buffer and an Signal Message is sent to the VMC driver in
+the management partition. The driver RDMA’s the buffer into the partition
+and passes the data up to the appropriate management application via a
+read() to the VMC device. The read() request blocks if there is no buffer
+available to read. The management application may use select() to wait for
+the VMC device to become ready with data to read.
+
+::
+
+        Management Partition             Hypervisor
+        		MSG RDMA
+        ---------------------------------------->
+        		SIGNAL MSG
+        ---------------------------------------->
+        		SIGNAL MSG
+        <----------------------------------------
+        		MSG RDMA
+        <----------------------------------------
+
+VMC Interface Close
+-------------------
+
+HMC session level connections are closed by the management partition when
+the application layer performs a close() against the device. This action
+results in an Interface Close message flowing to the hypervisor, which
+causes the session to be terminated. The device driver must free any
+storage allocated for buffers for this HMC connection.
+
+::
+
+        Management Partition             Hypervisor
+        	     INTERFACE CLOSE
+        ---------------------------------------->
+                INTERFACE CLOSE RESPONSE
+        <----------------------------------------
+
+Additional Information
+======================
+
+For more information on the documentation for CRQ Messages, VMC Messages,
+HMC interface Buffers, and signal messages please refer to the Linux on
+Power Architecture Platform Reference. Section F.

MAINTAINERS

@@ -6757,6 +6757,12 @@ L:	linux-scsi@vger.kernel.org
 S:	Supported
 F:	drivers/scsi/ibmvscsi/ibmvfc*
 
+IBM Power Virtual Management Channel Driver
+M:	Bryant G. Ly <bryantly@linux.vnet.ibm.com>
+M:	Steven Royer <seroyer@linux.vnet.ibm.com>
+S:	Supported
+F:	drivers/misc/ibmvmc.*
+
 IBM Power Virtual SCSI Device Drivers
 M:	Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
 L:	linux-scsi@vger.kernel.org

arch/powerpc/include/asm/hvcall.h

@@ -279,6 +279,7 @@
 #define H_GET_MPP_X		0x314
 #define H_SET_MODE		0x31C
 #define H_CLEAR_HPT		0x358
+#define H_REQUEST_VMC		0x360
 #define H_RESIZE_HPT_PREPARE	0x36C
 #define H_RESIZE_HPT_COMMIT	0x370
 #define H_REGISTER_PROC_TBL	0x37C

drivers/misc/Kconfig

@@ -113,6 +113,20 @@ config IBM_ASM
 	  for information on the specific driver level and support statement
 	  for your IBM server.
 
+config IBMVMC
+	tristate "IBM Virtual Management Channel support"
+	depends on PPC_PSERIES
+	help
+	  This is the IBM POWER Virtual Management Channel
+
+	  This driver is to be used for the POWER Virtual
+	  Management Channel virtual adapter on the PowerVM
+	  platform. It provides both request/response and
+	  async message support through the /dev/ibmvmc node.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called ibmvmc.
+
 config PHANTOM
 	tristate "Sensable PHANToM (PCI)"
 	depends on PCI

drivers/misc/Makefile

@@ -4,6 +4,7 @@
 #
 
 obj-$(CONFIG_IBM_ASM)		+= ibmasm/
+obj-$(CONFIG_IBMVMC)		+= ibmvmc.o
 obj-$(CONFIG_AD525X_DPOT)	+= ad525x_dpot.o
 obj-$(CONFIG_AD525X_DPOT_I2C)	+= ad525x_dpot-i2c.o
 obj-$(CONFIG_AD525X_DPOT_SPI)	+= ad525x_dpot-spi.o

drivers/misc/ibmvmc.h

+/* SPDX-License-Identifier: GPL-2.0+
+ *
+ * linux/drivers/misc/ibmvmc.h
+ *
+ * IBM Power Systems Virtual Management Channel Support.
+ *
+ * Copyright (c) 2004, 2018 IBM Corp.
+ *   Dave Engebretsen engebret@us.ibm.com
+ *   Steven Royer seroyer@linux.vnet.ibm.com
+ *   Adam Reznechek adreznec@linux.vnet.ibm.com
+ *   Bryant G. Ly <bryantly@linux.vnet.ibm.com>
+ */
+#ifndef IBMVMC_H
+#define IBMVMC_H
+
+#include <linux/types.h>
+#include <linux/cdev.h>
+
+#include <asm/vio.h>
+
+#define IBMVMC_PROTOCOL_VERSION    0x0101
+
+#define MIN_BUF_POOL_SIZE 16
+#define MIN_HMCS          1
+#define MIN_MTU           4096
+#define MAX_BUF_POOL_SIZE 64
+#define MAX_HMCS          2
+#define MAX_MTU           (4 * 4096)
+#define DEFAULT_BUF_POOL_SIZE 32
+#define DEFAULT_HMCS          1
+#define DEFAULT_MTU           4096
+#define HMC_ID_LEN        32
+
+#define VMC_INVALID_BUFFER_ID 0xFFFF
+
+/* ioctl numbers */
+#define VMC_BASE	     0xCC
+#define VMC_IOCTL_SETHMCID   _IOW(VMC_BASE, 0x00, unsigned char *)
+#define VMC_IOCTL_QUERY      _IOR(VMC_BASE, 0x01, struct ibmvmc_query_struct)
+#define VMC_IOCTL_REQUESTVMC _IOR(VMC_BASE, 0x02, u32)
+
+#define VMC_MSG_CAP          0x01
+#define VMC_MSG_CAP_RESP     0x81
+#define VMC_MSG_OPEN         0x02
+#define VMC_MSG_OPEN_RESP    0x82
+#define VMC_MSG_CLOSE        0x03
+#define VMC_MSG_CLOSE_RESP   0x83
+#define VMC_MSG_ADD_BUF      0x04
+#define VMC_MSG_ADD_BUF_RESP 0x84
+#define VMC_MSG_REM_BUF      0x05
+#define VMC_MSG_REM_BUF_RESP 0x85
+#define VMC_MSG_SIGNAL       0x06
+
+#define VMC_MSG_SUCCESS 0
+#define VMC_MSG_INVALID_HMC_INDEX 1
+#define VMC_MSG_INVALID_BUFFER_ID 2
+#define VMC_MSG_CLOSED_HMC        3
+#define VMC_MSG_INTERFACE_FAILURE 4
+#define VMC_MSG_NO_BUFFER         5
+
+#define VMC_BUF_OWNER_ALPHA 0
+#define VMC_BUF_OWNER_HV    1
+
+enum ibmvmc_states {
+	ibmvmc_state_sched_reset  = -1,
+	ibmvmc_state_initial      = 0,
+	ibmvmc_state_crqinit      = 1,
+	ibmvmc_state_capabilities = 2,
+	ibmvmc_state_ready        = 3,
+	ibmvmc_state_failed       = 4,
+};
+
+enum ibmhmc_states {
+	/* HMC connection not established */
+	ibmhmc_state_free    = 0,
+
+	/* HMC connection established (open called) */
+	ibmhmc_state_initial = 1,
+
+	/* open msg sent to HV, due to ioctl(1) call */
+	ibmhmc_state_opening = 2,
+
+	/* HMC connection ready, open resp msg from HV */
+	ibmhmc_state_ready   = 3,
+
+	/* HMC connection failure */
+	ibmhmc_state_failed  = 4,
+};
+
+struct ibmvmc_buffer {
+	u8 valid;	/* 1 when DMA storage allocated to buffer          */
+	u8 free;	/* 1 when buffer available for the Alpha Partition */
+	u8 owner;
+	u16 id;
+	u32 size;
+	u32 msg_len;
+	dma_addr_t dma_addr_local;
+	dma_addr_t dma_addr_remote;
+	void *real_addr_local;
+};
+
+struct ibmvmc_admin_crq_msg {
+	u8 valid;	/* RPA Defined           */
+	u8 type;	/* ibmvmc msg type       */
+	u8 status;	/* Response msg status. Zero is success and on failure,
+			 * either 1 - General Failure, or 2 - Invalid Version is
+			 * returned.
+			 */
+	u8 rsvd[2];
+	u8 max_hmc;	/* Max # of independent HMC connections supported */
+	__be16 pool_size;	/* Maximum number of buffers supported per HMC
+				 * connection
+				 */
+	__be32 max_mtu;		/* Maximum message size supported (bytes) */
+	__be16 crq_size;	/* # of entries available in the CRQ for the
+				 * source partition. The target partition must
+				 * limit the number of outstanding messages to
+				 * one half or less.
+				 */
+	__be16 version;	/* Indicates the code level of the management partition
+			 * or the hypervisor with the high-order byte
+			 * indicating a major version and the low-order byte
+			 * indicating a minor version.
+			 */
+};
+
+struct ibmvmc_crq_msg {
+	u8 valid;     /* RPA Defined           */
+	u8 type;      /* ibmvmc msg type       */
+	u8 status;    /* Response msg status   */
+	union {
+		u8 rsvd;  /* Reserved              */
+		u8 owner;
+	} var1;
+	u8 hmc_session;	/* Session Identifier for the current VMC connection */
+	u8 hmc_index;	/* A unique HMC Idx would be used if multiple management
+			 * applications running concurrently were desired
+			 */
+	union {
+		__be16 rsvd;
+		__be16 buffer_id;
+	} var2;
+	__be32 rsvd;
+	union {
+		__be32 rsvd;
+		__be32 lioba;
+		__be32 msg_len;
+	} var3;
+};
+
+/* an RPA command/response transport queue */
+struct crq_queue {
+	struct ibmvmc_crq_msg *msgs;
+	int size, cur;
+	dma_addr_t msg_token;
+	spinlock_t lock;
+};
+
+/* VMC server adapter settings */
+struct crq_server_adapter {
+	struct device *dev;
+	struct crq_queue queue;
+	u32 liobn;
+	u32 riobn;
+	struct tasklet_struct work_task;
+	wait_queue_head_t reset_wait_queue;
+	struct task_struct *reset_task;
+};
+
+/* Driver wide settings */
+struct ibmvmc_struct {
+	u32 state;
+	u32 max_mtu;
+	u32 max_buffer_pool_size;
+	u32 max_hmc_index;
+	struct crq_server_adapter *adapter;
+	struct cdev cdev;
+	u32 vmc_drc_index;
+};
+
+struct ibmvmc_file_session;
+
+/* Connection specific settings */
+struct ibmvmc_hmc {
+	u8 session;
+	u8 index;
+	u32 state;
+	struct crq_server_adapter *adapter;
+	spinlock_t lock;
+	unsigned char hmc_id[HMC_ID_LEN];
+	struct ibmvmc_buffer buffer[MAX_BUF_POOL_SIZE];
+	unsigned short queue_outbound_msgs[MAX_BUF_POOL_SIZE];
+	int queue_head, queue_tail;
+	struct ibmvmc_file_session *file_session;
+};
+
+struct ibmvmc_file_session {
+	struct file *file;
+	struct ibmvmc_hmc *hmc;
+	bool valid;
+};
+
+struct ibmvmc_query_struct {
+	int have_vmc;
+	int state;
+	int vmc_drc_index;
+};
+
+#endif /* __IBMVMC_H */