x86: introduce create_perdomain_mapping()

... as well as free_perdomain_mappings(), and use them to carry out the
existing per-domain mapping setup/teardown. This at once makes the
setup of the first sub-range PV domain specific (with idle domains also
excluded), as the GDT/LDT mapping area is needed only for those.

Also fix an improperly scaled BUILD_BUG_ON() expression in
mapcache_domain_init().

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -372,37 +372,16 @@ int switch_compat(struct domain *d)
 int vcpu_initialise(struct vcpu *v)
 {
     struct domain *d = v->domain;
-    unsigned int idx;
     int rc;
 
     v->arch.flags = TF_kernel_mode;
 
-    idx = perdomain_pt_idx(v);
-    if ( !d->arch.perdomain_pts[idx] )
-    {
-        void *pt;
-        l2_pgentry_t *l2tab;
-
-        pt = alloc_xenheap_pages(0, MEMF_node(vcpu_to_node(v)));
-        if ( !pt )
-            return -ENOMEM;
-        clear_page(pt);
-        d->arch.perdomain_pts[idx] = pt;
-
-        l2tab = __map_domain_page(d->arch.perdomain_l2_pg[0]);
-        l2tab[l2_table_offset(PERDOMAIN_VIRT_START) + idx]
-            = l2e_from_paddr(__pa(pt), __PAGE_HYPERVISOR);
-        unmap_domain_page(l2tab);
-    }
-
     rc = mapcache_vcpu_init(v);
     if ( rc )
         return rc;
 
     paging_vcpu_init(v);
 
-    v->arch.perdomain_ptes = perdomain_ptes(d, v);
-
     if ( (rc = vcpu_init_fpu(v)) != 0 )
         return rc;
 
@@ -420,6 +399,12 @@ int vcpu_initialise(struct vcpu *v)
 
     if ( !is_idle_domain(d) )
     {
+        rc = create_perdomain_mapping(d, GDT_VIRT_START(v),
+                                      1 << GDT_LDT_VCPU_SHIFT,
+                                      d->arch.pv_domain.gdt_ldt_l1tab, NULL);
+        if ( rc )
+            goto done;
+
         BUILD_BUG_ON(NR_VECTORS * sizeof(*v->arch.pv_vcpu.trap_ctxt) >
                      PAGE_SIZE);
         v->arch.pv_vcpu.trap_ctxt = xzalloc_array(struct trap_info,
@@ -478,8 +463,6 @@ void vcpu_destroy(struct vcpu *v)
 
 int arch_domain_create(struct domain *d, unsigned int domcr_flags)
 {
-    struct page_info *pg;
-    l3_pgentry_t *l3tab;
     int i, paging_initialised = 0;
     int rc = -ENOMEM;
 
@@ -510,29 +493,24 @@ int arch_domain_create(struct domain *d,
                d->domain_id);
     }
 
-    BUILD_BUG_ON(PDPT_L2_ENTRIES * sizeof(*d->arch.perdomain_pts)
-                 != PAGE_SIZE);
-    d->arch.perdomain_pts =
-        alloc_xenheap_pages(0, MEMF_node(domain_to_node(d)));
-    if ( !d->arch.perdomain_pts )
-        goto fail;
-    clear_page(d->arch.perdomain_pts);
-
-    pg = alloc_domheap_page(NULL, MEMF_node(domain_to_node(d)));
-    if ( pg == NULL )
-        goto fail;
-    d->arch.perdomain_l2_pg[0] = pg;
-    clear_domain_page(page_to_mfn(pg));
+    if ( is_hvm_domain(d) )
+        rc = create_perdomain_mapping(d, PERDOMAIN_VIRT_START, 0, NULL, NULL);
+    else if ( is_idle_domain(d) )
+        rc = 0;
+    else
+    {
+        d->arch.pv_domain.gdt_ldt_l1tab =
+            alloc_xenheap_pages(0, MEMF_node(domain_to_node(d)));
+        if ( !d->arch.pv_domain.gdt_ldt_l1tab )
+            goto fail;
+        clear_page(d->arch.pv_domain.gdt_ldt_l1tab);
 
-    pg = alloc_domheap_page(NULL, MEMF_node(domain_to_node(d)));
-    if ( pg == NULL )
+        rc = create_perdomain_mapping(d, GDT_LDT_VIRT_START,
+                                      GDT_LDT_MBYTES << (20 - PAGE_SHIFT),
+                                      NULL, NULL);
+    }
+    if ( rc )
         goto fail;
-    d->arch.perdomain_l3_pg = pg;
-    l3tab = __map_domain_page(pg);
-    clear_page(l3tab);
-    l3tab[l3_table_offset(PERDOMAIN_VIRT_START)] =
-        l3e_from_page(d->arch.perdomain_l2_pg[0], __PAGE_HYPERVISOR);
-    unmap_domain_page(l3tab);
 
     mapcache_domain_init(d);
 
@@ -608,19 +586,14 @@ int arch_domain_create(struct domain *d,
     if ( paging_initialised )
         paging_final_teardown(d);
     mapcache_domain_exit(d);
-    for ( i = 0; i < PERDOMAIN_SLOTS; ++i)
-        if ( d->arch.perdomain_l2_pg[i] )
-            free_domheap_page(d->arch.perdomain_l2_pg[i]);
-    if ( d->arch.perdomain_l3_pg )
-        free_domheap_page(d->arch.perdomain_l3_pg);
-    free_xenheap_page(d->arch.perdomain_pts);
+    free_perdomain_mappings(d);
+    if ( !is_hvm_domain(d) )
+        free_xenheap_page(d->arch.pv_domain.gdt_ldt_l1tab);
     return rc;
 }
 
 void arch_domain_destroy(struct domain *d)
 {
-    unsigned int i;
-
     if ( is_hvm_domain(d) )
         hvm_domain_destroy(d);
     else
@@ -634,13 +607,9 @@ void arch_domain_destroy(struct domain *
 
     mapcache_domain_exit(d);
 
-    for ( i = 0; i < PDPT_L2_ENTRIES; ++i )
-        free_xenheap_page(d->arch.perdomain_pts[i]);
-    free_xenheap_page(d->arch.perdomain_pts);
-    for ( i = 0; i < PERDOMAIN_SLOTS; ++i)
-        if ( d->arch.perdomain_l2_pg[i] )
-            free_domheap_page(d->arch.perdomain_l2_pg[i]);
-    free_domheap_page(d->arch.perdomain_l3_pg);
+    free_perdomain_mappings(d);
+    if ( !is_hvm_domain(d) )
+        free_xenheap_page(d->arch.pv_domain.gdt_ldt_l1tab);
 
     free_xenheap_page(d->shared_info);
     cleanup_domain_irq_mapping(d);
@@ -1515,10 +1484,11 @@ static void __context_switch(void)
     if ( need_full_gdt(n) )
     {
         unsigned long mfn = virt_to_mfn(gdt);
+        l1_pgentry_t *pl1e = gdt_ldt_ptes(n->domain, n);
         unsigned int i;
+
         for ( i = 0; i < NR_RESERVED_GDT_PAGES; i++ )
-            l1e_write(n->arch.perdomain_ptes +
-                      FIRST_RESERVED_GDT_PAGE + i,
+            l1e_write(pl1e + FIRST_RESERVED_GDT_PAGE + i,
                       l1e_from_pfn(mfn + i, __PAGE_HYPERVISOR));
     }
 
--- a/xen/arch/x86/domain_page.c
+++ b/xen/arch/x86/domain_page.c
@@ -243,10 +243,7 @@ void copy_domain_page(unsigned long dmfn
 int mapcache_domain_init(struct domain *d)
 {
     struct mapcache_domain *dcache = &d->arch.pv_domain.mapcache;
-    l3_pgentry_t *l3tab;
-    l2_pgentry_t *l2tab;
-    unsigned int i, bitmap_pages, memf = MEMF_node(domain_to_node(d));
-    unsigned long *end;
+    unsigned int bitmap_pages;
 
     if ( is_hvm_domain(d) || is_idle_domain(d) )
         return 0;
@@ -256,48 +253,23 @@ int mapcache_domain_init(struct domain *
         return 0;
 #endif
 
-    dcache->l1tab = xzalloc_array(l1_pgentry_t *, MAPCACHE_L2_ENTRIES + 1);
-    d->arch.perdomain_l2_pg[MAPCACHE_SLOT] = alloc_domheap_page(NULL, memf);
-    if ( !dcache->l1tab || !d->arch.perdomain_l2_pg[MAPCACHE_SLOT] )
+    dcache->l1tab = xzalloc_array(l1_pgentry_t *, MAPCACHE_L2_ENTRIES);
+    if ( !dcache->l1tab )
         return -ENOMEM;
 
-    clear_domain_page(page_to_mfn(d->arch.perdomain_l2_pg[MAPCACHE_SLOT]));
-    l3tab = __map_domain_page(d->arch.perdomain_l3_pg);
-    l3tab[l3_table_offset(MAPCACHE_VIRT_START)] =
-        l3e_from_page(d->arch.perdomain_l2_pg[MAPCACHE_SLOT],
-                      __PAGE_HYPERVISOR);
-    unmap_domain_page(l3tab);
-
-    l2tab = __map_domain_page(d->arch.perdomain_l2_pg[MAPCACHE_SLOT]);
-
-    BUILD_BUG_ON(MAPCACHE_VIRT_END + 3 +
-                 2 * PFN_UP(BITS_TO_LONGS(MAPCACHE_ENTRIES) * sizeof(long)) >
+    BUILD_BUG_ON(MAPCACHE_VIRT_END + PAGE_SIZE * (3 +
+                 2 * PFN_UP(BITS_TO_LONGS(MAPCACHE_ENTRIES) * sizeof(long))) >
                  MAPCACHE_VIRT_START + (PERDOMAIN_SLOT_MBYTES << 20));
     bitmap_pages = PFN_UP(BITS_TO_LONGS(MAPCACHE_ENTRIES) * sizeof(long));
     dcache->inuse = (void *)MAPCACHE_VIRT_END + PAGE_SIZE;
     dcache->garbage = dcache->inuse +
                       (bitmap_pages + 1) * PAGE_SIZE / sizeof(long);
-    end = dcache->garbage + bitmap_pages * PAGE_SIZE / sizeof(long);
-
-    for ( i = l2_table_offset((unsigned long)dcache->inuse);
-          i <= l2_table_offset((unsigned long)(end - 1)); ++i )
-    {
-        ASSERT(i <= MAPCACHE_L2_ENTRIES);
-        dcache->l1tab[i] = alloc_xenheap_pages(0, memf);
-        if ( !dcache->l1tab[i] )
-        {
-            unmap_domain_page(l2tab);
-            return -ENOMEM;
-        }
-        clear_page(dcache->l1tab[i]);
-        l2tab[i] = l2e_from_paddr(__pa(dcache->l1tab[i]), __PAGE_HYPERVISOR);
-    }
-
-    unmap_domain_page(l2tab);
 
     spin_lock_init(&dcache->lock);
 
-    return 0;
+    return create_perdomain_mapping(d, (unsigned long)dcache->inuse,
+                                    2 * bitmap_pages + 1,
+                                    NIL(l1_pgentry_t *), NULL);
 }
 
 void mapcache_domain_exit(struct domain *d)
@@ -307,94 +279,41 @@ void mapcache_domain_exit(struct domain 
     if ( is_hvm_domain(d) )
         return;
 
-    if ( dcache->l1tab )
-    {
-        unsigned long i;
-
-        for ( i = (unsigned long)dcache->inuse; ; i += PAGE_SIZE )
-        {
-            l1_pgentry_t *pl1e;
-
-            if ( l2_table_offset(i) > MAPCACHE_L2_ENTRIES ||
-                 !dcache->l1tab[l2_table_offset(i)] )
-                break;
-
-            pl1e = &dcache->l1tab[l2_table_offset(i)][l1_table_offset(i)];
-            if ( l1e_get_flags(*pl1e) )
-                free_domheap_page(l1e_get_page(*pl1e));
-        }
-
-        for ( i = 0; i < MAPCACHE_L2_ENTRIES + 1; ++i )
-            free_xenheap_page(dcache->l1tab[i]);
-
-        xfree(dcache->l1tab);
-    }
+    xfree(dcache->l1tab);
 }
 
 int mapcache_vcpu_init(struct vcpu *v)
 {
     struct domain *d = v->domain;
     struct mapcache_domain *dcache = &d->arch.pv_domain.mapcache;
-    l2_pgentry_t *l2tab;
     unsigned long i;
-    unsigned int memf = MEMF_node(vcpu_to_node(v));
+    unsigned int ents = d->max_vcpus * MAPCACHE_VCPU_ENTRIES;
+    unsigned int nr = PFN_UP(BITS_TO_LONGS(ents) * sizeof(long));
 
     if ( is_hvm_vcpu(v) || !dcache->l1tab )
         return 0;
 
-    l2tab = __map_domain_page(d->arch.perdomain_l2_pg[MAPCACHE_SLOT]);
-
-    while ( dcache->entries < d->max_vcpus * MAPCACHE_VCPU_ENTRIES )
+    if ( ents > dcache->entries )
     {
-        unsigned int ents = dcache->entries + MAPCACHE_VCPU_ENTRIES;
-        l1_pgentry_t *pl1e;
-
         /* Populate page tables. */
-        if ( !dcache->l1tab[i = mapcache_l2_entry(ents - 1)] )
-        {
-            dcache->l1tab[i] = alloc_xenheap_pages(0, memf);
-            if ( !dcache->l1tab[i] )
-            {
-                unmap_domain_page(l2tab);
-                return -ENOMEM;
-            }
-            clear_page(dcache->l1tab[i]);
-            l2tab[i] = l2e_from_paddr(__pa(dcache->l1tab[i]),
-                                      __PAGE_HYPERVISOR);
-        }
+        int rc = create_perdomain_mapping(d, MAPCACHE_VIRT_START,
+                                          d->max_vcpus * MAPCACHE_VCPU_ENTRIES,
+                                          dcache->l1tab, NULL);
 
         /* Populate bit maps. */
-        i = (unsigned long)(dcache->inuse + BITS_TO_LONGS(ents));
-        pl1e = &dcache->l1tab[l2_table_offset(i)][l1_table_offset(i)];
-        if ( !l1e_get_flags(*pl1e) )
-        {
-            struct page_info *pg = alloc_domheap_page(NULL, memf);
+        if ( !rc )
+            rc = create_perdomain_mapping(d, (unsigned long)dcache->inuse,
+                                          nr, NULL, NIL(struct page_info *));
+        if ( !rc )
+            rc = create_perdomain_mapping(d, (unsigned long)dcache->garbage,
+                                          nr, NULL, NIL(struct page_info *));
 
-            if ( pg )
-            {
-                clear_domain_page(page_to_mfn(pg));
-                *pl1e = l1e_from_page(pg, __PAGE_HYPERVISOR);
-                pg = alloc_domheap_page(NULL, memf);
-            }
-            if ( !pg )
-            {
-                unmap_domain_page(l2tab);
-                return -ENOMEM;
-            }
-
-            i = (unsigned long)(dcache->garbage + BITS_TO_LONGS(ents));
-            pl1e = &dcache->l1tab[l2_table_offset(i)][l1_table_offset(i)];
-            ASSERT(!l1e_get_flags(*pl1e));
-
-            clear_domain_page(page_to_mfn(pg));
-            *pl1e = l1e_from_page(pg, __PAGE_HYPERVISOR);
-        }
+        if ( rc )
+            return rc;
 
         dcache->entries = ents;
     }
 
-    unmap_domain_page(l2tab);
-
     /* Mark all maphash entries as not in use. */
     BUILD_BUG_ON(MAPHASHENT_NOTINUSE < MAPCACHE_ENTRIES);
     for ( i = 0; i < MAPHASH_ENTRIES; i++ )
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -511,6 +511,7 @@ void update_cr3(struct vcpu *v)
 
 static void invalidate_shadow_ldt(struct vcpu *v, int flush)
 {
+    l1_pgentry_t *pl1e;
     int i;
     unsigned long pfn;
     struct page_info *page;
@@ -523,12 +524,13 @@ static void invalidate_shadow_ldt(struct
         goto out;
 
     v->arch.pv_vcpu.shadow_ldt_mapcnt = 0;
+    pl1e = gdt_ldt_ptes(v->domain, v);
 
     for ( i = 16; i < 32; i++ )
     {
-        pfn = l1e_get_pfn(v->arch.perdomain_ptes[i]);
+        pfn = l1e_get_pfn(pl1e[i]);
         if ( pfn == 0 ) continue;
-        l1e_write(&v->arch.perdomain_ptes[i], l1e_empty());
+        l1e_write(&pl1e[i], l1e_empty());
         page = mfn_to_page(pfn);
         ASSERT_PAGE_IS_TYPE(page, PGT_seg_desc_page);
         ASSERT_PAGE_IS_DOMAIN(page, v->domain);
@@ -596,7 +598,7 @@ int map_ldt_shadow_page(unsigned int off
     nl1e = l1e_from_pfn(page_to_mfn(page), l1e_get_flags(l1e) | _PAGE_RW);
 
     spin_lock(&v->arch.pv_vcpu.shadow_ldt_lock);
-    l1e_write(&v->arch.perdomain_ptes[off + 16], nl1e);
+    l1e_write(&gdt_ldt_ptes(d, v)[off + 16], nl1e);
     v->arch.pv_vcpu.shadow_ldt_mapcnt++;
     spin_unlock(&v->arch.pv_vcpu.shadow_ldt_lock);
 
@@ -4073,15 +4075,17 @@ long do_update_va_mapping_otherdomain(un
 
 void destroy_gdt(struct vcpu *v)
 {
+    l1_pgentry_t *pl1e;
     int i;
     unsigned long pfn;
 
     v->arch.pv_vcpu.gdt_ents = 0;
+    pl1e = gdt_ldt_ptes(v->domain, v);
     for ( i = 0; i < FIRST_RESERVED_GDT_PAGE; i++ )
     {
-        if ( (pfn = l1e_get_pfn(v->arch.perdomain_ptes[i])) != 0 )
+        if ( (pfn = l1e_get_pfn(pl1e[i])) != 0 )
             put_page_and_type(mfn_to_page(pfn));
-        l1e_write(&v->arch.perdomain_ptes[i], l1e_empty());
+        l1e_write(&pl1e[i], l1e_empty());
         v->arch.pv_vcpu.gdt_frames[i] = 0;
     }
 }
@@ -4092,6 +4096,7 @@ long set_gdt(struct vcpu *v, 
              unsigned int entries)
 {
     struct domain *d = v->domain;
+    l1_pgentry_t *pl1e;
     /* NB. There are 512 8-byte entries per GDT page. */
     int i, nr_pages = (entries + 511) / 512;
     unsigned long mfn, *pfns;
@@ -4124,11 +4129,11 @@ long set_gdt(struct vcpu *v, 
 
     /* Install the new GDT. */
     v->arch.pv_vcpu.gdt_ents = entries;
+    pl1e = gdt_ldt_ptes(d, v);
     for ( i = 0; i < nr_pages; i++ )
     {
         v->arch.pv_vcpu.gdt_frames[i] = frames[i];
-        l1e_write(&v->arch.perdomain_ptes[i],
-                  l1e_from_pfn(frames[i], __PAGE_HYPERVISOR));
+        l1e_write(&pl1e[i], l1e_from_pfn(frames[i], __PAGE_HYPERVISOR));
     }
 
     xfree(pfns);
@@ -5528,6 +5533,175 @@ void __iomem *ioremap(paddr_t pa, size_t
     return (void __force __iomem *)va;
 }
 
+int create_perdomain_mapping(struct domain *d, unsigned long va,
+                             unsigned int nr, l1_pgentry_t **pl1tab,
+                             struct page_info **ppg)
+{
+    struct page_info *pg;
+    l3_pgentry_t *l3tab;
+    l2_pgentry_t *l2tab;
+    l1_pgentry_t *l1tab;
+    unsigned int memf = MEMF_node(domain_to_node(d));
+    int rc = 0;
+
+    ASSERT(va >= PERDOMAIN_VIRT_START &&
+           va < PERDOMAIN_VIRT_SLOT(PERDOMAIN_SLOTS));
+
+    if ( !d->arch.perdomain_l3_pg )
+    {
+        pg = alloc_domheap_page(NULL, MEMF_node(domain_to_node(d)));
+        if ( !pg )
+            return -ENOMEM;
+        l3tab = __map_domain_page(pg);
+        clear_page(l3tab);
+        d->arch.perdomain_l3_pg = pg;
+        if ( !nr )
+        {
+            unmap_domain_page(l3tab);
+            return 0;
+        }
+    }
+    else if ( !nr )
+        return 0;
+    else
+        l3tab = __map_domain_page(d->arch.perdomain_l3_pg);
+
+    ASSERT(!l3_table_offset(va ^ (va + nr * PAGE_SIZE - 1)));
+
+    if ( !(l3e_get_flags(l3tab[l3_table_offset(va)]) & _PAGE_PRESENT) )
+    {
+        pg = alloc_domheap_page(NULL, memf);
+        if ( !pg )
+        {
+            unmap_domain_page(l3tab);
+            return -ENOMEM;
+        }
+        l2tab = __map_domain_page(pg);
+        clear_page(l2tab);
+        l3tab[l3_table_offset(va)] = l3e_from_page(pg, __PAGE_HYPERVISOR);
+    }
+    else
+        l2tab = map_domain_page(l3e_get_pfn(l3tab[l3_table_offset(va)]));
+
+    unmap_domain_page(l3tab);
+
+    if ( !pl1tab && !ppg )
+    {
+        unmap_domain_page(l2tab);
+        return 0;
+    }
+
+    for ( l1tab = NULL; !rc && nr--; )
+    {
+        l2_pgentry_t *pl2e = l2tab + l2_table_offset(va);
+
+        if ( !(l2e_get_flags(*pl2e) & _PAGE_PRESENT) )
+        {
+            if ( pl1tab && !IS_NIL(pl1tab) )
+            {
+                l1tab = alloc_xenheap_pages(0, memf);
+                if ( !l1tab )
+                {
+                    rc = -ENOMEM;
+                    break;
+                }
+                ASSERT(!pl1tab[l2_table_offset(va)]);
+                pl1tab[l2_table_offset(va)] = l1tab;
+                pg = virt_to_page(l1tab);
+            }
+            else
+            {
+                pg = alloc_domheap_page(NULL, memf);
+                if ( !pg )
+                {
+                    rc = -ENOMEM;
+                    break;
+                }
+                l1tab = __map_domain_page(pg);
+            }
+            clear_page(l1tab);
+            *pl2e = l2e_from_page(pg, __PAGE_HYPERVISOR);
+        }
+        else if ( !l1tab )
+            l1tab = map_domain_page(l2e_get_pfn(*pl2e));
+
+        if ( ppg &&
+             !(l1e_get_flags(l1tab[l1_table_offset(va)]) & _PAGE_PRESENT) )
+        {
+            pg = alloc_domheap_page(NULL, memf);
+            if ( pg )
+            {
+                clear_domain_page(page_to_mfn(pg));
+                if ( !IS_NIL(ppg) )
+                    *ppg++ = pg;
+                l1tab[l1_table_offset(va)] =
+                    l1e_from_page(pg, __PAGE_HYPERVISOR | _PAGE_AVAIL0);
+                l2e_add_flags(*pl2e, _PAGE_AVAIL0);
+            }
+            else
+                rc = -ENOMEM;
+        }
+
+        va += PAGE_SIZE;
+        if ( rc || !nr || !l1_table_offset(va) )
+        {
+            /* Note that this is a no-op for the alloc_xenheap_page() case. */
+            unmap_domain_page(l1tab);
+            l1tab = NULL;
+        }
+    }
+
+    ASSERT(!l1tab);
+    unmap_domain_page(l2tab);
+
+    return rc;
+}
+
+void free_perdomain_mappings(struct domain *d)
+{
+    l3_pgentry_t *l3tab = __map_domain_page(d->arch.perdomain_l3_pg);
+    unsigned int i;
+
+    for ( i = 0; i < PERDOMAIN_SLOTS; ++i)
+        if ( l3e_get_flags(l3tab[i]) & _PAGE_PRESENT )
+        {
+            struct page_info *l2pg = l3e_get_page(l3tab[i]);
+            l2_pgentry_t *l2tab = __map_domain_page(l2pg);
+            unsigned int j;
+
+            for ( j = 0; j < L2_PAGETABLE_ENTRIES; ++j )
+                if ( l2e_get_flags(l2tab[j]) & _PAGE_PRESENT )
+                {
+                    struct page_info *l1pg = l2e_get_page(l2tab[j]);
+
+                    if ( l2e_get_flags(l2tab[j]) & _PAGE_AVAIL0 )
+                    {
+                        l1_pgentry_t *l1tab = __map_domain_page(l1pg);
+                        unsigned int k;
+
+                        for ( k = 0; k < L1_PAGETABLE_ENTRIES; ++k )
+                            if ( (l1e_get_flags(l1tab[k]) &
+                                  (_PAGE_PRESENT | _PAGE_AVAIL0)) ==
+                                 (_PAGE_PRESENT | _PAGE_AVAIL0) )
+                                free_domheap_page(l1e_get_page(l1tab[k]));
+
+                        unmap_domain_page(l1tab);
+                    }
+
+                    if ( is_xen_heap_page(l1pg) )
+                        free_xenheap_page(page_to_virt(l1pg));
+                    else
+                        free_domheap_page(l1pg);
+                }
+
+            unmap_domain_page(l2tab);
+            free_domheap_page(l2pg);
+        }
+
+    unmap_domain_page(l3tab);
+    free_domheap_page(d->arch.perdomain_l3_pg);
+}
+
 #ifdef MEMORY_GUARD
 
 void memguard_init(void)
--- a/xen/include/asm-x86/config.h
+++ b/xen/include/asm-x86/config.h
@@ -304,19 +304,13 @@ extern unsigned long xen_phys_start;
 #define LDT_VIRT_START(v)    \
     (GDT_VIRT_START(v) + (64*1024))
 
-/* map_domain_page() map cache. The last per-domain-mapping sub-area. */
+/* map_domain_page() map cache. The second per-domain-mapping sub-area. */
 #define MAPCACHE_VCPU_ENTRIES    (CONFIG_PAGING_LEVELS * CONFIG_PAGING_LEVELS)
 #define MAPCACHE_ENTRIES         (MAX_VIRT_CPUS * MAPCACHE_VCPU_ENTRIES)
-#define MAPCACHE_SLOT            (PERDOMAIN_SLOTS - 1)
-#define MAPCACHE_VIRT_START      PERDOMAIN_VIRT_SLOT(MAPCACHE_SLOT)
+#define MAPCACHE_VIRT_START      PERDOMAIN_VIRT_SLOT(1)
 #define MAPCACHE_VIRT_END        (MAPCACHE_VIRT_START + \
                                   MAPCACHE_ENTRIES * PAGE_SIZE)
 
-#define PDPT_L1_ENTRIES       \
-    ((PERDOMAIN_VIRT_SLOT(PERDOMAIN_SLOTS - 1) - PERDOMAIN_VIRT_START) >> PAGE_SHIFT)
-#define PDPT_L2_ENTRIES       \
-    ((PDPT_L1_ENTRIES + (1 << PAGETABLE_ORDER) - 1) >> PAGETABLE_ORDER)
-
 #define ELFSIZE 64
 
 #define ARCH_CRASH_SAVE_VMCOREINFO
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -223,6 +223,8 @@ struct time_scale {
 
 struct pv_domain
 {
+    l1_pgentry_t **gdt_ldt_l1tab;
+
     /* Shared page for notifying that explicit PIRQ EOI is required. */
     unsigned long *pirq_eoi_map;
     unsigned long pirq_eoi_map_mfn;
@@ -241,8 +243,6 @@ struct pv_domain
 
 struct arch_domain
 {
-    void **perdomain_pts;
-    struct page_info *perdomain_l2_pg[PERDOMAIN_SLOTS];
     struct page_info *perdomain_l3_pg;
 
     unsigned int hv_compat_vstart;
@@ -318,10 +318,10 @@ struct arch_domain
 #define has_arch_pdevs(d)    (!list_empty(&(d)->arch.pdev_list))
 #define has_arch_mmios(d)    (!rangeset_is_empty((d)->iomem_caps))
 
-#define perdomain_pt_idx(v) \
+#define gdt_ldt_pt_idx(v) \
       ((v)->vcpu_id >> (PAGETABLE_ORDER - GDT_LDT_VCPU_SHIFT))
-#define perdomain_ptes(d, v) \
-    ((l1_pgentry_t *)(d)->arch.perdomain_pts[perdomain_pt_idx(v)] + \
+#define gdt_ldt_ptes(d, v) \
+    ((d)->arch.pv_domain.gdt_ldt_l1tab[gdt_ldt_pt_idx(v)] + \
      (((v)->vcpu_id << GDT_LDT_VCPU_SHIFT) & (L1_PAGETABLE_ENTRIES - 1)))
 
 struct pv_vcpu
@@ -406,12 +406,6 @@ struct arch_vcpu
         struct hvm_vcpu hvm_vcpu;
     };
 
-    /*
-     * Every domain has a L1 pagetable of its own. Per-domain mappings
-     * are put in this table (eg. the current GDT is mapped here).
-     */
-    l1_pgentry_t *perdomain_ptes;
-
     pagetable_t guest_table_user;       /* (MFN) x86/64 user-space pagetable */
     pagetable_t guest_table;            /* (MFN) guest notion of cr3 */
     /* guest_table holds a ref to the page, and also a type-count unless
--- a/xen/include/asm-x86/mm.h
+++ b/xen/include/asm-x86/mm.h
@@ -573,6 +573,14 @@ int donate_page(
 
 int map_ldt_shadow_page(unsigned int);
 
+#define NIL(type) ((type *)NULL - 1)
+#define IS_NIL(ptr) (!((ptr) + 1))
+
+int create_perdomain_mapping(struct domain *, unsigned long va,
+                             unsigned int nr, l1_pgentry_t **,
+                             struct page_info **);
+void free_perdomain_mappings(struct domain *);
+
 extern int memory_add(unsigned long spfn, unsigned long epfn, unsigned int pxm);
 
 void domain_set_alloc_bitsize(struct domain *d);