Adding upstream version 4.19.249.upstream/4.19.249

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2459 insertions, 0 deletions

diff --git a/drivers/misc/sgi-xp/xpc_sn2.c b/drivers/misc/sgi-xp/xpc_sn2.c
new file mode 100644
index 000000000..5a12d2a54
--- /dev/null
+++ b/drivers/misc/sgi-xp/xpc_sn2.c
@@ -0,0 +1,2459 @@
+/*
+ * 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) 2008-2009 Silicon Graphics, Inc.  All Rights Reserved.
+ */
+
+/*
+ * Cross Partition Communication (XPC) sn2-based functions.
+ *
+ *     Architecture specific implementation of common functions.
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <asm/uncached.h>
+#include <asm/sn/mspec.h>
+#include <asm/sn/sn_sal.h>
+#include "xpc.h"
+
+/*
+ * Define the number of u64s required to represent all the C-brick nasids
+ * as a bitmap.  The cross-partition kernel modules deal only with
+ * C-brick nasids, thus the need for bitmaps which don't account for
+ * odd-numbered (non C-brick) nasids.
+ */
+#define XPC_MAX_PHYSNODES_SN2	(MAX_NUMALINK_NODES / 2)
+#define XP_NASID_MASK_BYTES_SN2	((XPC_MAX_PHYSNODES_SN2 + 7) / 8)
+#define XP_NASID_MASK_WORDS_SN2	((XPC_MAX_PHYSNODES_SN2 + 63) / 64)
+
+/*
+ * 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
+ * amo variables (based on XP_MAX_NPARTITIONS_SN2) to identify the senders of
+ * NOTIFY IRQs, 128 amo variables (based on XP_NASID_MASK_WORDS_SN2) to identify
+ * the senders of ACTIVATE IRQs, 1 amo variable to identify which remote
+ * partitions (i.e., XPCs) consider themselves currently engaged with the
+ * local XPC and 1 amo variable to request partition deactivation.
+ */
+#define XPC_NOTIFY_IRQ_AMOS_SN2		0
+#define XPC_ACTIVATE_IRQ_AMOS_SN2	(XPC_NOTIFY_IRQ_AMOS_SN2 + \
+					 XP_MAX_NPARTITIONS_SN2)
+#define XPC_ENGAGED_PARTITIONS_AMO_SN2	(XPC_ACTIVATE_IRQ_AMOS_SN2 + \
+					 XP_NASID_MASK_WORDS_SN2)
+#define XPC_DEACTIVATE_REQUEST_AMO_SN2	(XPC_ENGAGED_PARTITIONS_AMO_SN2 + 1)
+
+/*
+ * Buffer used to store a local copy of portions of a remote partition's
+ * reserved page (either its header and part_nasids mask, or its vars).
+ */
+static void *xpc_remote_copy_buffer_base_sn2;
+static char *xpc_remote_copy_buffer_sn2;
+
+static struct xpc_vars_sn2 *xpc_vars_sn2;
+static struct xpc_vars_part_sn2 *xpc_vars_part_sn2;
+
+static int
+xpc_setup_partitions_sn2(void)
+{
+	/* nothing needs to be done */
+	return 0;
+}
+
+static void
+xpc_teardown_partitions_sn2(void)
+{
+	/* nothing needs to be done */
+}
+
+/* SH_IPI_ACCESS shub register value on startup */
+static u64 xpc_sh1_IPI_access_sn2;
+static u64 xpc_sh2_IPI_access0_sn2;
+static u64 xpc_sh2_IPI_access1_sn2;
+static u64 xpc_sh2_IPI_access2_sn2;
+static u64 xpc_sh2_IPI_access3_sn2;
+
+/*
+ * Change protections to allow IPI operations.
+ */
+static void
+xpc_allow_IPI_ops_sn2(void)
+{
+	int node;
+	int nasid;
+
+	/* !!! The following should get moved into SAL. */
+	if (is_shub2()) {
+		xpc_sh2_IPI_access0_sn2 =
+		    (u64)HUB_L((u64 *)LOCAL_MMR_ADDR(SH2_IPI_ACCESS0));
+		xpc_sh2_IPI_access1_sn2 =
+		    (u64)HUB_L((u64 *)LOCAL_MMR_ADDR(SH2_IPI_ACCESS1));
+		xpc_sh2_IPI_access2_sn2 =
+		    (u64)HUB_L((u64 *)LOCAL_MMR_ADDR(SH2_IPI_ACCESS2));
+		xpc_sh2_IPI_access3_sn2 =
+		    (u64)HUB_L((u64 *)LOCAL_MMR_ADDR(SH2_IPI_ACCESS3));
+
+		for_each_online_node(node) {
+			nasid = cnodeid_to_nasid(node);
+			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS0),
+			      -1UL);
+			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS1),
+			      -1UL);
+			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS2),
+			      -1UL);
+			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS3),
+			      -1UL);
+		}
+	} else {
+		xpc_sh1_IPI_access_sn2 =
+		    (u64)HUB_L((u64 *)LOCAL_MMR_ADDR(SH1_IPI_ACCESS));
+
+		for_each_online_node(node) {
+			nasid = cnodeid_to_nasid(node);
+			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH1_IPI_ACCESS),
+			      -1UL);
+		}
+	}
+}
+
+/*
+ * Restrict protections to disallow IPI operations.
+ */
+static void
+xpc_disallow_IPI_ops_sn2(void)
+{
+	int node;
+	int nasid;
+
+	/* !!! The following should get moved into SAL. */
+	if (is_shub2()) {
+		for_each_online_node(node) {
+			nasid = cnodeid_to_nasid(node);
+			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS0),
+			      xpc_sh2_IPI_access0_sn2);
+			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS1),
+			      xpc_sh2_IPI_access1_sn2);
+			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS2),
+			      xpc_sh2_IPI_access2_sn2);
+			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS3),
+			      xpc_sh2_IPI_access3_sn2);
+		}
+	} else {
+		for_each_online_node(node) {
+			nasid = cnodeid_to_nasid(node);
+			HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid, SH1_IPI_ACCESS),
+			      xpc_sh1_IPI_access_sn2);
+		}
+	}
+}
+
+/*
+ * The following set of functions are used for the sending and receiving of
+ * IRQs (also known as IPIs). There are two flavors of IRQs, 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_receive_IRQ_amo_sn2(struct amo *amo)
+{
+	return FETCHOP_LOAD_OP(TO_AMO((u64)&amo->variable), FETCHOP_CLEAR);
+}
+
+static enum xp_retval
+xpc_send_IRQ_sn2(struct amo *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 IRQs 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 struct amo *
+xpc_init_IRQ_amo_sn2(int index)
+{
+	struct amo *amo = xpc_vars_sn2->amos_page + index;
+
+	(void)xpc_receive_IRQ_amo_sn2(amo);	/* clear amo variable */
+	return amo;
+}
+
+/*
+ * Functions associated with SGI_XPC_ACTIVATE IRQ.
+ */
+
+/*
+ * Notify the heartbeat check thread that an activate IRQ has been received.
+ */
+static irqreturn_t
+xpc_handle_activate_IRQ_sn2(int irq, void *dev_id)
+{
+	unsigned long irq_flags;
+
+	spin_lock_irqsave(&xpc_activate_IRQ_rcvd_lock, irq_flags);
+	xpc_activate_IRQ_rcvd++;
+	spin_unlock_irqrestore(&xpc_activate_IRQ_rcvd_lock, irq_flags);
+
+	wake_up_interruptible(&xpc_activate_IRQ_wq);
+	return IRQ_HANDLED;
+}
+
+/*
+ * Flag the appropriate amo variable and send an IRQ to the specified node.
+ */
+static void
+xpc_send_activate_IRQ_sn2(unsigned long amos_page_pa, int from_nasid,
+			  int to_nasid, int to_phys_cpuid)
+{
+	struct amo *amos = (struct amo *)__va(amos_page_pa +
+					      (XPC_ACTIVATE_IRQ_AMOS_SN2 *
+					      sizeof(struct amo)));
+
+	(void)xpc_send_IRQ_sn2(&amos[BIT_WORD(from_nasid / 2)],
+			       BIT_MASK(from_nasid / 2), to_nasid,
+			       to_phys_cpuid, SGI_XPC_ACTIVATE);
+}
+
+static void
+xpc_send_local_activate_IRQ_sn2(int from_nasid)
+{
+	unsigned long irq_flags;
+	struct amo *amos = (struct amo *)__va(xpc_vars_sn2->amos_page_pa +
+					      (XPC_ACTIVATE_IRQ_AMOS_SN2 *
+					      sizeof(struct amo)));
+
+	/* fake the sending and receipt of an activate IRQ from remote nasid */
+	FETCHOP_STORE_OP(TO_AMO((u64)&amos[BIT_WORD(from_nasid / 2)].variable),
+			 FETCHOP_OR, BIT_MASK(from_nasid / 2));
+
+	spin_lock_irqsave(&xpc_activate_IRQ_rcvd_lock, irq_flags);
+	xpc_activate_IRQ_rcvd++;
+	spin_unlock_irqrestore(&xpc_activate_IRQ_rcvd_lock, irq_flags);
+
+	wake_up_interruptible(&xpc_activate_IRQ_wq);
+}
+
+/*
+ * Functions associated with SGI_XPC_NOTIFY IRQ.
+ */
+
+/*
+ * Check to see if any chctl flags were sent from the specified partition.
+ */
+static void
+xpc_check_for_sent_chctl_flags_sn2(struct xpc_partition *part)
+{
+	union xpc_channel_ctl_flags chctl;
+	unsigned long irq_flags;
+
+	chctl.all_flags = xpc_receive_IRQ_amo_sn2(part->sn.sn2.
+						  local_chctl_amo_va);
+	if (chctl.all_flags == 0)
+		return;
+
+	spin_lock_irqsave(&part->chctl_lock, irq_flags);
+	part->chctl.all_flags |= chctl.all_flags;
+	spin_unlock_irqrestore(&part->chctl_lock, irq_flags);
+
+	dev_dbg(xpc_chan, "received notify IRQ from partid=%d, chctl.all_flags="
+		"0x%llx\n", XPC_PARTID(part), chctl.all_flags);
+
+	xpc_wakeup_channel_mgr(part);
+}
+
+/*
+ * Handle the receipt of a SGI_XPC_NOTIFY IRQ by seeing whether the specified
+ * partition actually sent it. Since SGI_XPC_NOTIFY IRQs may be shared by more
+ * than one partition, we use an amo structure per partition to indicate
+ * whether a partition has sent an IRQ or not.  If it has, then wake up the
+ * associated kthread to handle it.
+ *
+ * All SGI_XPC_NOTIFY IRQs received by XPC are the result of IRQs sent by XPC
+ * running on other partitions.
+ *
+ * Noteworthy Arguments:
+ *
+ *	irq - Interrupt ReQuest number. NOT USED.
+ *
+ *	dev_id - partid of IRQ's potential sender.
+ */
+static irqreturn_t
+xpc_handle_notify_IRQ_sn2(int irq, void *dev_id)
+{
+	short partid = (short)(u64)dev_id;
+	struct xpc_partition *part = &xpc_partitions[partid];
+
+	DBUG_ON(partid < 0 || partid >= XP_MAX_NPARTITIONS_SN2);
+
+	if (xpc_part_ref(part)) {
+		xpc_check_for_sent_chctl_flags_sn2(part);
+
+		xpc_part_deref(part);
+	}
+	return IRQ_HANDLED;
+}
+
+/*
+ * Check to see if xpc_handle_notify_IRQ_sn2() dropped any IRQs on the floor
+ * because the write to their associated amo variable completed after the IRQ
+ * was received.
+ */
+static void
+xpc_check_for_dropped_notify_IRQ_sn2(struct timer_list *t)
+{
+	struct xpc_partition *part =
+		from_timer(part, t, sn.sn2.dropped_notify_IRQ_timer);
+
+	if (xpc_part_ref(part)) {
+		xpc_check_for_sent_chctl_flags_sn2(part);
+
+		t->expires = jiffies + XPC_DROPPED_NOTIFY_IRQ_WAIT_INTERVAL;
+		add_timer(t);
+		xpc_part_deref(part);
+	}
+}
+
+/*
+ * Send a notify IRQ to the remote partition that is associated with the
+ * specified channel.
+ */
+static void
+xpc_send_notify_IRQ_sn2(struct xpc_channel *ch, u8 chctl_flag,
+			char *chctl_flag_string, unsigned long *irq_flags)
+{
+	struct xpc_partition *part = &xpc_partitions[ch->partid];
+	struct xpc_partition_sn2 *part_sn2 = &part->sn.sn2;
+	union xpc_channel_ctl_flags chctl = { 0 };
+	enum xp_retval ret;
+
+	if (likely(part->act_state != XPC_P_AS_DEACTIVATING)) {
+		chctl.flags[ch->number] = chctl_flag;
+		ret = xpc_send_IRQ_sn2(part_sn2->remote_chctl_amo_va,
+				       chctl.all_flags,
+				       part_sn2->notify_IRQ_nasid,
+				       part_sn2->notify_IRQ_phys_cpuid,
+				       SGI_XPC_NOTIFY);
+		dev_dbg(xpc_chan, "%s sent to partid=%d, channel=%d, ret=%d\n",
+			chctl_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_SEND_NOTIFY_IRQ_SN2(_ch, _ipi_f, _irq_f) \
+		xpc_send_notify_IRQ_sn2(_ch, _ipi_f, #_ipi_f, _irq_f)
+
+/*
+ * Make it look like the remote partition, which is associated with the
+ * specified channel, sent us a notify IRQ. This faked IRQ will be handled
+ * by xpc_check_for_dropped_notify_IRQ_sn2().
+ */
+static void
+xpc_send_local_notify_IRQ_sn2(struct xpc_channel *ch, u8 chctl_flag,
+			      char *chctl_flag_string)
+{
+	struct xpc_partition *part = &xpc_partitions[ch->partid];
+	union xpc_channel_ctl_flags chctl = { 0 };
+
+	chctl.flags[ch->number] = chctl_flag;
+	FETCHOP_STORE_OP(TO_AMO((u64)&part->sn.sn2.local_chctl_amo_va->
+				variable), FETCHOP_OR, chctl.all_flags);
+	dev_dbg(xpc_chan, "%s sent local from partid=%d, channel=%d\n",
+		chctl_flag_string, ch->partid, ch->number);
+}
+
+#define XPC_SEND_LOCAL_NOTIFY_IRQ_SN2(_ch, _ipi_f) \
+		xpc_send_local_notify_IRQ_sn2(_ch, _ipi_f, #_ipi_f)
+
+static void
+xpc_send_chctl_closerequest_sn2(struct xpc_channel *ch,
+				unsigned long *irq_flags)
+{
+	struct xpc_openclose_args *args = ch->sn.sn2.local_openclose_args;
+
+	args->reason = ch->reason;
+	XPC_SEND_NOTIFY_IRQ_SN2(ch, XPC_CHCTL_CLOSEREQUEST, irq_flags);
+}
+
+static void
+xpc_send_chctl_closereply_sn2(struct xpc_channel *ch, unsigned long *irq_flags)
+{
+	XPC_SEND_NOTIFY_IRQ_SN2(ch, XPC_CHCTL_CLOSEREPLY, irq_flags);
+}
+
+static void
+xpc_send_chctl_openrequest_sn2(struct xpc_channel *ch, unsigned long *irq_flags)
+{
+	struct xpc_openclose_args *args = ch->sn.sn2.local_openclose_args;
+
+	args->entry_size = ch->entry_size;
+	args->local_nentries = ch->local_nentries;
+	XPC_SEND_NOTIFY_IRQ_SN2(ch, XPC_CHCTL_OPENREQUEST, irq_flags);
+}
+
+static void
+xpc_send_chctl_openreply_sn2(struct xpc_channel *ch, unsigned long *irq_flags)
+{
+	struct xpc_openclose_args *args = ch->sn.sn2.local_openclose_args;
+
+	args->remote_nentries = ch->remote_nentries;
+	args->local_nentries = ch->local_nentries;
+	args->local_msgqueue_pa = xp_pa(ch->sn.sn2.local_msgqueue);
+	XPC_SEND_NOTIFY_IRQ_SN2(ch, XPC_CHCTL_OPENREPLY, irq_flags);
+}
+
+static void
+xpc_send_chctl_opencomplete_sn2(struct xpc_channel *ch,
+				unsigned long *irq_flags)
+{
+	XPC_SEND_NOTIFY_IRQ_SN2(ch, XPC_CHCTL_OPENCOMPLETE, irq_flags);
+}
+
+static void
+xpc_send_chctl_msgrequest_sn2(struct xpc_channel *ch)
+{
+	XPC_SEND_NOTIFY_IRQ_SN2(ch, XPC_CHCTL_MSGREQUEST, NULL);
+}
+
+static void
+xpc_send_chctl_local_msgrequest_sn2(struct xpc_channel *ch)
+{
+	XPC_SEND_LOCAL_NOTIFY_IRQ_SN2(ch, XPC_CHCTL_MSGREQUEST);
+}
+
+static enum xp_retval
+xpc_save_remote_msgqueue_pa_sn2(struct xpc_channel *ch,
+				unsigned long msgqueue_pa)
+{
+	ch->sn.sn2.remote_msgqueue_pa = msgqueue_pa;
+	return xpSuccess;
+}
+
+/*
+ * 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_indicate_partition_engaged_sn2(struct xpc_partition *part)
+{
+	unsigned long irq_flags;
+	struct amo *amo = (struct amo *)__va(part->sn.sn2.remote_amos_page_pa +
+					     (XPC_ENGAGED_PARTITIONS_AMO_SN2 *
+					     sizeof(struct amo)));
+
+	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,
+			 BIT(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 IRQs 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_indicate_partition_disengaged_sn2(struct xpc_partition *part)
+{
+	struct xpc_partition_sn2 *part_sn2 = &part->sn.sn2;
+	unsigned long irq_flags;
+	struct amo *amo = (struct amo *)__va(part_sn2->remote_amos_page_pa +
+					     (XPC_ENGAGED_PARTITIONS_AMO_SN2 *
+					     sizeof(struct amo)));
+
+	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,
+			 ~BIT(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 IRQs 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);
+
+	/*
+	 * Send activate IRQ to get other side to see that we've cleared our
+	 * bit in their engaged partitions amo.
+	 */
+	xpc_send_activate_IRQ_sn2(part_sn2->remote_amos_page_pa,
+				  cnodeid_to_nasid(0),
+				  part_sn2->activate_IRQ_nasid,
+				  part_sn2->activate_IRQ_phys_cpuid);
+}
+
+static void
+xpc_assume_partition_disengaged_sn2(short partid)
+{
+	struct amo *amo = xpc_vars_sn2->amos_page +
+			  XPC_ENGAGED_PARTITIONS_AMO_SN2;
+
+	/* clear bit(s) based on partid mask in our partition's amo */
+	FETCHOP_STORE_OP(TO_AMO((u64)&amo->variable), FETCHOP_AND,
+			 ~BIT(partid));
+}
+
+static int
+xpc_partition_engaged_sn2(short partid)
+{
+	struct amo *amo = xpc_vars_sn2->amos_page +
+			  XPC_ENGAGED_PARTITIONS_AMO_SN2;
+
+	/* our partition's amo variable ANDed with partid mask */
+	return (FETCHOP_LOAD_OP(TO_AMO((u64)&amo->variable), FETCHOP_LOAD) &
+		BIT(partid)) != 0;
+}
+
+static int
+xpc_any_partition_engaged_sn2(void)
+{
+	struct amo *amo = xpc_vars_sn2->amos_page +
+			  XPC_ENGAGED_PARTITIONS_AMO_SN2;
+
+	/* our partition's amo variable */
+	return FETCHOP_LOAD_OP(TO_AMO((u64)&amo->variable), FETCHOP_LOAD) != 0;
+}
+
+/* original protection values for each node */
+static u64 xpc_prot_vec_sn2[MAX_NUMNODES];
+
+/*
+ * Change protections to allow amo operations on non-Shub 1.1 systems.
+ */
+static enum xp_retval
+xpc_allow_amo_ops_sn2(struct amo *amos_page)
+{
+	enum xp_retval ret = xpSuccess;
+
+	/*
+	 * On SHUB 1.1, we cannot call sn_change_memprotect() since the BIST
+	 * collides with memory operations. On those systems we call
+	 * xpc_allow_amo_ops_shub_wars_1_1_sn2() instead.
+	 */
+	if (!enable_shub_wars_1_1())
+		ret = xp_expand_memprotect(ia64_tpa((u64)amos_page), PAGE_SIZE);
+
+	return ret;
+}
+
+/*
+ * Change protections to allow amo operations on Shub 1.1 systems.
+ */
+static void
+xpc_allow_amo_ops_shub_wars_1_1_sn2(void)
+{
+	int node;
+	int nasid;
+
+	if (!enable_shub_wars_1_1())
+		return;
+
+	for_each_online_node(node) {
+		nasid = cnodeid_to_nasid(node);
+		/* save current protection values */
+		xpc_prot_vec_sn2[node] =
+		    (u64)HUB_L((u64 *)GLOBAL_MMR_ADDR(nasid,
+						  SH1_MD_DQLP_MMR_DIR_PRIVEC0));
+		/* open up everything */
+		HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid,
+					     SH1_MD_DQLP_MMR_DIR_PRIVEC0),
+		      -1UL);
+		HUB_S((u64 *)GLOBAL_MMR_ADDR(nasid,
+					     SH1_MD_DQRP_MMR_DIR_PRIVEC0),
+		      -1UL);
+	}
+}
+
+static enum xp_retval
+xpc_get_partition_rsvd_page_pa_sn2(void *buf, u64 *cookie, unsigned long *rp_pa,
+				   size_t *len)
+{
+	s64 status;
+	enum xp_retval ret;
+
+	status = sn_partition_reserved_page_pa((u64)buf, cookie,
+			(u64 *)rp_pa, (u64 *)len);
+	if (status == SALRET_OK)
+		ret = xpSuccess;
+	else if (status == SALRET_MORE_PASSES)
+		ret = xpNeedMoreInfo;
+	else
+		ret = xpSalError;
+
+	return ret;
+}
+
+
+static int
+xpc_setup_rsvd_page_sn2(struct xpc_rsvd_page *rp)
+{
+	struct amo *amos_page;
+	int i;
+	int ret;
+
+	xpc_vars_sn2 = XPC_RP_VARS(rp);
+
+	rp->sn.sn2.vars_pa = xp_pa(xpc_vars_sn2);
+
+	/* vars_part array follows immediately after vars */
+	xpc_vars_part_sn2 = (struct xpc_vars_part_sn2 *)((u8 *)XPC_RP_VARS(rp) +
+							 XPC_RP_VARS_SIZE);
+
+	/*
+	 * Before clearing xpc_vars_sn2, see if a page of amos had been
+	 * previously allocated. If not we'll need to allocate one and set
+	 * permissions so that cross-partition amos are allowed.
+	 *
+	 * The allocated amo page needs MCA reporting to remain disabled after
+	 * XPC has unloaded.  To make this work, we keep a copy of the pointer
+	 * to this page (i.e., amos_page) in the struct xpc_vars_sn2 structure,
+	 * which is pointed to by the reserved page, and re-use that saved copy
+	 * on subsequent loads of XPC. This amo page is never freed, and its
+	 * memory protections are never restricted.
+	 */
+	amos_page = xpc_vars_sn2->amos_page;
+	if (amos_page == NULL) {
+		amos_page = (struct amo *)TO_AMO(uncached_alloc_page(0, 1));
+		if (amos_page == NULL) {
+			dev_err(xpc_part, "can't allocate page of amos\n");
+			return -ENOMEM;
+		}
+
+		/*
+		 * Open up amo-R/W to cpu.  This is done on Shub 1.1 systems
+		 * when xpc_allow_amo_ops_shub_wars_1_1_sn2() is called.
+		 */
+		ret = xpc_allow_amo_ops_sn2(amos_page);
+		if (ret != xpSuccess) {
+			dev_err(xpc_part, "can't allow amo operations\n");
+			uncached_free_page(__IA64_UNCACHED_OFFSET |
+					   TO_PHYS((u64)amos_page), 1);
+			return -EPERM;
+		}
+	}
+
+	/* clear xpc_vars_sn2 */
+	memset(xpc_vars_sn2, 0, sizeof(struct xpc_vars_sn2));
+
+	xpc_vars_sn2->version = XPC_V_VERSION;
+	xpc_vars_sn2->activate_IRQ_nasid = cpuid_to_nasid(0);
+	xpc_vars_sn2->activate_IRQ_phys_cpuid = cpu_physical_id(0);
+	xpc_vars_sn2->vars_part_pa = xp_pa(xpc_vars_part_sn2);
+	xpc_vars_sn2->amos_page_pa = ia64_tpa((u64)amos_page);
+	xpc_vars_sn2->amos_page = amos_page;	/* save for next load of XPC */
+
+	/* clear xpc_vars_part_sn2 */
+	memset((u64 *)xpc_vars_part_sn2, 0, sizeof(struct xpc_vars_part_sn2) *
+	       XP_MAX_NPARTITIONS_SN2);
+
+	/* initialize the activate IRQ related amo variables */
+	for (i = 0; i < xpc_nasid_mask_nlongs; i++)
+		(void)xpc_init_IRQ_amo_sn2(XPC_ACTIVATE_IRQ_AMOS_SN2 + i);
+
+	/* initialize the engaged remote partitions related amo variables */
+	(void)xpc_init_IRQ_amo_sn2(XPC_ENGAGED_PARTITIONS_AMO_SN2);
+	(void)xpc_init_IRQ_amo_sn2(XPC_DEACTIVATE_REQUEST_AMO_SN2);
+
+	return 0;
+}
+
+static int
+xpc_hb_allowed_sn2(short partid, void *heartbeating_to_mask)
+{
+	return test_bit(partid, heartbeating_to_mask);
+}
+
+static void
+xpc_allow_hb_sn2(short partid)
+{
+	DBUG_ON(xpc_vars_sn2 == NULL);
+	set_bit(partid, xpc_vars_sn2->heartbeating_to_mask);
+}
+
+static void
+xpc_disallow_hb_sn2(short partid)
+{
+	DBUG_ON(xpc_vars_sn2 == NULL);
+	clear_bit(partid, xpc_vars_sn2->heartbeating_to_mask);
+}
+
+static void
+xpc_disallow_all_hbs_sn2(void)
+{
+	DBUG_ON(xpc_vars_sn2 == NULL);
+	bitmap_zero(xpc_vars_sn2->heartbeating_to_mask, xp_max_npartitions);
+}
+
+static void
+xpc_increment_heartbeat_sn2(void)
+{
+	xpc_vars_sn2->heartbeat++;
+}
+
+static void
+xpc_offline_heartbeat_sn2(void)
+{
+	xpc_increment_heartbeat_sn2();
+	xpc_vars_sn2->heartbeat_offline = 1;
+}
+
+static void
+xpc_online_heartbeat_sn2(void)
+{
+	xpc_increment_heartbeat_sn2();
+	xpc_vars_sn2->heartbeat_offline = 0;
+}
+
+static void
+xpc_heartbeat_init_sn2(void)
+{
+	DBUG_ON(xpc_vars_sn2 == NULL);
+
+	bitmap_zero(xpc_vars_sn2->heartbeating_to_mask, XP_MAX_NPARTITIONS_SN2);
+	xpc_online_heartbeat_sn2();
+}
+
+static void
+xpc_heartbeat_exit_sn2(void)
+{
+	xpc_offline_heartbeat_sn2();
+}
+
+static enum xp_retval
+xpc_get_remote_heartbeat_sn2(struct xpc_partition *part)
+{
+	struct xpc_vars_sn2 *remote_vars;
+	enum xp_retval ret;
+
+	remote_vars = (struct xpc_vars_sn2 *)xpc_remote_copy_buffer_sn2;
+
+	/* pull the remote vars structure that contains the heartbeat */
+	ret = xp_remote_memcpy(xp_pa(remote_vars),
+			       part->sn.sn2.remote_vars_pa,
+			       XPC_RP_VARS_SIZE);
+	if (ret != xpSuccess)
+		return ret;
+
+	dev_dbg(xpc_part, "partid=%d, heartbeat=%lld, last_heartbeat=%lld, "
+		"heartbeat_offline=%lld, HB_mask[0]=0x%lx\n", XPC_PARTID(part),
+		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) ||
+	    !xpc_hb_allowed_sn2(sn_partition_id,
+				remote_vars->heartbeating_to_mask)) {
+		ret = xpNoHeartbeat;
+	} else {
+		part->last_heartbeat = remote_vars->heartbeat;
+	}
+
+	return ret;
+}
+
+/*
+ * 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(unsigned long 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(xp_pa(remote_vars), 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_request_partition_activation_sn2(struct xpc_rsvd_page *remote_rp,
+				     unsigned long remote_rp_pa, int nasid)
+{
+	xpc_send_local_activate_IRQ_sn2(nasid);
+}
+
+static void
+xpc_request_partition_reactivation_sn2(struct xpc_partition *part)
+{
+	xpc_send_local_activate_IRQ_sn2(part->sn.sn2.activate_IRQ_nasid);
+}
+
+static void
+xpc_request_partition_deactivation_sn2(struct xpc_partition *part)
+{
+	struct xpc_partition_sn2 *part_sn2 = &part->sn.sn2;
+	unsigned long irq_flags;
+	struct amo *amo = (struct amo *)__va(part_sn2->remote_amos_page_pa +
+					     (XPC_DEACTIVATE_REQUEST_AMO_SN2 *
+					     sizeof(struct amo)));
+
+	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,
+			 BIT(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 IRQs 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);
+
+	/*
+	 * Send activate IRQ to get other side to see that we've set our
+	 * bit in their deactivate request amo.
+	 */
+	xpc_send_activate_IRQ_sn2(part_sn2->remote_amos_page_pa,
+				  cnodeid_to_nasid(0),
+				  part_sn2->activate_IRQ_nasid,
+				  part_sn2->activate_IRQ_phys_cpuid);
+}
+
+static void
+xpc_cancel_partition_deactivation_request_sn2(struct xpc_partition *part)
+{
+	unsigned long irq_flags;
+	struct amo *amo = (struct amo *)__va(part->sn.sn2.remote_amos_page_pa +
+					     (XPC_DEACTIVATE_REQUEST_AMO_SN2 *
+					     sizeof(struct amo)));
+
+	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,
+			 ~BIT(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 IRQs 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 int
+xpc_partition_deactivation_requested_sn2(short partid)
+{
+	struct amo *amo = xpc_vars_sn2->amos_page +
+			  XPC_DEACTIVATE_REQUEST_AMO_SN2;
+
+	/* our partition's amo variable ANDed with partid mask */
+	return (FETCHOP_LOAD_OP(TO_AMO((u64)&amo->variable), FETCHOP_LOAD) &
+		BIT(partid)) != 0;
+}
+
+/*
+ * Update the remote partition's info.
+ */
+static void
+xpc_update_partition_info_sn2(struct xpc_partition *part, u8 remote_rp_version,
+			      unsigned long *remote_rp_ts_jiffies,
+			      unsigned long remote_rp_pa,
+			      unsigned long remote_vars_pa,
+			      struct xpc_vars_sn2 *remote_vars)
+{
+	struct xpc_partition_sn2 *part_sn2 = &part->sn.sn2;
+
+	part->remote_rp_version = remote_rp_version;
+	dev_dbg(xpc_part, "  remote_rp_version = 0x%016x\n",
+		part->remote_rp_version);
+
+	part->remote_rp_ts_jiffies = *remote_rp_ts_jiffies;
+	dev_dbg(xpc_part, "  remote_rp_ts_jiffies = 0x%016lx\n",
+		part->remote_rp_ts_jiffies);
+
+	part->remote_rp_pa = remote_rp_pa;
+	dev_dbg(xpc_part, "  remote_rp_pa = 0x%016lx\n", part->remote_rp_pa);
+
+	part_sn2->remote_vars_pa = remote_vars_pa;
+	dev_dbg(xpc_part, "  remote_vars_pa = 0x%016lx\n",
+		part_sn2->remote_vars_pa);
+
+	part->last_heartbeat = remote_vars->heartbeat - 1;
+	dev_dbg(xpc_part, "  last_heartbeat = 0x%016llx\n",
+		part->last_heartbeat);
+
+	part_sn2->remote_vars_part_pa = remote_vars->vars_part_pa;
+	dev_dbg(xpc_part, "  remote_vars_part_pa = 0x%016lx\n",
+		part_sn2->remote_vars_part_pa);
+
+	part_sn2->activate_IRQ_nasid = remote_vars->activate_IRQ_nasid;
+	dev_dbg(xpc_part, "  activate_IRQ_nasid = 0x%x\n",
+		part_sn2->activate_IRQ_nasid);
+
+	part_sn2->activate_IRQ_phys_cpuid =
+	    remote_vars->activate_IRQ_phys_cpuid;
+	dev_dbg(xpc_part, "  activate_IRQ_phys_cpuid = 0x%x\n",
+		part_sn2->activate_IRQ_phys_cpuid);
+
+	part_sn2->remote_amos_page_pa = remote_vars->amos_page_pa;
+	dev_dbg(xpc_part, "  remote_amos_page_pa = 0x%lx\n",
+		part_sn2->remote_amos_page_pa);
+
+	part_sn2->remote_vars_version = remote_vars->version;
+	dev_dbg(xpc_part, "  remote_vars_version = 0x%x\n",
+		part_sn2->remote_vars_version);
+}
+
+/*
+ * Prior code has determined the nasid which generated a activate IRQ.
+ * Inspect that nasid to determine if its partition needs to be activated
+ * or deactivated.
+ *
+ * A partition is considered "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_activate_IRQ_req_sn2(int nasid)
+{
+	struct xpc_rsvd_page *remote_rp;
+	struct xpc_vars_sn2 *remote_vars;
+	unsigned long remote_rp_pa;
+	unsigned long remote_vars_pa;
+	int remote_rp_version;
+	int reactivate = 0;
+	unsigned long remote_rp_ts_jiffies = 0;
+	short partid;
+	struct xpc_partition *part;
+	struct xpc_partition_sn2 *part_sn2;
+	enum xp_retval ret;
+
+	/* pull over the reserved page structure */
+
+	remote_rp = (struct xpc_rsvd_page *)xpc_remote_copy_buffer_sn2;
+
+	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.sn2.vars_pa;
+	remote_rp_version = remote_rp->version;
+	remote_rp_ts_jiffies = remote_rp->ts_jiffies;
+
+	partid = remote_rp->SAL_partid;
+	part = &xpc_partitions[partid];
+	part_sn2 = &part->sn.sn2;
+
+	/* pull over the cross partition variables */
+
+	remote_vars = (struct xpc_vars_sn2 *)xpc_remote_copy_buffer_sn2;
+
+	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->activate_IRQ_rcvd++;
+
+	dev_dbg(xpc_part, "partid for nasid %d is %d; IRQs = %d; HB = "
+		"%lld:0x%lx\n", (int)nasid, (int)partid,
+		part->activate_IRQ_rcvd,
+		remote_vars->heartbeat, remote_vars->heartbeating_to_mask[0]);
+
+	if (xpc_partition_disengaged(part) &&
+	    part->act_state == XPC_P_AS_INACTIVE) {
+
+		xpc_update_partition_info_sn2(part, remote_rp_version,
+					      &remote_rp_ts_jiffies,
+					      remote_rp_pa, remote_vars_pa,
+					      remote_vars);
+
+		if (xpc_partition_deactivation_requested_sn2(partid)) {
+			/*
+			 * Other side is waiting on us to deactivate even though
+			 * we already have.
+			 */
+			return;
+		}
+
+		xpc_activate_partition(part);
+		return;
+	}
+
+	DBUG_ON(part->remote_rp_version == 0);
+	DBUG_ON(part_sn2->remote_vars_version == 0);
+
+	if (remote_rp_ts_jiffies != part->remote_rp_ts_jiffies) {
+
+		/* the other side rebooted */
+
+		DBUG_ON(xpc_partition_engaged_sn2(partid));
+		DBUG_ON(xpc_partition_deactivation_requested_sn2(partid));
+
+		xpc_update_partition_info_sn2(part, remote_rp_version,
+					      &remote_rp_ts_jiffies,
+					      remote_rp_pa, remote_vars_pa,
+					      remote_vars);
+		reactivate = 1;
+	}
+
+	if (part->disengage_timeout > 0 && !xpc_partition_disengaged(part)) {
+		/* still waiting on other side to disengage from us */
+		return;
+	}
+
+	if (reactivate)
+		XPC_DEACTIVATE_PARTITION(part, xpReactivating);
+	else if (xpc_partition_deactivation_requested_sn2(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_activate_IRQ_sender_sn2(void)
+{
+	int l;
+	int b;
+	unsigned long nasid_mask_long;
+	u64 nasid;		/* remote nasid */
+	int n_IRQs_detected = 0;
+	struct amo *act_amos;
+
+	act_amos = xpc_vars_sn2->amos_page + XPC_ACTIVATE_IRQ_AMOS_SN2;
+
+	/* scan through activate amo variables looking for non-zero entries */
+	for (l = 0; l < xpc_nasid_mask_nlongs; l++) {
+
+		if (xpc_exiting)
+			break;
+
+		nasid_mask_long = xpc_receive_IRQ_amo_sn2(&act_amos[l]);
+
+		b = find_first_bit(&nasid_mask_long, BITS_PER_LONG);
+		if (b >= BITS_PER_LONG) {
+			/* no IRQs from nasids in this amo variable */
+			continue;
+		}
+
+		dev_dbg(xpc_part, "amo[%d] gave back 0x%lx\n", l,
+			nasid_mask_long);
+
+		/*
+		 * 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[l] |= nasid_mask_long;
+
+		/* locate the nasid(s) which sent interrupts */
+
+		do {
+			n_IRQs_detected++;
+			nasid = (l * BITS_PER_LONG + b) * 2;
+			dev_dbg(xpc_part, "interrupt from nasid %lld\n", nasid);
+			xpc_identify_activate_IRQ_req_sn2(nasid);
+
+			b = find_next_bit(&nasid_mask_long, BITS_PER_LONG,
+					  b + 1);
+		} while (b < BITS_PER_LONG);
+	}
+	return n_IRQs_detected;
+}
+
+static void
+xpc_process_activate_IRQ_rcvd_sn2(void)
+{
+	unsigned long irq_flags;
+	int n_IRQs_expected;
+	int n_IRQs_detected;
+
+	spin_lock_irqsave(&xpc_activate_IRQ_rcvd_lock, irq_flags);
+	n_IRQs_expected = xpc_activate_IRQ_rcvd;
+	xpc_activate_IRQ_rcvd = 0;
+	spin_unlock_irqrestore(&xpc_activate_IRQ_rcvd_lock, irq_flags);
+
+	n_IRQs_detected = xpc_identify_activate_IRQ_sender_sn2();
+	if (n_IRQs_detected < n_IRQs_expected) {
+		/* retry once to help avoid missing amo */
+		(void)xpc_identify_activate_IRQ_sender_sn2();
+	}
+}
+
+/*
+ * Setup the channel structures that are sn2 specific.
+ */
+static enum xp_retval
+xpc_setup_ch_structures_sn2(struct xpc_partition *part)
+{
+	struct xpc_partition_sn2 *part_sn2 = &part->sn.sn2;
+	struct xpc_channel_sn2 *ch_sn2;
+	enum xp_retval retval;
+	int ret;
+	int cpuid;
+	int ch_number;
+	struct timer_list *timer;
+	short partid = XPC_PARTID(part);
+
+	/* allocate all the required GET/PUT values */
+
+	part_sn2->local_GPs =
+	    xpc_kzalloc_cacheline_aligned(XPC_GP_SIZE, GFP_KERNEL,
+					  &part_sn2->local_GPs_base);
+	if (part_sn2->local_GPs == NULL) {
+		dev_err(xpc_chan, "can't get memory for local get/put "
+			"values\n");
+		return xpNoMemory;
+	}
+
+	part_sn2->remote_GPs =
+	    xpc_kzalloc_cacheline_aligned(XPC_GP_SIZE, GFP_KERNEL,
+					  &part_sn2->remote_GPs_base);
+	if (part_sn2->remote_GPs == NULL) {
+		dev_err(xpc_chan, "can't get memory for remote get/put "
+			"values\n");
+		retval = xpNoMemory;
+		goto out_1;
+	}
+
+	part_sn2->remote_GPs_pa = 0;
+
+	/* allocate all the required open and close args */
+
+	part_sn2->local_openclose_args =
+	    xpc_kzalloc_cacheline_aligned(XPC_OPENCLOSE_ARGS_SIZE,
+					  GFP_KERNEL, &part_sn2->
+					  local_openclose_args_base);
+	if (part_sn2->local_openclose_args == NULL) {
+		dev_err(xpc_chan, "can't get memory for local connect args\n");
+		retval = xpNoMemory;
+		goto out_2;
+	}
+
+	part_sn2->remote_openclose_args_pa = 0;
+
+	part_sn2->local_chctl_amo_va = xpc_init_IRQ_amo_sn2(partid);
+
+	part_sn2->notify_IRQ_nasid = 0;
+	part_sn2->notify_IRQ_phys_cpuid = 0;
+	part_sn2->remote_chctl_amo_va = NULL;
+
+	sprintf(part_sn2->notify_IRQ_owner, "xpc%02d", partid);
+	ret = request_irq(SGI_XPC_NOTIFY, xpc_handle_notify_IRQ_sn2,
+			  IRQF_SHARED, part_sn2->notify_IRQ_owner,
+			  (void *)(u64)partid);
+	if (ret != 0) {
+		dev_err(xpc_chan, "can't register NOTIFY IRQ handler, "
+			"errno=%d\n", -ret);
+		retval = xpLackOfResources;
+		goto out_3;
+	}
+
+	/* Setup a timer to check for dropped notify IRQs */
+	timer = &part_sn2->dropped_notify_IRQ_timer;
+	timer_setup(timer, xpc_check_for_dropped_notify_IRQ_sn2, 0);
+	timer->expires = jiffies + XPC_DROPPED_NOTIFY_IRQ_WAIT_INTERVAL;
+	add_timer(timer);
+
+	for (ch_number = 0; ch_number < part->nchannels; ch_number++) {
+		ch_sn2 = &part->channels[ch_number].sn.sn2;
+
+		ch_sn2->local_GP = &part_sn2->local_GPs[ch_number];
+		ch_sn2->local_openclose_args =
+		    &part_sn2->local_openclose_args[ch_number];
+
+		mutex_init(&ch_sn2->msg_to_pull_mutex);
+	}
+
+	/*
+	 * Setup the per partition specific variables required by the
+	 * remote partition to establish channel connections with us.
+	 *
+	 * The setting of the magic # indicates that these per partition
+	 * specific variables are ready to be used.
+	 */
+	xpc_vars_part_sn2[partid].GPs_pa = xp_pa(part_sn2->local_GPs);
+	xpc_vars_part_sn2[partid].openclose_args_pa =
+	    xp_pa(part_sn2->local_openclose_args);
+	xpc_vars_part_sn2[partid].chctl_amo_pa =
+	    xp_pa(part_sn2->local_chctl_amo_va);
+	cpuid = raw_smp_processor_id();	/* any CPU in this partition will do */
+	xpc_vars_part_sn2[partid].notify_IRQ_nasid = cpuid_to_nasid(cpuid);
+	xpc_vars_part_sn2[partid].notify_IRQ_phys_cpuid =
+	    cpu_physical_id(cpuid);
+	xpc_vars_part_sn2[partid].nchannels = part->nchannels;
+	xpc_vars_part_sn2[partid].magic = XPC_VP_MAGIC1_SN2;
+
+	return xpSuccess;
+
+	/* setup of ch structures failed */
+out_3:
+	kfree(part_sn2->local_openclose_args_base);
+	part_sn2->local_openclose_args = NULL;
+out_2:
+	kfree(part_sn2->remote_GPs_base);
+	part_sn2->remote_GPs = NULL;
+out_1:
+	kfree(part_sn2->local_GPs_base);
+	part_sn2->local_GPs = NULL;
+	return retval;
+}
+
+/*
+ * Teardown the channel structures that are sn2 specific.
+ */
+static void
+xpc_teardown_ch_structures_sn2(struct xpc_partition *part)
+{
+	struct xpc_partition_sn2 *part_sn2 = &part->sn.sn2;
+	short partid = XPC_PARTID(part);
+
+	/*
+	 * Indicate that the variables specific to the remote partition are no
+	 * longer available for its use.
+	 */
+	xpc_vars_part_sn2[partid].magic = 0;
+
+	/* in case we've still got outstanding timers registered... */
+	del_timer_sync(&part_sn2->dropped_notify_IRQ_timer);
+	free_irq(SGI_XPC_NOTIFY, (void *)(u64)partid);
+
+	kfree(part_sn2->local_openclose_args_base);
+	part_sn2->local_openclose_args = NULL;
+	kfree(part_sn2->remote_GPs_base);
+	part_sn2->remote_GPs = NULL;
+	kfree(part_sn2->local_GPs_base);
+	part_sn2->local_GPs = NULL;
+	part_sn2->local_chctl_amo_va = NULL;
+}
+
+/*
+ * Create a wrapper that hides the underlying mechanism for pulling a cacheline
+ * (or multiple cachelines) from a remote partition.
+ *
+ * src_pa must be a cacheline aligned physical address on the remote partition.
+ * dst must be a cacheline aligned virtual address on this partition.
+ * cnt must be cacheline sized
+ */
+/* ??? Replace this function by call to xp_remote_memcpy() or bte_copy()? */
+static enum xp_retval
+xpc_pull_remote_cachelines_sn2(struct xpc_partition *part, void *dst,
+			       const unsigned long src_pa, size_t cnt)
+{
+	enum xp_retval ret;
+
+	DBUG_ON(src_pa != L1_CACHE_ALIGN(src_pa));
+	DBUG_ON((unsigned long)dst != L1_CACHE_ALIGN((unsigned long)dst));
+	DBUG_ON(cnt != L1_CACHE_ALIGN(cnt));
+
+	if (part->act_state == XPC_P_AS_DEACTIVATING)
+		return part->reason;
+
+	ret = xp_remote_memcpy(xp_pa(dst), src_pa, cnt);
+	if (ret != xpSuccess) {
+		dev_dbg(xpc_chan, "xp_remote_memcpy() from partition %d failed,"
+			" ret=%d\n", XPC_PARTID(part), ret);
+	}
+	return ret;
+}
+
+/*
+ * Pull the remote per partition specific variables from the specified
+ * partition.
+ */
+static enum xp_retval
+xpc_pull_remote_vars_part_sn2(struct xpc_partition *part)
+{
+	struct xpc_partition_sn2 *part_sn2 = &part->sn.sn2;
+	u8 buffer[L1_CACHE_BYTES * 2];
+	struct xpc_vars_part_sn2 *pulled_entry_cacheline =
+	    (struct xpc_vars_part_sn2 *)L1_CACHE_ALIGN((u64)buffer);
+	struct xpc_vars_part_sn2 *pulled_entry;
+	unsigned long remote_entry_cacheline_pa;
+	unsigned long remote_entry_pa;
+	short partid = XPC_PARTID(part);
+	enum xp_retval ret;
+
+	/* pull the cacheline that contains the variables we're interested in */
+
+	DBUG_ON(part_sn2->remote_vars_part_pa !=
+		L1_CACHE_ALIGN(part_sn2->remote_vars_part_pa));
+	DBUG_ON(sizeof(struct xpc_vars_part_sn2) != L1_CACHE_BYTES / 2);
+
+	remote_entry_pa = part_sn2->remote_vars_part_pa +
+	    sn_partition_id * sizeof(struct xpc_vars_part_sn2);
+
+	remote_entry_cacheline_pa = (remote_entry_pa & ~(L1_CACHE_BYTES - 1));
+
+	pulled_entry = (struct xpc_vars_part_sn2 *)((u64)pulled_entry_cacheline
+						    + (remote_entry_pa &
+						    (L1_CACHE_BYTES - 1)));
+
+	ret = xpc_pull_remote_cachelines_sn2(part, pulled_entry_cacheline,
+					     remote_entry_cacheline_pa,
+					     L1_CACHE_BYTES);
+	if (ret != xpSuccess) {
+		dev_dbg(xpc_chan, "failed to pull XPC vars_part from "
+			"partition %d, ret=%d\n", partid, ret);
+		return ret;
+	}
+
+	/* see if they've been set up yet */
+
+	if (pulled_entry->magic != XPC_VP_MAGIC1_SN2 &&
+	    pulled_entry->magic != XPC_VP_MAGIC2_SN2) {
+
+		if (pulled_entry->magic != 0) {
+			dev_dbg(xpc_chan, "partition %d's XPC vars_part for "
+				"partition %d has bad magic value (=0x%llx)\n",
+				partid, sn_partition_id, pulled_entry->magic);
+			return xpBadMagic;
+		}
+
+		/* they've not been initialized yet */
+		return xpRetry;
+	}
+
+	if (xpc_vars_part_sn2[partid].magic == XPC_VP_MAGIC1_SN2) {
+
+		/* validate the variables */
+
+		if (pulled_entry->GPs_pa == 0 ||
+		    pulled_entry->openclose_args_pa == 0 ||
+		    pulled_entry->chctl_amo_pa == 0) {
+
+			dev_err(xpc_chan, "partition %d's XPC vars_part for "
+				"partition %d are not valid\n", partid,
+				sn_partition_id);
+			return xpInvalidAddress;
+		}
+
+		/* the variables we imported look to be valid */
+
+		part_sn2->remote_GPs_pa = pulled_entry->GPs_pa;
+		part_sn2->remote_openclose_args_pa =
+		    pulled_entry->openclose_args_pa;
+		part_sn2->remote_chctl_amo_va =
+		    (struct amo *)__va(pulled_entry->chctl_amo_pa);
+		part_sn2->notify_IRQ_nasid = pulled_entry->notify_IRQ_nasid;
+		part_sn2->notify_IRQ_phys_cpuid =
+		    pulled_entry->notify_IRQ_phys_cpuid;
+
+		if (part->nchannels > pulled_entry->nchannels)
+			part->nchannels = pulled_entry->nchannels;
+
+		/* let the other side know that we've pulled their variables */
+
+		xpc_vars_part_sn2[partid].magic = XPC_VP_MAGIC2_SN2;
+	}
+
+	if (pulled_entry->magic == XPC_VP_MAGIC1_SN2)
+		return xpRetry;
+
+	return xpSuccess;
+}
+
+/*
+ * Establish first contact with the remote partititon. This involves pulling
+ * the XPC per partition variables from the remote partition and waiting for
+ * the remote partition to pull ours.
+ */
+static enum xp_retval
+xpc_make_first_contact_sn2(struct xpc_partition *part)
+{
+	struct xpc_partition_sn2 *part_sn2 = &part->sn.sn2;
+	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_sn2->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;
+	}
+
+	/*
+	 * Send activate IRQ to get other side to activate if they've not
+	 * already begun to do so.
+	 */
+	xpc_send_activate_IRQ_sn2(part_sn2->remote_amos_page_pa,
+				  cnodeid_to_nasid(0),
+				  part_sn2->activate_IRQ_nasid,
+				  part_sn2->activate_IRQ_phys_cpuid);
+
+	while ((ret = xpc_pull_remote_vars_part_sn2(part)) != xpSuccess) {
+		if (ret != xpRetry) {
+			XPC_DEACTIVATE_PARTITION(part, ret);
+			return ret;
+		}
+
+		dev_dbg(xpc_part, "waiting to make first contact with "
+			"partition %d\n", XPC_PARTID(part));
+
+		/* wait a 1/4 of a second or so */
+		(void)msleep_interruptible(250);
+
+		if (part->act_state == XPC_P_AS_DEACTIVATING)
+			return part->reason;
+	}
+
+	return xpSuccess;
+}
+
+/*
+ * Get the chctl flags and pull the openclose args and/or remote GPs as needed.
+ */
+static u64
+xpc_get_chctl_all_flags_sn2(struct xpc_partition *part)
+{
+	struct xpc_partition_sn2 *part_sn2 = &part->sn.sn2;
+	unsigned long irq_flags;
+	union xpc_channel_ctl_flags chctl;
+	enum xp_retval ret;
+
+	/*
+	 * See if there are any chctl flags to be handled.
+	 */
+
+	spin_lock_irqsave(&part->chctl_lock, irq_flags);
+	chctl = part->chctl;
+	if (chctl.all_flags != 0)
+		part->chctl.all_flags = 0;
+
+	spin_unlock_irqrestore(&part->chctl_lock, irq_flags);
+
+	if (xpc_any_openclose_chctl_flags_set(&chctl)) {
+		ret = xpc_pull_remote_cachelines_sn2(part, part->
+						     remote_openclose_args,
+						     part_sn2->
+						     remote_openclose_args_pa,
+						     XPC_OPENCLOSE_ARGS_SIZE);
+		if (ret != xpSuccess) {
+			XPC_DEACTIVATE_PARTITION(part, ret);
+
+			dev_dbg(xpc_chan, "failed to pull openclose args from "
+				"partition %d, ret=%d\n", XPC_PARTID(part),
+				ret);
+
+			/* don't bother processing chctl flags anymore */
+			chctl.all_flags = 0;
+		}
+	}
+
+	if (xpc_any_msg_chctl_flags_set(&chctl)) {
+		ret = xpc_pull_remote_cachelines_sn2(part, part_sn2->remote_GPs,
+						     part_sn2->remote_GPs_pa,
+						     XPC_GP_SIZE);
+		if (ret != xpSuccess) {
+			XPC_DEACTIVATE_PARTITION(part, ret);
+
+			dev_dbg(xpc_chan, "failed to pull GPs from partition "
+				"%d, ret=%d\n", XPC_PARTID(part), ret);
+
+			/* don't bother processing chctl flags anymore */
+			chctl.all_flags = 0;
+		}
+	}
+
+	return chctl.all_flags;
+}
+
+/*
+ * Allocate the local message queue and the notify queue.
+ */
+static enum xp_retval
+xpc_allocate_local_msgqueue_sn2(struct xpc_channel *ch)
+{
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	unsigned long irq_flags;
+	int nentries;
+	size_t nbytes;
+
+	for (nentries = ch->local_nentries; nentries > 0; nentries--) {
+
+		nbytes = nentries * ch->entry_size;
+		ch_sn2->local_msgqueue =
+		    xpc_kzalloc_cacheline_aligned(nbytes, GFP_KERNEL,
+						  &ch_sn2->local_msgqueue_base);
+		if (ch_sn2->local_msgqueue == NULL)
+			continue;
+
+		nbytes = nentries * sizeof(struct xpc_notify_sn2);
+		ch_sn2->notify_queue = kzalloc(nbytes, GFP_KERNEL);
+		if (ch_sn2->notify_queue == NULL) {
+			kfree(ch_sn2->local_msgqueue_base);
+			ch_sn2->local_msgqueue = NULL;
+			continue;
+		}
+
+		spin_lock_irqsave(&ch->lock, irq_flags);
+		if (nentries < ch->local_nentries) {
+			dev_dbg(xpc_chan, "nentries=%d local_nentries=%d, "
+				"partid=%d, channel=%d\n", nentries,
+				ch->local_nentries, ch->partid, ch->number);
+
+			ch->local_nentries = nentries;
+		}
+		spin_unlock_irqrestore(&ch->lock, irq_flags);
+		return xpSuccess;
+	}
+
+	dev_dbg(xpc_chan, "can't get memory for local message queue and notify "
+		"queue, partid=%d, channel=%d\n", ch->partid, ch->number);
+	return xpNoMemory;
+}
+
+/*
+ * Allocate the cached remote message queue.
+ */
+static enum xp_retval
+xpc_allocate_remote_msgqueue_sn2(struct xpc_channel *ch)
+{
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	unsigned long irq_flags;
+	int nentries;
+	size_t nbytes;
+
+	DBUG_ON(ch->remote_nentries <= 0);
+
+	for (nentries = ch->remote_nentries; nentries > 0; nentries--) {
+
+		nbytes = nentries * ch->entry_size;
+		ch_sn2->remote_msgqueue =
+		    xpc_kzalloc_cacheline_aligned(nbytes, GFP_KERNEL, &ch_sn2->
+						  remote_msgqueue_base);
+		if (ch_sn2->remote_msgqueue == NULL)
+			continue;
+
+		spin_lock_irqsave(&ch->lock, irq_flags);
+		if (nentries < ch->remote_nentries) {
+			dev_dbg(xpc_chan, "nentries=%d remote_nentries=%d, "
+				"partid=%d, channel=%d\n", nentries,
+				ch->remote_nentries, ch->partid, ch->number);
+
+			ch->remote_nentries = nentries;
+		}
+		spin_unlock_irqrestore(&ch->lock, irq_flags);
+		return xpSuccess;
+	}
+
+	dev_dbg(xpc_chan, "can't get memory for cached remote message queue, "
+		"partid=%d, channel=%d\n", ch->partid, ch->number);
+	return xpNoMemory;
+}
+
+/*
+ * Allocate message queues and other stuff associated with a channel.
+ *
+ * Note: Assumes all of the channel sizes are filled in.
+ */
+static enum xp_retval
+xpc_setup_msg_structures_sn2(struct xpc_channel *ch)
+{
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	enum xp_retval ret;
+
+	DBUG_ON(ch->flags & XPC_C_SETUP);
+
+	ret = xpc_allocate_local_msgqueue_sn2(ch);
+	if (ret == xpSuccess) {
+
+		ret = xpc_allocate_remote_msgqueue_sn2(ch);
+		if (ret != xpSuccess) {
+			kfree(ch_sn2->local_msgqueue_base);
+			ch_sn2->local_msgqueue = NULL;
+			kfree(ch_sn2->notify_queue);
+			ch_sn2->notify_queue = NULL;
+		}
+	}
+	return ret;
+}
+
+/*
+ * Free up message queues and other stuff that were allocated for the specified
+ * channel.
+ */
+static void
+xpc_teardown_msg_structures_sn2(struct xpc_channel *ch)
+{
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+
+	DBUG_ON(!spin_is_locked(&ch->lock));
+
+	ch_sn2->remote_msgqueue_pa = 0;
+
+	ch_sn2->local_GP->get = 0;
+	ch_sn2->local_GP->put = 0;
+	ch_sn2->remote_GP.get = 0;
+	ch_sn2->remote_GP.put = 0;
+	ch_sn2->w_local_GP.get = 0;
+	ch_sn2->w_local_GP.put = 0;
+	ch_sn2->w_remote_GP.get = 0;
+	ch_sn2->w_remote_GP.put = 0;
+	ch_sn2->next_msg_to_pull = 0;
+
+	if (ch->flags & XPC_C_SETUP) {
+		dev_dbg(xpc_chan, "ch->flags=0x%x, partid=%d, channel=%d\n",
+			ch->flags, ch->partid, ch->number);
+
+		kfree(ch_sn2->local_msgqueue_base);
+		ch_sn2->local_msgqueue = NULL;
+		kfree(ch_sn2->remote_msgqueue_base);
+		ch_sn2->remote_msgqueue = NULL;
+		kfree(ch_sn2->notify_queue);
+		ch_sn2->notify_queue = NULL;
+	}
+}
+
+/*
+ * Notify those who wanted to be notified upon delivery of their message.
+ */
+static void
+xpc_notify_senders_sn2(struct xpc_channel *ch, enum xp_retval reason, s64 put)
+{
+	struct xpc_notify_sn2 *notify;
+	u8 notify_type;
+	s64 get = ch->sn.sn2.w_remote_GP.get - 1;
+
+	while (++get < put && atomic_read(&ch->n_to_notify) > 0) {
+
+		notify = &ch->sn.sn2.notify_queue[get % ch->local_nentries];
+
+		/*
+		 * See if the notify entry indicates it was associated with
+		 * a message who's sender wants to be notified. It is possible
+		 * that it is, but someone else is doing or has done the
+		 * notification.
+		 */
+		notify_type = notify->type;
+		if (notify_type == 0 ||
+		    cmpxchg(&notify->type, notify_type, 0) != notify_type) {
+			continue;
+		}
+
+		DBUG_ON(notify_type != XPC_N_CALL);
+
+		atomic_dec(&ch->n_to_notify);
+
+		if (notify->func != NULL) {
+			dev_dbg(xpc_chan, "notify->func() called, notify=0x%p "
+				"msg_number=%lld partid=%d channel=%d\n",
+				(void *)notify, get, ch->partid, ch->number);
+
+			notify->func(reason, ch->partid, ch->number,
+				     notify->key);
+
+			dev_dbg(xpc_chan, "notify->func() returned, notify=0x%p"
+				" msg_number=%lld partid=%d channel=%d\n",
+				(void *)notify, get, ch->partid, ch->number);
+		}
+	}
+}
+
+static void
+xpc_notify_senders_of_disconnect_sn2(struct xpc_channel *ch)
+{
+	xpc_notify_senders_sn2(ch, ch->reason, ch->sn.sn2.w_local_GP.put);
+}
+
+/*
+ * Clear some of the msg flags in the local message queue.
+ */
+static inline void
+xpc_clear_local_msgqueue_flags_sn2(struct xpc_channel *ch)
+{
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	struct xpc_msg_sn2 *msg;
+	s64 get;
+
+	get = ch_sn2->w_remote_GP.get;
+	do {
+		msg = (struct xpc_msg_sn2 *)((u64)ch_sn2->local_msgqueue +
+					     (get % ch->local_nentries) *
+					     ch->entry_size);
+		DBUG_ON(!(msg->flags & XPC_M_SN2_READY));
+		msg->flags = 0;
+	} while (++get < ch_sn2->remote_GP.get);
+}
+
+/*
+ * Clear some of the msg flags in the remote message queue.
+ */
+static inline void
+xpc_clear_remote_msgqueue_flags_sn2(struct xpc_channel *ch)
+{
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	struct xpc_msg_sn2 *msg;
+	s64 put, remote_nentries = ch->remote_nentries;
+
+	/* flags are zeroed when the buffer is allocated */
+	if (ch_sn2->remote_GP.put < remote_nentries)
+		return;
+
+	put = max(ch_sn2->w_remote_GP.put, remote_nentries);
+	do {
+		msg = (struct xpc_msg_sn2 *)((u64)ch_sn2->remote_msgqueue +
+					     (put % remote_nentries) *
+					     ch->entry_size);
+		DBUG_ON(!(msg->flags & XPC_M_SN2_READY));
+		DBUG_ON(!(msg->flags & XPC_M_SN2_DONE));
+		DBUG_ON(msg->number != put - remote_nentries);
+		msg->flags = 0;
+	} while (++put < ch_sn2->remote_GP.put);
+}
+
+static int
+xpc_n_of_deliverable_payloads_sn2(struct xpc_channel *ch)
+{
+	return ch->sn.sn2.w_remote_GP.put - ch->sn.sn2.w_local_GP.get;
+}
+
+static void
+xpc_process_msg_chctl_flags_sn2(struct xpc_partition *part, int ch_number)
+{
+	struct xpc_channel *ch = &part->channels[ch_number];
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	int npayloads_sent;
+
+	ch_sn2->remote_GP = part->sn.sn2.remote_GPs[ch_number];
+
+	/* See what, if anything, has changed for each connected channel */
+
+	xpc_msgqueue_ref(ch);
+
+	if (ch_sn2->w_remote_GP.get == ch_sn2->remote_GP.get &&
+	    ch_sn2->w_remote_GP.put == ch_sn2->remote_GP.put) {
+		/* nothing changed since GPs were last pulled */
+		xpc_msgqueue_deref(ch);
+		return;
+	}
+
+	if (!(ch->flags & XPC_C_CONNECTED)) {
+		xpc_msgqueue_deref(ch);
+		return;
+	}
+
+	/*
+	 * First check to see if messages recently sent by us have been
+	 * received by the other side. (The remote GET value will have
+	 * changed since we last looked at it.)
+	 */
+
+	if (ch_sn2->w_remote_GP.get != ch_sn2->remote_GP.get) {
+
+		/*
+		 * We need to notify any senders that want to be notified
+		 * that their sent messages have been received by their
+		 * intended recipients. We need to do this before updating
+		 * w_remote_GP.get so that we don't allocate the same message
+		 * queue entries prematurely (see xpc_allocate_msg()).
+		 */
+		if (atomic_read(&ch->n_to_notify) > 0) {
+			/*
+			 * Notify senders that messages sent have been
+			 * received and delivered by the other side.
+			 */
+			xpc_notify_senders_sn2(ch, xpMsgDelivered,
+					       ch_sn2->remote_GP.get);
+		}
+
+		/*
+		 * Clear msg->flags in previously sent messages, so that
+		 * they're ready for xpc_allocate_msg().
+		 */
+		xpc_clear_local_msgqueue_flags_sn2(ch);
+
+		ch_sn2->w_remote_GP.get = ch_sn2->remote_GP.get;
+
+		dev_dbg(xpc_chan, "w_remote_GP.get changed to %lld, partid=%d, "
+			"channel=%d\n", ch_sn2->w_remote_GP.get, ch->partid,
+			ch->number);
+
+		/*
+		 * If anyone was waiting for message queue entries to become
+		 * available, wake them up.
+		 */
+		if (atomic_read(&ch->n_on_msg_allocate_wq) > 0)
+			wake_up(&ch->msg_allocate_wq);
+	}
+
+	/*
+	 * Now check for newly sent messages by the other side. (The remote
+	 * PUT value will have changed since we last looked at it.)
+	 */
+
+	if (ch_sn2->w_remote_GP.put != ch_sn2->remote_GP.put) {
+		/*
+		 * Clear msg->flags in previously received messages, so that
+		 * they're ready for xpc_get_deliverable_payload_sn2().
+		 */
+		xpc_clear_remote_msgqueue_flags_sn2(ch);
+
+		smp_wmb(); /* ensure flags have been cleared before bte_copy */
+		ch_sn2->w_remote_GP.put = ch_sn2->remote_GP.put;
+
+		dev_dbg(xpc_chan, "w_remote_GP.put changed to %lld, partid=%d, "
+			"channel=%d\n", ch_sn2->w_remote_GP.put, ch->partid,
+			ch->number);
+
+		npayloads_sent = xpc_n_of_deliverable_payloads_sn2(ch);
+		if (npayloads_sent > 0) {
+			dev_dbg(xpc_chan, "msgs waiting to be copied and "
+				"delivered=%d, partid=%d, channel=%d\n",
+				npayloads_sent, ch->partid, ch->number);
+
+			if (ch->flags & XPC_C_CONNECTEDCALLOUT_MADE)
+				xpc_activate_kthreads(ch, npayloads_sent);
+		}
+	}
+
+	xpc_msgqueue_deref(ch);
+}
+
+static struct xpc_msg_sn2 *
+xpc_pull_remote_msg_sn2(struct xpc_channel *ch, s64 get)
+{
+	struct xpc_partition *part = &xpc_partitions[ch->partid];
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	unsigned long remote_msg_pa;
+	struct xpc_msg_sn2 *msg;
+	u32 msg_index;
+	u32 nmsgs;
+	u64 msg_offset;
+	enum xp_retval ret;
+
+	if (mutex_lock_interruptible(&ch_sn2->msg_to_pull_mutex) != 0) {
+		/* we were interrupted by a signal */
+		return NULL;
+	}
+
+	while (get >= ch_sn2->next_msg_to_pull) {
+
+		/* pull as many messages as are ready and able to be pulled */
+
+		msg_index = ch_sn2->next_msg_to_pull % ch->remote_nentries;
+
+		DBUG_ON(ch_sn2->next_msg_to_pull >= ch_sn2->w_remote_GP.put);
+		nmsgs = ch_sn2->w_remote_GP.put - ch_sn2->next_msg_to_pull;
+		if (msg_index + nmsgs > ch->remote_nentries) {
+			/* ignore the ones that wrap the msg queue for now */
+			nmsgs = ch->remote_nentries - msg_index;
+		}
+
+		msg_offset = msg_index * ch->entry_size;
+		msg = (struct xpc_msg_sn2 *)((u64)ch_sn2->remote_msgqueue +
+		    msg_offset);
+		remote_msg_pa = ch_sn2->remote_msgqueue_pa + msg_offset;
+
+		ret = xpc_pull_remote_cachelines_sn2(part, msg, remote_msg_pa,
+						     nmsgs * ch->entry_size);
+		if (ret != xpSuccess) {
+
+			dev_dbg(xpc_chan, "failed to pull %d msgs starting with"
+				" msg %lld from partition %d, channel=%d, "
+				"ret=%d\n", nmsgs, ch_sn2->next_msg_to_pull,
+				ch->partid, ch->number, ret);
+
+			XPC_DEACTIVATE_PARTITION(part, ret);
+
+			mutex_unlock(&ch_sn2->msg_to_pull_mutex);
+			return NULL;
+		}
+
+		ch_sn2->next_msg_to_pull += nmsgs;
+	}
+
+	mutex_unlock(&ch_sn2->msg_to_pull_mutex);
+
+	/* return the message we were looking for */
+	msg_offset = (get % ch->remote_nentries) * ch->entry_size;
+	msg = (struct xpc_msg_sn2 *)((u64)ch_sn2->remote_msgqueue + msg_offset);
+
+	return msg;
+}
+
+/*
+ * Get the next deliverable message's payload.
+ */
+static void *
+xpc_get_deliverable_payload_sn2(struct xpc_channel *ch)
+{
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	struct xpc_msg_sn2 *msg;
+	void *payload = NULL;
+	s64 get;
+
+	do {
+		if (ch->flags & XPC_C_DISCONNECTING)
+			break;
+
+		get = ch_sn2->w_local_GP.get;
+		smp_rmb();	/* guarantee that .get loads before .put */
+		if (get == ch_sn2->w_remote_GP.put)
+			break;
+
+		/* There are messages waiting to be pulled and delivered.
+		 * We need to try to secure one for ourselves. We'll do this
+		 * by trying to increment w_local_GP.get and hope that no one
+		 * else beats us to it. If they do, we'll we'll simply have
+		 * to try again for the next one.
+		 */
+
+		if (cmpxchg(&ch_sn2->w_local_GP.get, get, get + 1) == get) {
+			/* we got the entry referenced by get */
+
+			dev_dbg(xpc_chan, "w_local_GP.get changed to %lld, "
+				"partid=%d, channel=%d\n", get + 1,
+				ch->partid, ch->number);
+
+			/* pull the message from the remote partition */
+
+			msg = xpc_pull_remote_msg_sn2(ch, get);
+
+			if (msg != NULL) {
+				DBUG_ON(msg->number != get);
+				DBUG_ON(msg->flags & XPC_M_SN2_DONE);
+				DBUG_ON(!(msg->flags & XPC_M_SN2_READY));
+
+				payload = &msg->payload;
+			}
+			break;
+		}
+
+	} while (1);
+
+	return payload;
+}
+
+/*
+ * Now we actually send the messages that are ready to be sent by advancing
+ * the local message queue's Put value and then send a chctl msgrequest to the
+ * recipient partition.
+ */
+static void
+xpc_send_msgs_sn2(struct xpc_channel *ch, s64 initial_put)
+{
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	struct xpc_msg_sn2 *msg;
+	s64 put = initial_put + 1;
+	int send_msgrequest = 0;
+
+	while (1) {
+
+		while (1) {
+			if (put == ch_sn2->w_local_GP.put)
+				break;
+
+			msg = (struct xpc_msg_sn2 *)((u64)ch_sn2->
+						     local_msgqueue + (put %
+						     ch->local_nentries) *
+						     ch->entry_size);
+
+			if (!(msg->flags & XPC_M_SN2_READY))
+				break;
+
+			put++;
+		}
+
+		if (put == initial_put) {
+			/* nothing's changed */
+			break;
+		}
+
+		if (cmpxchg_rel(&ch_sn2->local_GP->put, initial_put, put) !=
+		    initial_put) {
+			/* someone else beat us to it */
+			DBUG_ON(ch_sn2->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 %lld, partid=%d, "
+			"channel=%d\n", put, ch->partid, ch->number);
+
+		send_msgrequest = 1;
+
+		/*
+		 * We need to ensure that the message referenced by
+		 * local_GP->put is not XPC_M_SN2_READY or that local_GP->put
+		 * equals w_local_GP.put, so we'll go have a look.
+		 */
+		initial_put = put;
+	}
+
+	if (send_msgrequest)
+		xpc_send_chctl_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_sn2 **address_of_msg)
+{
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	struct xpc_msg_sn2 *msg;
+	enum xp_retval ret;
+	s64 put;
+
+	/*
+	 * 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_sn2->w_local_GP.put;
+		smp_rmb();	/* guarantee that .put loads before .get */
+		if (put - ch_sn2->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_sn2->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 interrupts. This lets us fake a notify IRQ
+		 * that will cause the notify IRQ handler to fetch the latest
+		 * GP values as if an interrupt was sent by the other side.
+		 */
+		if (ret == xpTimeout)
+			xpc_send_chctl_local_msgrequest_sn2(ch);
+
+		if (flags & XPC_NOWAIT)
+			return xpNoWait;
+
+		ret = xpc_allocate_msg_wait(ch);
+		if (ret != xpInterrupted && ret != xpTimeout)
+			return ret;
+	}
+
+	/* get the message's address and initialize it */
+	msg = (struct xpc_msg_sn2 *)((u64)ch_sn2->local_msgqueue +
+				     (put % ch->local_nentries) *
+				     ch->entry_size);
+
+	DBUG_ON(msg->flags != 0);
+	msg->number = put;
+
+	dev_dbg(xpc_chan, "w_local_GP.put changed to %lld; msg=0x%p, "
+		"msg_number=%lld, 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 a chctl msgrequest to the
+ * partition the message is being sent to.
+ */
+static enum xp_retval
+xpc_send_payload_sn2(struct xpc_channel *ch, u32 flags, void *payload,
+		     u16 payload_size, u8 notify_type, xpc_notify_func func,
+		     void *key)
+{
+	enum xp_retval ret = xpSuccess;
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	struct xpc_msg_sn2 *msg = msg;
+	struct xpc_notify_sn2 *notify = notify;
+	s64 msg_number;
+	s64 put;
+
+	DBUG_ON(notify_type == XPC_N_CALL && func == NULL);
+
+	if (XPC_MSG_SIZE(payload_size) > ch->entry_size)
+		return xpPayloadTooBig;
+
+	xpc_msgqueue_ref(ch);
+
+	if (ch->flags & XPC_C_DISCONNECTING) {
+		ret = ch->reason;
+		goto out_1;
+	}
+	if (!(ch->flags & XPC_C_CONNECTED)) {
+		ret = xpNotConnected;
+		goto out_1;
+	}
+
+	ret = xpc_allocate_msg_sn2(ch, flags, &msg);
+	if (ret != xpSuccess)
+		goto out_1;
+
+	msg_number = msg->number;
+
+	if (notify_type != 0) {
+		/*
+		 * Tell the remote side to send an ACK interrupt when the
+		 * message has been delivered.
+		 */
+		msg->flags |= XPC_M_SN2_INTERRUPT;
+
+		atomic_inc(&ch->n_to_notify);
+
+		notify = &ch_sn2->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;
+			}
+			goto out_1;
+		}
+	}
+
+	memcpy(&msg->payload, payload, payload_size);
+
+	msg->flags |= XPC_M_SN2_READY;
+
+	/*
+	 * The preceding store of msg->flags must occur before the following
+	 * load of local_GP->put.
+	 */
+	smp_mb();
+
+	/* see if the message is next in line to be sent, if so send it */
+
+	put = ch_sn2->local_GP->put;
+	if (put == msg_number)
+		xpc_send_msgs_sn2(ch, put);
+
+out_1:
+	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 a chctl msgrequest to the message sender's partition.
+ *
+ * If a message has XPC_M_SN2_INTERRUPT set, send an interrupt to the partition
+ * that sent the message.
+ */
+static void
+xpc_acknowledge_msgs_sn2(struct xpc_channel *ch, s64 initial_get, u8 msg_flags)
+{
+	struct xpc_channel_sn2 *ch_sn2 = &ch->sn.sn2;
+	struct xpc_msg_sn2 *msg;
+	s64 get = initial_get + 1;
+	int send_msgrequest = 0;
+
+	while (1) {
+
+		while (1) {
+			if (get == ch_sn2->w_local_GP.get)
+				break;
+
+			msg = (struct xpc_msg_sn2 *)((u64)ch_sn2->
+						     remote_msgqueue + (get %
+						     ch->remote_nentries) *
+						     ch->entry_size);
+
+			if (!(msg->flags & XPC_M_SN2_DONE))
+				break;
+
+			msg_flags |= msg->flags;
+			get++;
+		}
+
+		if (get == initial_get) {
+			/* nothing's changed */
+			break;
+		}
+
+		if (cmpxchg_rel(&ch_sn2->local_GP->get, initial_get, get) !=
+		    initial_get) {
+			/* someone else beat us to it */
+			DBUG_ON(ch_sn2->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 %lld, partid=%d, "
+			"channel=%d\n", get, ch->partid, ch->number);
+
+		send_msgrequest = (msg_flags & XPC_M_SN2_INTERRUPT);
+
+		/*
+		 * We need to ensure that the message referenced by
+		 * local_GP->get is not XPC_M_SN2_DONE or that local_GP->get
+		 * equals w_local_GP.get, so we'll go have a look.
+		 */
+		initial_get = get;
+	}
+
+	if (send_msgrequest)
+		xpc_send_chctl_msgrequest_sn2(ch);
+}
+
+static void
+xpc_received_payload_sn2(struct xpc_channel *ch, void *payload)
+{
+	struct xpc_msg_sn2 *msg;
+	s64 msg_number;
+	s64 get;
+
+	msg = container_of(payload, struct xpc_msg_sn2, payload);
+	msg_number = msg->number;
+
+	dev_dbg(xpc_chan, "msg=0x%p, msg_number=%lld, partid=%d, channel=%d\n",
+		(void *)msg, msg_number, ch->partid, ch->number);
+
+	DBUG_ON((((u64)msg - (u64)ch->sn.sn2.remote_msgqueue) / ch->entry_size) !=
+		msg_number % ch->remote_nentries);
+	DBUG_ON(!(msg->flags & XPC_M_SN2_READY));
+	DBUG_ON(msg->flags & XPC_M_SN2_DONE);
+
+	msg->flags |= XPC_M_SN2_DONE;
+
+	/*
+	 * The preceding store of msg->flags must occur before the following
+	 * load of local_GP->get.
+	 */
+	smp_mb();
+
+	/*
+	 * See if this message is next in line to be acknowledged as having
+	 * been delivered.
+	 */
+	get = ch->sn.sn2.local_GP->get;
+	if (get == msg_number)
+		xpc_acknowledge_msgs_sn2(ch, get, msg->flags);
+}
+
+static struct xpc_arch_operations xpc_arch_ops_sn2 = {
+	.setup_partitions = xpc_setup_partitions_sn2,
+	.teardown_partitions = xpc_teardown_partitions_sn2,
+	.process_activate_IRQ_rcvd = xpc_process_activate_IRQ_rcvd_sn2,
+	.get_partition_rsvd_page_pa = xpc_get_partition_rsvd_page_pa_sn2,
+	.setup_rsvd_page = xpc_setup_rsvd_page_sn2,
+
+	.allow_hb = xpc_allow_hb_sn2,
+	.disallow_hb = xpc_disallow_hb_sn2,
+	.disallow_all_hbs = xpc_disallow_all_hbs_sn2,
+	.increment_heartbeat = xpc_increment_heartbeat_sn2,
+	.offline_heartbeat = xpc_offline_heartbeat_sn2,
+	.online_heartbeat = xpc_online_heartbeat_sn2,
+	.heartbeat_init = xpc_heartbeat_init_sn2,
+	.heartbeat_exit = xpc_heartbeat_exit_sn2,
+	.get_remote_heartbeat = xpc_get_remote_heartbeat_sn2,
+
+	.request_partition_activation =
+		xpc_request_partition_activation_sn2,
+	.request_partition_reactivation =
+		xpc_request_partition_reactivation_sn2,
+	.request_partition_deactivation =
+		xpc_request_partition_deactivation_sn2,
+	.cancel_partition_deactivation_request =
+		xpc_cancel_partition_deactivation_request_sn2,
+
+	.setup_ch_structures = xpc_setup_ch_structures_sn2,
+	.teardown_ch_structures = xpc_teardown_ch_structures_sn2,
+
+	.make_first_contact = xpc_make_first_contact_sn2,
+
+	.get_chctl_all_flags = xpc_get_chctl_all_flags_sn2,
+	.send_chctl_closerequest = xpc_send_chctl_closerequest_sn2,
+	.send_chctl_closereply = xpc_send_chctl_closereply_sn2,
+	.send_chctl_openrequest = xpc_send_chctl_openrequest_sn2,
+	.send_chctl_openreply = xpc_send_chctl_openreply_sn2,
+	.send_chctl_opencomplete = xpc_send_chctl_opencomplete_sn2,
+	.process_msg_chctl_flags = xpc_process_msg_chctl_flags_sn2,
+
+	.save_remote_msgqueue_pa = xpc_save_remote_msgqueue_pa_sn2,
+
+	.setup_msg_structures = xpc_setup_msg_structures_sn2,
+	.teardown_msg_structures = xpc_teardown_msg_structures_sn2,
+
+	.indicate_partition_engaged = xpc_indicate_partition_engaged_sn2,
+	.indicate_partition_disengaged = xpc_indicate_partition_disengaged_sn2,
+	.partition_engaged = xpc_partition_engaged_sn2,
+	.any_partition_engaged = xpc_any_partition_engaged_sn2,
+	.assume_partition_disengaged = xpc_assume_partition_disengaged_sn2,
+
+	.n_of_deliverable_payloads = xpc_n_of_deliverable_payloads_sn2,
+	.send_payload = xpc_send_payload_sn2,
+	.get_deliverable_payload = xpc_get_deliverable_payload_sn2,
+	.received_payload = xpc_received_payload_sn2,
+	.notify_senders_of_disconnect = xpc_notify_senders_of_disconnect_sn2,
+};
+
+int
+xpc_init_sn2(void)
+{
+	int ret;
+	size_t buf_size;
+
+	xpc_arch_ops = xpc_arch_ops_sn2;
+
+	if (offsetof(struct xpc_msg_sn2, payload) > XPC_MSG_HDR_MAX_SIZE) {
+		dev_err(xpc_part, "header portion of struct xpc_msg_sn2 is "
+			"larger than %d\n", XPC_MSG_HDR_MAX_SIZE);
+		return -E2BIG;
+	}
+
+	buf_size = max(XPC_RP_VARS_SIZE,
+		       XPC_RP_HEADER_SIZE + XP_NASID_MASK_BYTES_SN2);
+	xpc_remote_copy_buffer_sn2 = xpc_kmalloc_cacheline_aligned(buf_size,
+								   GFP_KERNEL,
+					      &xpc_remote_copy_buffer_base_sn2);
+	if (xpc_remote_copy_buffer_sn2 == NULL) {
+		dev_err(xpc_part, "can't get memory for remote copy buffer\n");
+		return -ENOMEM;
+	}
+
+	/* open up protections for IPI and [potentially] amo operations */
+	xpc_allow_IPI_ops_sn2();
+	xpc_allow_amo_ops_shub_wars_1_1_sn2();
+
+	/*
+	 * This is safe to do before the xpc_hb_checker thread has started
+	 * because the handler releases a wait queue.  If an interrupt is
+	 * received before the thread is waiting, it will not go to sleep,
+	 * but rather immediately process the interrupt.
+	 */
+	ret = request_irq(SGI_XPC_ACTIVATE, xpc_handle_activate_IRQ_sn2, 0,
+			  "xpc hb", NULL);
+	if (ret != 0) {
+		dev_err(xpc_part, "can't register ACTIVATE IRQ handler, "
+			"errno=%d\n", -ret);
+		xpc_disallow_IPI_ops_sn2();
+		kfree(xpc_remote_copy_buffer_base_sn2);
+	}
+	return ret;
+}
+
+void
+xpc_exit_sn2(void)
+{
+	free_irq(SGI_XPC_ACTIVATE, NULL);
+	xpc_disallow_IPI_ops_sn2();
+	kfree(xpc_remote_copy_buffer_base_sn2);
+}