Merge tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace...

[drm/drm-misc.git] / drivers / iommu / iova.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright © 2006-2009, Intel Corporation.
 *
 * Author: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
 */

#include <linux/iova.h>
#include <linux/kmemleak.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/bitops.h>
#include <linux/cpu.h>
#include <linux/workqueue.h>

/* The anchor node sits above the top of the usable address space */
#define IOVA_ANCHOR     ~0UL

#define IOVA_RANGE_CACHE_MAX_SIZE 6     /* log of max cached IOVA range size (in pages) */

static bool iova_rcache_insert(struct iova_domain *iovad,
                               unsigned long pfn,
                               unsigned long size);
static unsigned long iova_rcache_get(struct iova_domain *iovad,
                                     unsigned long size,
                                     unsigned long limit_pfn);
static void free_iova_rcaches(struct iova_domain *iovad);
static void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad);
static void free_global_cached_iovas(struct iova_domain *iovad);

static struct iova *to_iova(struct rb_node *node)
{
        return rb_entry(node, struct iova, node);
}

void
init_iova_domain(struct iova_domain *iovad, unsigned long granule,
        unsigned long start_pfn)
{
        /*
         * IOVA granularity will normally be equal to the smallest
         * supported IOMMU page size; both *must* be capable of
         * representing individual CPU pages exactly.
         */
        BUG_ON((granule > PAGE_SIZE) || !is_power_of_2(granule));

        spin_lock_init(&iovad->iova_rbtree_lock);
        iovad->rbroot = RB_ROOT;
        iovad->cached_node = &iovad->anchor.node;
        iovad->cached32_node = &iovad->anchor.node;
        iovad->granule = granule;
        iovad->start_pfn = start_pfn;
        iovad->dma_32bit_pfn = 1UL << (32 - iova_shift(iovad));
        iovad->max32_alloc_size = iovad->dma_32bit_pfn;
        iovad->anchor.pfn_lo = iovad->anchor.pfn_hi = IOVA_ANCHOR;
        rb_link_node(&iovad->anchor.node, NULL, &iovad->rbroot.rb_node);
        rb_insert_color(&iovad->anchor.node, &iovad->rbroot);
}
EXPORT_SYMBOL_GPL(init_iova_domain);

static struct rb_node *
__get_cached_rbnode(struct iova_domain *iovad, unsigned long limit_pfn)
{
        if (limit_pfn <= iovad->dma_32bit_pfn)
                return iovad->cached32_node;

        return iovad->cached_node;
}

static void
__cached_rbnode_insert_update(struct iova_domain *iovad, struct iova *new)
{
        if (new->pfn_hi < iovad->dma_32bit_pfn)
                iovad->cached32_node = &new->node;
        else
                iovad->cached_node = &new->node;
}

static void
__cached_rbnode_delete_update(struct iova_domain *iovad, struct iova *free)
{
        struct iova *cached_iova;

        cached_iova = to_iova(iovad->cached32_node);
        if (free == cached_iova ||
            (free->pfn_hi < iovad->dma_32bit_pfn &&
             free->pfn_lo >= cached_iova->pfn_lo))
                iovad->cached32_node = rb_next(&free->node);

        if (free->pfn_lo < iovad->dma_32bit_pfn)
                iovad->max32_alloc_size = iovad->dma_32bit_pfn;

        cached_iova = to_iova(iovad->cached_node);
        if (free->pfn_lo >= cached_iova->pfn_lo)
                iovad->cached_node = rb_next(&free->node);
}

static struct rb_node *iova_find_limit(struct iova_domain *iovad, unsigned long limit_pfn)
{
        struct rb_node *node, *next;
        /*
         * Ideally what we'd like to judge here is whether limit_pfn is close
         * enough to the highest-allocated IOVA that starting the allocation
         * walk from the anchor node will be quicker than this initial work to
         * find an exact starting point (especially if that ends up being the
         * anchor node anyway). This is an incredibly crude approximation which
         * only really helps the most likely case, but is at least trivially easy.
         */
        if (limit_pfn > iovad->dma_32bit_pfn)
                return &iovad->anchor.node;

        node = iovad->rbroot.rb_node;
        while (to_iova(node)->pfn_hi < limit_pfn)
                node = node->rb_right;

search_left:
        while (node->rb_left && to_iova(node->rb_left)->pfn_lo >= limit_pfn)
                node = node->rb_left;

        if (!node->rb_left)
                return node;

        next = node->rb_left;
        while (next->rb_right) {
                next = next->rb_right;
                if (to_iova(next)->pfn_lo >= limit_pfn) {
                        node = next;
                        goto search_left;
                }
        }

        return node;
}

/* Insert the iova into domain rbtree by holding writer lock */
static void
iova_insert_rbtree(struct rb_root *root, struct iova *iova,
                   struct rb_node *start)
{
        struct rb_node **new, *parent = NULL;

        new = (start) ? &start : &(root->rb_node);
        /* Figure out where to put new node */
        while (*new) {
                struct iova *this = to_iova(*new);

                parent = *new;

                if (iova->pfn_lo < this->pfn_lo)
                        new = &((*new)->rb_left);
                else if (iova->pfn_lo > this->pfn_lo)
                        new = &((*new)->rb_right);
                else {
                        WARN_ON(1); /* this should not happen */
                        return;
                }
        }
        /* Add new node and rebalance tree. */
        rb_link_node(&iova->node, parent, new);
        rb_insert_color(&iova->node, root);
}

static int __alloc_and_insert_iova_range(struct iova_domain *iovad,
                unsigned long size, unsigned long limit_pfn,
                        struct iova *new, bool size_aligned)
{
        struct rb_node *curr, *prev;
        struct iova *curr_iova;
        unsigned long flags;
        unsigned long new_pfn, retry_pfn;
        unsigned long align_mask = ~0UL;
        unsigned long high_pfn = limit_pfn, low_pfn = iovad->start_pfn;

        if (size_aligned)
                align_mask <<= fls_long(size - 1);

        /* Walk the tree backwards */
        spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
        if (limit_pfn <= iovad->dma_32bit_pfn &&
                        size >= iovad->max32_alloc_size)
                goto iova32_full;

        curr = __get_cached_rbnode(iovad, limit_pfn);
        curr_iova = to_iova(curr);
        retry_pfn = curr_iova->pfn_hi;

retry:
        do {
                high_pfn = min(high_pfn, curr_iova->pfn_lo);
                new_pfn = (high_pfn - size) & align_mask;
                prev = curr;
                curr = rb_prev(curr);
                curr_iova = to_iova(curr);
        } while (curr && new_pfn <= curr_iova->pfn_hi && new_pfn >= low_pfn);

        if (high_pfn < size || new_pfn < low_pfn) {
                if (low_pfn == iovad->start_pfn && retry_pfn < limit_pfn) {
                        high_pfn = limit_pfn;
                        low_pfn = retry_pfn + 1;
                        curr = iova_find_limit(iovad, limit_pfn);
                        curr_iova = to_iova(curr);
                        goto retry;
                }
                iovad->max32_alloc_size = size;
                goto iova32_full;
        }

        /* pfn_lo will point to size aligned address if size_aligned is set */
        new->pfn_lo = new_pfn;
        new->pfn_hi = new->pfn_lo + size - 1;

        /* If we have 'prev', it's a valid place to start the insertion. */
        iova_insert_rbtree(&iovad->rbroot, new, prev);
        __cached_rbnode_insert_update(iovad, new);

        spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
        return 0;

iova32_full:
        spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
        return -ENOMEM;
}

static struct kmem_cache *iova_cache;
static unsigned int iova_cache_users;
static DEFINE_MUTEX(iova_cache_mutex);

static struct iova *alloc_iova_mem(void)
{
        return kmem_cache_zalloc(iova_cache, GFP_ATOMIC | __GFP_NOWARN);
}

static void free_iova_mem(struct iova *iova)
{
        if (iova->pfn_lo != IOVA_ANCHOR)
                kmem_cache_free(iova_cache, iova);
}

/**
 * alloc_iova - allocates an iova
 * @iovad: - iova domain in question
 * @size: - size of page frames to allocate
 * @limit_pfn: - max limit address
 * @size_aligned: - set if size_aligned address range is required
 * This function allocates an iova in the range iovad->start_pfn to limit_pfn,
 * searching top-down from limit_pfn to iovad->start_pfn. If the size_aligned
 * flag is set then the allocated address iova->pfn_lo will be naturally
 * aligned on roundup_power_of_two(size).
 */
struct iova *
alloc_iova(struct iova_domain *iovad, unsigned long size,
        unsigned long limit_pfn,
        bool size_aligned)
{
        struct iova *new_iova;
        int ret;

        new_iova = alloc_iova_mem();
        if (!new_iova)
                return NULL;

        ret = __alloc_and_insert_iova_range(iovad, size, limit_pfn + 1,
                        new_iova, size_aligned);

        if (ret) {
                free_iova_mem(new_iova);
                return NULL;
        }

        return new_iova;
}
EXPORT_SYMBOL_GPL(alloc_iova);

static struct iova *
private_find_iova(struct iova_domain *iovad, unsigned long pfn)
{
        struct rb_node *node = iovad->rbroot.rb_node;

        assert_spin_locked(&iovad->iova_rbtree_lock);

        while (node) {
                struct iova *iova = to_iova(node);

                if (pfn < iova->pfn_lo)
                        node = node->rb_left;
                else if (pfn > iova->pfn_hi)
                        node = node->rb_right;
                else
                        return iova;    /* pfn falls within iova's range */
        }

        return NULL;
}

static void remove_iova(struct iova_domain *iovad, struct iova *iova)
{
        assert_spin_locked(&iovad->iova_rbtree_lock);
        __cached_rbnode_delete_update(iovad, iova);
        rb_erase(&iova->node, &iovad->rbroot);
}

/**
 * find_iova - finds an iova for a given pfn
 * @iovad: - iova domain in question.
 * @pfn: - page frame number
 * This function finds and returns an iova belonging to the
 * given domain which matches the given pfn.
 */
struct iova *find_iova(struct iova_domain *iovad, unsigned long pfn)
{
        unsigned long flags;
        struct iova *iova;

        /* Take the lock so that no other thread is manipulating the rbtree */
        spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
        iova = private_find_iova(iovad, pfn);
        spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
        return iova;
}
EXPORT_SYMBOL_GPL(find_iova);

/**
 * __free_iova - frees the given iova
 * @iovad: iova domain in question.
 * @iova: iova in question.
 * Frees the given iova belonging to the giving domain
 */
void
__free_iova(struct iova_domain *iovad, struct iova *iova)
{
        unsigned long flags;

        spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
        remove_iova(iovad, iova);
        spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
        free_iova_mem(iova);
}
EXPORT_SYMBOL_GPL(__free_iova);

/**
 * free_iova - finds and frees the iova for a given pfn
 * @iovad: - iova domain in question.
 * @pfn: - pfn that is allocated previously
 * This functions finds an iova for a given pfn and then
 * frees the iova from that domain.
 */
void
free_iova(struct iova_domain *iovad, unsigned long pfn)
{
        unsigned long flags;
        struct iova *iova;

        spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
        iova = private_find_iova(iovad, pfn);
        if (!iova) {
                spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
                return;
        }
        remove_iova(iovad, iova);
        spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
        free_iova_mem(iova);
}
EXPORT_SYMBOL_GPL(free_iova);

/**
 * alloc_iova_fast - allocates an iova from rcache
 * @iovad: - iova domain in question
 * @size: - size of page frames to allocate
 * @limit_pfn: - max limit address
 * @flush_rcache: - set to flush rcache on regular allocation failure
 * This function tries to satisfy an iova allocation from the rcache,
 * and falls back to regular allocation on failure. If regular allocation
 * fails too and the flush_rcache flag is set then the rcache will be flushed.
*/
unsigned long
alloc_iova_fast(struct iova_domain *iovad, unsigned long size,
                unsigned long limit_pfn, bool flush_rcache)
{
        unsigned long iova_pfn;
        struct iova *new_iova;

        /*
         * Freeing non-power-of-two-sized allocations back into the IOVA caches
         * will come back to bite us badly, so we have to waste a bit of space
         * rounding up anything cacheable to make sure that can't happen. The
         * order of the unadjusted size will still match upon freeing.
         */
        if (size < (1 << (IOVA_RANGE_CACHE_MAX_SIZE - 1)))
                size = roundup_pow_of_two(size);

        iova_pfn = iova_rcache_get(iovad, size, limit_pfn + 1);
        if (iova_pfn)
                return iova_pfn;

retry:
        new_iova = alloc_iova(iovad, size, limit_pfn, true);
        if (!new_iova) {
                unsigned int cpu;

                if (!flush_rcache)
                        return 0;

                /* Try replenishing IOVAs by flushing rcache. */
                flush_rcache = false;
                for_each_online_cpu(cpu)
                        free_cpu_cached_iovas(cpu, iovad);
                free_global_cached_iovas(iovad);
                goto retry;
        }

        return new_iova->pfn_lo;
}
EXPORT_SYMBOL_GPL(alloc_iova_fast);

/**
 * free_iova_fast - free iova pfn range into rcache
 * @iovad: - iova domain in question.
 * @pfn: - pfn that is allocated previously
 * @size: - # of pages in range
 * This functions frees an iova range by trying to put it into the rcache,
 * falling back to regular iova deallocation via free_iova() if this fails.
 */
void
free_iova_fast(struct iova_domain *iovad, unsigned long pfn, unsigned long size)
{
        if (iova_rcache_insert(iovad, pfn, size))
                return;

        free_iova(iovad, pfn);
}
EXPORT_SYMBOL_GPL(free_iova_fast);

static void iova_domain_free_rcaches(struct iova_domain *iovad)
{
        cpuhp_state_remove_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
                                            &iovad->cpuhp_dead);
        free_iova_rcaches(iovad);
}

/**
 * put_iova_domain - destroys the iova domain
 * @iovad: - iova domain in question.
 * All the iova's in that domain are destroyed.
 */
void put_iova_domain(struct iova_domain *iovad)
{
        struct iova *iova, *tmp;

        if (iovad->rcaches)
                iova_domain_free_rcaches(iovad);

        rbtree_postorder_for_each_entry_safe(iova, tmp, &iovad->rbroot, node)
                free_iova_mem(iova);
}
EXPORT_SYMBOL_GPL(put_iova_domain);

static int
__is_range_overlap(struct rb_node *node,
        unsigned long pfn_lo, unsigned long pfn_hi)
{
        struct iova *iova = to_iova(node);

        if ((pfn_lo <= iova->pfn_hi) && (pfn_hi >= iova->pfn_lo))
                return 1;
        return 0;
}

static inline struct iova *
alloc_and_init_iova(unsigned long pfn_lo, unsigned long pfn_hi)
{
        struct iova *iova;

        iova = alloc_iova_mem();
        if (iova) {
                iova->pfn_lo = pfn_lo;
                iova->pfn_hi = pfn_hi;
        }

        return iova;
}

static struct iova *
__insert_new_range(struct iova_domain *iovad,
        unsigned long pfn_lo, unsigned long pfn_hi)
{
        struct iova *iova;

        iova = alloc_and_init_iova(pfn_lo, pfn_hi);
        if (iova)
                iova_insert_rbtree(&iovad->rbroot, iova, NULL);

        return iova;
}

static void
__adjust_overlap_range(struct iova *iova,
        unsigned long *pfn_lo, unsigned long *pfn_hi)
{
        if (*pfn_lo < iova->pfn_lo)
                iova->pfn_lo = *pfn_lo;
        if (*pfn_hi > iova->pfn_hi)
                *pfn_lo = iova->pfn_hi + 1;
}

/**
 * reserve_iova - reserves an iova in the given range
 * @iovad: - iova domain pointer
 * @pfn_lo: - lower page frame address
 * @pfn_hi:- higher pfn address
 * This function allocates reserves the address range from pfn_lo to pfn_hi so
 * that this address is not dished out as part of alloc_iova.
 */
struct iova *
reserve_iova(struct iova_domain *iovad,
        unsigned long pfn_lo, unsigned long pfn_hi)
{
        struct rb_node *node;
        unsigned long flags;
        struct iova *iova;
        unsigned int overlap = 0;

        /* Don't allow nonsensical pfns */
        if (WARN_ON((pfn_hi | pfn_lo) > (ULLONG_MAX >> iova_shift(iovad))))
                return NULL;

        spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);
        for (node = rb_first(&iovad->rbroot); node; node = rb_next(node)) {
                if (__is_range_overlap(node, pfn_lo, pfn_hi)) {
                        iova = to_iova(node);
                        __adjust_overlap_range(iova, &pfn_lo, &pfn_hi);
                        if ((pfn_lo >= iova->pfn_lo) &&
                                (pfn_hi <= iova->pfn_hi))
                                goto finish;
                        overlap = 1;

                } else if (overlap)
                                break;
        }

        /* We are here either because this is the first reserver node
         * or need to insert remaining non overlap addr range
         */
        iova = __insert_new_range(iovad, pfn_lo, pfn_hi);
finish:

        spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);
        return iova;
}
EXPORT_SYMBOL_GPL(reserve_iova);

/*
 * Magazine caches for IOVA ranges.  For an introduction to magazines,
 * see the USENIX 2001 paper "Magazines and Vmem: Extending the Slab
 * Allocator to Many CPUs and Arbitrary Resources" by Bonwick and Adams.
 * For simplicity, we use a static magazine size and don't implement the
 * dynamic size tuning described in the paper.
 */

/*
 * As kmalloc's buffer size is fixed to power of 2, 127 is chosen to
 * assure size of 'iova_magazine' to be 1024 bytes, so that no memory
 * will be wasted. Since only full magazines are inserted into the depot,
 * we don't need to waste PFN capacity on a separate list head either.
 */
#define IOVA_MAG_SIZE 127

#define IOVA_DEPOT_DELAY msecs_to_jiffies(100)

struct iova_magazine {
        union {
                unsigned long size;
                struct iova_magazine *next;
        };
        unsigned long pfns[IOVA_MAG_SIZE];
};
static_assert(!(sizeof(struct iova_magazine) & (sizeof(struct iova_magazine) - 1)));

struct iova_cpu_rcache {
        spinlock_t lock;
        struct iova_magazine *loaded;
        struct iova_magazine *prev;
};

struct iova_rcache {
        spinlock_t lock;
        unsigned int depot_size;
        struct iova_magazine *depot;
        struct iova_cpu_rcache __percpu *cpu_rcaches;
        struct iova_domain *iovad;
        struct delayed_work work;
};

static struct kmem_cache *iova_magazine_cache;

unsigned long iova_rcache_range(void)
{
        return PAGE_SIZE << (IOVA_RANGE_CACHE_MAX_SIZE - 1);
}

static struct iova_magazine *iova_magazine_alloc(gfp_t flags)
{
        struct iova_magazine *mag;

        mag = kmem_cache_alloc(iova_magazine_cache, flags);
        if (mag)
                mag->size = 0;

        return mag;
}

static void iova_magazine_free(struct iova_magazine *mag)
{
        kmem_cache_free(iova_magazine_cache, mag);
}

static void
iova_magazine_free_pfns(struct iova_magazine *mag, struct iova_domain *iovad)
{
        unsigned long flags;
        int i;

        spin_lock_irqsave(&iovad->iova_rbtree_lock, flags);

        for (i = 0 ; i < mag->size; ++i) {
                struct iova *iova = private_find_iova(iovad, mag->pfns[i]);

                if (WARN_ON(!iova))
                        continue;

                remove_iova(iovad, iova);
                free_iova_mem(iova);
        }

        spin_unlock_irqrestore(&iovad->iova_rbtree_lock, flags);

        mag->size = 0;
}

static bool iova_magazine_full(struct iova_magazine *mag)
{
        return mag->size == IOVA_MAG_SIZE;
}

static bool iova_magazine_empty(struct iova_magazine *mag)
{
        return mag->size == 0;
}

static unsigned long iova_magazine_pop(struct iova_magazine *mag,
                                       unsigned long limit_pfn)
{
        int i;
        unsigned long pfn;

        /* Only fall back to the rbtree if we have no suitable pfns at all */
        for (i = mag->size - 1; mag->pfns[i] > limit_pfn; i--)
                if (i == 0)
                        return 0;

        /* Swap it to pop it */
        pfn = mag->pfns[i];
        mag->pfns[i] = mag->pfns[--mag->size];

        return pfn;
}

static void iova_magazine_push(struct iova_magazine *mag, unsigned long pfn)
{
        mag->pfns[mag->size++] = pfn;
}

static struct iova_magazine *iova_depot_pop(struct iova_rcache *rcache)
{
        struct iova_magazine *mag = rcache->depot;

        /*
         * As the mag->next pointer is moved to rcache->depot and reset via
         * the mag->size assignment, mark it as a transient false positive.
         */
        kmemleak_transient_leak(mag->next);
        rcache->depot = mag->next;
        mag->size = IOVA_MAG_SIZE;
        rcache->depot_size--;
        return mag;
}

static void iova_depot_push(struct iova_rcache *rcache, struct iova_magazine *mag)
{
        mag->next = rcache->depot;
        rcache->depot = mag;
        rcache->depot_size++;
}

static void iova_depot_work_func(struct work_struct *work)
{
        struct iova_rcache *rcache = container_of(work, typeof(*rcache), work.work);
        struct iova_magazine *mag = NULL;
        unsigned long flags;

        spin_lock_irqsave(&rcache->lock, flags);
        if (rcache->depot_size > num_online_cpus())
                mag = iova_depot_pop(rcache);
        spin_unlock_irqrestore(&rcache->lock, flags);

        if (mag) {
                iova_magazine_free_pfns(mag, rcache->iovad);
                iova_magazine_free(mag);
                schedule_delayed_work(&rcache->work, IOVA_DEPOT_DELAY);
        }
}

int iova_domain_init_rcaches(struct iova_domain *iovad)
{
        unsigned int cpu;
        int i, ret;

        iovad->rcaches = kcalloc(IOVA_RANGE_CACHE_MAX_SIZE,
                                 sizeof(struct iova_rcache),
                                 GFP_KERNEL);
        if (!iovad->rcaches)
                return -ENOMEM;

        for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
                struct iova_cpu_rcache *cpu_rcache;
                struct iova_rcache *rcache;

                rcache = &iovad->rcaches[i];
                spin_lock_init(&rcache->lock);
                rcache->iovad = iovad;
                INIT_DELAYED_WORK(&rcache->work, iova_depot_work_func);
                rcache->cpu_rcaches = __alloc_percpu(sizeof(*cpu_rcache),
                                                     cache_line_size());
                if (!rcache->cpu_rcaches) {
                        ret = -ENOMEM;
                        goto out_err;
                }
                for_each_possible_cpu(cpu) {
                        cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu);

                        spin_lock_init(&cpu_rcache->lock);
                        cpu_rcache->loaded = iova_magazine_alloc(GFP_KERNEL);
                        cpu_rcache->prev = iova_magazine_alloc(GFP_KERNEL);
                        if (!cpu_rcache->loaded || !cpu_rcache->prev) {
                                ret = -ENOMEM;
                                goto out_err;
                        }
                }
        }

        ret = cpuhp_state_add_instance_nocalls(CPUHP_IOMMU_IOVA_DEAD,
                                               &iovad->cpuhp_dead);
        if (ret)
                goto out_err;
        return 0;

out_err:
        free_iova_rcaches(iovad);
        return ret;
}
EXPORT_SYMBOL_GPL(iova_domain_init_rcaches);

/*
 * Try inserting IOVA range starting with 'iova_pfn' into 'rcache', and
 * return true on success.  Can fail if rcache is full and we can't free
 * space, and free_iova() (our only caller) will then return the IOVA
 * range to the rbtree instead.
 */
static bool __iova_rcache_insert(struct iova_domain *iovad,
                                 struct iova_rcache *rcache,
                                 unsigned long iova_pfn)
{
        struct iova_cpu_rcache *cpu_rcache;
        bool can_insert = false;
        unsigned long flags;

        cpu_rcache = raw_cpu_ptr(rcache->cpu_rcaches);
        spin_lock_irqsave(&cpu_rcache->lock, flags);

        if (!iova_magazine_full(cpu_rcache->loaded)) {
                can_insert = true;
        } else if (!iova_magazine_full(cpu_rcache->prev)) {
                swap(cpu_rcache->prev, cpu_rcache->loaded);
                can_insert = true;
        } else {
                struct iova_magazine *new_mag = iova_magazine_alloc(GFP_ATOMIC);

                if (new_mag) {
                        spin_lock(&rcache->lock);
                        iova_depot_push(rcache, cpu_rcache->loaded);
                        spin_unlock(&rcache->lock);
                        schedule_delayed_work(&rcache->work, IOVA_DEPOT_DELAY);

                        cpu_rcache->loaded = new_mag;
                        can_insert = true;
                }
        }

        if (can_insert)
                iova_magazine_push(cpu_rcache->loaded, iova_pfn);

        spin_unlock_irqrestore(&cpu_rcache->lock, flags);

        return can_insert;
}

static bool iova_rcache_insert(struct iova_domain *iovad, unsigned long pfn,
                               unsigned long size)
{
        unsigned int log_size = order_base_2(size);

        if (log_size >= IOVA_RANGE_CACHE_MAX_SIZE)
                return false;

        return __iova_rcache_insert(iovad, &iovad->rcaches[log_size], pfn);
}

/*
 * Caller wants to allocate a new IOVA range from 'rcache'.  If we can
 * satisfy the request, return a matching non-NULL range and remove
 * it from the 'rcache'.
 */
static unsigned long __iova_rcache_get(struct iova_rcache *rcache,
                                       unsigned long limit_pfn)
{
        struct iova_cpu_rcache *cpu_rcache;
        unsigned long iova_pfn = 0;
        bool has_pfn = false;
        unsigned long flags;

        cpu_rcache = raw_cpu_ptr(rcache->cpu_rcaches);
        spin_lock_irqsave(&cpu_rcache->lock, flags);

        if (!iova_magazine_empty(cpu_rcache->loaded)) {
                has_pfn = true;
        } else if (!iova_magazine_empty(cpu_rcache->prev)) {
                swap(cpu_rcache->prev, cpu_rcache->loaded);
                has_pfn = true;
        } else {
                spin_lock(&rcache->lock);
                if (rcache->depot) {
                        iova_magazine_free(cpu_rcache->loaded);
                        cpu_rcache->loaded = iova_depot_pop(rcache);
                        has_pfn = true;
                }
                spin_unlock(&rcache->lock);
        }

        if (has_pfn)
                iova_pfn = iova_magazine_pop(cpu_rcache->loaded, limit_pfn);

        spin_unlock_irqrestore(&cpu_rcache->lock, flags);

        return iova_pfn;
}

/*
 * Try to satisfy IOVA allocation range from rcache.  Fail if requested
 * size is too big or the DMA limit we are given isn't satisfied by the
 * top element in the magazine.
 */
static unsigned long iova_rcache_get(struct iova_domain *iovad,
                                     unsigned long size,
                                     unsigned long limit_pfn)
{
        unsigned int log_size = order_base_2(size);

        if (log_size >= IOVA_RANGE_CACHE_MAX_SIZE)
                return 0;

        return __iova_rcache_get(&iovad->rcaches[log_size], limit_pfn - size);
}

/*
 * free rcache data structures.
 */
static void free_iova_rcaches(struct iova_domain *iovad)
{
        struct iova_rcache *rcache;
        struct iova_cpu_rcache *cpu_rcache;
        unsigned int cpu;

        for (int i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
                rcache = &iovad->rcaches[i];
                if (!rcache->cpu_rcaches)
                        break;
                for_each_possible_cpu(cpu) {
                        cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu);
                        iova_magazine_free(cpu_rcache->loaded);
                        iova_magazine_free(cpu_rcache->prev);
                }
                free_percpu(rcache->cpu_rcaches);
                cancel_delayed_work_sync(&rcache->work);
                while (rcache->depot)
                        iova_magazine_free(iova_depot_pop(rcache));
        }

        kfree(iovad->rcaches);
        iovad->rcaches = NULL;
}

/*
 * free all the IOVA ranges cached by a cpu (used when cpu is unplugged)
 */
static void free_cpu_cached_iovas(unsigned int cpu, struct iova_domain *iovad)
{
        struct iova_cpu_rcache *cpu_rcache;
        struct iova_rcache *rcache;
        unsigned long flags;
        int i;

        for (i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
                rcache = &iovad->rcaches[i];
                cpu_rcache = per_cpu_ptr(rcache->cpu_rcaches, cpu);
                spin_lock_irqsave(&cpu_rcache->lock, flags);
                iova_magazine_free_pfns(cpu_rcache->loaded, iovad);
                iova_magazine_free_pfns(cpu_rcache->prev, iovad);
                spin_unlock_irqrestore(&cpu_rcache->lock, flags);
        }
}

/*
 * free all the IOVA ranges of global cache
 */
static void free_global_cached_iovas(struct iova_domain *iovad)
{
        struct iova_rcache *rcache;
        unsigned long flags;

        for (int i = 0; i < IOVA_RANGE_CACHE_MAX_SIZE; ++i) {
                rcache = &iovad->rcaches[i];
                spin_lock_irqsave(&rcache->lock, flags);
                while (rcache->depot) {
                        struct iova_magazine *mag = iova_depot_pop(rcache);

                        iova_magazine_free_pfns(mag, iovad);
                        iova_magazine_free(mag);
                }
                spin_unlock_irqrestore(&rcache->lock, flags);
        }
}

static int iova_cpuhp_dead(unsigned int cpu, struct hlist_node *node)
{
        struct iova_domain *iovad;

        iovad = hlist_entry_safe(node, struct iova_domain, cpuhp_dead);

        free_cpu_cached_iovas(cpu, iovad);
        return 0;
}

int iova_cache_get(void)
{
        int err = -ENOMEM;

        mutex_lock(&iova_cache_mutex);
        if (!iova_cache_users) {
                iova_cache = kmem_cache_create("iommu_iova", sizeof(struct iova), 0,
                                               SLAB_HWCACHE_ALIGN, NULL);
                if (!iova_cache)
                        goto out_err;

                iova_magazine_cache = kmem_cache_create("iommu_iova_magazine",
                                                        sizeof(struct iova_magazine),
                                                        0, SLAB_HWCACHE_ALIGN, NULL);
                if (!iova_magazine_cache)
                        goto out_err;

                err = cpuhp_setup_state_multi(CPUHP_IOMMU_IOVA_DEAD, "iommu/iova:dead",
                                              NULL, iova_cpuhp_dead);
                if (err) {
                        pr_err("IOVA: Couldn't register cpuhp handler: %pe\n", ERR_PTR(err));
                        goto out_err;
                }
        }

        iova_cache_users++;
        mutex_unlock(&iova_cache_mutex);

        return 0;

out_err:
        kmem_cache_destroy(iova_cache);
        kmem_cache_destroy(iova_magazine_cache);
        mutex_unlock(&iova_cache_mutex);
        return err;
}
EXPORT_SYMBOL_GPL(iova_cache_get);

void iova_cache_put(void)
{
        mutex_lock(&iova_cache_mutex);
        if (WARN_ON(!iova_cache_users)) {
                mutex_unlock(&iova_cache_mutex);
                return;
        }
        iova_cache_users--;
        if (!iova_cache_users) {
                cpuhp_remove_multi_state(CPUHP_IOMMU_IOVA_DEAD);
                kmem_cache_destroy(iova_cache);
                kmem_cache_destroy(iova_magazine_cache);
        }
        mutex_unlock(&iova_cache_mutex);
}
EXPORT_SYMBOL_GPL(iova_cache_put);

MODULE_AUTHOR("Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>");
MODULE_DESCRIPTION("IOMMU I/O Virtual Address management");
MODULE_LICENSE("GPL");