/*
 * 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.
 *
 * (C) Copyright 2020 Hewlett Packard Enterprise Development LP
 * Copyright (c) 2004-2008 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/device.h>
#include <linux/hardirq.h>
#include <linux/slab.h>
#include "xpc.h"
#include <asm/uv/uv_hub.h>

/* XPC is exiting flag */
int xpc_exiting;

/* this partition's reserved page pointers */
struct xpc_rsvd_page *xpc_rsvd_page;
static unsigned long *xpc_part_nasids;
unsigned long *xpc_mach_nasids;

static int xpc_nasid_mask_nbytes;       /* #of bytes in nasid mask */
int xpc_nasid_mask_nlongs;      /* #of longs in nasid mask */

struct xpc_partition *xpc_partitions;

/*
 * 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 unsigned long
xpc_get_rsvd_page_pa(int nasid)
{
        enum xp_retval ret;
        u64 cookie = 0;
        unsigned long rp_pa = nasid;    /* seed with nasid */
        size_t len = 0;
        size_t buf_len = 0;
        void *buf = NULL;
        void *buf_base = NULL;
        enum xp_retval (*get_partition_rsvd_page_pa)
                (void *, u64 *, unsigned long *, size_t *) =
                xpc_arch_ops.get_partition_rsvd_page_pa;

        while (1) {

                /* !!! rp_pa will need to be _gpa on UV.
                 * ??? So do we save it into the architecture specific parts
                 * ??? of the xpc_partition structure? Do we rename this
                 * ??? function or have two versions? Rename rp_pa for UV to
                 * ??? rp_gpa?
                 */
                ret = get_partition_rsvd_page_pa(buf, &cookie, &rp_pa, &len);

                dev_dbg(xpc_part, "SAL returned with ret=%d, cookie=0x%016lx, "
                        "address=0x%016lx, len=0x%016lx\n", ret,
                        (unsigned long)cookie, rp_pa, len);

                if (ret != xpNeedMoreInfo)
                        break;

                if (len > buf_len) {
                        kfree(buf_base);
                        buf_len = L1_CACHE_ALIGN(len);
                        buf = 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);
                                ret = xpNoMemory;
                                break;
                        }
                }

                ret = xp_remote_memcpy(xp_pa(buf), rp_pa, len);
                if (ret != xpSuccess) {
                        dev_dbg(xpc_part, "xp_remote_memcpy failed %d\n", ret);
                        break;
                }
        }

        kfree(buf_base);

        if (ret != xpSuccess)
                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.
 */
int
xpc_setup_rsvd_page(void)
{
        int ret;
        struct xpc_rsvd_page *rp;
        unsigned long rp_pa;
        unsigned long new_ts_jiffies;

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

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

        if (rp->SAL_version < 3) {
                /* SAL_versions < 3 had a SAL_partid defined as a u8 */
                rp->SAL_partid &= 0xff;
        }
        BUG_ON(rp->SAL_partid != xp_partition_id);

        if (rp->SAL_partid < 0 || rp->SAL_partid >= xp_max_npartitions) {
                dev_err(xpc_part, "the reserved page's partid of %d is outside "
                        "supported range (< 0 || >= %d)\n", rp->SAL_partid,
                        xp_max_npartitions);
                return -EINVAL;
        }

        rp->version = XPC_RP_VERSION;
        rp->max_npartitions = xp_max_npartitions;

        /* establish the actual sizes of the nasid masks */
        if (rp->SAL_version == 1) {
                /* SAL_version 1 didn't set the nasids_size field */
                rp->SAL_nasids_size = 128;
        }
        xpc_nasid_mask_nbytes = rp->SAL_nasids_size;
        xpc_nasid_mask_nlongs = BITS_TO_LONGS(rp->SAL_nasids_size *
                                              BITS_PER_BYTE);

        /* 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);

        ret = xpc_arch_ops.setup_rsvd_page(rp);
        if (ret != 0)
                return ret;

        /*
         * Set timestamp of when reserved page was setup by XPC.
         * This signifies to the remote partition that our reserved
         * page is initialized.
         */
        new_ts_jiffies = jiffies;
        if (new_ts_jiffies == 0 || new_ts_jiffies == rp->ts_jiffies)
                new_ts_jiffies++;
        rp->ts_jiffies = new_ts_jiffies;

        xpc_rsvd_page = rp;
        return 0;
}

void
xpc_teardown_rsvd_page(void)
{
        /* a zero timestamp indicates our rsvd page is not initialized */
        xpc_rsvd_page->ts_jiffies = 0;
}

/*
 * 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.
 */
enum xp_retval
xpc_get_remote_rp(int nasid, unsigned long *discovered_nasids,
                  struct xpc_rsvd_page *remote_rp, unsigned long *remote_rp_pa)
{
        int l;
        enum xp_retval ret;

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

        *remote_rp_pa = xpc_get_rsvd_page_pa(nasid);
        if (*remote_rp_pa == 0)
                return xpNoRsvdPageAddr;

        /* pull over the reserved page header and part_nasids mask */
        ret = xp_remote_memcpy(xp_pa(remote_rp), *remote_rp_pa,
                               XPC_RP_HEADER_SIZE + xpc_nasid_mask_nbytes);
        if (ret != xpSuccess)
                return ret;

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

                for (l = 0; l < xpc_nasid_mask_nlongs; l++)
                        discovered_nasids[l] |= remote_part_nasids[l];
        }

        /* zero timestamp indicates the reserved page has not been setup */
        if (remote_rp->ts_jiffies == 0)
                return xpRsvdPageNotSet;

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

        /* check that both remote and local partids are valid for each side */
        if (remote_rp->SAL_partid < 0 ||
            remote_rp->SAL_partid >= xp_max_npartitions ||
            remote_rp->max_npartitions <= xp_partition_id) {
                return xpInvalidPartid;
        }

        if (remote_rp->SAL_partid == xp_partition_id)
                return xpLocalPartid;

        return xpSuccess;
}

/*
 * See if the other side has responded to a partition deactivate request
 * from us. Though we requested the remote partition to deactivate with regard
 * to us, we really only need to wait for the other side to disengage from us.
 */
static int __xpc_partition_disengaged(struct xpc_partition *part,
                                      bool from_timer)
{
        short partid = XPC_PARTID(part);
        int disengaged;

        disengaged = !xpc_arch_ops.partition_engaged(partid);
        if (part->disengage_timeout) {
                if (!disengaged) {
                        if (time_is_after_jiffies(part->disengage_timeout)) {
                                /* timelimit hasn't been reached yet */
                                return 0;
                        }

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

                        dev_info(xpc_part, "deactivate request to remote "
                                 "partition %d timed out\n", partid);
                        xpc_disengage_timedout = 1;
                        xpc_arch_ops.assume_partition_disengaged(partid);
                        disengaged = 1;
                }
                part->disengage_timeout = 0;

                /* Cancel the timer function if not called from it */
                if (!from_timer)
                        del_timer_sync(&part->disengage_timer);

                DBUG_ON(part->act_state != XPC_P_AS_DEACTIVATING &&
                        part->act_state != XPC_P_AS_INACTIVE);
                if (part->act_state != XPC_P_AS_INACTIVE)
                        xpc_wakeup_channel_mgr(part);

                xpc_arch_ops.cancel_partition_deactivation_request(part);
        }
        return disengaged;
}

int xpc_partition_disengaged(struct xpc_partition *part)
{
        return __xpc_partition_disengaged(part, false);
}

int xpc_partition_disengaged_from_timer(struct xpc_partition *part)
{
        return __xpc_partition_disengaged(part, true);
}

/*
 * Mark specified partition as active.
 */
enum xp_retval
xpc_mark_partition_active(struct xpc_partition *part)
{
        unsigned long irq_flags;
        enum xp_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_AS_ACTIVATING) {
                part->act_state = XPC_P_AS_ACTIVE;
                ret = xpSuccess;
        } else {
                DBUG_ON(part->reason == xpSuccess);
                ret = part->reason;
        }
        spin_unlock_irqrestore(&part->act_lock, irq_flags);

        return ret;
}

/*
 * Start the process of deactivating the specified partition.
 */
void
xpc_deactivate_partition(const int line, struct xpc_partition *part,
                         enum xp_retval reason)
{
        unsigned long irq_flags;

        spin_lock_irqsave(&part->act_lock, irq_flags);

        if (part->act_state == XPC_P_AS_INACTIVE) {
                XPC_SET_REASON(part, reason, line);
                spin_unlock_irqrestore(&part->act_lock, irq_flags);
                if (reason == xpReactivating) {
                        /* we interrupt ourselves to reactivate partition */
                        xpc_arch_ops.request_partition_reactivation(part);
                }
                return;
        }
        if (part->act_state == XPC_P_AS_DEACTIVATING) {
                if ((part->reason == xpUnloading && reason != xpUnloading) ||
                    reason == xpReactivating) {
                        XPC_SET_REASON(part, reason, line);
                }
                spin_unlock_irqrestore(&part->act_lock, irq_flags);
                return;
        }

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

        spin_unlock_irqrestore(&part->act_lock, irq_flags);

        /* ask remote partition to deactivate with regard to us */
        xpc_arch_ops.request_partition_deactivation(part);

        /* set a timelimit on the disengage phase of the deactivation request */
        part->disengage_timeout = jiffies + (xpc_disengage_timelimit * HZ);
        part->disengage_timer.expires = part->disengage_timeout;
        add_timer(&part->disengage_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_AS_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;
        unsigned long remote_rp_pa;
        int region;
        int region_size;
        int max_regions;
        int nasid;
        unsigned long *discovered_nasids;
        enum xp_retval ret;

        remote_rp = xpc_kmalloc_cacheline_aligned(XPC_RP_HEADER_SIZE +
                                                  xpc_nasid_mask_nbytes,
                                                  GFP_KERNEL, &remote_rp_base);
        if (remote_rp == NULL)
                return;

        discovered_nasids = kcalloc(xpc_nasid_mask_nlongs, sizeof(long),
                                    GFP_KERNEL);
        if (discovered_nasids == NULL) {
                kfree(remote_rp_base);
                return;
        }

        /*
         * 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.
         */
        region_size = xp_region_size;

        if (is_uv_system())
                max_regions = 256;
        else {
                max_regions = 64;

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

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

                if (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 (xpc_exiting)
                                break;

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

                        if (test_bit(nasid / 2, xpc_part_nasids)) {
                                dev_dbg(xpc_part, "PROM indicates Nasid %d is "
                                        "part of the local partition; skipping "
                                        "region\n", nasid);
                                break;
                        }

                        if (!(test_bit(nasid / 2, xpc_mach_nasids))) {
                                dev_dbg(xpc_part, "PROM indicates Nasid %d was "
                                        "not on Numa-Link network at reset\n",
                                        nasid);
                                continue;
                        }

                        if (test_bit(nasid / 2, discovered_nasids)) {
                                dev_dbg(xpc_part, "Nasid %d is part of a "
                                        "partition which was previously "
                                        "discovered\n", nasid);
                                continue;
                        }

                        /* pull over the rsvd page header & part_nasids mask */

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

                                if (ret == xpLocalPartid)
                                        break;

                                continue;
                        }

                        xpc_arch_ops.request_partition_activation(remote_rp,
                                                         remote_rp_pa, nasid);
                }
        }

        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 xp_retval
xpc_initiate_partid_to_nasids(short partid, void *nasid_mask)
{
        struct xpc_partition *part;
        unsigned long part_nasid_pa;

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

        memset(nasid_mask, 0, xpc_nasid_mask_nbytes);

        part_nasid_pa = (unsigned long)XPC_RP_PART_NASIDS(part->remote_rp_pa);

        return xp_remote_memcpy(xp_pa(nasid_mask), part_nasid_pa,
                                xpc_nasid_mask_nbytes);
}