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xpc_partition.c

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (c) 2004-2006 Silicon Graphics, Inc.  All Rights Reserved.
 */


/*
 * Cross Partition Communication (XPC) partition support.
 *
 *    This is the part of XPC that detects the presence/absence of
 *    other partitions. It provides a heartbeat and monitors the
 *    heartbeats of other partitions.
 *
 */


#include <linux/kernel.h>
#include <linux/sysctl.h>
#include <linux/cache.h>
#include <linux/mmzone.h>
#include <linux/nodemask.h>
#include <asm/uncached.h>
#include <asm/sn/bte.h>
#include <asm/sn/intr.h>
#include <asm/sn/sn_sal.h>
#include <asm/sn/nodepda.h>
#include <asm/sn/addrs.h>
#include <asm/sn/xpc.h>


/* XPC is exiting flag */
int xpc_exiting;


/* SH_IPI_ACCESS shub register value on startup */
static u64 xpc_sh1_IPI_access;
static u64 xpc_sh2_IPI_access0;
static u64 xpc_sh2_IPI_access1;
static u64 xpc_sh2_IPI_access2;
static u64 xpc_sh2_IPI_access3;


/* original protection values for each node */
u64 xpc_prot_vec[MAX_NUMNODES];


/* this partition's reserved page pointers */
struct xpc_rsvd_page *xpc_rsvd_page;
static u64 *xpc_part_nasids;
static u64 *xpc_mach_nasids;
struct xpc_vars *xpc_vars;
struct xpc_vars_part *xpc_vars_part;

static int xp_nasid_mask_bytes;     /* actual size in bytes of nasid mask */
static int xp_nasid_mask_words;     /* actual size in words of nasid mask */


/*
 * For performance reasons, each entry of xpc_partitions[] is cacheline
 * aligned. And xpc_partitions[] is padded with an additional entry at the
 * end so that the last legitimate entry doesn't share its cacheline with
 * another variable.
 */
struct xpc_partition xpc_partitions[XP_MAX_PARTITIONS + 1];


/*
 * Generic 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).
 */
char *xpc_remote_copy_buffer;
void *xpc_remote_copy_buffer_base;


/*
 * Guarantee that the kmalloc'd memory is cacheline aligned.
 */
void *
xpc_kmalloc_cacheline_aligned(size_t size, gfp_t flags, void **base)
{
      /* see if kmalloc will give us cachline aligned memory by default */
      *base = kmalloc(size, flags);
      if (*base == NULL) {
            return NULL;
      }
      if ((u64) *base == L1_CACHE_ALIGN((u64) *base)) {
            return *base;
      }
      kfree(*base);

      /* nope, we'll have to do it ourselves */
      *base = kmalloc(size + L1_CACHE_BYTES, flags);
      if (*base == NULL) {
            return NULL;
      }
      return (void *) L1_CACHE_ALIGN((u64) *base);
}


/*
 * Given a nasid, get the physical address of the  partition's reserved page
 * for that nasid. This function returns 0 on any error.
 */
static u64
xpc_get_rsvd_page_pa(int nasid)
{
      bte_result_t bte_res;
      s64 status;
      u64 cookie = 0;
      u64 rp_pa = nasid;      /* seed with nasid */
      u64 len = 0;
      u64 buf = buf;
      u64 buf_len = 0;
      void *buf_base = NULL;


      while (1) {

            status = sn_partition_reserved_page_pa(buf, &cookie, &rp_pa,
                                                &len);

            dev_dbg(xpc_part, "SAL returned with status=%li, cookie="
                  "0x%016lx, address=0x%016lx, len=0x%016lx\n",
                  status, cookie, rp_pa, len);

            if (status != SALRET_MORE_PASSES) {
                  break;
            }

            if (L1_CACHE_ALIGN(len) > buf_len) {
                  kfree(buf_base);
                  buf_len = L1_CACHE_ALIGN(len);
                  buf = (u64) xpc_kmalloc_cacheline_aligned(buf_len,
                                          GFP_KERNEL, &buf_base);
                  if (buf_base == NULL) {
                        dev_err(xpc_part, "unable to kmalloc "
                              "len=0x%016lx\n", buf_len);
                        status = SALRET_ERROR;
                        break;
                  }
            }

            bte_res = xp_bte_copy(rp_pa, buf, buf_len,
                              (BTE_NOTIFY | BTE_WACQUIRE), NULL);
            if (bte_res != BTE_SUCCESS) {
                  dev_dbg(xpc_part, "xp_bte_copy failed %i\n", bte_res);
                  status = SALRET_ERROR;
                  break;
            }
      }

      kfree(buf_base);

      if (status != SALRET_OK) {
            rp_pa = 0;
      }
      dev_dbg(xpc_part, "reserved page at phys address 0x%016lx\n", rp_pa);
      return rp_pa;
}


/*
 * Fill the partition reserved page with the information needed by
 * other partitions to discover we are alive and establish initial
 * communications.
 */
struct xpc_rsvd_page *
xpc_rsvd_page_init(void)
{
      struct xpc_rsvd_page *rp;
      AMO_t *amos_page;
      u64 rp_pa, nasid_array = 0;
      int i, ret;


      /* get the local reserved page's address */

      preempt_disable();
      rp_pa = xpc_get_rsvd_page_pa(cpuid_to_nasid(smp_processor_id()));
      preempt_enable();
      if (rp_pa == 0) {
            dev_err(xpc_part, "SAL failed to locate the reserved page\n");
            return NULL;
      }
      rp = (struct xpc_rsvd_page *) __va(rp_pa);

      if (rp->partid != sn_partition_id) {
            dev_err(xpc_part, "the reserved page's partid of %d should be "
                  "%d\n", rp->partid, sn_partition_id);
            return NULL;
      }

      rp->version = XPC_RP_VERSION;

      /* establish the actual sizes of the nasid masks */
      if (rp->SAL_version == 1) {
            /* SAL_version 1 didn't set the nasids_size field */
            rp->nasids_size = 128;
      }
      xp_nasid_mask_bytes = rp->nasids_size;
      xp_nasid_mask_words = xp_nasid_mask_bytes / 8;

      /* setup the pointers to the various items in the reserved page */
      xpc_part_nasids = XPC_RP_PART_NASIDS(rp);
      xpc_mach_nasids = XPC_RP_MACH_NASIDS(rp);
      xpc_vars = XPC_RP_VARS(rp);
      xpc_vars_part = XPC_RP_VARS_PART(rp);

      /*
       * Before clearing xpc_vars, 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 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.
       */
      if ((amos_page = xpc_vars->amos_page) == NULL) {
            amos_page = (AMO_t *) TO_AMO(uncached_alloc_page(0));
            if (amos_page == NULL) {
                  dev_err(xpc_part, "can't allocate page of AMOs\n");
                  return NULL;
            }

            /*
             * Open up AMO-R/W to cpu.  This is done for Shub 1.1 systems
             * when xpc_allow_IPI_ops() is called via xpc_hb_init().
             */
            if (!enable_shub_wars_1_1()) {
                  ret = sn_change_memprotect(ia64_tpa((u64) amos_page),
                              PAGE_SIZE, SN_MEMPROT_ACCESS_CLASS_1,
                              &nasid_array);
                  if (ret != 0) {
                        dev_err(xpc_part, "can't change memory "
                              "protections\n");
                        uncached_free_page(__IA64_UNCACHED_OFFSET |
                                       TO_PHYS((u64) amos_page));
                        return NULL;
                  }
            }
      } else if (!IS_AMO_ADDRESS((u64) amos_page)) {
            /*
             * EFI's XPBOOT can also set amos_page in the reserved page,
             * but it happens to leave it as an uncached physical address
             * and we need it to be an uncached virtual, so we'll have to
             * convert it.
             */
            if (!IS_AMO_PHYS_ADDRESS((u64) amos_page)) {
                  dev_err(xpc_part, "previously used amos_page address "
                        "is bad = 0x%p\n", (void *) amos_page);
                  return NULL;
            }
            amos_page = (AMO_t *) TO_AMO((u64) amos_page);
      }

      /* clear xpc_vars */
      memset(xpc_vars, 0, sizeof(struct xpc_vars));

      xpc_vars->version = XPC_V_VERSION;
      xpc_vars->act_nasid = cpuid_to_nasid(0);
      xpc_vars->act_phys_cpuid = cpu_physical_id(0);
      xpc_vars->vars_part_pa = __pa(xpc_vars_part);
      xpc_vars->amos_page_pa = ia64_tpa((u64) amos_page);
      xpc_vars->amos_page = amos_page;  /* save for next load of XPC */


      /* clear xpc_vars_part */
      memset((u64 *) xpc_vars_part, 0, sizeof(struct xpc_vars_part) *
                                          XP_MAX_PARTITIONS);

      /* 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);
      }

      /* initialize the engaged remote partitions related AMO variables */
      (void) xpc_IPI_init(XPC_ENGAGED_PARTITIONS_AMO);
      (void) xpc_IPI_init(XPC_DISENGAGE_REQUEST_AMO);

      /* timestamp of when reserved page was setup by XPC */
      rp->stamp = CURRENT_TIME;

      /*
       * This signifies to the remote partition that our reserved
       * page is initialized.
       */
      rp->vars_pa = __pa(xpc_vars);

      return rp;
}


/*
 * Change protections to allow IPI operations (and AMO operations on
 * Shub 1.1 systems).
 */
void
xpc_allow_IPI_ops(void)
{
      int node;
      int nasid;


      // >>> Change SH_IPI_ACCESS code to use SAL call once it is available.

      if (is_shub2()) {
            xpc_sh2_IPI_access0 =
                  (u64) HUB_L((u64 *) LOCAL_MMR_ADDR(SH2_IPI_ACCESS0));
            xpc_sh2_IPI_access1 =
                  (u64) HUB_L((u64 *) LOCAL_MMR_ADDR(SH2_IPI_ACCESS1));
            xpc_sh2_IPI_access2 =
                  (u64) HUB_L((u64 *) LOCAL_MMR_ADDR(SH2_IPI_ACCESS2));
            xpc_sh2_IPI_access3 =
                  (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 =
                  (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);

                  /*
                   * Since the BIST collides with memory operations on
                   * SHUB 1.1 sn_change_memprotect() cannot be used.
                   */
                  if (enable_shub_wars_1_1()) {
                        /* open up everything */
                        xpc_prot_vec[node] = (u64) HUB_L((u64 *)
                                    GLOBAL_MMR_ADDR(nasid,
                                    SH1_MD_DQLP_MMR_DIR_PRIVEC0));
                        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);
                  }
            }
      }
}


/*
 * Restrict protections to disallow IPI operations (and AMO operations on
 * Shub 1.1 systems).
 */
void
xpc_restrict_IPI_ops(void)
{
      int node;
      int nasid;


      // >>> Change SH_IPI_ACCESS code to use SAL call once it is available.

      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);
                  HUB_S((u64 *) GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS1),
                                          xpc_sh2_IPI_access1);
                  HUB_S((u64 *) GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS2),
                                          xpc_sh2_IPI_access2);
                  HUB_S((u64 *) GLOBAL_MMR_ADDR(nasid, SH2_IPI_ACCESS3),
                                          xpc_sh2_IPI_access3);
            }

      } 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);

                  if (enable_shub_wars_1_1()) {
                        HUB_S((u64 *) GLOBAL_MMR_ADDR(nasid,
                                    SH1_MD_DQLP_MMR_DIR_PRIVEC0),
                                          xpc_prot_vec[node]);
                        HUB_S((u64 *) GLOBAL_MMR_ADDR(nasid,
                                    SH1_MD_DQRP_MMR_DIR_PRIVEC0),
                                          xpc_prot_vec[node]);
                  }
            }
      }
}


/*
 * At periodic intervals, scan through all active partitions and ensure
 * their heartbeat is still active.  If not, the partition is deactivated.
 */
void
xpc_check_remote_hb(void)
{
      struct xpc_vars *remote_vars;
      struct xpc_partition *part;
      partid_t partid;
      bte_result_t bres;


      remote_vars = (struct xpc_vars *) xpc_remote_copy_buffer;

      for (partid = 1; partid < XP_MAX_PARTITIONS; 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 */
            bres = xp_bte_copy(part->remote_vars_pa,
                              (u64) remote_vars,
                              XPC_RP_VARS_SIZE,
                              (BTE_NOTIFY | BTE_WACQUIRE), NULL);
            if (bres != BTE_SUCCESS) {
                  XPC_DEACTIVATE_PARTITION(part,
                                    xpc_map_bte_errors(bres));
                  continue;
            }

            dev_dbg(xpc_part, "partid = %d, heartbeat = %ld, last_heartbeat"
                  " = %ld, heartbeat_offline = %ld, HB_mask = 0x%lx\n",
                  partid, remote_vars->heartbeat, part->last_heartbeat,
                  remote_vars->heartbeat_offline,
                  remote_vars->heartbeating_to_mask);

            if (((remote_vars->heartbeat == part->last_heartbeat) &&
                  (remote_vars->heartbeat_offline == 0)) ||
                       !xpc_hb_allowed(sn_partition_id, remote_vars)) {

                  XPC_DEACTIVATE_PARTITION(part, xpcNoHeartbeat);
                  continue;
            }

            part->last_heartbeat = remote_vars->heartbeat;
      }
}


/*
 * Get a copy of a portion of the remote partition's rsvd page.
 *
 * remote_rp points to a buffer that is cacheline aligned for BTE copies and
 * is large enough to contain a copy of their reserved page header and
 * part_nasids mask.
 */
static enum xpc_retval
xpc_get_remote_rp(int nasid, u64 *discovered_nasids,
            struct xpc_rsvd_page *remote_rp, u64 *remote_rp_pa)
{
      int bres, i;


      /* get the reserved page's physical address */

      *remote_rp_pa = xpc_get_rsvd_page_pa(nasid);
      if (*remote_rp_pa == 0) {
            return xpcNoRsvdPageAddr;
      }


      /* pull over the reserved page header and part_nasids mask */
      bres = xp_bte_copy(*remote_rp_pa, (u64) remote_rp,
                        XPC_RP_HEADER_SIZE + xp_nasid_mask_bytes,
                        (BTE_NOTIFY | BTE_WACQUIRE), NULL);
      if (bres != BTE_SUCCESS) {
            return xpc_map_bte_errors(bres);
      }


      if (discovered_nasids != NULL) {
            u64 *remote_part_nasids = XPC_RP_PART_NASIDS(remote_rp);


            for (i = 0; i < xp_nasid_mask_words; i++) {
                  discovered_nasids[i] |= remote_part_nasids[i];
            }
      }


      /* check that the partid is for another partition */

      if (remote_rp->partid < 1 ||
                        remote_rp->partid > (XP_MAX_PARTITIONS - 1)) {
            return xpcInvalidPartid;
      }

      if (remote_rp->partid == sn_partition_id) {
            return xpcLocalPartid;
      }


      if (XPC_VERSION_MAJOR(remote_rp->version) !=
                              XPC_VERSION_MAJOR(XPC_RP_VERSION)) {
            return xpcBadVersion;
      }

      return xpcSuccess;
}


/*
 * 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 xpc_retval
xpc_get_remote_vars(u64 remote_vars_pa, struct xpc_vars *remote_vars)
{
      int bres;


      if (remote_vars_pa == 0) {
            return xpcVarsNotSet;
      }

      /* pull over the cross partition variables */
      bres = xp_bte_copy(remote_vars_pa, (u64) remote_vars, XPC_RP_VARS_SIZE,
                        (BTE_NOTIFY | BTE_WACQUIRE), NULL);
      if (bres != BTE_SUCCESS) {
            return xpc_map_bte_errors(bres);
      }

      if (XPC_VERSION_MAJOR(remote_vars->version) !=
                              XPC_VERSION_MAJOR(XPC_V_VERSION)) {
            return xpcBadVersion;
      }

      return xpcSuccess;
}


/*
 * Update the remote partition's info.
 */
static void
xpc_update_partition_info(struct xpc_partition *part, u8 remote_rp_version,
            struct timespec *remote_rp_stamp, u64 remote_rp_pa,
            u64 remote_vars_pa, struct xpc_vars *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(int nasid)
{
      struct xpc_rsvd_page *remote_rp;
      struct xpc_vars *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 };
      partid_t partid;
      struct xpc_partition *part;
      enum xpc_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 != xpcSuccess) {
            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->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->partid;
      part = &xpc_partitions[partid];


      /* pull over the cross partition variables */

      remote_vars = (struct xpc_vars *) xpc_remote_copy_buffer;

      ret = xpc_get_remote_vars(remote_vars_pa, remote_vars);
      if (ret != xpcSuccess) {

            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);

      if (xpc_partition_disengaged(part) &&
                              part->act_state == XPC_P_INACTIVE) {

            xpc_update_partition_info(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)) {
                        /* 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(part, remote_rp_version,
                                    &remote_rp_stamp, remote_rp_pa,
                                    remote_vars_pa, remote_vars);
            part->reactivate_nasid = nasid;
            XPC_DEACTIVATE_PARTITION(part, xpcReactivating);
            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(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(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, xpcReactivating);

      } else if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version) &&
                  xpc_partition_disengage_requested(1UL << partid)) {
            XPC_DEACTIVATE_PARTITION(part, xpcOtherGoingDown);
      }
}


/*
 * 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(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(&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(nasid);
                  }
            }
      }
      return n_IRQs_detected;
}


/*
 * See if the other side has responded to a partition disengage request
 * from us.
 */
int
xpc_partition_disengaged(struct xpc_partition *part)
{
      partid_t partid = XPC_PARTID(part);
      int disengaged;


      disengaged = (xpc_partition_engaged(1UL << partid) == 0);
      if (part->disengage_request_timeout) {
            if (!disengaged) {
                  if (jiffies < part->disengage_request_timeout) {
                        /* timelimit hasn't been reached yet */
                        return 0;
                  }

                  /*
                   * Other side hasn't responded to our disengage
                   * request in a timely fashion, so assume it's dead.
                   */

                  dev_info(xpc_part, "disengage from remote partition %d "
                        "timed out\n", partid);
                  xpc_disengage_request_timedout = 1;
                  xpc_clear_partition_engaged(1UL << partid);
                  disengaged = 1;
            }
            part->disengage_request_timeout = 0;

            /* cancel the timer function, provided it's not us */
            if (!in_interrupt()) {
                  del_singleshot_timer_sync(&part->
                                          disengage_request_timer);
            }

            DBUG_ON(part->act_state != XPC_P_DEACTIVATING &&
                              part->act_state != XPC_P_INACTIVE);
            if (part->act_state != XPC_P_INACTIVE) {
                  xpc_wakeup_channel_mgr(part);
            }

            if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version)) {
                  xpc_cancel_partition_disengage_request(part);
            }
      }
      return disengaged;
}


/*
 * Mark specified partition as active.
 */
enum xpc_retval
xpc_mark_partition_active(struct xpc_partition *part)
{
      unsigned long irq_flags;
      enum xpc_retval ret;


      dev_dbg(xpc_part, "setting partition %d to ACTIVE\n", XPC_PARTID(part));

      spin_lock_irqsave(&part->act_lock, irq_flags);
      if (part->act_state == XPC_P_ACTIVATING) {
            part->act_state = XPC_P_ACTIVE;
            ret = xpcSuccess;
      } else {
            DBUG_ON(part->reason == xpcSuccess);
            ret = part->reason;
      }
      spin_unlock_irqrestore(&part->act_lock, irq_flags);

      return ret;
}


/*
 * Notify XPC that the partition is down.
 */
void
xpc_deactivate_partition(const int line, struct xpc_partition *part,
                        enum xpc_retval reason)
{
      unsigned long irq_flags;


      spin_lock_irqsave(&part->act_lock, irq_flags);

      if (part->act_state == XPC_P_INACTIVE) {
            XPC_SET_REASON(part, reason, line);
            spin_unlock_irqrestore(&part->act_lock, irq_flags);
            if (reason == xpcReactivating) {
                  /* we interrupt ourselves to reactivate partition */
                  xpc_IPI_send_reactivate(part);
            }
            return;
      }
      if (part->act_state == XPC_P_DEACTIVATING) {
            if ((part->reason == xpcUnloading && reason != xpcUnloading) ||
                              reason == xpcReactivating) {
                  XPC_SET_REASON(part, reason, line);
            }
            spin_unlock_irqrestore(&part->act_lock, irq_flags);
            return;
      }

      part->act_state = XPC_P_DEACTIVATING;
      XPC_SET_REASON(part, reason, line);

      spin_unlock_irqrestore(&part->act_lock, irq_flags);

      if (XPC_SUPPORTS_DISENGAGE_REQUEST(part->remote_vars_version)) {
            xpc_request_partition_disengage(part);
            xpc_IPI_send_disengage(part);

            /* set a timelimit on the disengage request */
            part->disengage_request_timeout = jiffies +
                              (xpc_disengage_request_timelimit * HZ);
            part->disengage_request_timer.expires =
                              part->disengage_request_timeout;
            add_timer(&part->disengage_request_timer);
      }

      dev_dbg(xpc_part, "bringing partition %d down, reason = %d\n",
            XPC_PARTID(part), reason);

      xpc_partition_going_down(part, reason);
}


/*
 * Mark specified partition as inactive.
 */
void
xpc_mark_partition_inactive(struct xpc_partition *part)
{
      unsigned long irq_flags;


      dev_dbg(xpc_part, "setting partition %d to INACTIVE\n",
            XPC_PARTID(part));

      spin_lock_irqsave(&part->act_lock, irq_flags);
      part->act_state = XPC_P_INACTIVE;
      spin_unlock_irqrestore(&part->act_lock, irq_flags);
      part->remote_rp_pa = 0;
}


/*
 * SAL has provided a partition and machine mask.  The partition mask
 * contains a bit for each even nasid in our partition.  The machine
 * mask contains a bit for each even nasid in the entire machine.
 *
 * Using those two bit arrays, we can determine which nasids are
 * known in the machine.  Each should also have a reserved page
 * initialized if they are available for partitioning.
 */
void
xpc_discovery(void)
{
      void *remote_rp_base;
      struct xpc_rsvd_page *remote_rp;
      struct xpc_vars *remote_vars;
      u64 remote_rp_pa;
      u64 remote_vars_pa;
      int region;
      int region_size;
      int max_regions;
      int nasid;
      struct xpc_rsvd_page *rp;
      partid_t partid;
      struct xpc_partition *part;
      u64 *discovered_nasids;
      enum xpc_retval ret;


      remote_rp = xpc_kmalloc_cacheline_aligned(XPC_RP_HEADER_SIZE +
                                    xp_nasid_mask_bytes,
                                    GFP_KERNEL, &remote_rp_base);
      if (remote_rp == NULL) {
            return;
      }
      remote_vars = (struct xpc_vars *) remote_rp;


      discovered_nasids = kzalloc(sizeof(u64) * xp_nasid_mask_words,
                                          GFP_KERNEL);
      if (discovered_nasids == NULL) {
            kfree(remote_rp_base);
            return;
      }

      rp = (struct xpc_rsvd_page *) xpc_rsvd_page;

      /*
       * The term 'region' in this context refers to the minimum number of
       * nodes that can comprise an access protection grouping. The access
       * protection is in regards to memory, IOI and IPI.
       */
      max_regions = 64;
      region_size = sn_region_size;

      switch (region_size) {
      case 128:
            max_regions *= 2;
      case 64:
            max_regions *= 2;
      case 32:
            max_regions *= 2;
            region_size = 16;
            DBUG_ON(!is_shub2());
      }

      for (region = 0; region < max_regions; region++) {

            if ((volatile int) xpc_exiting) {
                  break;
            }

            dev_dbg(xpc_part, "searching region %d\n", region);

            for (nasid = (region * region_size * 2);
                 nasid < ((region + 1) * region_size * 2);
                 nasid += 2) {

                  if ((volatile int) xpc_exiting) {
                        break;
                  }

                  dev_dbg(xpc_part, "checking nasid %d\n", nasid);


                  if (XPC_NASID_IN_ARRAY(nasid, xpc_part_nasids)) {
                        dev_dbg(xpc_part, "PROM indicates Nasid %d is "
                              "part of the local partition; skipping "
                              "region\n", nasid);
                        break;
                  }

                  if (!(XPC_NASID_IN_ARRAY(nasid, xpc_mach_nasids))) {
                        dev_dbg(xpc_part, "PROM indicates Nasid %d was "
                              "not on Numa-Link network at reset\n",
                              nasid);
                        continue;
                  }

                  if (XPC_NASID_IN_ARRAY(nasid, discovered_nasids)) {
                        dev_dbg(xpc_part, "Nasid %d is part of a "
                              "partition which was previously "
                              "discovered\n", nasid);
                        continue;
                  }


                  /* pull over the reserved page structure */

                  ret = xpc_get_remote_rp(nasid, discovered_nasids,
                                    remote_rp, &remote_rp_pa);
                  if (ret != xpcSuccess) {
                        dev_dbg(xpc_part, "unable to get reserved page "
                              "from nasid %d, reason=%d\n", nasid,
                              ret);

                        if (ret == xpcLocalPartid) {
                              break;
                        }
                        continue;
                  }

                  remote_vars_pa = remote_rp->vars_pa;

                  partid = remote_rp->partid;
                  part = &xpc_partitions[partid];


                  /* pull over the cross partition variables */

                  ret = xpc_get_remote_vars(remote_vars_pa, remote_vars);
                  if (ret != xpcSuccess) {
                        dev_dbg(xpc_part, "unable to get XPC variables "
                              "from nasid %d, reason=%d\n", nasid,
                              ret);

                        XPC_DEACTIVATE_PARTITION(part, ret);
                        continue;
                  }

                  if (part->act_state != XPC_P_INACTIVE) {
                        dev_dbg(xpc_part, "partition %d on nasid %d is "
                              "already activating\n", partid, nasid);
                        break;
                  }

                  /*
                   * 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 thus 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_act_amos_pa after
                   * module reloads and system reboots.
                   */
                  if (sn_register_xp_addr_region(
                                  remote_vars->amos_page_pa,
                                          PAGE_SIZE, 1) < 0) {
                        dev_dbg(xpc_part, "partition %d failed to "
                              "register xp_addr region 0x%016lx\n",
                              partid, remote_vars->amos_page_pa);

                        XPC_SET_REASON(part, xpcPhysAddrRegFailed,
                                    __LINE__);
                        break;
                  }

                  /*
                   * The remote nasid is valid and available.
                   * Send an interrupt to that nasid to notify
                   * it that we are ready to begin activation.
                   */
                  dev_dbg(xpc_part, "sending an interrupt to AMO 0x%lx, "
                        "nasid %d, phys_cpuid 0x%x\n",
                        remote_vars->amos_page_pa,
                        remote_vars->act_nasid,
                        remote_vars->act_phys_cpuid);

                  if (XPC_SUPPORTS_DISENGAGE_REQUEST(remote_vars->
                                                version)) {
                        part->remote_amos_page_pa =
                                    remote_vars->amos_page_pa;
                        xpc_mark_partition_disengaged(part);
                        xpc_cancel_partition_disengage_request(part);
                  }
                  xpc_IPI_send_activate(remote_vars);
            }
      }

      kfree(discovered_nasids);
      kfree(remote_rp_base);
}


/*
 * Given a partid, get the nasids owned by that partition from the
 * remote partition's reserved page.
 */
enum xpc_retval
xpc_initiate_partid_to_nasids(partid_t partid, void *nasid_mask)
{
      struct xpc_partition *part;
      u64 part_nasid_pa;
      int bte_res;


      part = &xpc_partitions[partid];
      if (part->remote_rp_pa == 0) {
            return xpcPartitionDown;
      }

      memset(nasid_mask, 0, XP_NASID_MASK_BYTES);

      part_nasid_pa = (u64) XPC_RP_PART_NASIDS(part->remote_rp_pa);

      bte_res = xp_bte_copy(part_nasid_pa, (u64) nasid_mask,
                  xp_nasid_mask_bytes, (BTE_NOTIFY | BTE_WACQUIRE), NULL);

      return xpc_map_bte_errors(bte_res);
}


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