sgi-xp: isolate xpc_vars structure to sn2 only

Isolate the xpc_vars structure of XPC's reserved page to sn2 only.

Signed-off-by: Dean Nelson <dcn@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1175 insertions, 6 deletions

diff --git a/drivers/misc/sgi-xp/xpc_sn2.c b/drivers/misc/sgi-xp/xpc_sn2.c
index ee28e231dc47..89c0bb9a27f5 100644
--- a/drivers/misc/sgi-xp/xpc_sn2.c
+++ b/drivers/misc/sgi-xp/xpc_sn2.c
@@ -19,9 +19,370 @@
 #include <asm/sn/sn_sal.h>
 #include "xpc.h"
 
-struct xpc_vars *xpc_vars;
+static struct xpc_vars_sn2 *xpc_vars;	/* >>> Add _sn2 suffix? */
 static struct xpc_vars_part_sn2 *xpc_vars_part; /* >>> Add _sn2 suffix? */
 
+/*
+ * The following set of macros and functions 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 u64
+xpc_IPI_receive_sn2(AMO_t *amo)
+{
+	return FETCHOP_LOAD_OP(TO_AMO((u64)&amo->variable), FETCHOP_CLEAR);
+}
+
+static enum xp_retval
+xpc_IPI_send_sn2(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) ? xpSuccess : xpPioReadError);
+}
+
+static AMO_t *
+xpc_IPI_init_sn2(int index)
+{
+	AMO_t *amo = xpc_vars->amos_page + index;
+
+	(void)xpc_IPI_receive_sn2(amo);	/* clear AMO variable */
+	return amo;
+}
+
+/*
+ * IPIs associated with SGI_XPC_ACTIVATE IRQ.
+ */
+
+/*
+ * Flag the appropriate AMO variable and send an IPI to the specified node.
+ */
+static void
+xpc_activate_IRQ_send_sn2(u64 amos_page_pa, 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_pa +
+				    (XPC_ACTIVATE_IRQ_AMOS * sizeof(AMO_t)));
+
+	(void)xpc_IPI_send_sn2(&amos[w_index], (1UL << b_index), to_nasid,
+			       to_phys_cpuid, SGI_XPC_ACTIVATE);
+}
+
+static void
+xpc_activate_IRQ_send_local_sn2(int from_nasid)
+{
+	int w_index = XPC_NASID_W_INDEX(from_nasid);
+	int b_index = XPC_NASID_B_INDEX(from_nasid);
+	AMO_t *amos = (AMO_t *)__va(xpc_vars->amos_page_pa +
+				    (XPC_ACTIVATE_IRQ_AMOS * sizeof(AMO_t)));
+
+	/* fake the sending and receipt of an activate IRQ from remote nasid */
+	FETCHOP_STORE_OP(TO_AMO((u64)&amos[w_index].variable), FETCHOP_OR,
+			 (1UL << b_index));
+	atomic_inc(&xpc_act_IRQ_rcvd);
+	wake_up_interruptible(&xpc_act_IRQ_wq);
+}
+
+static void
+xpc_IPI_send_local_activate_sn2(int from_nasid)
+{
+	xpc_activate_IRQ_send_local_sn2(from_nasid);
+}
+
+static void
+xpc_IPI_send_activated_sn2(struct xpc_partition *part)
+{
+	xpc_activate_IRQ_send_sn2(part->remote_amos_page_pa,
+				  cnodeid_to_nasid(0), part->remote_act_nasid,
+				  part->remote_act_phys_cpuid);
+}
+
+static void
+xpc_IPI_send_local_reactivate_sn2(int from_nasid)
+{
+	xpc_activate_IRQ_send_local_sn2(from_nasid);
+}
+
+static void
+xpc_IPI_send_disengage_sn2(struct xpc_partition *part)
+{
+	xpc_activate_IRQ_send_sn2(part->remote_amos_page_pa,
+				  cnodeid_to_nasid(0), part->remote_act_nasid,
+				  part->remote_act_phys_cpuid);
+}
+
+/*
+ * IPIs associated with SGI_XPC_NOTIFY IRQ.
+ */
+
+/*
+ * Send an IPI to the remote partition that is associated with the
+ * specified channel.
+ */
+static void
+xpc_notify_IRQ_send_sn2(struct xpc_channel *ch, u8 ipi_flag,
+			char *ipi_flag_string, unsigned long *irq_flags)
+{
+	struct xpc_partition *part = &xpc_partitions[ch->partid];
+	enum xp_retval ret;
+
+	if (likely(part->act_state != XPC_P_DEACTIVATING)) {
+		ret = xpc_IPI_send_sn2(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 != xpSuccess)) {
+			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);
+		}
+	}
+}
+
+#define XPC_NOTIFY_IRQ_SEND_SN2(_ch, _ipi_f, _irq_f) \
+		xpc_notify_IRQ_send_sn2(_ch, _ipi_f, #_ipi_f, _irq_f)
+
+/*
+ * 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().
+ */
+static void
+xpc_notify_IRQ_send_local_sn2(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);
+}
+
+#define XPC_NOTIFY_IRQ_SEND_LOCAL_SN2(_ch, _ipi_f) \
+		xpc_notify_IRQ_send_local_sn2(_ch, _ipi_f, #_ipi_f)
+
+static void
+xpc_IPI_send_closerequest_sn2(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_SN2(ch, XPC_IPI_CLOSEREQUEST, irq_flags);
+}
+
+static void
+xpc_IPI_send_closereply_sn2(struct xpc_channel *ch, unsigned long *irq_flags)
+{
+	XPC_NOTIFY_IRQ_SEND_SN2(ch, XPC_IPI_CLOSEREPLY, irq_flags);
+}
+
+static void
+xpc_IPI_send_openrequest_sn2(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_SN2(ch, XPC_IPI_OPENREQUEST, irq_flags);
+}
+
+static void
+xpc_IPI_send_openreply_sn2(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_SN2(ch, XPC_IPI_OPENREPLY, irq_flags);
+}
+
+static void
+xpc_IPI_send_msgrequest_sn2(struct xpc_channel *ch)
+{
+	XPC_NOTIFY_IRQ_SEND_SN2(ch, XPC_IPI_MSGREQUEST, NULL);
+}
+
+static void
+xpc_IPI_send_local_msgrequest_sn2(struct xpc_channel *ch)
+{
+	XPC_NOTIFY_IRQ_SEND_LOCAL_SN2(ch, XPC_IPI_MSGREQUEST);
+}
+
+/*
+ * This next set of functions are used to keep track of when a partition is
+ * potentially engaged in accessing memory belonging to another partition.
+ */
+
+static void
+xpc_mark_partition_engaged_sn2(struct xpc_partition *part)
+{
+	unsigned long irq_flags;
+	AMO_t *amo = (AMO_t *)__va(part->remote_amos_page_pa +
+				   (XPC_ENGAGED_PARTITIONS_AMO *
+				    sizeof(AMO_t)));
+
+	local_irq_save(irq_flags);
+
+	/* set bit corresponding to our partid in remote partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_OR,
+			 (1UL << sn_partition_id));
+	/*
+	 * 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.
+	 */
+	(void)xp_nofault_PIOR((u64 *)GLOBAL_MMR_ADDR(NASID_GET(&amo->
+							       variable),
+						     xp_nofault_PIOR_target));
+
+	local_irq_restore(irq_flags);
+}
+
+static void
+xpc_mark_partition_disengaged_sn2(struct xpc_partition *part)
+{
+	unsigned long irq_flags;
+	AMO_t *amo = (AMO_t *)__va(part->remote_amos_page_pa +
+				   (XPC_ENGAGED_PARTITIONS_AMO *
+				    sizeof(AMO_t)));
+
+	local_irq_save(irq_flags);
+
+	/* clear bit corresponding to our partid in remote partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_AND,
+			 ~(1UL << sn_partition_id));
+	/*
+	 * 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.
+	 */
+	(void)xp_nofault_PIOR((u64 *)GLOBAL_MMR_ADDR(NASID_GET(&amo->
+							       variable),
+						     xp_nofault_PIOR_target));
+
+	local_irq_restore(irq_flags);
+}
+
+static void
+xpc_request_partition_disengage_sn2(struct xpc_partition *part)
+{
+	unsigned long irq_flags;
+	AMO_t *amo = (AMO_t *)__va(part->remote_amos_page_pa +
+				   (XPC_DISENGAGE_REQUEST_AMO * sizeof(AMO_t)));
+
+	local_irq_save(irq_flags);
+
+	/* set bit corresponding to our partid in remote partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_OR,
+			 (1UL << sn_partition_id));
+	/*
+	 * 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.
+	 */
+	(void)xp_nofault_PIOR((u64 *)GLOBAL_MMR_ADDR(NASID_GET(&amo->
+							       variable),
+						     xp_nofault_PIOR_target));
+
+	local_irq_restore(irq_flags);
+}
+
+static void
+xpc_cancel_partition_disengage_request_sn2(struct xpc_partition *part)
+{
+	unsigned long irq_flags;
+	AMO_t *amo = (AMO_t *)__va(part->remote_amos_page_pa +
+				   (XPC_DISENGAGE_REQUEST_AMO * sizeof(AMO_t)));
+
+	local_irq_save(irq_flags);
+
+	/* clear bit corresponding to our partid in remote partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_AND,
+			 ~(1UL << sn_partition_id));
+	/*
+	 * 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.
+	 */
+	(void)xp_nofault_PIOR((u64 *)GLOBAL_MMR_ADDR(NASID_GET(&amo->
+							       variable),
+						     xp_nofault_PIOR_target));
+
+	local_irq_restore(irq_flags);
+}
+
+static u64
+xpc_partition_engaged_sn2(u64 partid_mask)
+{
+	AMO_t *amo = xpc_vars->amos_page + XPC_ENGAGED_PARTITIONS_AMO;
+
+	/* return our partition's AMO variable ANDed with partid_mask */
+	return (FETCHOP_LOAD_OP(TO_AMO((u64)&amo->variable), FETCHOP_LOAD) &
+		partid_mask);
+}
+
+static u64
+xpc_partition_disengage_requested_sn2(u64 partid_mask)
+{
+	AMO_t *amo = xpc_vars->amos_page + XPC_DISENGAGE_REQUEST_AMO;
+
+	/* return our partition's AMO variable ANDed with partid_mask */
+	return (FETCHOP_LOAD_OP(TO_AMO((u64)&amo->variable), FETCHOP_LOAD) &
+		partid_mask);
+}
+
+static void
+xpc_clear_partition_engaged_sn2(u64 partid_mask)
+{
+	AMO_t *amo = xpc_vars->amos_page + XPC_ENGAGED_PARTITIONS_AMO;
+
+	/* clear bit(s) based on partid_mask in our partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_AND,
+			 ~partid_mask);
+}
+
+static void
+xpc_clear_partition_disengage_request_sn2(u64 partid_mask)
+{
+	AMO_t *amo = xpc_vars->amos_page + XPC_DISENGAGE_REQUEST_AMO;
+
+	/* clear bit(s) based on partid_mask in our partition's AMO */
+	FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_AND,
+			 ~partid_mask);
+}
+
 static enum xp_retval
 xpc_rsvd_page_init_sn2(struct xpc_rsvd_page *rp)
 {
@@ -79,7 +440,7 @@ xpc_rsvd_page_init_sn2(struct xpc_rsvd_page *rp)
 	}
 
 	/* clear xpc_vars */
-	memset(xpc_vars, 0, sizeof(struct xpc_vars));
+	memset(xpc_vars, 0, sizeof(struct xpc_vars_sn2));
 
 	xpc_vars->version = XPC_V_VERSION;
 	xpc_vars->act_nasid = cpuid_to_nasid(0);
@@ -94,15 +455,446 @@ xpc_rsvd_page_init_sn2(struct xpc_rsvd_page *rp)
 
 	/* initialize the activate IRQ related AMO variables */
 	for (i = 0; i < xp_nasid_mask_words; i++)
-		(void)xpc_IPI_init(XPC_ACTIVATE_IRQ_AMOS + i);
+		(void)xpc_IPI_init_sn2(XPC_ACTIVATE_IRQ_AMOS + i);
 
 	/* initialize the engaged remote partitions related AMO variables */
-	(void)xpc_IPI_init(XPC_ENGAGED_PARTITIONS_AMO);
-	(void)xpc_IPI_init(XPC_DISENGAGE_REQUEST_AMO);
+	(void)xpc_IPI_init_sn2(XPC_ENGAGED_PARTITIONS_AMO);
+	(void)xpc_IPI_init_sn2(XPC_DISENGAGE_REQUEST_AMO);
+
+	return xpSuccess;
+}
+
+static void
+xpc_increment_heartbeat_sn2(void)
+{
+	xpc_vars->heartbeat++;
+}
+
+static void
+xpc_offline_heartbeat_sn2(void)
+{
+	xpc_increment_heartbeat_sn2();
+	xpc_vars->heartbeat_offline = 1;
+}
+
+static void
+xpc_online_heartbeat_sn2(void)
+{
+	xpc_increment_heartbeat_sn2();
+	xpc_vars->heartbeat_offline = 0;
+}
+
+static void
+xpc_heartbeat_init_sn2(void)
+{
+	DBUG_ON(xpc_vars == NULL);
+
+	bitmap_zero(xpc_vars->heartbeating_to_mask, XP_MAX_NPARTITIONS_SN2);
+	xpc_heartbeating_to_mask = &xpc_vars->heartbeating_to_mask[0];
+	xpc_online_heartbeat_sn2();
+}
+
+static void
+xpc_heartbeat_exit_sn2(void)
+{
+	xpc_offline_heartbeat_sn2();
+}
+
+/*
+ * At periodic intervals, scan through all active partitions and ensure
+ * their heartbeat is still active.  If not, the partition is deactivated.
+ */
+static void
+xpc_check_remote_hb_sn2(void)
+{
+	struct xpc_vars_sn2 *remote_vars;
+	struct xpc_partition *part;
+	short partid;
+	enum xp_retval ret;
+
+	remote_vars = (struct xpc_vars_sn2 *)xpc_remote_copy_buffer;
+
+	for (partid = 0; partid < xp_max_npartitions; partid++) {
+
+		if (xpc_exiting)
+			break;
+
+		if (partid == sn_partition_id)
+			continue;
+
+		part = &xpc_partitions[partid];
+
+		if (part->act_state == XPC_P_INACTIVE ||
+		    part->act_state == XPC_P_DEACTIVATING) {
+			continue;
+		}
+
+		/* pull the remote_hb cache line */
+		ret = xp_remote_memcpy(remote_vars,
+				       (void *)part->remote_vars_pa,
+				       XPC_RP_VARS_SIZE);
+		if (ret != xpSuccess) {
+			XPC_DEACTIVATE_PARTITION(part, ret);
+			continue;
+		}
+
+		dev_dbg(xpc_part, "partid = %d, heartbeat = %ld, last_heartbeat"
+			" = %ld, heartbeat_offline = %ld, HB_mask[0] = 0x%lx\n",
+			partid, remote_vars->heartbeat, part->last_heartbeat,
+			remote_vars->heartbeat_offline,
+			remote_vars->heartbeating_to_mask[0]);
+
+		if (((remote_vars->heartbeat == part->last_heartbeat) &&
+		     (remote_vars->heartbeat_offline == 0)) ||
+		    !xpc_hb_allowed(sn_partition_id,
+				    &remote_vars->heartbeating_to_mask)) {
+
+			XPC_DEACTIVATE_PARTITION(part, xpNoHeartbeat);
+			continue;
+		}
+
+		part->last_heartbeat = remote_vars->heartbeat;
+	}
+}
+
+/*
+ * Get a copy of the remote partition's XPC variables from the reserved page.
+ *
+ * remote_vars points to a buffer that is cacheline aligned for BTE copies and
+ * assumed to be of size XPC_RP_VARS_SIZE.
+ */
+static enum xp_retval
+xpc_get_remote_vars_sn2(u64 remote_vars_pa, struct xpc_vars_sn2 *remote_vars)
+{
+	enum xp_retval ret;
+
+	if (remote_vars_pa == 0)
+		return xpVarsNotSet;
+
+	/* pull over the cross partition variables */
+	ret = xp_remote_memcpy(remote_vars, (void *)remote_vars_pa,
+			       XPC_RP_VARS_SIZE);
+	if (ret != xpSuccess)
+		return ret;
+
+	if (XPC_VERSION_MAJOR(remote_vars->version) !=
+	    XPC_VERSION_MAJOR(XPC_V_VERSION)) {
+		return xpBadVersion;
+	}
 
 	return xpSuccess;
 }
 
+static void
+xpc_initiate_partition_activation_sn2(struct xpc_rsvd_page *remote_rp,
+				      u64 remote_rp_pa, int nasid)
+{
+	xpc_IPI_send_local_activate(nasid);
+}
+
+/*
+ * Update the remote partition's info.
+ */
+static void
+xpc_update_partition_info_sn2(struct xpc_partition *part, u8 remote_rp_version,
+			      struct timespec *remote_rp_stamp,
+			      u64 remote_rp_pa, u64 remote_vars_pa,
+			      struct xpc_vars_sn2 *remote_vars)
+{
+	part->remote_rp_version = remote_rp_version;
+	dev_dbg(xpc_part, "  remote_rp_version = 0x%016x\n",
+		part->remote_rp_version);
+
+	part->remote_rp_stamp = *remote_rp_stamp;
+	dev_dbg(xpc_part, "  remote_rp_stamp (tv_sec = 0x%lx tv_nsec = 0x%lx\n",
+		part->remote_rp_stamp.tv_sec, part->remote_rp_stamp.tv_nsec);
+
+	part->remote_rp_pa = remote_rp_pa;
+	dev_dbg(xpc_part, "  remote_rp_pa = 0x%016lx\n", part->remote_rp_pa);
+
+	part->remote_vars_pa = remote_vars_pa;
+	dev_dbg(xpc_part, "  remote_vars_pa = 0x%016lx\n",
+		part->remote_vars_pa);
+
+	part->last_heartbeat = remote_vars->heartbeat;
+	dev_dbg(xpc_part, "  last_heartbeat = 0x%016lx\n",
+		part->last_heartbeat);
+
+	part->remote_vars_part_pa = remote_vars->vars_part_pa;
+	dev_dbg(xpc_part, "  remote_vars_part_pa = 0x%016lx\n",
+		part->remote_vars_part_pa);
+
+	part->remote_act_nasid = remote_vars->act_nasid;
+	dev_dbg(xpc_part, "  remote_act_nasid = 0x%x\n",
+		part->remote_act_nasid);
+
+	part->remote_act_phys_cpuid = remote_vars->act_phys_cpuid;
+	dev_dbg(xpc_part, "  remote_act_phys_cpuid = 0x%x\n",
+		part->remote_act_phys_cpuid);
+
+	part->remote_amos_page_pa = remote_vars->amos_page_pa;
+	dev_dbg(xpc_part, "  remote_amos_page_pa = 0x%lx\n",
+		part->remote_amos_page_pa);
+
+	part->remote_vars_version = remote_vars->version;
+	dev_dbg(xpc_part, "  remote_vars_version = 0x%x\n",
+		part->remote_vars_version);
+}
+
+/*
+ * Prior code has determined the nasid which generated an IPI.  Inspect
+ * that nasid to determine if its partition needs to be activated or
+ * deactivated.
+ *
+ * A partition is consider "awaiting activation" if our partition
+ * flags indicate it is not active and it has a heartbeat.  A
+ * partition is considered "awaiting deactivation" if our partition
+ * flags indicate it is active but it has no heartbeat or it is not
+ * sending its heartbeat to us.
+ *
+ * To determine the heartbeat, the remote nasid must have a properly
+ * initialized reserved page.
+ */
+static void
+xpc_identify_act_IRQ_req_sn2(int nasid)
+{
+	struct xpc_rsvd_page *remote_rp;
+	struct xpc_vars_sn2 *remote_vars;
+	u64 remote_rp_pa;
+	u64 remote_vars_pa;
+	int remote_rp_version;
+	int reactivate = 0;
+	int stamp_diff;
+	struct timespec remote_rp_stamp = { 0, 0 }; /*>>> ZERO_STAMP */
+	short partid;
+	struct xpc_partition *part;
+	enum xp_retval ret;
+
+	/* pull over the reserved page structure */
+
+	remote_rp = (struct xpc_rsvd_page *)xpc_remote_copy_buffer;
+
+	ret = xpc_get_remote_rp(nasid, NULL, remote_rp, &remote_rp_pa);
+	if (ret != xpSuccess) {
+		dev_warn(xpc_part, "unable to get reserved page from nasid %d, "
+			 "which sent interrupt, reason=%d\n", nasid, ret);
+		return;
+	}
+
+	remote_vars_pa = remote_rp->sn.vars_pa;
+	remote_rp_version = remote_rp->version;
+	if (XPC_SUPPORTS_RP_STAMP(remote_rp_version))
+		remote_rp_stamp = remote_rp->stamp;
+
+	partid = remote_rp->SAL_partid;
+	part = &xpc_partitions[partid];
+
+	/* pull over the cross partition variables */
+
+	remote_vars = (struct xpc_vars_sn2 *)xpc_remote_copy_buffer;
+
+	ret = xpc_get_remote_vars_sn2(remote_vars_pa, remote_vars);
+	if (ret != xpSuccess) {
+
+		dev_warn(xpc_part, "unable to get XPC variables from nasid %d, "
+			 "which sent interrupt, reason=%d\n", nasid, ret);
+
+		XPC_DEACTIVATE_PARTITION(part, ret);
+		return;
+	}
+
+	part->act_IRQ_rcvd++;
+
+	dev_dbg(xpc_part, "partid for nasid %d is %d; IRQs = %d; HB = "
+		"%ld:0x%lx\n", (int)nasid, (int)partid, part->act_IRQ_rcvd,
+		remote_vars->heartbeat, remote_vars->heartbeating_to_mask[0]);
+
+	if (xpc_partition_disengaged(part) &&
+	    part->act_state == XPC_P_INACTIVE) {
+
+		xpc_update_partition_info_sn2(part, remote_rp_version,
+					      &remote_rp_stamp, remote_rp_pa,
+					      remote_vars_pa, remote_vars);
+
+		if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version)) {
+			if (xpc_partition_disengage_requested(1UL << partid)) {
+				/*
+				 * Other side is waiting on us to disengage,
+				 * even though we already have.
+				 */
+				return;
+			}
+
+		} else {
+			/* other side doesn't support disengage requests */
+			xpc_clear_partition_disengage_request(1UL << partid);
+		}
+
+		xpc_activate_partition(part);
+		return;
+	}
+
+	DBUG_ON(part->remote_rp_version == 0);
+	DBUG_ON(part->remote_vars_version == 0);
+
+	if (!XPC_SUPPORTS_RP_STAMP(part->remote_rp_version)) {
+		DBUG_ON(XPC_SUPPORTS_DISENGAGE_REQUEST(part->
+						       remote_vars_version));
+
+		if (!XPC_SUPPORTS_RP_STAMP(remote_rp_version)) {
+			DBUG_ON(XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->
+							       version));
+			/* see if the other side rebooted */
+			if (part->remote_amos_page_pa ==
+			    remote_vars->amos_page_pa &&
+			    xpc_hb_allowed(sn_partition_id,
+					  &remote_vars->heartbeating_to_mask)) {
+				/* doesn't look that way, so ignore the IPI */
+				return;
+			}
+		}
+
+		/*
+		 * Other side rebooted and previous XPC didn't support the
+		 * disengage request, so we don't need to do anything special.
+		 */
+
+		xpc_update_partition_info_sn2(part, remote_rp_version,
+					      &remote_rp_stamp, remote_rp_pa,
+					      remote_vars_pa, remote_vars);
+		part->reactivate_nasid = nasid;
+		XPC_DEACTIVATE_PARTITION(part, xpReactivating);
+		return;
+	}
+
+	DBUG_ON(!XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version));
+
+	if (!XPC_SUPPORTS_RP_STAMP(remote_rp_version)) {
+		DBUG_ON(!XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->version));
+
+		/*
+		 * Other side rebooted and previous XPC did support the
+		 * disengage request, but the new one doesn't.
+		 */
+
+		xpc_clear_partition_engaged(1UL << partid);
+		xpc_clear_partition_disengage_request(1UL << partid);
+
+		xpc_update_partition_info_sn2(part, remote_rp_version,
+					      &remote_rp_stamp, remote_rp_pa,
+					      remote_vars_pa, remote_vars);
+		reactivate = 1;
+
+	} else {
+		DBUG_ON(!XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->version));
+
+		stamp_diff = xpc_compare_stamps(&part->remote_rp_stamp,
+						&remote_rp_stamp);
+		if (stamp_diff != 0) {
+			DBUG_ON(stamp_diff >= 0);
+
+			/*
+			 * Other side rebooted and the previous XPC did support
+			 * the disengage request, as does the new one.
+			 */
+
+			DBUG_ON(xpc_partition_engaged(1UL << partid));
+			DBUG_ON(xpc_partition_disengage_requested(1UL <<
+								  partid));
+
+			xpc_update_partition_info_sn2(part, remote_rp_version,
+						      &remote_rp_stamp,
+						      remote_rp_pa,
+						      remote_vars_pa,
+						      remote_vars);
+			reactivate = 1;
+		}
+	}
+
+	if (part->disengage_request_timeout > 0 &&
+	    !xpc_partition_disengaged(part)) {
+		/* still waiting on other side to disengage from us */
+		return;
+	}
+
+	if (reactivate) {
+		part->reactivate_nasid = nasid;
+		XPC_DEACTIVATE_PARTITION(part, xpReactivating);
+
+	} else if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version) &&
+		   xpc_partition_disengage_requested(1UL << partid)) {
+		XPC_DEACTIVATE_PARTITION(part, xpOtherGoingDown);
+	}
+}
+
+/*
+ * Loop through the activation AMO variables and process any bits
+ * which are set.  Each bit indicates a nasid sending a partition
+ * activation or deactivation request.
+ *
+ * Return #of IRQs detected.
+ */
+int
+xpc_identify_act_IRQ_sender_sn2(void)
+{
+	int word, bit;
+	u64 nasid_mask;
+	u64 nasid;		/* remote nasid */
+	int n_IRQs_detected = 0;
+	AMO_t *act_amos;
+
+	act_amos = xpc_vars->amos_page + XPC_ACTIVATE_IRQ_AMOS;
+
+	/* scan through act AMO variable looking for non-zero entries */
+	for (word = 0; word < xp_nasid_mask_words; word++) {
+
+		if (xpc_exiting)
+			break;
+
+		nasid_mask = xpc_IPI_receive_sn2(&act_amos[word]);
+		if (nasid_mask == 0) {
+			/* no IRQs from nasids in this variable */
+			continue;
+		}
+
+		dev_dbg(xpc_part, "AMO[%d] gave back 0x%lx\n", word,
+			nasid_mask);
+
+		/*
+		 * If this nasid has been added to the machine since
+		 * our partition was reset, this will retain the
+		 * remote nasid in our reserved pages machine mask.
+		 * This is used in the event of module reload.
+		 */
+		xpc_mach_nasids[word] |= nasid_mask;
+
+		/* locate the nasid(s) which sent interrupts */
+
+		for (bit = 0; bit < (8 * sizeof(u64)); bit++) {
+			if (nasid_mask & (1UL << bit)) {
+				n_IRQs_detected++;
+				nasid = XPC_NASID_FROM_W_B(word, bit);
+				dev_dbg(xpc_part, "interrupt from nasid %ld\n",
+					nasid);
+				xpc_identify_act_IRQ_req_sn2(nasid);
+			}
+		}
+	}
+	return n_IRQs_detected;
+}
+
+static void
+xpc_process_act_IRQ_rcvd_sn2(int n_IRQs_expected)
+{
+	int n_IRQs_detected;
+
+	n_IRQs_detected = xpc_identify_act_IRQ_sender_sn2();
+	if (n_IRQs_detected < n_IRQs_expected) {
+		/* retry once to help avoid missing AMO */
+		(void)xpc_identify_act_IRQ_sender_sn2();
+	}
+}
+
 /*
  * Setup the infrastructure necessary to support XPartition Communication
  * between the specified remote partition and the local one.
@@ -177,7 +969,7 @@ xpc_setup_infrastructure_sn2(struct xpc_partition *part)
 
 	part->remote_openclose_args_pa = 0;
 
-	part->local_IPI_amo_va = xpc_IPI_init(partid);
+	part->local_IPI_amo_va = xpc_IPI_init_sn2(partid);
 	part->local_IPI_amo = 0;
 	spin_lock_init(&part->IPI_lock);
 
@@ -468,6 +1260,28 @@ xpc_make_first_contact_sn2(struct xpc_partition *part)
 {
 	enum xp_retval ret;
 
+	/*
+	 * Register the remote partition's AMOs with SAL so it can handle
+	 * and cleanup errors within that address range should the remote
+	 * partition go down. We don't unregister this range because it is
+	 * difficult to tell when outstanding writes to the remote partition
+	 * are finished and thus when it is safe to unregister. This should
+	 * not result in wasted space in the SAL xp_addr_region table because
+	 * we should get the same page for remote_amos_page_pa after module
+	 * reloads and system reboots.
+	 */
+	if (sn_register_xp_addr_region(part->remote_amos_page_pa,
+				       PAGE_SIZE, 1) < 0) {
+		dev_warn(xpc_part, "xpc_activating(%d) failed to register "
+			 "xp_addr region\n", XPC_PARTID(part));
+
+		ret = xpPhysAddrRegFailed;
+		XPC_DEACTIVATE_PARTITION(part, ret);
+		return ret;
+	}
+
+	xpc_IPI_send_activated(part);
+
 	while ((ret = xpc_pull_remote_vars_part_sn2(part)) != xpSuccess) {
 		if (ret != xpRetry) {
 			XPC_DEACTIVATE_PARTITION(part, ret);
@@ -651,15 +1465,370 @@ xpc_get_deliverable_msg_sn2(struct xpc_channel *ch)
 	return msg;
 }
 
+/*
+ * Now we actually send the messages that are ready to be sent by advancing
+ * the local message queue's Put value and then send an IPI to the recipient
+ * partition.
+ */
+static void
+xpc_send_msgs_sn2(struct xpc_channel *ch, s64 initial_put)
+{
+	struct xpc_msg *msg;
+	s64 put = initial_put + 1;
+	int send_IPI = 0;
+
+	while (1) {
+
+		while (1) {
+			if (put == ch->w_local_GP.put)
+				break;
+
+			msg = (struct xpc_msg *)((u64)ch->local_msgqueue +
+						 (put % ch->local_nentries) *
+						 ch->msg_size);
+
+			if (!(msg->flags & XPC_M_READY))
+				break;
+
+			put++;
+		}
+
+		if (put == initial_put) {
+			/* nothing's changed */
+			break;
+		}
+
+		if (cmpxchg_rel(&ch->local_GP->put, initial_put, put) !=
+		    initial_put) {
+			/* someone else beat us to it */
+			DBUG_ON(ch->local_GP->put < initial_put);
+			break;
+		}
+
+		/* we just set the new value of local_GP->put */
+
+		dev_dbg(xpc_chan, "local_GP->put changed to %ld, partid=%d, "
+			"channel=%d\n", put, ch->partid, ch->number);
+
+		send_IPI = 1;
+
+		/*
+		 * We need to ensure that the message referenced by
+		 * local_GP->put is not XPC_M_READY or that local_GP->put
+		 * equals w_local_GP.put, so we'll go have a look.
+		 */
+		initial_put = put;
+	}
+
+	if (send_IPI)
+		xpc_IPI_send_msgrequest_sn2(ch);
+}
+
+/*
+ * Allocate an entry for a message from the message queue associated with the
+ * specified channel.
+ */
+static enum xp_retval
+xpc_allocate_msg_sn2(struct xpc_channel *ch, u32 flags,
+		     struct xpc_msg **address_of_msg)
+{
+	struct xpc_msg *msg;
+	enum xp_retval ret;
+	s64 put;
+
+	/* this reference will be dropped in xpc_send_msg_sn2() */
+	xpc_msgqueue_ref(ch);
+
+	if (ch->flags & XPC_C_DISCONNECTING) {
+		xpc_msgqueue_deref(ch);
+		return ch->reason;
+	}
+	if (!(ch->flags & XPC_C_CONNECTED)) {
+		xpc_msgqueue_deref(ch);
+		return xpNotConnected;
+	}
+
+	/*
+	 * Get the next available message entry from the local message queue.
+	 * If none are available, we'll make sure that we grab the latest
+	 * GP values.
+	 */
+	ret = xpTimeout;
+
+	while (1) {
+
+		put = ch->w_local_GP.put;
+		rmb();	/* guarantee that .put loads before .get */
+		if (put - ch->w_remote_GP.get < ch->local_nentries) {
+
+			/* There are available message entries. We need to try
+			 * to secure one for ourselves. We'll do this by trying
+			 * to increment w_local_GP.put as long as someone else
+			 * doesn't beat us to it. If they do, we'll have to
+			 * try again.
+			 */
+			if (cmpxchg(&ch->w_local_GP.put, put, put + 1) == put) {
+				/* we got the entry referenced by put */
+				break;
+			}
+			continue;	/* try again */
+		}
+
+		/*
+		 * There aren't any available msg entries at this time.
+		 *
+		 * In waiting for a message entry to become available,
+		 * we set a timeout in case the other side is not
+		 * sending completion IPIs. This lets us fake an IPI
+		 * that will cause the IPI handler to fetch the latest
+		 * GP values as if an IPI was sent by the other side.
+		 */
+		if (ret == xpTimeout)
+			xpc_IPI_send_local_msgrequest_sn2(ch);
+
+		if (flags & XPC_NOWAIT) {
+			xpc_msgqueue_deref(ch);
+			return xpNoWait;
+		}
+
+		ret = xpc_allocate_msg_wait(ch);
+		if (ret != xpInterrupted && ret != xpTimeout) {
+			xpc_msgqueue_deref(ch);
+			return ret;
+		}
+	}
+
+	/* get the message's address and initialize it */
+	msg = (struct xpc_msg *)((u64)ch->local_msgqueue +
+				 (put % ch->local_nentries) * ch->msg_size);
+
+	DBUG_ON(msg->flags != 0);
+	msg->number = put;
+
+	dev_dbg(xpc_chan, "w_local_GP.put changed to %ld; msg=0x%p, "
+		"msg_number=%ld, partid=%d, channel=%d\n", put + 1,
+		(void *)msg, msg->number, ch->partid, ch->number);
+
+	*address_of_msg = msg;
+
+	return xpSuccess;
+}
+
+/*
+ * Common code that does the actual sending of the message by advancing the
+ * local message queue's Put value and sends an IPI to the partition the
+ * message is being sent to.
+ */
+static enum xp_retval
+xpc_send_msg_sn2(struct xpc_channel *ch, struct xpc_msg *msg, u8 notify_type,
+		 xpc_notify_func func, void *key)
+{
+	enum xp_retval ret = xpSuccess;
+	struct xpc_notify *notify = notify;
+	s64 put, msg_number = msg->number;
+
+	DBUG_ON(notify_type == XPC_N_CALL && func == NULL);
+	DBUG_ON((((u64)msg - (u64)ch->local_msgqueue) / ch->msg_size) !=
+		msg_number % ch->local_nentries);
+	DBUG_ON(msg->flags & XPC_M_READY);
+
+	if (ch->flags & XPC_C_DISCONNECTING) {
+		/* drop the reference grabbed in xpc_allocate_msg_sn2() */
+		xpc_msgqueue_deref(ch);
+		return ch->reason;
+	}
+
+	if (notify_type != 0) {
+		/*
+		 * Tell the remote side to send an ACK interrupt when the
+		 * message has been delivered.
+		 */
+		msg->flags |= XPC_M_INTERRUPT;
+
+		atomic_inc(&ch->n_to_notify);
+
+		notify = &ch->notify_queue[msg_number % ch->local_nentries];
+		notify->func = func;
+		notify->key = key;
+		notify->type = notify_type;
+
+		/* >>> is a mb() needed here? */
+
+		if (ch->flags & XPC_C_DISCONNECTING) {
+			/*
+			 * An error occurred between our last error check and
+			 * this one. We will try to clear the type field from
+			 * the notify entry. If we succeed then
+			 * xpc_disconnect_channel() didn't already process
+			 * the notify entry.
+			 */
+			if (cmpxchg(&notify->type, notify_type, 0) ==
+			    notify_type) {
+				atomic_dec(&ch->n_to_notify);
+				ret = ch->reason;
+			}
+
+			/* drop reference grabbed in xpc_allocate_msg_sn2() */
+			xpc_msgqueue_deref(ch);
+			return ret;
+		}
+	}
+
+	msg->flags |= XPC_M_READY;
+
+	/*
+	 * The preceding store of msg->flags must occur before the following
+	 * load of ch->local_GP->put.
+	 */
+	mb();
+
+	/* see if the message is next in line to be sent, if so send it */
+
+	put = ch->local_GP->put;
+	if (put == msg_number)
+		xpc_send_msgs_sn2(ch, put);
+
+	/* drop the reference grabbed in xpc_allocate_msg_sn2() */
+	xpc_msgqueue_deref(ch);
+	return ret;
+}
+
+/*
+ * Now we actually acknowledge the messages that have been delivered and ack'd
+ * by advancing the cached remote message queue's Get value and if requested
+ * send an IPI to the message sender's partition.
+ */
+static void
+xpc_acknowledge_msgs_sn2(struct xpc_channel *ch, s64 initial_get, u8 msg_flags)
+{
+	struct xpc_msg *msg;
+	s64 get = initial_get + 1;
+	int send_IPI = 0;
+
+	while (1) {
+
+		while (1) {
+			if (get == ch->w_local_GP.get)
+				break;
+
+			msg = (struct xpc_msg *)((u64)ch->remote_msgqueue +
+						 (get % ch->remote_nentries) *
+						 ch->msg_size);
+
+			if (!(msg->flags & XPC_M_DONE))
+				break;
+
+			msg_flags |= msg->flags;
+			get++;
+		}
+
+		if (get == initial_get) {
+			/* nothing's changed */
+			break;
+		}
+
+		if (cmpxchg_rel(&ch->local_GP->get, initial_get, get) !=
+		    initial_get) {
+			/* someone else beat us to it */
+			DBUG_ON(ch->local_GP->get <= initial_get);
+			break;
+		}
+
+		/* we just set the new value of local_GP->get */
+
+		dev_dbg(xpc_chan, "local_GP->get changed to %ld, partid=%d, "
+			"channel=%d\n", get, ch->partid, ch->number);
+
+		send_IPI = (msg_flags & XPC_M_INTERRUPT);
+
+		/*
+		 * We need to ensure that the message referenced by
+		 * local_GP->get is not XPC_M_DONE or that local_GP->get
+		 * equals w_local_GP.get, so we'll go have a look.
+		 */
+		initial_get = get;
+	}
+
+	if (send_IPI)
+		xpc_IPI_send_msgrequest_sn2(ch);
+}
+
+static void
+xpc_received_msg_sn2(struct xpc_channel *ch, struct xpc_msg *msg)
+{
+	s64 get;
+	s64 msg_number = msg->number;
+
+	dev_dbg(xpc_chan, "msg=0x%p, msg_number=%ld, partid=%d, channel=%d\n",
+		(void *)msg, msg_number, ch->partid, ch->number);
+
+	DBUG_ON((((u64)msg - (u64)ch->remote_msgqueue) / ch->msg_size) !=
+		msg_number % ch->remote_nentries);
+	DBUG_ON(msg->flags & XPC_M_DONE);
+
+	msg->flags |= XPC_M_DONE;
+
+	/*
+	 * The preceding store of msg->flags must occur before the following
+	 * load of ch->local_GP->get.
+	 */
+	mb();
+
+	/*
+	 * See if this message is next in line to be acknowledged as having
+	 * been delivered.
+	 */
+	get = ch->local_GP->get;
+	if (get == msg_number)
+		xpc_acknowledge_msgs_sn2(ch, get, msg->flags);
+}
+
 void
 xpc_init_sn2(void)
 {
 	xpc_rsvd_page_init = xpc_rsvd_page_init_sn2;
+	xpc_increment_heartbeat = xpc_increment_heartbeat_sn2;
+	xpc_offline_heartbeat = xpc_offline_heartbeat_sn2;
+	xpc_online_heartbeat = xpc_online_heartbeat_sn2;
+	xpc_heartbeat_init = xpc_heartbeat_init_sn2;
+	xpc_heartbeat_exit = xpc_heartbeat_exit_sn2;
+	xpc_check_remote_hb = xpc_check_remote_hb_sn2;
+
+	xpc_initiate_partition_activation =
+	    xpc_initiate_partition_activation_sn2;
+	xpc_process_act_IRQ_rcvd = xpc_process_act_IRQ_rcvd_sn2;
 	xpc_setup_infrastructure = xpc_setup_infrastructure_sn2;
 	xpc_teardown_infrastructure = xpc_teardown_infrastructure_sn2;
 	xpc_make_first_contact = xpc_make_first_contact_sn2;
 	xpc_get_IPI_flags = xpc_get_IPI_flags_sn2;
 	xpc_get_deliverable_msg = xpc_get_deliverable_msg_sn2;
+
+	xpc_mark_partition_engaged = xpc_mark_partition_engaged_sn2;
+	xpc_mark_partition_disengaged = xpc_mark_partition_disengaged_sn2;
+	xpc_request_partition_disengage = xpc_request_partition_disengage_sn2;
+	xpc_cancel_partition_disengage_request =
+	    xpc_cancel_partition_disengage_request_sn2;
+	xpc_partition_engaged = xpc_partition_engaged_sn2;
+	xpc_partition_disengage_requested =
+	    xpc_partition_disengage_requested_sn2;
+	xpc_clear_partition_engaged = xpc_clear_partition_engaged_sn2;
+	xpc_clear_partition_disengage_request =
+	    xpc_clear_partition_disengage_request_sn2;
+
+	xpc_IPI_send_local_activate = xpc_IPI_send_local_activate_sn2;
+	xpc_IPI_send_activated = xpc_IPI_send_activated_sn2;
+	xpc_IPI_send_local_reactivate = xpc_IPI_send_local_reactivate_sn2;
+	xpc_IPI_send_disengage = xpc_IPI_send_disengage_sn2;
+
+	xpc_IPI_send_closerequest = xpc_IPI_send_closerequest_sn2;
+	xpc_IPI_send_closereply = xpc_IPI_send_closereply_sn2;
+	xpc_IPI_send_openrequest = xpc_IPI_send_openrequest_sn2;
+	xpc_IPI_send_openreply = xpc_IPI_send_openreply_sn2;
+
+	xpc_allocate_msg = xpc_allocate_msg_sn2;
+
+	xpc_send_msg = xpc_send_msg_sn2;
+	xpc_received_msg = xpc_received_msg_sn2;
 }
 
 void