Ejemplo n.º 1
0
/*
 * Mark (via clearing the U flag) as needing P2M type re-calculation all valid
 * present entries at the targeted level for the passed in GFN range, which is
 * guaranteed to not cross a page (table) boundary at that level.
 */
static int p2m_pt_set_recalc_range(struct p2m_domain *p2m,
                                   unsigned int level,
                                   unsigned long first_gfn,
                                   unsigned long last_gfn)
{
    void *table;
    unsigned long gfn_remainder = first_gfn, remainder;
    unsigned int i;
    l1_pgentry_t *pent, *plast;
    int err = 0;

    table = map_domain_page(pagetable_get_mfn(p2m_get_pagetable(p2m)));
    for ( i = 4; i-- > level; )
    {
        remainder = gfn_remainder;
        pent = p2m_find_entry(table, &remainder, first_gfn,
                              i * PAGETABLE_ORDER, 1 << PAGETABLE_ORDER);
        if ( !pent )
        {
            err = -EINVAL;
            goto out;
        }

        if ( !(l1e_get_flags(*pent) & _PAGE_PRESENT) )
            goto out;

        err = p2m_next_level(p2m, &table, &gfn_remainder, first_gfn,
                             i * PAGETABLE_ORDER, 1 << PAGETABLE_ORDER,
                             pgt[i - 1], 1);
        if ( err )
            goto out;
    }

    remainder = gfn_remainder + (last_gfn - first_gfn);
    pent = p2m_find_entry(table, &gfn_remainder, first_gfn,
                          i * PAGETABLE_ORDER, 1 << PAGETABLE_ORDER);
    plast = p2m_find_entry(table, &remainder, last_gfn,
                           i * PAGETABLE_ORDER, 1 << PAGETABLE_ORDER);
    if ( pent && plast )
        for ( ; pent <= plast; ++pent )
        {
            l1_pgentry_t e = *pent;

            if ( (l1e_get_flags(e) & _PAGE_PRESENT) && !needs_recalc(l1, e) )
            {
                set_recalc(l1, e);
                p2m->write_p2m_entry(p2m, first_gfn, pent, e, level);
            }
            first_gfn += 1UL << (i * PAGETABLE_ORDER);
        }
    else
        err = -EIO;

 out:
    unmap_domain_page(table);

    return err;
}
Ejemplo n.º 2
0
/*
 * Handle possibly necessary P2M type re-calculation (U flag clear for a
 * present entry) for the entries in the page table hierarchy for the given
 * GFN. Propagate the re-calculation flag down to the next page table level
 * for entries not involved in the translation of the given GFN.
 */
static int do_recalc(struct p2m_domain *p2m, unsigned long gfn)
{
    void *table;
    unsigned long gfn_remainder = gfn;
    unsigned int level = 4;
    l1_pgentry_t *pent;
    int err = 0;

    table = map_domain_page(pagetable_get_mfn(p2m_get_pagetable(p2m)));
    while ( --level )
    {
        unsigned long remainder = gfn_remainder;

        pent = p2m_find_entry(table, &remainder, gfn,
                              level * PAGETABLE_ORDER, 1 << PAGETABLE_ORDER);
        if ( !pent || !(l1e_get_flags(*pent) & _PAGE_PRESENT) )
            goto out;

        if ( l1e_get_flags(*pent) & _PAGE_PSE )
        {
            unsigned long mask = ~0UL << (level * PAGETABLE_ORDER);

            if ( !needs_recalc(l1, *pent) ||
                 !p2m_is_changeable(p2m_flags_to_type(l1e_get_flags(*pent))) ||
                 p2m_is_logdirty_range(p2m, gfn & mask, gfn | ~mask) >= 0 )
                break;
        }

        err = p2m_next_level(p2m, &table, &gfn_remainder, gfn,
                             level * PAGETABLE_ORDER, 1 << PAGETABLE_ORDER,
                             pgt[level - 1], 0);
        if ( err )
            goto out;

        if ( needs_recalc(l1, *pent) )
        {
            l1_pgentry_t e = *pent, *ptab = table;
            unsigned int i;

            if ( !valid_recalc(l1, e) )
                P2M_DEBUG("bogus recalc state at d%d:%lx:%u\n",
                          p2m->domain->domain_id, gfn, level);
            remainder = gfn_remainder;
            for ( i = 0; i < (1 << PAGETABLE_ORDER); ++i )
            {
                l1_pgentry_t ent = ptab[i];

                if ( (l1e_get_flags(ent) & _PAGE_PRESENT) &&
                     !needs_recalc(l1, ent) )
                {
                    set_recalc(l1, ent);
                    p2m->write_p2m_entry(p2m, gfn - remainder, &ptab[i],
                                         ent, level);
                }
                remainder -= 1UL << ((level - 1) * PAGETABLE_ORDER);
            }
            smp_wmb();
            clear_recalc(l1, e);
            p2m->write_p2m_entry(p2m, gfn, pent, e, level + 1);
        }
        unmap_domain_page((void *)((unsigned long)pent & PAGE_MASK));
    }

    pent = p2m_find_entry(table, &gfn_remainder, gfn,
                          level * PAGETABLE_ORDER, 1 << PAGETABLE_ORDER);
    if ( pent && (l1e_get_flags(*pent) & _PAGE_PRESENT) &&
         needs_recalc(l1, *pent) )
    {
        l1_pgentry_t e = *pent;

        if ( !valid_recalc(l1, e) )
            P2M_DEBUG("bogus recalc leaf at d%d:%lx:%u\n",
                      p2m->domain->domain_id, gfn, level);
        if ( p2m_is_changeable(p2m_flags_to_type(l1e_get_flags(e))) )
        {
            unsigned long mask = ~0UL << (level * PAGETABLE_ORDER);
            p2m_type_t p2mt = p2m_is_logdirty_range(p2m, gfn & mask, gfn | ~mask)
                              ? p2m_ram_logdirty : p2m_ram_rw;
            unsigned long mfn = l1e_get_pfn(e);
            unsigned long flags = p2m_type_to_flags(p2mt, _mfn(mfn));

            if ( level )
            {
                if ( flags & _PAGE_PAT )
                {
                     BUILD_BUG_ON(_PAGE_PAT != _PAGE_PSE);
                     mfn |= _PAGE_PSE_PAT >> PAGE_SHIFT;
                }
                else
                     mfn &= ~(_PAGE_PSE_PAT >> PAGE_SHIFT);
                flags |= _PAGE_PSE;
            }
Ejemplo n.º 3
0
// Returns 0 on error (out of memory)
static int
p2m_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn, 
              unsigned int page_order, p2m_type_t p2mt, p2m_access_t p2ma)
{
    // XXX -- this might be able to be faster iff current->domain == d
    mfn_t table_mfn = pagetable_get_mfn(p2m_get_pagetable(p2m));
    void *table =map_domain_page(mfn_x(table_mfn));
    unsigned long i, gfn_remainder = gfn;
    l1_pgentry_t *p2m_entry;
    l1_pgentry_t entry_content;
    l2_pgentry_t l2e_content;
    l3_pgentry_t l3e_content;
    int rv=0;
    unsigned int iommu_pte_flags = (p2mt == p2m_ram_rw) ?
                                   IOMMUF_readable|IOMMUF_writable:
                                   0; 
    unsigned long old_mfn = 0;

    if ( tb_init_done )
    {
        struct {
            u64 gfn, mfn;
            int p2mt;
            int d:16,order:16;
        } t;

        t.gfn = gfn;
        t.mfn = mfn_x(mfn);
        t.p2mt = p2mt;
        t.d = p2m->domain->domain_id;
        t.order = page_order;

        __trace_var(TRC_MEM_SET_P2M_ENTRY, 0, sizeof(t), &t);
    }

#if CONFIG_PAGING_LEVELS >= 4
    if ( !p2m_next_level(p2m, &table_mfn, &table, &gfn_remainder, gfn,
                         L4_PAGETABLE_SHIFT - PAGE_SHIFT,
                         L4_PAGETABLE_ENTRIES, PGT_l3_page_table) )
        goto out;
#endif
    /*
     * Try to allocate 1GB page table if this feature is supported.
     */
    if ( page_order == PAGE_ORDER_1G )
    {
        l1_pgentry_t old_entry = l1e_empty();
        p2m_entry = p2m_find_entry(table, &gfn_remainder, gfn,
                                   L3_PAGETABLE_SHIFT - PAGE_SHIFT,
                                   L3_PAGETABLE_ENTRIES);
        ASSERT(p2m_entry);
        if ( (l1e_get_flags(*p2m_entry) & _PAGE_PRESENT) &&
             !(l1e_get_flags(*p2m_entry) & _PAGE_PSE) )
        {
            /* We're replacing a non-SP page with a superpage.  Make sure to
             * handle freeing the table properly. */
            old_entry = *p2m_entry;
        }

        ASSERT(!mfn_valid(mfn) || p2mt != p2m_mmio_direct);
        l3e_content = mfn_valid(mfn) 
            ? l3e_from_pfn(mfn_x(mfn),
                           p2m_type_to_flags(p2mt, mfn) | _PAGE_PSE)
            : l3e_empty();
        entry_content.l1 = l3e_content.l3;

        if ( entry_content.l1 != 0 )
        {
            p2m_add_iommu_flags(&entry_content, 0, iommu_pte_flags);
            old_mfn = l1e_get_pfn(*p2m_entry);
        }

        p2m->write_p2m_entry(p2m, gfn, p2m_entry, table_mfn, entry_content, 3);
        /* NB: paging_write_p2m_entry() handles tlb flushes properly */

        /* Free old intermediate tables if necessary */
        if ( l1e_get_flags(old_entry) & _PAGE_PRESENT )
            p2m_free_entry(p2m, &old_entry, page_order);
    }
    /*
     * 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.
     * When using AMD's NPT on PAE Xen, we are restricted to 4GB.
     */
    else if ( !p2m_next_level(p2m, &table_mfn, &table, &gfn_remainder, gfn,
                              L3_PAGETABLE_SHIFT - PAGE_SHIFT,
                              ((CONFIG_PAGING_LEVELS == 3)
                               ? (hap_enabled(p2m->domain) ? 4 : 8)
                               : L3_PAGETABLE_ENTRIES),
                              PGT_l2_page_table) )
        goto out;

    if ( page_order == PAGE_ORDER_4K )
    {
        if ( !p2m_next_level(p2m, &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);
        
        if ( mfn_valid(mfn) || (p2mt == p2m_mmio_direct)
                            || p2m_is_paging(p2mt) )
            entry_content = p2m_l1e_from_pfn(mfn_x(mfn),
                                             p2m_type_to_flags(p2mt, mfn));
        else
            entry_content = l1e_empty();

        if ( entry_content.l1 != 0 )
        {
            p2m_add_iommu_flags(&entry_content, 0, iommu_pte_flags);
            old_mfn = l1e_get_pfn(*p2m_entry);
        }
        /* level 1 entry */
        p2m->write_p2m_entry(p2m, gfn, p2m_entry, table_mfn, entry_content, 1);
        /* NB: paging_write_p2m_entry() handles tlb flushes properly */
    }
    else if ( page_order == PAGE_ORDER_2M )
    {
        l1_pgentry_t old_entry = l1e_empty();
        p2m_entry = p2m_find_entry(table, &gfn_remainder, gfn,
                                   L2_PAGETABLE_SHIFT - PAGE_SHIFT,
                                   L2_PAGETABLE_ENTRIES);
        ASSERT(p2m_entry);
        
        /* FIXME: Deal with 4k replaced by 2meg pages */
        if ( (l1e_get_flags(*p2m_entry) & _PAGE_PRESENT) &&
             !(l1e_get_flags(*p2m_entry) & _PAGE_PSE) )
        {
            /* We're replacing a non-SP page with a superpage.  Make sure to
             * handle freeing the table properly. */
            old_entry = *p2m_entry;
        }
        
        ASSERT(!mfn_valid(mfn) || p2mt != p2m_mmio_direct);
        if ( mfn_valid(mfn) || p2m_is_magic(p2mt) )
            l2e_content = l2e_from_pfn(mfn_x(mfn),
                                       p2m_type_to_flags(p2mt, mfn) |
                                       _PAGE_PSE);
        else
            l2e_content = l2e_empty();
        
        entry_content.l1 = l2e_content.l2;

        if ( entry_content.l1 != 0 )
        {
            p2m_add_iommu_flags(&entry_content, 0, iommu_pte_flags);
            old_mfn = l1e_get_pfn(*p2m_entry);
        }

        p2m->write_p2m_entry(p2m, gfn, p2m_entry, table_mfn, entry_content, 2);
        /* NB: paging_write_p2m_entry() handles tlb flushes properly */

        /* Free old intermediate tables if necessary */
        if ( l1e_get_flags(old_entry) & _PAGE_PRESENT )
            p2m_free_entry(p2m, &old_entry, page_order);
    }

    /* Track the highest gfn for which we have ever had a valid mapping */
    if ( p2mt != p2m_invalid
         && (gfn + (1UL << page_order) - 1 > p2m->max_mapped_pfn) )
        p2m->max_mapped_pfn = gfn + (1UL << page_order) - 1;

    if ( iommu_enabled && need_iommu(p2m->domain) )
    {
        if ( iommu_hap_pt_share )
        {
            if ( old_mfn && (old_mfn != mfn_x(mfn)) )
                amd_iommu_flush_pages(p2m->domain, gfn, page_order);
        }
        else
        {
            if ( p2mt == p2m_ram_rw )
                for ( i = 0; i < (1UL << page_order); i++ )
                    iommu_map_page(p2m->domain, gfn+i, mfn_x(mfn)+i,
                                   IOMMUF_readable|IOMMUF_writable);
            else
                for ( int i = 0; i < (1UL << page_order); i++ )
                    iommu_unmap_page(p2m->domain, gfn+i);
        }
    }

    /* Success */
    rv = 1;

out:
    unmap_domain_page(table);
    return rv;
}
Ejemplo n.º 4
0
/* Returns: 0 for success, -errno for failure */
static int
p2m_next_level(struct p2m_domain *p2m, void **table,
               unsigned long *gfn_remainder, unsigned long gfn, u32 shift,
               u32 max, unsigned long type, bool_t unmap)
{
    l1_pgentry_t *l1_entry;
    l1_pgentry_t *p2m_entry;
    l1_pgentry_t new_entry;
    void *next;
    int i;

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

    /* PoD/paging: Not present doesn't imply empty. */
    if ( !l1e_get_flags(*p2m_entry) )
    {
        struct page_info *pg;

        pg = p2m_alloc_ptp(p2m, type);
        if ( pg == NULL )
            return -ENOMEM;

        new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)),
                                 P2M_BASE_FLAGS | _PAGE_RW);

        switch ( type ) {
        case PGT_l3_page_table:
            p2m_add_iommu_flags(&new_entry, 3, IOMMUF_readable|IOMMUF_writable);
            p2m->write_p2m_entry(p2m, gfn, p2m_entry, new_entry, 4);
            break;
        case PGT_l2_page_table:
            p2m_add_iommu_flags(&new_entry, 2, IOMMUF_readable|IOMMUF_writable);
            p2m->write_p2m_entry(p2m, gfn, p2m_entry, new_entry, 3);
            break;
        case PGT_l1_page_table:
            p2m_add_iommu_flags(&new_entry, 1, IOMMUF_readable|IOMMUF_writable);
            p2m->write_p2m_entry(p2m, gfn, p2m_entry, new_entry, 2);
            break;
        default:
            BUG();
            break;
        }
    }

    ASSERT(l1e_get_flags(*p2m_entry) & (_PAGE_PRESENT|_PAGE_PSE));

    /* split 1GB pages into 2MB pages */
    if ( type == PGT_l2_page_table && (l1e_get_flags(*p2m_entry) & _PAGE_PSE) )
    {
        unsigned long flags, pfn;
        struct page_info *pg;

        pg = p2m_alloc_ptp(p2m, PGT_l2_page_table);
        if ( pg == NULL )
            return -ENOMEM;

        flags = l1e_get_flags(*p2m_entry);
        pfn = l1e_get_pfn(*p2m_entry);

        l1_entry = __map_domain_page(pg);
        for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
        {
            new_entry = l1e_from_pfn(pfn + (i * L1_PAGETABLE_ENTRIES), flags);
            p2m_add_iommu_flags(&new_entry, 1, IOMMUF_readable|IOMMUF_writable);
            p2m->write_p2m_entry(p2m, gfn, l1_entry + i, new_entry, 2);
        }
        unmap_domain_page(l1_entry);
        new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)),
                                 P2M_BASE_FLAGS | _PAGE_RW); /* disable PSE */
        p2m_add_iommu_flags(&new_entry, 2, IOMMUF_readable|IOMMUF_writable);
        p2m->write_p2m_entry(p2m, gfn, p2m_entry, new_entry, 3);
    }


    /* split single 2MB large page into 4KB page in P2M table */
    if ( type == PGT_l1_page_table && (l1e_get_flags(*p2m_entry) & _PAGE_PSE) )
    {
        unsigned long flags, pfn;
        struct page_info *pg;

        pg = p2m_alloc_ptp(p2m, PGT_l1_page_table);
        if ( pg == NULL )
            return -ENOMEM;

        /* New splintered mappings inherit the flags of the old superpage, 
         * with a little reorganisation for the _PAGE_PSE_PAT bit. */
        flags = l1e_get_flags(*p2m_entry);
        pfn = l1e_get_pfn(*p2m_entry);
        if ( pfn & 1 )           /* ==> _PAGE_PSE_PAT was set */
            pfn -= 1;            /* Clear it; _PAGE_PSE becomes _PAGE_PAT */
        else
            flags &= ~_PAGE_PSE; /* Clear _PAGE_PSE (== _PAGE_PAT) */
        
        l1_entry = __map_domain_page(pg);
        for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
        {
            new_entry = l1e_from_pfn(pfn + i, flags);
            p2m_add_iommu_flags(&new_entry, 0, 0);
            p2m->write_p2m_entry(p2m, gfn, l1_entry + i, new_entry, 1);
        }
        unmap_domain_page(l1_entry);
        
        new_entry = l1e_from_pfn(mfn_x(page_to_mfn(pg)),
                                 P2M_BASE_FLAGS | _PAGE_RW);
        p2m_add_iommu_flags(&new_entry, 1, IOMMUF_readable|IOMMUF_writable);
        p2m->write_p2m_entry(p2m, gfn, p2m_entry, new_entry, 2);
    }

    next = map_domain_page(_mfn(l1e_get_pfn(*p2m_entry)));
    if ( unmap )
        unmap_domain_page(*table);
    *table = next;

    return 0;
}
Ejemplo n.º 5
0
/* Returns: 0 for success, -errno for failure */
static int
p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
                 unsigned int page_order, p2m_type_t p2mt, p2m_access_t p2ma)
{
    /* XXX -- this might be able to be faster iff current->domain == d */
    mfn_t table_mfn = pagetable_get_mfn(p2m_get_pagetable(p2m));
    void *table = map_domain_page(mfn_x(table_mfn));
    unsigned long i, gfn_remainder = gfn;
    l1_pgentry_t *p2m_entry;
    l1_pgentry_t entry_content;
    l2_pgentry_t l2e_content;
    l3_pgentry_t l3e_content;
    int rc;
    unsigned int iommu_pte_flags = (p2mt == p2m_ram_rw) ?
                                   IOMMUF_readable|IOMMUF_writable:
                                   0; 
    unsigned long old_mfn = 0;

    if ( tb_init_done )
    {
        struct {
            u64 gfn, mfn;
            int p2mt;
            int d:16,order:16;
        } t;

        t.gfn = gfn;
        t.mfn = mfn_x(mfn);
        t.p2mt = p2mt;
        t.d = p2m->domain->domain_id;
        t.order = page_order;

        __trace_var(TRC_MEM_SET_P2M_ENTRY, 0, sizeof(t), &t);
    }

    rc = p2m_next_level(p2m, &table_mfn, &table, &gfn_remainder, gfn,
                        L4_PAGETABLE_SHIFT - PAGE_SHIFT,
                        L4_PAGETABLE_ENTRIES, PGT_l3_page_table);
    if ( rc )
        goto out;

    /*
     * Try to allocate 1GB page table if this feature is supported.
     */
    if ( page_order == PAGE_ORDER_1G )
    {
        l1_pgentry_t old_entry = l1e_empty();
        p2m_entry = p2m_find_entry(table, &gfn_remainder, gfn,
                                   L3_PAGETABLE_SHIFT - PAGE_SHIFT,
                                   L3_PAGETABLE_ENTRIES);
        ASSERT(p2m_entry);
        if ( (l1e_get_flags(*p2m_entry) & _PAGE_PRESENT) &&
             !(l1e_get_flags(*p2m_entry) & _PAGE_PSE) )
        {
            /* We're replacing a non-SP page with a superpage.  Make sure to
             * handle freeing the table properly. */
            old_entry = *p2m_entry;
        }

        ASSERT(!mfn_valid(mfn) || p2mt != p2m_mmio_direct);
        l3e_content = mfn_valid(mfn) 
            ? l3e_from_pfn(mfn_x(mfn),
                           p2m_type_to_flags(p2mt, mfn) | _PAGE_PSE)
            : l3e_empty();
        entry_content.l1 = l3e_content.l3;

        if ( entry_content.l1 != 0 )
        {
            p2m_add_iommu_flags(&entry_content, 0, iommu_pte_flags);
            old_mfn = l1e_get_pfn(*p2m_entry);
        }

        p2m->write_p2m_entry(p2m, gfn, p2m_entry, table_mfn, entry_content, 3);
        /* NB: paging_write_p2m_entry() handles tlb flushes properly */

        /* Free old intermediate tables if necessary */
        if ( l1e_get_flags(old_entry) & _PAGE_PRESENT )
            p2m_free_entry(p2m, &old_entry, page_order);
    }
    else 
    {
        rc = p2m_next_level(p2m, &table_mfn, &table, &gfn_remainder,
                            gfn, L3_PAGETABLE_SHIFT - PAGE_SHIFT,
                            L3_PAGETABLE_ENTRIES, PGT_l2_page_table);
        if ( rc )
            goto out;
    }

    if ( page_order == PAGE_ORDER_4K )
    {
        rc = p2m_next_level(p2m, &table_mfn, &table, &gfn_remainder, gfn,
                            L2_PAGETABLE_SHIFT - PAGE_SHIFT,
                            L2_PAGETABLE_ENTRIES, PGT_l1_page_table);
        if ( rc )
            goto out;

        p2m_entry = p2m_find_entry(table, &gfn_remainder, gfn,
                                   0, L1_PAGETABLE_ENTRIES);
        ASSERT(p2m_entry);
        
        if ( mfn_valid(mfn) || (p2mt == p2m_mmio_direct)
                            || p2m_is_paging(p2mt) )
            entry_content = p2m_l1e_from_pfn(mfn_x(mfn),
                                             p2m_type_to_flags(p2mt, mfn));
        else
            entry_content = l1e_empty();

        if ( entry_content.l1 != 0 )
        {
            p2m_add_iommu_flags(&entry_content, 0, iommu_pte_flags);
            old_mfn = l1e_get_pfn(*p2m_entry);
        }
        /* level 1 entry */
        p2m->write_p2m_entry(p2m, gfn, p2m_entry, table_mfn, entry_content, 1);
        /* NB: paging_write_p2m_entry() handles tlb flushes properly */
    }
    else if ( page_order == PAGE_ORDER_2M )
    {
        l1_pgentry_t old_entry = l1e_empty();
        p2m_entry = p2m_find_entry(table, &gfn_remainder, gfn,
                                   L2_PAGETABLE_SHIFT - PAGE_SHIFT,
                                   L2_PAGETABLE_ENTRIES);
        ASSERT(p2m_entry);
        
        /* FIXME: Deal with 4k replaced by 2meg pages */
        if ( (l1e_get_flags(*p2m_entry) & _PAGE_PRESENT) &&
             !(l1e_get_flags(*p2m_entry) & _PAGE_PSE) )
        {
            /* We're replacing a non-SP page with a superpage.  Make sure to
             * handle freeing the table properly. */
            old_entry = *p2m_entry;
        }
        
        ASSERT(!mfn_valid(mfn) || p2mt != p2m_mmio_direct);
        if ( mfn_valid(mfn) || p2m_is_pod(p2mt) )
            l2e_content = l2e_from_pfn(mfn_x(mfn),
                                       p2m_type_to_flags(p2mt, mfn) |
                                       _PAGE_PSE);
        else
            l2e_content = l2e_empty();
        
        entry_content.l1 = l2e_content.l2;

        if ( entry_content.l1 != 0 )
        {
            p2m_add_iommu_flags(&entry_content, 0, iommu_pte_flags);
            old_mfn = l1e_get_pfn(*p2m_entry);
        }

        p2m->write_p2m_entry(p2m, gfn, p2m_entry, table_mfn, entry_content, 2);
        /* NB: paging_write_p2m_entry() handles tlb flushes properly */

        /* Free old intermediate tables if necessary */
        if ( l1e_get_flags(old_entry) & _PAGE_PRESENT )
            p2m_free_entry(p2m, &old_entry, page_order);
    }

    /* Track the highest gfn for which we have ever had a valid mapping */
    if ( p2mt != p2m_invalid
         && (gfn + (1UL << page_order) - 1 > p2m->max_mapped_pfn) )
        p2m->max_mapped_pfn = gfn + (1UL << page_order) - 1;

    if ( iommu_enabled && need_iommu(p2m->domain) )
    {
        if ( iommu_hap_pt_share )
        {
            if ( old_mfn && (old_mfn != mfn_x(mfn)) )
                amd_iommu_flush_pages(p2m->domain, gfn, page_order);
        }
        else
        {
            if ( p2mt == p2m_ram_rw )
                for ( i = 0; i < (1UL << page_order); i++ )
                    iommu_map_page(p2m->domain, gfn+i, mfn_x(mfn)+i,
                                   IOMMUF_readable|IOMMUF_writable);
            else
                for ( int i = 0; i < (1UL << page_order); i++ )
                    iommu_unmap_page(p2m->domain, gfn+i);
        }
    }

 out:
    unmap_domain_page(table);
    return rc;
}