[IA64-SGI] SGI Altix cross partition functionality [2/3]

This patch contains the communication module (XPC) for cross partition
communication on a partitioned SGI Altix.

Signed-off-by: Dean Nelson <dcn@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

1 files changed, 991 insertions, 0 deletions

diff --git a/arch/ia64/sn/kernel/xpc.h b/arch/ia64/sn/kernel/xpc.h
new file mode 100644
index 0000000..1a0aed8
--- /dev/null
+++ b/arch/ia64/sn/kernel/xpc.h
@@ -0,0 +1,991 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (c) 2004-2005 Silicon Graphics, Inc.  All Rights Reserved.
+ */
+
+
+/*
+ * Cross Partition Communication (XPC) structures and macros.
+ */
+
+#ifndef _IA64_SN_KERNEL_XPC_H
+#define _IA64_SN_KERNEL_XPC_H
+
+
+#include <linux/config.h>
+#include <linux/interrupt.h>
+#include <linux/sysctl.h>
+#include <linux/device.h>
+#include <asm/pgtable.h>
+#include <asm/processor.h>
+#include <asm/sn/bte.h>
+#include <asm/sn/clksupport.h>
+#include <asm/sn/addrs.h>
+#include <asm/sn/mspec.h>
+#include <asm/sn/shub_mmr.h>
+#include <asm/sn/xp.h>
+
+
+/*
+ * XPC Version numbers consist of a major and minor number. XPC can always
+ * talk to versions with same major #, and never talk to versions with a
+ * different major #.
+ */
+#define _XPC_VERSION(_maj, _min)	(((_maj) << 4) | ((_min) & 0xf))
+#define XPC_VERSION_MAJOR(_v)		((_v) >> 4)
+#define XPC_VERSION_MINOR(_v)		((_v) & 0xf)
+
+
+/*
+ * The next macros define word or bit representations for given
+ * C-brick nasid in either the SAL provided bit array representing
+ * nasids in the partition/machine or the AMO_t array used for
+ * inter-partition initiation communications.
+ *
+ * For SN2 machines, C-Bricks are alway even numbered NASIDs.  As
+ * such, some space will be saved by insisting that nasid information
+ * passed from SAL always be packed for C-Bricks and the
+ * cross-partition interrupts use the same packing scheme.
+ */
+#define XPC_NASID_W_INDEX(_n)	(((_n) / 64) / 2)
+#define XPC_NASID_B_INDEX(_n)	(((_n) / 2) & (64 - 1))
+#define XPC_NASID_IN_ARRAY(_n, _p) ((_p)[XPC_NASID_W_INDEX(_n)] & \
+				    (1UL << XPC_NASID_B_INDEX(_n)))
+#define XPC_NASID_FROM_W_B(_w, _b) (((_w) * 64 + (_b)) * 2)
+
+#define XPC_HB_DEFAULT_INTERVAL		5	/* incr HB every x secs */
+#define XPC_HB_CHECK_DEFAULT_TIMEOUT	20	/* check HB every x secs */
+
+/* define the process name of HB checker and the CPU it is pinned to */
+#define XPC_HB_CHECK_THREAD_NAME	"xpc_hb"
+#define XPC_HB_CHECK_CPU		0
+
+/* define the process name of the discovery thread */
+#define XPC_DISCOVERY_THREAD_NAME	"xpc_discovery"
+
+
+#define XPC_HB_ALLOWED(_p, _v)	((_v)->heartbeating_to_mask & (1UL << (_p)))
+#define XPC_ALLOW_HB(_p, _v)	(_v)->heartbeating_to_mask |= (1UL << (_p))
+#define XPC_DISALLOW_HB(_p, _v)	(_v)->heartbeating_to_mask &= (~(1UL << (_p)))
+
+
+/*
+ * Reserved Page provided by SAL.
+ *
+ * SAL provides one page per partition of reserved memory.  When SAL
+ * initialization is complete, SAL_signature, SAL_version, partid,
+ * part_nasids, and mach_nasids are set.
+ *
+ * Note: Until vars_pa is set, the partition XPC code has not been initialized.
+ */
+struct xpc_rsvd_page {
+	u64 SAL_signature;	/* SAL unique signature */
+	u64 SAL_version;	/* SAL specified version */
+	u8 partid;		/* partition ID from SAL */
+	u8 version;
+	u8 pad[6];		/* pad to u64 align */
+	u64 vars_pa;
+	u64 part_nasids[XP_NASID_MASK_WORDS] ____cacheline_aligned;
+	u64 mach_nasids[XP_NASID_MASK_WORDS] ____cacheline_aligned;
+};
+#define XPC_RP_VERSION _XPC_VERSION(1,0) /* version 1.0 of the reserved page */
+
+#define XPC_RSVD_PAGE_ALIGNED_SIZE \
+			(L1_CACHE_ALIGN(sizeof(struct xpc_rsvd_page)))
+
+
+/*
+ * Define the structures by which XPC variables can be exported to other
+ * partitions. (There are two: struct xpc_vars and struct xpc_vars_part)
+ */
+
+/*
+ * The following structure describes the partition generic variables
+ * needed by other partitions in order to properly initialize.
+ *
+ * struct xpc_vars version number also applies to struct xpc_vars_part.
+ * Changes to either structure and/or related functionality should be
+ * reflected by incrementing either the major or minor version numbers
+ * of struct xpc_vars.
+ */
+struct xpc_vars {
+	u8 version;
+	u64 heartbeat;
+	u64 heartbeating_to_mask;
+	u64 kdb_status;		/* 0 = machine running */
+	int act_nasid;
+	int act_phys_cpuid;
+	u64 vars_part_pa;
+	u64 amos_page_pa;	/* paddr of page of AMOs from MSPEC driver */
+	AMO_t *amos_page;	/* vaddr of page of AMOs from MSPEC driver */
+	AMO_t *act_amos;	/* pointer to the first activation AMO */
+};
+#define XPC_V_VERSION _XPC_VERSION(3,0) /* version 3.0 of the cross vars */
+
+#define XPC_VARS_ALIGNED_SIZE  (L1_CACHE_ALIGN(sizeof(struct xpc_vars)))
+
+/*
+ * The following structure describes the per partition specific variables.
+ *
+ * An array of these structures, one per partition, will be defined. As a
+ * partition becomes active XPC will copy the array entry corresponding to
+ * itself from that partition. It is desirable that the size of this
+ * structure evenly divide into a cacheline, such that none of the entries
+ * in this array crosses a cacheline boundary. As it is now, each entry
+ * occupies half a cacheline.
+ */
+struct xpc_vars_part {
+	u64 magic;
+
+	u64 openclose_args_pa;	/* physical address of open and close args */
+	u64 GPs_pa;		/* physical address of Get/Put values */
+
+	u64 IPI_amo_pa;		/* physical address of IPI AMO_t structure */
+	int IPI_nasid;		/* nasid of where to send IPIs */
+	int IPI_phys_cpuid;	/* physical CPU ID of where to send IPIs */
+
+	u8 nchannels;		/* #of defined channels supported */
+
+	u8 reserved[23];	/* pad to a full 64 bytes */
+};
+
+/*
+ * The vars_part MAGIC numbers play a part in the first contact protocol.
+ *
+ * MAGIC1 indicates that the per partition specific variables for a remote
+ * partition have been initialized by this partition.
+ *
+ * MAGIC2 indicates that this partition has pulled the remote partititions
+ * per partition variables that pertain to this partition.
+ */
+#define XPC_VP_MAGIC1	0x0053524156435058L  /* 'XPCVARS\0'L (little endian) */
+#define XPC_VP_MAGIC2	0x0073726176435058L  /* 'XPCvars\0'L (little endian) */
+
+
+
+/*
+ * Functions registered by add_timer() or called by kernel_thread() only
+ * allow for a single 64-bit argument. The following macros can be used to
+ * pack and unpack two (32-bit, 16-bit or 8-bit) arguments into or out from
+ * the passed argument.
+ */
+#define XPC_PACK_ARGS(_arg1, _arg2) \
+			((((u64) _arg1) & 0xffffffff) | \
+			((((u64) _arg2) & 0xffffffff) << 32))
+
+#define XPC_UNPACK_ARG1(_args)	(((u64) _args) & 0xffffffff)
+#define XPC_UNPACK_ARG2(_args)	((((u64) _args) >> 32) & 0xffffffff)
+
+
+
+/*
+ * Define a Get/Put value pair (pointers) used with a message queue.
+ */
+struct xpc_gp {
+	s64 get;	/* Get value */
+	s64 put;	/* Put value */
+};
+
+#define XPC_GP_SIZE \
+		L1_CACHE_ALIGN(sizeof(struct xpc_gp) * XPC_NCHANNELS)
+
+
+
+/*
+ * Define a structure that contains arguments associated with opening and
+ * closing a channel.
+ */
+struct xpc_openclose_args {
+	u16 reason;		/* reason why channel is closing */
+	u16 msg_size;		/* sizeof each message entry */
+	u16 remote_nentries;	/* #of message entries in remote msg queue */
+	u16 local_nentries;	/* #of message entries in local msg queue */
+	u64 local_msgqueue_pa;	/* physical address of local message queue */
+};
+
+#define XPC_OPENCLOSE_ARGS_SIZE \
+	      L1_CACHE_ALIGN(sizeof(struct xpc_openclose_args) * XPC_NCHANNELS)
+
+
+
+/* struct xpc_msg flags */
+
+#define	XPC_M_DONE		0x01	/* msg has been received/consumed */
+#define	XPC_M_READY		0x02	/* msg is ready to be sent */
+#define	XPC_M_INTERRUPT		0x04	/* send interrupt when msg consumed */
+
+
+#define XPC_MSG_ADDRESS(_payload) \
+		((struct xpc_msg *)((u8 *)(_payload) - XPC_MSG_PAYLOAD_OFFSET))
+
+
+
+/*
+ * Defines notify entry.
+ *
+ * This is used to notify a message's sender that their message was received
+ * and consumed by the intended recipient.
+ */
+struct xpc_notify {
+	struct semaphore sema;		/* notify semaphore */
+	u8 type;			/* type of notification */
+
+	/* the following two fields are only used if type == XPC_N_CALL */
+	xpc_notify_func func;		/* user's notify function */
+	void *key;			/* pointer to user's key */
+};
+
+/* struct xpc_notify type of notification */
+
+#define	XPC_N_CALL		0x01	/* notify function provided by user */
+
+
+
+/*
+ * Define the structure that manages all the stuff required by a channel. In
+ * particular, they are used to manage the messages sent across the channel.
+ *
+ * This structure is private to a partition, and is NOT shared across the
+ * partition boundary.
+ *
+ * There is an array of these structures for each remote partition. It is
+ * allocated at the time a partition becomes active. The array contains one
+ * of these structures for each potential channel connection to that partition.
+ *
+ * Each of these structures manages two message queues (circular buffers).
+ * They are allocated at the time a channel connection is made. One of
+ * these message queues (local_msgqueue) holds the locally created messages
+ * that are destined for the remote partition. The other of these message
+ * queues (remote_msgqueue) is a locally cached copy of the remote partition's
+ * own local_msgqueue.
+ *
+ * The following is a description of the Get/Put pointers used to manage these
+ * two message queues. Consider the local_msgqueue to be on one partition
+ * and the remote_msgqueue to be its cached copy on another partition. A
+ * description of what each of the lettered areas contains is included.
+ *
+ *
+ *                     local_msgqueue      remote_msgqueue
+ *
+ *                        |/////////|      |/////////|
+ *    w_remote_GP.get --> +---------+      |/////////|
+ *                        |    F    |      |/////////|
+ *     remote_GP.get  --> +---------+      +---------+ <-- local_GP->get
+ *                        |         |      |         |
+ *                        |         |      |    E    |
+ *                        |         |      |         |
+ *                        |         |      +---------+ <-- w_local_GP.get
+ *                        |    B    |      |/////////|
+ *                        |         |      |////D////|
+ *                        |         |      |/////////|
+ *                        |         |      +---------+ <-- w_remote_GP.put
+ *                        |         |      |////C////|
+ *      local_GP->put --> +---------+      +---------+ <-- remote_GP.put
+ *                        |         |      |/////////|
+ *                        |    A    |      |/////////|
+ *                        |         |      |/////////|
+ *     w_local_GP.put --> +---------+      |/////////|
+ *                        |/////////|      |/////////|
+ *
+ *
+ *	    ( remote_GP.[get|put] are cached copies of the remote
+ *	      partition's local_GP->[get|put], and thus their values can
+ *	      lag behind their counterparts on the remote partition. )
+ *
+ *
+ *  A - Messages that have been allocated, but have not yet been sent to the
+ *	remote partition.
+ *
+ *  B - Messages that have been sent, but have not yet been acknowledged by the
+ *      remote partition as having been received.
+ *
+ *  C - Area that needs to be prepared for the copying of sent messages, by
+ *	the clearing of the message flags of any previously received messages.
+ *
+ *  D - Area into which sent messages are to be copied from the remote
+ *	partition's local_msgqueue and then delivered to their intended
+ *	recipients. [ To allow for a multi-message copy, another pointer
+ *	(next_msg_to_pull) has been added to keep track of the next message
+ *	number needing to be copied (pulled). It chases after w_remote_GP.put.
+ *	Any messages lying between w_local_GP.get and next_msg_to_pull have
+ *	been copied and are ready to be delivered. ]
+ *
+ *  E - Messages that have been copied and delivered, but have not yet been
+ *	acknowledged by the recipient as having been received.
+ *
+ *  F - Messages that have been acknowledged, but XPC has not yet notified the
+ *	sender that the message was received by its intended recipient.
+ *	This is also an area that needs to be prepared for the allocating of
+ *	new messages, by the clearing of the message flags of the acknowledged
+ *	messages.
+ */
+struct xpc_channel {
+	partid_t partid;		/* ID of remote partition connected */
+	spinlock_t lock;		/* lock for updating this structure */
+	u32 flags;			/* general flags */
+
+	enum xpc_retval reason;		/* reason why channel is disconnect'g */
+	int reason_line;		/* line# disconnect initiated from */
+
+	u16 number;			/* channel # */
+
+	u16 msg_size;			/* sizeof each msg entry */
+	u16 local_nentries;		/* #of msg entries in local msg queue */
+	u16 remote_nentries;		/* #of msg entries in remote msg queue*/
+
+	void *local_msgqueue_base;	/* base address of kmalloc'd space */
+	struct xpc_msg *local_msgqueue;	/* local message queue */
+	void *remote_msgqueue_base;	/* base address of kmalloc'd space */
+	struct xpc_msg *remote_msgqueue;/* cached copy of remote partition's */
+					/* local message queue */
+	u64 remote_msgqueue_pa;		/* phys addr of remote partition's */
+					/* local message queue */
+
+	atomic_t references;		/* #of external references to queues */
+
+	atomic_t n_on_msg_allocate_wq;   /* #on msg allocation wait queue */
+	wait_queue_head_t msg_allocate_wq; /* msg allocation wait queue */
+
+	/* queue of msg senders who want to be notified when msg received */
+
+	atomic_t n_to_notify;		/* #of msg senders to notify */
+	struct xpc_notify *notify_queue;/* notify queue for messages sent */
+
+	xpc_channel_func func;		/* user's channel function */
+	void *key;			/* pointer to user's key */
+
+	struct semaphore msg_to_pull_sema; /* next msg to pull serialization */
+	struct semaphore teardown_sema;    /* wait for teardown completion */
+
+	struct xpc_openclose_args *local_openclose_args; /* args passed on */
+					/* opening or closing of channel */
+
+	/* various flavors of local and remote Get/Put values */
+
+	struct xpc_gp *local_GP;	/* local Get/Put values */
+	struct xpc_gp remote_GP;	/* remote Get/Put values */
+	struct xpc_gp w_local_GP;	/* working local Get/Put values */
+	struct xpc_gp w_remote_GP;	/* working remote Get/Put values */
+	s64 next_msg_to_pull;		/* Put value of next msg to pull */
+
+	/* kthread management related fields */
+
+// >>> rethink having kthreads_assigned_limit and kthreads_idle_limit; perhaps
+// >>> allow the assigned limit be unbounded and let the idle limit be dynamic
+// >>> dependent on activity over the last interval of time
+	atomic_t kthreads_assigned;	/* #of kthreads assigned to channel */
+	u32 kthreads_assigned_limit; 	/* limit on #of kthreads assigned */
+	atomic_t kthreads_idle;		/* #of kthreads idle waiting for work */
+	u32 kthreads_idle_limit;	/* limit on #of kthreads idle */
+	atomic_t kthreads_active;	/* #of kthreads actively working */
+	// >>> following field is temporary
+	u32 kthreads_created;		/* total #of kthreads created */
+
+	wait_queue_head_t idle_wq;	/* idle kthread wait queue */
+
+} ____cacheline_aligned;
+
+
+/* struct xpc_channel flags */
+
+#define	XPC_C_WASCONNECTED	0x00000001 /* channel was connected */
+
+#define	XPC_C_ROPENREPLY	0x00000002 /* remote open channel reply */
+#define	XPC_C_OPENREPLY		0x00000004 /* local open channel reply */
+#define	XPC_C_ROPENREQUEST	0x00000008 /* remote open channel request */
+#define	XPC_C_OPENREQUEST	0x00000010 /* local open channel request */
+
+#define	XPC_C_SETUP		0x00000020 /* channel's msgqueues are alloc'd */
+#define	XPC_C_CONNECTCALLOUT	0x00000040 /* channel connected callout made */
+#define	XPC_C_CONNECTED		0x00000080 /* local channel is connected */
+#define	XPC_C_CONNECTING	0x00000100 /* channel is being connected */
+
+#define	XPC_C_RCLOSEREPLY	0x00000200 /* remote close channel reply */
+#define	XPC_C_CLOSEREPLY	0x00000400 /* local close channel reply */
+#define	XPC_C_RCLOSEREQUEST	0x00000800 /* remote close channel request */
+#define	XPC_C_CLOSEREQUEST	0x00001000 /* local close channel request */
+
+#define	XPC_C_DISCONNECTED	0x00002000 /* channel is disconnected */
+#define	XPC_C_DISCONNECTING	0x00004000 /* channel is being disconnected */
+
+
+
+/*
+ * Manages channels on a partition basis. There is one of these structures
+ * for each partition (a partition will never utilize the structure that
+ * represents itself).
+ */
+struct xpc_partition {
+
+	/* XPC HB infrastructure */
+
+	u64 remote_rp_pa;		/* phys addr of partition's rsvd pg */
+	u64 remote_vars_pa;		/* phys addr of partition's vars */
+	u64 remote_vars_part_pa;	/* phys addr of partition's vars part */
+	u64 last_heartbeat;		/* HB at last read */
+	u64 remote_amos_page_pa;	/* phys addr of partition's amos page */
+	int remote_act_nasid;		/* active part's act/deact nasid */
+	int remote_act_phys_cpuid;	/* active part's act/deact phys cpuid */
+	u32 act_IRQ_rcvd;		/* IRQs since activation */
+	spinlock_t act_lock;		/* protect updating of act_state */
+	u8 act_state;			/* from XPC HB viewpoint */
+	enum xpc_retval reason;		/* reason partition is deactivating */
+	int reason_line;		/* line# deactivation initiated from */
+	int reactivate_nasid;		/* nasid in partition to reactivate */
+
+
+	/* XPC infrastructure referencing and teardown control */
+
+	u8 setup_state;			/* infrastructure setup state */
+	wait_queue_head_t teardown_wq;	/* kthread waiting to teardown infra */
+	atomic_t references;		/* #of references to infrastructure */
+
+
+	/*
+	 * NONE OF THE PRECEDING FIELDS OF THIS STRUCTURE WILL BE CLEARED WHEN
+	 * XPC SETS UP THE NECESSARY INFRASTRUCTURE TO SUPPORT CROSS PARTITION
+	 * COMMUNICATION. ALL OF THE FOLLOWING FIELDS WILL BE CLEARED. (THE
+	 * 'nchannels' FIELD MUST BE THE FIRST OF THE FIELDS TO BE CLEARED.)
+	 */
+
+
+	u8 nchannels;		   /* #of defined channels supported */
+	atomic_t nchannels_active; /* #of channels that are not DISCONNECTED */
+	struct xpc_channel *channels;/* array of channel structures */
+
+	void *local_GPs_base;	  /* base address of kmalloc'd space */
+	struct xpc_gp *local_GPs; /* local Get/Put values */
+	void *remote_GPs_base;    /* base address of kmalloc'd space */
+	struct xpc_gp *remote_GPs;/* copy of remote partition's local Get/Put */
+				  /* values */
+	u64 remote_GPs_pa;	  /* phys address of remote partition's local */
+				  /* Get/Put values */
+
+
+	/* fields used to pass args when opening or closing a channel */
+
+	void *local_openclose_args_base;  /* base address of kmalloc'd space */
+	struct xpc_openclose_args *local_openclose_args;  /* local's args */
+	void *remote_openclose_args_base; /* base address of kmalloc'd space */
+	struct xpc_openclose_args *remote_openclose_args; /* copy of remote's */
+					  /* args */
+	u64 remote_openclose_args_pa;	  /* phys addr of remote's args */
+
+
+	/* IPI sending, receiving and handling related fields */
+
+	int remote_IPI_nasid;	    /* nasid of where to send IPIs */
+	int remote_IPI_phys_cpuid;  /* phys CPU ID of where to send IPIs */
+	AMO_t *remote_IPI_amo_va;   /* address of remote IPI AMO_t structure */
+
+	AMO_t *local_IPI_amo_va;    /* address of IPI AMO_t structure */
+	u64 local_IPI_amo;	    /* IPI amo flags yet to be handled */
+	char IPI_owner[8];	    /* IPI owner's name */
+	struct timer_list dropped_IPI_timer; /* dropped IPI timer */
+
+	spinlock_t IPI_lock;	    /* IPI handler lock */
+
+
+	/* channel manager related fields */
+
+	atomic_t channel_mgr_requests;	/* #of requests to activate chan mgr */
+	wait_queue_head_t channel_mgr_wq; /* channel mgr's wait queue */
+
+} ____cacheline_aligned;
+
+
+/* struct xpc_partition act_state values (for XPC HB) */
+
+#define	XPC_P_INACTIVE		0x00	/* partition is not active */
+#define XPC_P_ACTIVATION_REQ	0x01	/* created thread to activate */
+#define XPC_P_ACTIVATING	0x02	/* activation thread started */
+#define XPC_P_ACTIVE		0x03	/* xpc_partition_up() was called */
+#define XPC_P_DEACTIVATING	0x04	/* partition deactivation initiated */
+
+
+#define XPC_DEACTIVATE_PARTITION(_p, _reason) \
+			xpc_deactivate_partition(__LINE__, (_p), (_reason))
+
+
+/* struct xpc_partition setup_state values */
+
+#define XPC_P_UNSET		0x00	/* infrastructure was never setup */
+#define XPC_P_SETUP		0x01	/* infrastructure is setup */
+#define XPC_P_WTEARDOWN		0x02	/* waiting to teardown infrastructure */
+#define XPC_P_TORNDOWN		0x03	/* infrastructure is torndown */
+
+
+/*
+ * struct xpc_partition IPI_timer #of seconds to wait before checking for
+ * dropped IPIs. These occur whenever an IPI amo write doesn't complete until
+ * after the IPI was received.
+ */
+#define XPC_P_DROPPED_IPI_WAIT	(0.25 * HZ)
+
+
+#define XPC_PARTID(_p)	((partid_t) ((_p) - &xpc_partitions[0]))
+
+
+
+/* found in xp_main.c */
+extern struct xpc_registration xpc_registrations[];
+
+
+/* >>> found in xpc_main.c only */
+extern struct device *xpc_part;
+extern struct device *xpc_chan;
+extern irqreturn_t xpc_notify_IRQ_handler(int, void *, struct pt_regs *);
+extern void xpc_dropped_IPI_check(struct xpc_partition *);
+extern void xpc_activate_kthreads(struct xpc_channel *, int);
+extern void xpc_create_kthreads(struct xpc_channel *, int);
+extern void xpc_disconnect_wait(int);
+
+
+/* found in xpc_main.c and efi-xpc.c */
+extern void xpc_activate_partition(struct xpc_partition *);
+
+
+/* found in xpc_partition.c */
+extern int xpc_exiting;
+extern int xpc_hb_interval;
+extern int xpc_hb_check_interval;
+extern struct xpc_vars *xpc_vars;
+extern struct xpc_rsvd_page *xpc_rsvd_page;
+extern struct xpc_vars_part *xpc_vars_part;
+extern struct xpc_partition xpc_partitions[XP_MAX_PARTITIONS + 1];
+extern char xpc_remote_copy_buffer[];
+extern struct xpc_rsvd_page *xpc_rsvd_page_init(void);
+extern void xpc_allow_IPI_ops(void);
+extern void xpc_restrict_IPI_ops(void);
+extern int xpc_identify_act_IRQ_sender(void);
+extern enum xpc_retval xpc_mark_partition_active(struct xpc_partition *);
+extern void xpc_mark_partition_inactive(struct xpc_partition *);
+extern void xpc_discovery(void);
+extern void xpc_check_remote_hb(void);
+extern void xpc_deactivate_partition(const int, struct xpc_partition *,
+						enum xpc_retval);
+extern enum xpc_retval xpc_initiate_partid_to_nasids(partid_t, void *);
+
+
+/* found in xpc_channel.c */
+extern void xpc_initiate_connect(int);
+extern void xpc_initiate_disconnect(int);
+extern enum xpc_retval xpc_initiate_allocate(partid_t, int, u32, void **);
+extern enum xpc_retval xpc_initiate_send(partid_t, int, void *);
+extern enum xpc_retval xpc_initiate_send_notify(partid_t, int, void *,
+						xpc_notify_func, void *);
+extern void xpc_initiate_received(partid_t, int, void *);
+extern enum xpc_retval xpc_setup_infrastructure(struct xpc_partition *);
+extern enum xpc_retval xpc_pull_remote_vars_part(struct xpc_partition *);
+extern void xpc_process_channel_activity(struct xpc_partition *);
+extern void xpc_connected_callout(struct xpc_channel *);
+extern void xpc_deliver_msg(struct xpc_channel *);
+extern void xpc_disconnect_channel(const int, struct xpc_channel *,
+					enum xpc_retval, unsigned long *);
+extern void xpc_disconnected_callout(struct xpc_channel *);
+extern void xpc_partition_down(struct xpc_partition *, enum xpc_retval);
+extern void xpc_teardown_infrastructure(struct xpc_partition *);
+
+
+
+static inline void
+xpc_wakeup_channel_mgr(struct xpc_partition *part)
+{
+	if (atomic_inc_return(&part->channel_mgr_requests) == 1) {
+		wake_up(&part->channel_mgr_wq);
+	}
+}
+
+
+
+/*
+ * These next two inlines are used to keep us from tearing down a channel's
+ * msg queues while a thread may be referencing them.
+ */
+static inline void
+xpc_msgqueue_ref(struct xpc_channel *ch)
+{
+	atomic_inc(&ch->references);
+}
+
+static inline void
+xpc_msgqueue_deref(struct xpc_channel *ch)
+{
+	s32 refs = atomic_dec_return(&ch->references);
+
+	DBUG_ON(refs < 0);
+	if (refs == 0) {
+		xpc_wakeup_channel_mgr(&xpc_partitions[ch->partid]);
+	}
+}
+
+
+
+#define XPC_DISCONNECT_CHANNEL(_ch, _reason, _irqflgs) \
+		xpc_disconnect_channel(__LINE__, _ch, _reason, _irqflgs)
+
+
+/*
+ * These two inlines are used to keep us from tearing down a partition's
+ * setup infrastructure while a thread may be referencing it.
+ */
+static inline void
+xpc_part_deref(struct xpc_partition *part)
+{
+	s32 refs = atomic_dec_return(&part->references);
+
+
+	DBUG_ON(refs < 0);
+	if (refs == 0 && part->setup_state == XPC_P_WTEARDOWN) {
+		wake_up(&part->teardown_wq);
+	}
+}
+
+static inline int
+xpc_part_ref(struct xpc_partition *part)
+{
+	int setup;
+
+
+	atomic_inc(&part->references);
+	setup = (part->setup_state == XPC_P_SETUP);
+	if (!setup) {
+		xpc_part_deref(part);
+	}
+	return setup;
+}
+
+
+
+/*
+ * The following macro is to be used for the setting of the reason and
+ * reason_line fields in both the struct xpc_channel and struct xpc_partition
+ * structures.
+ */
+#define XPC_SET_REASON(_p, _reason, _line) \
+	{ \
+		(_p)->reason = _reason; \
+		(_p)->reason_line = _line; \
+	}
+
+
+
+/*
+ * The following set of macros and inlines are used for the sending and
+ * receiving of IPIs (also known as IRQs). There are two flavors of IPIs,
+ * one that is associated with partition activity (SGI_XPC_ACTIVATE) and
+ * the other that is associated with channel activity (SGI_XPC_NOTIFY).
+ */
+
+static inline u64
+xpc_IPI_receive(AMO_t *amo)
+{
+	return FETCHOP_LOAD_OP(TO_AMO((u64) &amo->variable), FETCHOP_CLEAR);
+}
+
+
+static inline enum xpc_retval
+xpc_IPI_send(AMO_t *amo, u64 flag, int nasid, int phys_cpuid, int vector)
+{
+	int ret = 0;
+	unsigned long irq_flags;
+
+
+	local_irq_save(irq_flags);
+
+	FETCHOP_STORE_OP(TO_AMO((u64) &amo->variable), FETCHOP_OR, flag);
+	sn_send_IPI_phys(nasid, phys_cpuid, vector, 0);
+
+	/*
+	 * We must always use the nofault function regardless of whether we
+	 * are on a Shub 1.1 system or a Shub 1.2 slice 0xc processor. If we
+	 * didn't, we'd never know that the other partition is down and would
+	 * keep sending IPIs and AMOs to it until the heartbeat times out.
+	 */
+	ret = xp_nofault_PIOR((u64 *) GLOBAL_MMR_ADDR(NASID_GET(&amo->variable),
+				xp_nofault_PIOR_target));
+
+	local_irq_restore(irq_flags);
+
+	return ((ret == 0) ? xpcSuccess : xpcPioReadError);
+}
+
+
+/*
+ * IPIs associated with SGI_XPC_ACTIVATE IRQ.
+ */
+
+/*
+ * Flag the appropriate AMO variable and send an IPI to the specified node.
+ */
+static inline void
+xpc_activate_IRQ_send(u64 amos_page, int from_nasid, int to_nasid,
+			int to_phys_cpuid)
+{
+	int w_index = XPC_NASID_W_INDEX(from_nasid);
+	int b_index = XPC_NASID_B_INDEX(from_nasid);
+	AMO_t *amos = (AMO_t *) __va(amos_page +
+					(XP_MAX_PARTITIONS * sizeof(AMO_t)));
+
+
+	(void) xpc_IPI_send(&amos[w_index], (1UL << b_index), to_nasid,
+				to_phys_cpuid, SGI_XPC_ACTIVATE);
+}
+
+static inline void
+xpc_IPI_send_activate(struct xpc_vars *vars)
+{
+	xpc_activate_IRQ_send(vars->amos_page_pa, cnodeid_to_nasid(0),
+				vars->act_nasid, vars->act_phys_cpuid);
+}
+
+static inline void
+xpc_IPI_send_activated(struct xpc_partition *part)
+{
+	xpc_activate_IRQ_send(part->remote_amos_page_pa, cnodeid_to_nasid(0),
+			part->remote_act_nasid, part->remote_act_phys_cpuid);
+}
+
+static inline void
+xpc_IPI_send_reactivate(struct xpc_partition *part)
+{
+	xpc_activate_IRQ_send(xpc_vars->amos_page_pa, part->reactivate_nasid,
+				xpc_vars->act_nasid, xpc_vars->act_phys_cpuid);
+}
+
+
+/*
+ * IPIs associated with SGI_XPC_NOTIFY IRQ.
+ */
+
+/*
+ * Send an IPI to the remote partition that is associated with the
+ * specified channel.
+ */
+#define XPC_NOTIFY_IRQ_SEND(_ch, _ipi_f, _irq_f) \
+		xpc_notify_IRQ_send(_ch, _ipi_f, #_ipi_f, _irq_f)
+
+static inline void
+xpc_notify_IRQ_send(struct xpc_channel *ch, u8 ipi_flag, char *ipi_flag_string,
+			unsigned long *irq_flags)
+{
+	struct xpc_partition *part = &xpc_partitions[ch->partid];
+	enum xpc_retval ret;
+
+
+	if (likely(part->act_state != XPC_P_DEACTIVATING)) {
+		ret = xpc_IPI_send(part->remote_IPI_amo_va,
+					(u64) ipi_flag << (ch->number * 8),
+					part->remote_IPI_nasid,
+					part->remote_IPI_phys_cpuid,
+					SGI_XPC_NOTIFY);
+		dev_dbg(xpc_chan, "%s sent to partid=%d, channel=%d, ret=%d\n",
+			ipi_flag_string, ch->partid, ch->number, ret);
+		if (unlikely(ret != xpcSuccess)) {
+			if (irq_flags != NULL) {
+				spin_unlock_irqrestore(&ch->lock, *irq_flags);
+			}
+			XPC_DEACTIVATE_PARTITION(part, ret);
+			if (irq_flags != NULL) {
+				spin_lock_irqsave(&ch->lock, *irq_flags);
+			}
+		}
+	}
+}
+
+
+/*
+ * Make it look like the remote partition, which is associated with the
+ * specified channel, sent us an IPI. This faked IPI will be handled
+ * by xpc_dropped_IPI_check().
+ */
+#define XPC_NOTIFY_IRQ_SEND_LOCAL(_ch, _ipi_f) \
+		xpc_notify_IRQ_send_local(_ch, _ipi_f, #_ipi_f)
+
+static inline void
+xpc_notify_IRQ_send_local(struct xpc_channel *ch, u8 ipi_flag,
+				char *ipi_flag_string)
+{
+	struct xpc_partition *part = &xpc_partitions[ch->partid];
+
+
+	FETCHOP_STORE_OP(TO_AMO((u64) &part->local_IPI_amo_va->variable),
+			FETCHOP_OR, ((u64) ipi_flag << (ch->number * 8)));
+	dev_dbg(xpc_chan, "%s sent local from partid=%d, channel=%d\n",
+		ipi_flag_string, ch->partid, ch->number);
+}
+
+
+/*
+ * The sending and receiving of IPIs includes the setting of an AMO variable
+ * to indicate the reason the IPI was sent. The 64-bit variable is divided
+ * up into eight bytes, ordered from right to left. Byte zero pertains to
+ * channel 0, byte one to channel 1, and so on. Each byte is described by
+ * the following IPI flags.
+ */
+
+#define	XPC_IPI_CLOSEREQUEST	0x01
+#define	XPC_IPI_CLOSEREPLY	0x02
+#define	XPC_IPI_OPENREQUEST	0x04
+#define	XPC_IPI_OPENREPLY	0x08
+#define	XPC_IPI_MSGREQUEST	0x10
+
+
+/* given an AMO variable and a channel#, get its associated IPI flags */
+#define XPC_GET_IPI_FLAGS(_amo, _c)	((u8) (((_amo) >> ((_c) * 8)) & 0xff))
+
+#define	XPC_ANY_OPENCLOSE_IPI_FLAGS_SET(_amo) ((_amo) & 0x0f0f0f0f0f0f0f0f)
+#define XPC_ANY_MSG_IPI_FLAGS_SET(_amo)       ((_amo) & 0x1010101010101010)
+
+
+static inline void
+xpc_IPI_send_closerequest(struct xpc_channel *ch, unsigned long *irq_flags)
+{
+	struct xpc_openclose_args *args = ch->local_openclose_args;
+
+
+	args->reason = ch->reason;
+
+	XPC_NOTIFY_IRQ_SEND(ch, XPC_IPI_CLOSEREQUEST, irq_flags);
+}
+
+static inline void
+xpc_IPI_send_closereply(struct xpc_channel *ch, unsigned long *irq_flags)
+{
+	XPC_NOTIFY_IRQ_SEND(ch, XPC_IPI_CLOSEREPLY, irq_flags);
+}
+
+static inline void
+xpc_IPI_send_openrequest(struct xpc_channel *ch, unsigned long *irq_flags)
+{
+	struct xpc_openclose_args *args = ch->local_openclose_args;
+
+
+	args->msg_size = ch->msg_size;
+	args->local_nentries = ch->local_nentries;
+
+	XPC_NOTIFY_IRQ_SEND(ch, XPC_IPI_OPENREQUEST, irq_flags);
+}
+
+static inline void
+xpc_IPI_send_openreply(struct xpc_channel *ch, unsigned long *irq_flags)
+{
+	struct xpc_openclose_args *args = ch->local_openclose_args;
+
+
+	args->remote_nentries = ch->remote_nentries;
+	args->local_nentries = ch->local_nentries;
+	args->local_msgqueue_pa = __pa(ch->local_msgqueue);
+
+	XPC_NOTIFY_IRQ_SEND(ch, XPC_IPI_OPENREPLY, irq_flags);
+}
+
+static inline void
+xpc_IPI_send_msgrequest(struct xpc_channel *ch)
+{
+	XPC_NOTIFY_IRQ_SEND(ch, XPC_IPI_MSGREQUEST, NULL);
+}
+
+static inline void
+xpc_IPI_send_local_msgrequest(struct xpc_channel *ch)
+{
+	XPC_NOTIFY_IRQ_SEND_LOCAL(ch, XPC_IPI_MSGREQUEST);
+}
+
+
+/*
+ * Memory for XPC's AMO variables is allocated by the MSPEC driver. These
+ * pages are located in the lowest granule. The lowest granule uses 4k pages
+ * for cached references and an alternate TLB handler to never provide a
+ * cacheable mapping for the entire region. This will prevent speculative
+ * reading of cached copies of our lines from being issued which will cause
+ * a PI FSB Protocol error to be generated by the SHUB. For XPC, we need 64
+ * (XP_MAX_PARTITIONS) AMO variables for message notification (xpc_main.c)
+ * and an additional 16 AMO variables for partition activation (xpc_hb.c).
+ */
+static inline AMO_t *
+xpc_IPI_init(partid_t partid)
+{
+	AMO_t *part_amo = xpc_vars->amos_page + partid;
+
+
+	xpc_IPI_receive(part_amo);
+	return part_amo;
+}
+
+
+
+static inline enum xpc_retval
+xpc_map_bte_errors(bte_result_t error)
+{
+	switch (error) {
+	case BTE_SUCCESS:	return xpcSuccess;
+	case BTEFAIL_DIR:	return xpcBteDirectoryError;
+	case BTEFAIL_POISON:	return xpcBtePoisonError;
+	case BTEFAIL_WERR:	return xpcBteWriteError;
+	case BTEFAIL_ACCESS:	return xpcBteAccessError;
+	case BTEFAIL_PWERR:	return xpcBtePWriteError;
+	case BTEFAIL_PRERR:	return xpcBtePReadError;
+	case BTEFAIL_TOUT:	return xpcBteTimeOutError;
+	case BTEFAIL_XTERR:	return xpcBteXtalkError;
+	case BTEFAIL_NOTAVAIL:	return xpcBteNotAvailable;
+	default:		return xpcBteUnmappedError;
+	}
+}
+
+
+
+static inline void *
+xpc_kmalloc_cacheline_aligned(size_t size, int flags, void **base)
+{
+	/* see if kmalloc will give us cachline aligned memory by default */
+	*base = kmalloc(size, flags);
+	if (*base == NULL) {
+		return NULL;
+	}
+	if ((u64) *base == L1_CACHE_ALIGN((u64) *base)) {
+		return *base;
+	}
+	kfree(*base);
+
+	/* nope, we'll have to do it ourselves */
+	*base = kmalloc(size + L1_CACHE_BYTES, flags);
+	if (*base == NULL) {
+		return NULL;
+	}
+	return (void *) L1_CACHE_ALIGN((u64) *base);
+}
+
+
+/*
+ * Check to see if there is any channel activity to/from the specified
+ * partition.
+ */
+static inline void
+xpc_check_for_channel_activity(struct xpc_partition *part)
+{
+	u64 IPI_amo;
+	unsigned long irq_flags;
+
+
+	IPI_amo = xpc_IPI_receive(part->local_IPI_amo_va);
+	if (IPI_amo == 0) {
+		return;
+	}
+
+	spin_lock_irqsave(&part->IPI_lock, irq_flags);
+	part->local_IPI_amo |= IPI_amo;
+	spin_unlock_irqrestore(&part->IPI_lock, irq_flags);
+
+	dev_dbg(xpc_chan, "received IPI from partid=%d, IPI_amo=0x%lx\n",
+		XPC_PARTID(part), IPI_amo);
+
+	xpc_wakeup_channel_mgr(part);
+}
+
+
+#endif /* _IA64_SN_KERNEL_XPC_H */
+