tlb_track.c

xen 3.2.2 源码

/******************************************************************************
 * tlb_track.c
 *
 * Copyright (c) 2006 Isaku Yamahata <yamahata at valinux co jp>
 *                    VA Linux Systems Japan K.K.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#include <asm/tlb_track.h>
#include <asm/p2m_entry.h>
#include <asm/vmx_mm_def.h>  /* for IA64_RR_SHIFT */
#include <asm/vmx_vcpu.h>    /* for VRN7 */
#include <asm/vcpu.h>        /* for PSCB() */

#define CONFIG_TLB_TRACK_DEBUG
#ifdef CONFIG_TLB_TRACK_DEBUG
# define tlb_track_printd(fmt, ...)     \
    dprintk(XENLOG_DEBUG, fmt, ##__VA_ARGS__)
#else
# define tlb_track_printd(fmt, ...)     do { } while (0)
#endif

static int
tlb_track_allocate_entries(struct tlb_track* tlb_track)
{
    struct page_info* entry_page;
    struct tlb_track_entry* track_entries;
    unsigned int allocated;
    unsigned long i;

    BUG_ON(tlb_track->num_free > 0);
    if (tlb_track->num_entries >= tlb_track->limit) {
        dprintk(XENLOG_WARNING, "%s: num_entries %d limit %d\n",
                __func__, tlb_track->num_entries, tlb_track->limit);
        return -ENOMEM;
    }
    entry_page = alloc_domheap_page(NULL);
    if (entry_page == NULL) {
        dprintk(XENLOG_WARNING,
                "%s: domheap page failed. num_entries %d limit %d\n",
                __func__, tlb_track->num_entries, tlb_track->limit);
        return -ENOMEM;
    }

    list_add(&entry_page->list, &tlb_track->page_list);
    track_entries = (struct tlb_track_entry*)page_to_virt(entry_page);
    allocated = PAGE_SIZE / sizeof(track_entries[0]);
    tlb_track->num_entries += allocated;
    tlb_track->num_free += allocated;
    for (i = 0; i < allocated; i++) {
        list_add(&track_entries[i].list, &tlb_track->free_list);
        // tlb_track_printd("track_entries[%ld] 0x%p\n", i, &track_entries[i]);
    }
    tlb_track_printd("allocated %d num_entries %d num_free %d\n",
                     allocated, tlb_track->num_entries, tlb_track->num_free);
    return 0;
}


int
tlb_track_create(struct domain* d)
{
    struct tlb_track* tlb_track = NULL;
    struct page_info* hash_page = NULL;
    unsigned int hash_size;
    unsigned int hash_shift;
    unsigned int i;

    tlb_track = xmalloc(struct tlb_track);
    if (tlb_track == NULL)
        goto out;

    hash_page = alloc_domheap_page(NULL);
    if (hash_page == NULL)
        goto out;

    spin_lock_init(&tlb_track->free_list_lock);
    INIT_LIST_HEAD(&tlb_track->free_list);
    tlb_track->limit = TLB_TRACK_LIMIT_ENTRIES;
    tlb_track->num_entries = 0;
    tlb_track->num_free = 0;
    INIT_LIST_HEAD(&tlb_track->page_list);
    if (tlb_track_allocate_entries(tlb_track) < 0)
        goto out;

    spin_lock_init(&tlb_track->hash_lock);
    /* XXX hash size optimization */
    hash_size = PAGE_SIZE / sizeof(tlb_track->hash[0]);
    for (hash_shift = 0; (1 << (hash_shift + 1)) < hash_size; hash_shift++)
        /* nothing */;
    tlb_track->hash_size = (1 << hash_shift);
    tlb_track->hash_shift = hash_shift;
    tlb_track->hash_mask = (1 << hash_shift) - 1;
    tlb_track->hash = page_to_virt(hash_page);
    for (i = 0; i < tlb_track->hash_size; i++)
        INIT_LIST_HEAD(&tlb_track->hash[i]);

    smp_mb(); /* make initialization visible before use. */
    d->arch.tlb_track = tlb_track;
    dprintk(XENLOG_DEBUG, "hash 0x%p hash_size %d\n",
            tlb_track->hash, tlb_track->hash_size);

    return 0;

out:
    if (hash_page != NULL)
        free_domheap_page(hash_page);

    if (tlb_track != NULL)
        xfree(tlb_track);

    return -ENOMEM;
}

void
tlb_track_destroy(struct domain* d)
{
    struct tlb_track* tlb_track = d->arch.tlb_track;
    struct page_info* page;
    struct page_info* next;

    spin_lock(&tlb_track->free_list_lock);
    BUG_ON(tlb_track->num_free != tlb_track->num_entries);

    list_for_each_entry_safe(page, next, &tlb_track->page_list, list) {
        list_del(&page->list);
        free_domheap_page(page);
    }

    free_domheap_page(virt_to_page(tlb_track->hash));
    xfree(tlb_track);
    // d->tlb_track = NULL;
}

static struct tlb_track_entry*
tlb_track_get_entry(struct tlb_track* tlb_track)
{
    struct tlb_track_entry* entry = NULL;
    spin_lock(&tlb_track->free_list_lock);
    if (tlb_track->num_free == 0)
        (void)tlb_track_allocate_entries(tlb_track);

    if (tlb_track->num_free > 0) {
        BUG_ON(list_empty(&tlb_track->free_list));
        entry = list_entry(tlb_track->free_list.next,
                           struct tlb_track_entry, list);
        tlb_track->num_free--;
        list_del(&entry->list);
    }
    spin_unlock(&tlb_track->free_list_lock);
    return entry;
}

void
tlb_track_free_entry(struct tlb_track* tlb_track,
                     struct tlb_track_entry* entry)
{
    spin_lock(&tlb_track->free_list_lock);
    list_add(&entry->list, &tlb_track->free_list);
    tlb_track->num_free++;
    spin_unlock(&tlb_track->free_list_lock);
}


#include <linux/hash.h>
/* XXX hash function. */
static struct list_head*
tlb_track_hash_head(struct tlb_track* tlb_track, volatile pte_t* ptep)
{
    unsigned long hash = hash_long((unsigned long)ptep, tlb_track->hash_shift);
    BUG_ON(hash >= tlb_track->hash_size);
    BUG_ON((hash & tlb_track->hash_mask) != hash);
    return &tlb_track->hash[hash];
}

static int
tlb_track_pte_zapped(pte_t old_pte, pte_t ret_pte)
{
    if (pte_pfn(old_pte) != pte_pfn(ret_pte) ||
        (pte_val(old_pte) & ~(_PFN_MASK | _PAGE_TLB_TRACK_MASK)) !=
        (pte_val(ret_pte) & ~(_PFN_MASK | _PAGE_TLB_TRACK_MASK))) {
        /* Other thread zapped the p2m entry. */
        return 1;
    }
    return 0;
}

static TLB_TRACK_RET_T
tlb_track_insert_or_dirty(struct tlb_track* tlb_track, struct mm_struct* mm,
                          volatile pte_t* ptep, pte_t old_pte,
                          unsigned long vaddr, unsigned long rid)
{
    unsigned long mfn = pte_pfn(old_pte);
    struct list_head* head = tlb_track_hash_head(tlb_track, ptep);
    struct tlb_track_entry* entry;
    struct tlb_track_entry* new_entry = NULL;
    unsigned long bit_to_be_set = _PAGE_TLB_INSERTED;
    pte_t new_pte;
    pte_t ret_pte;

    struct vcpu* v = current;
    TLB_TRACK_RET_T ret = TLB_TRACK_NOT_FOUND;

#if 0 /* this is done at vcpu_tlb_track_insert_or_dirty() */
    perfc_incr(tlb_track_iod);
    if (!pte_tlb_tracking(old_pte)) {
        perfc_incr(tlb_track_iod_not_tracked);
        return TLB_TRACK_NOT_TRACKED;
    }
#endif
    if (pte_tlb_inserted_many(old_pte)) {
        perfc_incr(tlb_track_iod_tracked_many);
        return TLB_TRACK_MANY;
    }

    /* vaddr must be normalized so that it is in vrn7 and page aligned. */
    BUG_ON((vaddr >> IA64_RR_SHIFT) != VRN7);
    BUG_ON((vaddr & ~PAGE_MASK) != 0);
#if 0
    tlb_track_printd("\n"
                     "\tmfn 0x%016lx\n"
                     "\told_pte 0x%016lx ptep 0x%p\n"
                     "\tptep_val 0x%016lx vaddr 0x%016lx rid %ld\n"
                     "\ttlb_track 0x%p head 0x%p\n",
                     mfn,
                     pte_val(old_pte), ptep, pte_val(*ptep),
                     vaddr, rid,
                     tlb_track, head);
#endif

 again:
    /*
     * zapping side may zap the p2m entry and then remove tlb track entry
     * non-atomically. We may see the stale tlb track entry here.
     * p2m_entry_retry() handles such a case.
     * Or other thread may zap the p2m entry and remove tlb track entry
     * and inserted new tlb track entry.
     */
    spin_lock(&tlb_track->hash_lock);
    list_for_each_entry(entry, head, list) {
        if (entry->ptep != ptep)
            continue;

        if (pte_pfn(entry->pte_val) == mfn) {
            // tlb_track_entry_printf(entry);
            if (entry->vaddr == vaddr && entry->rid == rid) {
                // tlb_track_printd("TLB_TRACK_FOUND\n");
                ret = TLB_TRACK_FOUND;
                perfc_incr(tlb_track_iod_found);
#ifdef CONFIG_TLB_TRACK_CNT
                entry->cnt++;
                if (entry->cnt > TLB_TRACK_CNT_FORCE_MANY) {
                    /*