path: root/xen/arch/x86/mm/p2m.c

/******************************************************************************
 * arch/x86/mm/p2m.c
 *
 * physical-to-machine mappings for automatically-translated domains.
 * 
 * Parts of this code are Copyright (c) 2007 by Advanced Micro Devices.
 * Parts of this code are Copyright (c) 2006 by XenSource Inc.
 * Parts of this code are Copyright (c) 2006 by Michael A Fetterman
 * Parts based on earlier work by Michael A Fetterman, Ian Pratt et al.
 * 
 * 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/domain.h>
#include <asm/page.h>
#include <asm/paging.h>
#include <asm/p2m.h>

/* Debugging and auditing of the P2M code? */
#define P2M_AUDIT     0
#define P2M_DEBUGGING 1

/* The P2M lock.  This protects all updates to the p2m table.
 * Updates are expected to be safe against concurrent reads, 
 * which do *not* require the lock */

#define p2m_lock_init(_d)                            \
    do {                                             \
        spin_lock_init(&(_d)->arch.p2m.lock);        \
        (_d)->arch.p2m.locker = -1;                  \
        (_d)->arch.p2m.locker_function = "nobody";   \
    } while (0)

#define p2m_lock(_d)                                                \
    do {                                                            \
        if ( unlikely((_d)->arch.p2m.locker == current->processor) )\
        {                                                           \
            printk("Error: p2m lock held by %s\n",                  \
                   (_d)->arch.p2m.locker_function);                 \
            BUG();                                                  \
        }                                                           \
        spin_lock(&(_d)->arch.p2m.lock);                            \
        ASSERT((_d)->arch.p2m.locker == -1);                        \
        (_d)->arch.p2m.locker = current->processor;                 \
        (_d)->arch.p2m.locker_function = __func__;                  \
    } while (0)

#define p2m_unlock(_d)                                              \
    do {                                                            \
        ASSERT((_d)->arch.p2m.locker == current->processor); \
        (_d)->arch.p2m.locker = -1;                          \
        (_d)->arch.p2m.locker_function = "nobody";           \
        spin_unlock(&(_d)->arch.p2m.lock);                   \
    } while (0)



/* Printouts */
#define P2M_PRINTK(_f, _a...)                                \
    debugtrace_printk("p2m: %s(): " _f, __func__, ##_a)
#define P2M_ERROR(_f, _a...)                                 \
    printk("pg error: %s(): " _f, __func__, ##_a)
#if P2M_DEBUGGING
#define P2M_DEBUG(_f, _a...)                                 \
    debugtrace_printk("p2mdebug: %s(): " _f, __func__, ##_a)
#else
#define P2M_DEBUG(_f, _a...) do { (void)(_f); } while(0) 
#endif


/* Override macros from asm/page.h to make them work with mfn_t */
#undef mfn_to_page
#define mfn_to_page(_m) (frame_table + mfn_x(_m))
#undef mfn_valid
#define mfn_valid(_mfn) (mfn_x(_mfn) < max_page)
#undef page_to_mfn
#define page_to_mfn(_pg) (_mfn((_pg) - frame_table))



// Find the next level's P2M entry, checking for out-of-range gfn's...
// Returns NULL on error.
//
static l1_pgentry_t *
p2m_find_entry(void *table, unsigned long *gfn_remainder,
                   unsigned long gfn, u32 shift, u32 max)
{
    u32 index;

    index = *gfn_remainder >> shift;
    if ( index >= max )
    {
        P2M_DEBUG("gfn=0x%lx out of range "
                  "(gfn_remainder=0x%lx shift=%d index=0x%x max=0x%x)\n",
                  gfn, *gfn_remainder, shift, index, max);
        return NULL;
    }
    *gfn_remainder &= (1 << shift) - 1;
    return (l1_pgentry_t *)table + index;
}

// Walk one level of the P2M table, allocating a new table if required.
// Returns 0 on error.
//
static int
p2m_next_level(struct domain *d, mfn_t *table_mfn, void **table, 
               unsigned long *gfn_remainder, unsigned long gfn, u32 shift, 
               u32 max, unsigned long type)
{
    l1_pgentry_t *p2m_entry;
    l1_pgentry_t new_entry;
    void *next;
    ASSERT(d->arch.p2m.alloc_page);

    if ( !(p2m_entry = p2m_find_entry(*table, gfn_remainder, gfn,
                                      shift, max)) )
        return 0;

    if ( !(l1e_get_flags(*p2m_entry) & _PAGE_PRESENT) )
    {
        struct page_info *pg = d->arch.p2m.alloc_page(d);
        if ( pg == NULL )
            return 0;
        list_add_tail(&pg->list, &d->arch.p2m.pages);
        pg->u.inuse.type_info = type | 1 | PGT_validated;
        pg->count_info = 1;

        new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)),
                                 __PAGE_HYPERVISOR|_PAGE_USER);

        switch ( type ) {
        case PGT_l3_page_table:
            paging_write_p2m_entry(d, gfn, p2m_entry, new_entry, 4);
            break;
        case PGT_l2_page_table:
#if CONFIG_PAGING_LEVELS == 3
            /* for PAE mode, PDPE only has PCD/PWT/P bits available */
            new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)), _PAGE_PRESENT);
#endif
            paging_write_p2m_entry(d, gfn, p2m_entry, new_entry, 3);
            break;
        case PGT_l1_page_table:
            paging_write_p2m_entry(d, gfn, p2m_entry, new_entry, 2);
            break;
        default:
            BUG();
            break;
        }
    }
    *table_mfn = _mfn(l1e_get_pfn(*p2m_entry));
    next = map_domain_page(mfn_x(*table_mfn));
    unmap_domain_page(*table);
    *table = next;

    return 1;
}

// Returns 0 on error (out of memory)
static int
set_p2m_entry(struct domain *d, unsigned long gfn, mfn_t mfn)
{
    // XXX -- this might be able to be faster iff current->domain == d
    mfn_t table_mfn = pagetable_get_mfn(d->arch.phys_table);
    void *table =map_domain_page(mfn_x(table_mfn));
    unsigned long gfn_remainder = gfn;
    l1_pgentry_t *p2m_entry;
    l1_pgentry_t entry_content;
    int rv=0;

#if CONFIG_PAGING_LEVELS >= 4
    if ( !p2m_next_level(d, &table_mfn, &table, &gfn_remainder, gfn,
                         L4_PAGETABLE_SHIFT - PAGE_SHIFT,
                         L4_PAGETABLE_ENTRIES, PGT_l3_page_table) )
        goto out;
#endif
#if CONFIG_PAGING_LEVELS >= 3
    // When using PAE Xen, we only allow 33 bits of pseudo-physical
    // address in translated guests (i.e. 8 GBytes).  This restriction
    // comes from wanting to map the P2M table into the 16MB RO_MPT hole
    // in Xen's address space for translated PV guests.
    //
    if ( !p2m_next_level(d, &table_mfn, &table, &gfn_remainder, gfn,
                         L3_PAGETABLE_SHIFT - PAGE_SHIFT,
                         (CONFIG_PAGING_LEVELS == 3
                          ? 8
                          : L3_PAGETABLE_ENTRIES),
                         PGT_l2_page_table) )
        goto out;
#endif
    if ( !p2m_next_level(d, &table_mfn, &table, &gfn_remainder, gfn,
                         L2_PAGETABLE_SHIFT - PAGE_SHIFT,
                         L2_PAGETABLE_ENTRIES, PGT_l1_page_table) )
        goto out;

    p2m_entry = p2m_find_entry(table, &gfn_remainder, gfn,
                               0, L1_PAGETABLE_ENTRIES);
    ASSERT(p2m_entry);

    /* Track the highest gfn for which we have ever had a valid mapping */
    if ( mfn_valid(mfn) && (gfn > d->arch.p2m.max_mapped_pfn) ) 
        d->arch.p2m.max_mapped_pfn = gfn;

    if ( mfn_valid(mfn) )
        entry_content = l1e_from_pfn(mfn_x(mfn), __PAGE_HYPERVISOR|_PAGE_USER);
    else
        entry_content = l1e_empty();

    /* level 1 entry */
    paging_write_p2m_entry(d, gfn, p2m_entry, entry_content, 1);

    /* Success */
    rv = 1;
 
 out:
    unmap_domain_page(table);
    return rv;
}


/* Init the datastructures for later use by the p2m code */
void p2m_init(struct domain *d)
{
    p2m_lock_init(d);
    INIT_LIST_HEAD(&d->arch.p2m.pages);
}


// Allocate a new p2m table for a domain.
//
// The structure of the p2m table is that of a pagetable for xen (i.e. it is
// controlled by CONFIG_PAGING_LEVELS).
//
// The alloc_page and free_page functions will be used to get memory to
// build the p2m, and to release it again at the end of day. 
//
// Returns 0 for success or -errno.
//
int p2m_alloc_table(struct domain *d,
                    struct page_info * (*alloc_page)(struct domain *d),
                    void (*free_page)(struct domain *d, struct page_info *pg))

{
    mfn_t mfn;
    struct list_head *entry;
    struct page_info *page, *p2m_top;
    unsigned int page_count = 0;
    unsigned long gfn;
    
    p2m_lock(d);

    if ( pagetable_get_pfn(d->arch.phys_table) != 0 )
    {
        P2M_ERROR("p2m already allocated for this domain\n");
        p2m_unlock(d);
        return -EINVAL;
    }

    P2M_PRINTK("allocating p2m table\n");

    d->arch.p2m.alloc_page = alloc_page;
    d->arch.p2m.free_page = free_page;

    p2m_top = d->arch.p2m.alloc_page(d);
    if ( p2m_top == NULL )
    {
        p2m_unlock(d);
        return -ENOMEM;
    }
list_add_tail(&p2m_top->list, &d->arch.p2m.pages);

    p2m_top->count_info = 1;
    p2m_top->u.inuse.type_info = 
#if CONFIG_PAGING_LEVELS == 4
        PGT_l4_page_table
#elif CONFIG_PAGING_LEVELS == 3
        PGT_l3_page_table
#elif CONFIG_PAGING_LEVELS == 2
        PGT_l2_page_table
#endif
        | 1 | PGT_validated;

    d->arch.phys_table = pagetable_from_mfn(page_to_mfn(p2m_top));

    P2M_PRINTK("populating p2m table\n");
 
    /* Initialise physmap tables for slot zero. Other code assumes this. */
    gfn = 0;
mfn = _mfn(INVALID_MFN);
    if ( !set_p2m_entry(d, gfn, mfn) )
        goto error;

    for ( entry = d->page_list.next;
          entry != &d->page_list;
          entry = entry->next )
    {
        page = list_entry(entry, struct page_info, list);
        mfn = page_to_mfn(page);
        gfn = get_gpfn_from_mfn(mfn_x(mfn));
        page_count++;
        if (
#ifdef __x86_64__
            (gfn != 0x5555555555555555L)
#else
            (gfn != 0x55555555L)
#endif
             && gfn != INVALID_M2P_ENTRY
             && !set_p2m_entry(d, gfn, mfn) )
            goto error;
    }

    P2M_PRINTK("p2m table initialised (%u pages)\n", page_count);
    p2m_unlock(d);
    return 0;

 error:
    P2M_PRINTK("failed to initialize p2m table, gfn=%05lx, mfn=%"
               PRI_mfn "\n", gfn, mfn_x(mfn));
    p2m_unlock(d);
    return -ENOMEM;
}

void p2m_teardown(struct domain *d)
/* Return all the p2m pages to Xen.
 * We know we don't have any extra mappings to these pages */
{
    struct list_head *entry, *n;
    struct page_info *pg;

    p2m_lock(d);
    d->arch.phys_table = pagetable_null();

    list_for_each_safe(entry, n, &d->arch.p2m.pages)
    {
        pg = list_entry(entry, struct page_info, list);
        list_del(entry);
        d->arch.p2m.free_page(d, pg);
    }
    p2m_unlock(d);
}

mfn_t
gfn_to_mfn_foreign(struct domain *d, unsigned long gpfn)
/* Read another domain's p2m entries */
{
    mfn_t mfn;
    paddr_t addr = ((paddr_t)gpfn) << PAGE_SHIFT;
    l2_pgentry_t *l2e;
    l1_pgentry_t *l1e;
    
    ASSERT(paging_mode_translate(d));
    mfn = pagetable_get_mfn(d->arch.phys_table);


    if ( gpfn > d->arch.p2m.max_mapped_pfn ) 
        /* This pfn is higher than the highest the p2m map currently holds */
        return _mfn(INVALID_MFN);

#if CONFIG_PAGING_LEVELS >= 4
    { 
        l4_pgentry_t *l4e = map_domain_page(mfn_x(mfn));
        l4e += l4_table_offset(addr);
        if ( (l4e_get_flags(*l4e) & _PAGE_PRESENT) == 0 )
        {
            unmap_domain_page(l4e);
            return _mfn(INVALID_MFN);
        }
        mfn = _mfn(l4e_get_pfn(*l4e));
        unmap_domain_page(l4e);
    }
#endif
#if CONFIG_PAGING_LEVELS >= 3
    {
        l3_pgentry_t *l3e = map_domain_page(mfn_x(mfn));
#if CONFIG_PAGING_LEVELS == 3
        /* On PAE hosts the p2m has eight l3 entries, not four (see
         * shadow_set_p2m_entry()) so we can't use l3_table_offset.
         * Instead, just count the number of l3es from zero.  It's safe
         * to do this because we already checked that the gfn is within
         * the bounds of the p2m. */
        l3e += (addr >> L3_PAGETABLE_SHIFT);
#else
        l3e += l3_table_offset(addr);        
#endif
        if ( (l3e_get_flags(*l3e) & _PAGE_PRESENT) == 0 )
        {
            unmap_domain_page(l3e);
            return _mfn(INVALID_MFN);
        }
        mfn = _mfn(l3e_get_pfn(*l3e));
        unmap_domain_page(l3e);
    }
#endif

    l2e = map_domain_page(mfn_x(mfn));
    l2e += l2_table_offset(addr);
    if ( (l2e_get_flags(*l2e) & _PAGE_PRESENT) == 0 )
    {
        unmap_domain_page(l2e);
        return _mfn(INVALID_MFN);
    }
    mfn = _mfn(l2e_get_pfn(*l2e));
    unmap_domain_page(l2e);

    l1e = map_domain_page(mfn_x(mfn));
    l1e += l1_table_offset(addr);
    if ( (l1e_get_flags(*l1e) & _PAGE_PRESENT) == 0 )
    {
        unmap_domain_page(l1e);
        return _mfn(INVALID_MFN);
    }
    mfn = _mfn(l1e_get_pfn(*l1e));
    unmap_domain_page(l1e);

    return mfn;
}

#if P2M_AUDIT
static void audit_p2m(struct domain *d)
{
    struct list_head *entry;
    struct page_info *page;
    struct domain *od;
    unsigned long mfn, gfn, m2pfn, lp2mfn = 0;
    mfn_t p2mfn;
    unsigned long orphans_d = 0, orphans_i = 0, mpbad = 0, pmbad = 0;
    int test_linear;
    
    if ( !paging_mode_translate(d) )
        return;

    //P2M_PRINTK("p2m audit starts\n");

    test_linear = ( (d == current->domain) 
                    && !pagetable_is_null(current->arch.monitor_table) );
    if ( test_linear )
        local_flush_tlb(); 

    /* Audit part one: walk the domain's page allocation list, checking 
     * the m2p entries. */
    for ( entry = d->page_list.next;
          entry != &d->page_list;
          entry = entry->next )
    {
        page = list_entry(entry, struct page_info, list);
        mfn = mfn_x(page_to_mfn(page));

        // P2M_PRINTK("auditing guest page, mfn=%#lx\n", mfn); 

        od = page_get_owner(page);

        if ( od != d ) 
        {
            P2M_PRINTK("wrong owner %#lx -> %p(%u) != %p(%u)\n",
                       mfn, od, (od?od->domain_id:-1), d, d->domain_id);
            continue;
        }

        gfn = get_gpfn_from_mfn(mfn);
        if ( gfn == INVALID_M2P_ENTRY ) 
        {
            orphans_i++;
            //P2M_PRINTK("orphaned guest page: mfn=%#lx has invalid gfn\n",
            //               mfn); 
            continue;
        }

        if ( gfn == 0x55555555 ) 
        {
            orphans_d++;
            //P2M_PRINTK("orphaned guest page: mfn=%#lx has debug gfn\n", 
            //               mfn); 
            continue;
        }

        p2mfn = gfn_to_mfn_foreign(d, gfn);
        if ( mfn_x(p2mfn) != mfn )
        {
            mpbad++;
            P2M_PRINTK("map mismatch mfn %#lx -> gfn %#lx -> mfn %#lx"
                       " (-> gfn %#lx)\n",
                       mfn, gfn, mfn_x(p2mfn),
                       (mfn_valid(p2mfn)
                        ? get_gpfn_from_mfn(mfn_x(p2mfn))
                        : -1u));
            /* This m2p entry is stale: the domain has another frame in
             * this physical slot.  No great disaster, but for neatness,
             * blow away the m2p entry. */ 
            set_gpfn_from_mfn(mfn, INVALID_M2P_ENTRY);
        }

        if ( test_linear && (gfn <= d->arch.p2m.max_mapped_pfn) )
        {
            lp2mfn = mfn_x(gfn_to_mfn_current(gfn));
            if ( lp2mfn != mfn_x(p2mfn) )
            {
                P2M_PRINTK("linear mismatch gfn %#lx -> mfn %#lx "
                           "(!= mfn %#lx)\n", gfn, lp2mfn, mfn_x(p2mfn));
            }
        }

        // P2M_PRINTK("OK: mfn=%#lx, gfn=%#lx, p2mfn=%#lx, lp2mfn=%#lx\n", 
        //                mfn, gfn, p2mfn, lp2mfn); 
    }   

    /* Audit part two: walk the domain's p2m table, checking the entries. */
    if ( pagetable_get_pfn(d->arch.phys_table) != 0 )
    {
        l2_pgentry_t *l2e;
        l1_pgentry_t *l1e;
        int i1, i2;
        
#if CONFIG_PAGING_LEVELS == 4
        l4_pgentry_t *l4e;
        l3_pgentry_t *l3e;
        int i3, i4;
        l4e = map_domain_page(mfn_x(pagetable_get_mfn(d->arch.phys_table)));
#elif CONFIG_PAGING_LEVELS == 3
        l3_pgentry_t *l3e;
        int i3;
        l3e = map_domain_page(mfn_x(pagetable_get_mfn(d->arch.phys_table)));
#else /* CONFIG_PAGING_LEVELS == 2 */
        l2e = map_domain_page(mfn_x(pagetable_get_mfn(d->arch.phys_table)));
#endif

        gfn = 0;
#if CONFIG_PAGING_LEVELS >= 3
#if CONFIG_PAGING_LEVELS >= 4
        for ( i4 = 0; i4 < L4_PAGETABLE_ENTRIES; i4++ )
        {
            if ( !(l4e_get_flags(l4e[i4]) & _PAGE_PRESENT) )
            {
                gfn += 1 << (L4_PAGETABLE_SHIFT - PAGE_SHIFT);
                continue;
            }
            l3e = map_domain_page(mfn_x(_mfn(l4e_get_pfn(l4e[i4]))));
#endif /* now at levels 3 or 4... */
            for ( i3 = 0; 
                  i3 < ((CONFIG_PAGING_LEVELS==4) ? L3_PAGETABLE_ENTRIES : 8); 
                  i3++ )
            {
                if ( !(l3e_get_flags(l3e[i3]) & _PAGE_PRESENT) )
                {
                    gfn += 1 << (L3_PAGETABLE_SHIFT - PAGE_SHIFT);
                    continue;
                }
                l2e = map_domain_page(mfn_x(_mfn(l3e_get_pfn(l3e[i3]))));
#endif /* all levels... */
                for ( i2 = 0; i2 < L2_PAGETABLE_ENTRIES; i2++ )
                {
                    if ( !(l2e_get_flags(l2e[i2]) & _PAGE_PRESENT) )
                    {
                        gfn += 1 << (L2_PAGETABLE_SHIFT - PAGE_SHIFT);
                        continue;
                    }
                    l1e = map_domain_page(mfn_x(_mfn(l2e_get_pfn(l2e[i2]))));
                    
                    for ( i1 = 0; i1 < L1_PAGETABLE_ENTRIES; i1++, gfn++ )
                    {
                        if ( !(l1e_get_flags(l1e[i1]) & _PAGE_PRESENT) )
                            continue;
                        mfn = l1e_get_pfn(l1e[i1]);
                        ASSERT(mfn_valid(_mfn(mfn)));
                        m2pfn = get_gpfn_from_mfn(mfn);
                        if ( m2pfn != gfn )
                        {
                            pmbad++;
                            P2M_PRINTK("mismatch: gfn %#lx -> mfn %#lx"
                                       " -> gfn %#lx\n", gfn, mfn, m2pfn);
                            BUG();
                        }
                    }
                    unmap_domain_page(l1e);
                }
#if CONFIG_PAGING_LEVELS >= 3
                unmap_domain_page(l2e);
            }
#if CONFIG_PAGING_LEVELS >= 4
            unmap_domain_page(l3e);
        }
#endif
#endif

#if CONFIG_PAGING_LEVELS == 4
        unmap_domain_page(l4e);
#elif CONFIG_PAGING_LEVELS == 3
        unmap_domain_page(l3e);
#else /* CONFIG_PAGING_LEVELS == 2 */
        unmap_domain_page(l2e);
#endif

    }

    //P2M_PRINTK("p2m audit complete\n");
    //if ( orphans_i | orphans_d | mpbad | pmbad ) 
    //    P2M_PRINTK("p2m audit found %lu orphans (%lu inval %lu debug)\n",
    //                   orphans_i + orphans_d, orphans_i, orphans_d,
    if ( mpbad | pmbad ) 
        P2M_PRINTK("p2m audit found %lu odd p2m, %lu bad m2p entries\n",
                   pmbad, mpbad);
}
#else 
#define audit_p2m(_d) do { (void)(_d); } while(0)
#endif /* P2M_AUDIT */



static void
p2m_remove_page(struct domain *d, unsigned long gfn, unsigned long mfn)
{
    if ( !paging_mode_translate(d) )
        return;
    P2M_DEBUG("removing gfn=%#lx mfn=%#lx\n", gfn, mfn);

    ASSERT(mfn_x(gfn_to_mfn(d, gfn)) == mfn);
    //ASSERT(mfn_to_gfn(d, mfn) == gfn);

    set_p2m_entry(d, gfn, _mfn(INVALID_MFN));
    set_gpfn_from_mfn(mfn, INVALID_M2P_ENTRY);
}

void
guest_physmap_remove_page(struct domain *d, unsigned long gfn,
                          unsigned long mfn)
{
    p2m_lock(d);
    audit_p2m(d);
    p2m_remove_page(d, gfn, mfn);
    audit_p2m(d);
    p2m_unlock(d);    
}

void
guest_physmap_add_page(struct domain *d, unsigned long gfn,
                       unsigned long mfn)
{
    unsigned long ogfn;
    mfn_t omfn;

    if ( !paging_mode_translate(d) )
        return;

    p2m_lock(d);
    audit_p2m(d);

    P2M_DEBUG("adding gfn=%#lx mfn=%#lx\n", gfn, mfn);

    omfn = gfn_to_mfn(d, gfn);
    if ( mfn_valid(omfn) )
    {
        set_p2m_entry(d, gfn, _mfn(INVALID_MFN));
        set_gpfn_from_mfn(mfn_x(omfn), INVALID_M2P_ENTRY);
    }

    ogfn = mfn_to_gfn(d, _mfn(mfn));
    if (
#ifdef __x86_64__
        (ogfn != 0x5555555555555555L)
#else
        (ogfn != 0x55555555L)
#endif
        && (ogfn != INVALID_M2P_ENTRY)
        && (ogfn != gfn) )
    {
        /* This machine frame is already mapped at another physical address */
        P2M_DEBUG("aliased! mfn=%#lx, old gfn=%#lx, new gfn=%#lx\n",
                  mfn, ogfn, gfn);
        if ( mfn_valid(omfn = gfn_to_mfn(d, ogfn)) ) 
        {
            P2M_DEBUG("old gfn=%#lx -> mfn %#lx\n", 
                      ogfn , mfn_x(omfn));
            if ( mfn_x(omfn) == mfn ) 
                p2m_remove_page(d, ogfn, mfn);
        }
    }

    set_p2m_entry(d, gfn, _mfn(mfn));
    set_gpfn_from_mfn(mfn, gfn);

    audit_p2m(d);
    p2m_unlock(d);
}


/*
 * Local variables:
 * mode: C
 * c-set-style: "BSD"
 * c-basic-offset: 4
 * indent-tabs-mode: nil
 * End:
 */