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[Xen-changelog] [xen-unstable] [XEN] New memory_op XENMEM_exchange. Allows atomic



# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxxxx
# Node ID ee3d108289370351347f46284024f3347897d2bb
# Parent  231e07e22f9cd09e310a0db65ed62acb12c51855
[XEN] New memory_op XENMEM_exchange. Allows atomic
exchange of one memory reservation for another of the
same size, but with different properties.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 xen/arch/ia64/xen/domain.c         |    7 
 xen/arch/x86/domain_build.c        |    2 
 xen/arch/x86/mm.c                  |    7 
 xen/arch/x86/shadow.c              |    4 
 xen/arch/x86/shadow_public.c       |    4 
 xen/common/grant_table.c           |    2 
 xen/common/memory.c                |  274 +++++++++++++++++++++++++++++++++----
 xen/common/page_alloc.c            |   86 +++++++----
 xen/include/asm-ia64/grant_table.h |    4 
 xen/include/asm-ia64/mm.h          |    7 
 xen/include/asm-x86/grant_table.h  |    3 
 xen/include/asm-x86/mm.h           |    3 
 xen/include/public/memory.h        |   48 ++++++
 xen/include/xen/mm.h               |   14 +
 14 files changed, 386 insertions(+), 79 deletions(-)

diff -r 231e07e22f9c -r ee3d10828937 xen/arch/ia64/xen/domain.c
--- a/xen/arch/ia64/xen/domain.c        Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/arch/ia64/xen/domain.c        Fri Jun 16 14:43:54 2006 +0100
@@ -1308,10 +1308,10 @@ destroy_grant_host_mapping(unsigned long
 //XXX heavily depends on the struct page layout.
 //XXX SMP
 int
-steal_page_for_grant_transfer(struct domain *d, struct page_info *page)
+steal_page(struct domain *d, struct page_info *page, unsigned int memflags)
 {
 #if 0 /* if big endian */
-# error "implement big endian version of steal_page_for_grant_transfer()"
+# error "implement big endian version of steal_page()"
 #endif
     u32 _d, _nd;
     u64 x, nx, y;
@@ -1371,7 +1371,8 @@ steal_page_for_grant_transfer(struct dom
      * Unlink from 'd'. At least one reference remains (now anonymous), so
      * noone else is spinning to try to delete this page from 'd'.
      */
-    d->tot_pages--;
+    if ( !(memflags & MEMF_no_refcount) )
+        d->tot_pages--;
     list_del(&page->list);
 
     spin_unlock(&d->page_alloc_lock);
diff -r 231e07e22f9c -r ee3d10828937 xen/arch/x86/domain_build.c
--- a/xen/arch/x86/domain_build.c       Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/arch/x86/domain_build.c       Fri Jun 16 14:43:54 2006 +0100
@@ -374,7 +374,7 @@ int construct_dom0(struct domain *d,
      * Allocate from DMA pool: on i386 this ensures that our low-memory 1:1
      * mapping covers the allocation.
      */
-    if ( (page = alloc_domheap_pages(d, order, ALLOC_DOM_DMA)) == NULL )
+    if ( (page = alloc_domheap_pages(d, order, MEMF_dma)) == NULL )
         panic("Not enough RAM for domain 0 allocation.\n");
     alloc_spfn = page_to_mfn(page);
     alloc_epfn = alloc_spfn + d->tot_pages;
diff -r 231e07e22f9c -r ee3d10828937 xen/arch/x86/mm.c
--- a/xen/arch/x86/mm.c Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/arch/x86/mm.c Fri Jun 16 14:43:54 2006 +0100
@@ -2598,8 +2598,8 @@ int destroy_grant_host_mapping(
     return destroy_grant_va_mapping(addr, frame);
 }
 
-int steal_page_for_grant_transfer(
-    struct domain *d, struct page_info *page)
+int steal_page(
+    struct domain *d, struct page_info *page, unsigned int memflags)
 {
     u32 _d, _nd, x, y;
 
@@ -2636,7 +2636,8 @@ int steal_page_for_grant_transfer(
      * Unlink from 'd'. At least one reference remains (now anonymous), so 
      * noone else is spinning to try to delete this page from 'd'.
      */
-    d->tot_pages--;
+    if ( !(memflags & MEMF_no_refcount) )
+        d->tot_pages--;
     list_del(&page->list);
 
     spin_unlock(&d->page_alloc_lock);
diff -r 231e07e22f9c -r ee3d10828937 xen/arch/x86/shadow.c
--- a/xen/arch/x86/shadow.c     Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/arch/x86/shadow.c     Fri Jun 16 14:43:54 2006 +0100
@@ -292,10 +292,10 @@ alloc_shadow_page(struct domain *d,
 #elif CONFIG_PAGING_LEVELS >= 3
         if ( d->arch.ops->guest_paging_levels == PAGING_L2 &&
              psh_type == PGT_l4_shadow )      /* allocated for PAE PDP page */
-            page = alloc_domheap_pages(NULL, 0, ALLOC_DOM_DMA);
+            page = alloc_domheap_pages(NULL, 0, MEMF_dma);
         else if ( d->arch.ops->guest_paging_levels == PAGING_L3 &&
                   (psh_type == PGT_l3_shadow || psh_type == PGT_l4_shadow) )
-            page = alloc_domheap_pages(NULL, 0, ALLOC_DOM_DMA); /* allocated 
for PAE PDP page */
+            page = alloc_domheap_pages(NULL, 0, MEMF_dma); /* allocated for 
PAE PDP page */
         else
             page = alloc_domheap_page(NULL);
 #endif
diff -r 231e07e22f9c -r ee3d10828937 xen/arch/x86/shadow_public.c
--- a/xen/arch/x86/shadow_public.c      Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/arch/x86/shadow_public.c      Fri Jun 16 14:43:54 2006 +0100
@@ -43,7 +43,7 @@ int shadow_direct_map_init(struct domain
     struct page_info *page;
     l3_pgentry_t *root;
 
-    if ( !(page = alloc_domheap_pages(NULL, 0, ALLOC_DOM_DMA)) )
+    if ( !(page = alloc_domheap_pages(NULL, 0, MEMF_dma)) )
         return 0;
 
     root = map_domain_page(page_to_mfn(page));
@@ -395,7 +395,7 @@ static void alloc_monitor_pagetable(stru
 
     ASSERT(!pagetable_get_paddr(v->arch.monitor_table)); /* we should only get 
called once */
 
-    m3mfn_info = alloc_domheap_pages(NULL, 0, ALLOC_DOM_DMA);
+    m3mfn_info = alloc_domheap_pages(NULL, 0, MEMF_dma);
     ASSERT( m3mfn_info );
 
     m3mfn = page_to_mfn(m3mfn_info);
diff -r 231e07e22f9c -r ee3d10828937 xen/common/grant_table.c
--- a/xen/common/grant_table.c  Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/common/grant_table.c  Fri Jun 16 14:43:54 2006 +0100
@@ -634,7 +634,7 @@ gnttab_transfer(
             goto copyback;
         }
 
-        if ( steal_page_for_grant_transfer(d, page) < 0 )
+        if ( steal_page(d, page, 0) < 0 )
         {
             gop.status = GNTST_bad_page;
             goto copyback;
diff -r 231e07e22f9c -r ee3d10828937 xen/common/memory.c
--- a/xen/common/memory.c       Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/common/memory.c       Fri Jun 16 14:43:54 2006 +0100
@@ -34,7 +34,7 @@ increase_reservation(
     XEN_GUEST_HANDLE(xen_pfn_t) extent_list,
     unsigned int   nr_extents,
     unsigned int   extent_order,
-    unsigned int   flags,
+    unsigned int   memflags,
     int           *preempted)
 {
     struct page_info *page;
@@ -58,11 +58,11 @@ increase_reservation(
         }
 
         if ( unlikely((page = alloc_domheap_pages(
-            d, extent_order, flags)) == NULL) )
+            d, extent_order, memflags)) == NULL) )
         {
             DPRINTK("Could not allocate order=%d extent: "
-                    "id=%d flags=%x (%ld of %d)\n",
-                    extent_order, d->domain_id, flags, i, nr_extents);
+                    "id=%d memflags=%x (%ld of %d)\n",
+                    extent_order, d->domain_id, memflags, i, nr_extents);
             return i;
         }
 
@@ -84,7 +84,7 @@ populate_physmap(
     XEN_GUEST_HANDLE(xen_pfn_t) extent_list,
     unsigned int  nr_extents,
     unsigned int  extent_order,
-    unsigned int  flags,
+    unsigned int  memflags,
     int          *preempted)
 {
     struct page_info *page;
@@ -111,11 +111,11 @@ populate_physmap(
             goto out;
 
         if ( unlikely((page = alloc_domheap_pages(
-            d, extent_order, flags)) == NULL) )
+            d, extent_order, memflags)) == NULL) )
         {
             DPRINTK("Could not allocate order=%d extent: "
-                    "id=%d flags=%x (%ld of %d)\n",
-                    extent_order, d->domain_id, flags, i, nr_extents);
+                    "id=%d memflags=%x (%ld of %d)\n",
+                    extent_order, d->domain_id, memflags, i, nr_extents);
             goto out;
         }
 
@@ -183,7 +183,6 @@ decrease_reservation(
     XEN_GUEST_HANDLE(xen_pfn_t) extent_list,
     unsigned int   nr_extents,
     unsigned int   extent_order,
-    unsigned int   flags,
     int           *preempted)
 {
     unsigned long i, j;
@@ -276,10 +275,234 @@ translate_gpfn_list(
     return 0;
 }
 
+static long
+memory_exchange(XEN_GUEST_HANDLE(xen_memory_exchange_t) arg)
+{
+    struct xen_memory_exchange exch;
+    LIST_HEAD(in_chunk_list);
+    LIST_HEAD(out_chunk_list);
+    unsigned long in_chunk_order, out_chunk_order;
+    unsigned long gpfn, gmfn, mfn;
+    unsigned long i, j, k;
+    unsigned int  memflags = 0;
+    long          rc = 0;
+    struct domain *d;
+    struct page_info *page;
+
+    if ( copy_from_guest(&exch, arg, 1) )
+        return -EFAULT;
+
+    /* Various sanity checks. */
+    if ( (exch.nr_exchanged > exch.in.nr_extents) ||
+         /* Input and output domain identifiers match? */
+         (exch.in.domid != exch.out.domid) ||
+         /* Sizes of input and output lists do not overflow a long? */
+         ((~0UL >> exch.in.extent_order) < exch.in.nr_extents) ||
+         ((~0UL >> exch.out.extent_order) < exch.out.nr_extents) ||
+         /* Sizes of input and output lists match? */
+         ((exch.in.nr_extents << exch.in.extent_order) !=
+          (exch.out.nr_extents << exch.out.extent_order)) )
+    {
+        rc = -EINVAL;
+        goto fail_early;
+    }
+
+    /* Only privileged guests can allocate multi-page contiguous extents. */
+    if ( ((exch.in.extent_order != 0) || (exch.out.extent_order != 0)) &&
+         !multipage_allocation_permitted(current->domain) )
+    {
+        rc = -EPERM;
+        goto fail_early;
+    }
+
+    if ( (exch.out.address_bits != 0) &&
+         (exch.out.address_bits <
+          (get_order_from_pages(max_page) + PAGE_SHIFT)) )
+    {
+        if ( exch.out.address_bits < 31 )
+        {
+            rc = -ENOMEM;
+            goto fail_early;
+        }
+        memflags = MEMF_dma;
+    }
+
+    guest_handle_add_offset(exch.in.extent_start, exch.nr_exchanged);
+    exch.in.nr_extents -= exch.nr_exchanged;
+
+    if ( exch.in.extent_order <= exch.out.extent_order )
+    {
+        in_chunk_order  = exch.out.extent_order - exch.in.extent_order;
+        out_chunk_order = 0;
+        guest_handle_add_offset(
+            exch.out.extent_start, exch.nr_exchanged >> in_chunk_order);
+        exch.out.nr_extents -= exch.nr_exchanged >> in_chunk_order;
+    }
+    else
+    {
+        in_chunk_order  = 0;
+        out_chunk_order = exch.in.extent_order - exch.out.extent_order;
+        guest_handle_add_offset(
+            exch.out.extent_start, exch.nr_exchanged << out_chunk_order);
+        exch.out.nr_extents -= exch.nr_exchanged << out_chunk_order;
+    }
+
+    /*
+     * Only support exchange on calling domain right now. Otherwise there are
+     * tricky corner cases to consider (e.g., DOMF_dying domain).
+     */
+    if ( unlikely(exch.in.domid != DOMID_SELF) )
+    {
+        rc = IS_PRIV(current->domain) ? -EINVAL : -EPERM;
+        goto fail_early;
+    }
+    d = current->domain;
+
+    for ( i = 0; i < (exch.in.nr_extents >> in_chunk_order); i++ )
+    {
+        if ( hypercall_preempt_check() )
+        {
+            exch.nr_exchanged += i << in_chunk_order;
+            if ( copy_field_to_guest(arg, &exch, nr_exchanged) )
+                return -EFAULT;
+            return hypercall_create_continuation(
+                __HYPERVISOR_memory_op, "lh", XENMEM_exchange, arg);
+        }
+
+        /* Steal a chunk's worth of input pages from the domain. */
+        for ( j = 0; j < (1UL << in_chunk_order); j++ )
+        {
+            if ( unlikely(__copy_from_guest_offset(
+                &gmfn, exch.in.extent_start, (i<<in_chunk_order)+j, 1)) )
+            {
+                rc = -EFAULT;
+                goto fail;
+            }
+
+            for ( k = 0; k < (1UL << exch.in.extent_order); k++ )
+            {
+                mfn = gmfn_to_mfn(d, gmfn + k);
+                if ( unlikely(!mfn_valid(mfn)) )
+                {
+                    rc = -EINVAL;
+                    goto fail;
+                }
+
+                page = mfn_to_page(mfn);
+
+                if ( unlikely(steal_page(d, page, MEMF_no_refcount)) )
+                {
+                    rc = -EINVAL;
+                    goto fail;
+                }
+
+                list_add(&page->list, &in_chunk_list);
+            }
+        }
+
+        /* Allocate a chunk's worth of anonymous output pages. */
+        for ( j = 0; j < (1UL << out_chunk_order); j++ )
+        {
+            page = alloc_domheap_pages(
+                NULL, exch.out.extent_order, memflags);
+            if ( unlikely(page == NULL) )
+            {
+                rc = -ENOMEM;
+                goto fail;
+            }
+
+            list_add(&page->list, &out_chunk_list);
+        }
+
+        /*
+         * Success! Beyond this point we cannot fail for this chunk.
+         */
+
+        /* Destroy final reference to each input page. */
+        while ( !list_empty(&in_chunk_list) )
+        {
+            page = list_entry(in_chunk_list.next, struct page_info, list);
+            list_del(&page->list);
+            if ( !test_and_clear_bit(_PGC_allocated, &page->count_info) )
+                BUG();
+            mfn = page_to_mfn(page);
+            guest_physmap_remove_page(d, mfn_to_gmfn(d, mfn), mfn);
+            put_page(page);
+        }
+
+        /* Assign each output page to the domain. */
+        j = 0;
+        while ( !list_empty(&out_chunk_list) )
+        {
+            page = list_entry(out_chunk_list.next, struct page_info, list);
+            list_del(&page->list);
+            if ( assign_pages(d, page, exch.out.extent_order,
+                              MEMF_no_refcount) )
+                BUG();
+
+            /* Note that we ignore errors accessing the output extent list. */
+            (void)__copy_from_guest_offset(
+                &gpfn, exch.out.extent_start, (i<<out_chunk_order)+j, 1);
+
+            mfn = page_to_mfn(page);
+            if ( unlikely(shadow_mode_translate(d)) )
+            {
+                for ( k = 0; k < (1UL << exch.out.extent_order); k++ )
+                    guest_physmap_add_page(d, gpfn + k, mfn + k);
+            }
+            else
+            {
+                for ( k = 0; k < (1UL << exch.out.extent_order); k++ )
+                    set_gpfn_from_mfn(mfn + k, gpfn + k);
+                (void)__copy_to_guest_offset(
+                    exch.out.extent_start, (i<<out_chunk_order)+j, &mfn, 1);
+            }
+
+            j++;
+        }
+        BUG_ON(j != (1UL << out_chunk_order));
+    }
+
+    exch.nr_exchanged += exch.in.nr_extents;
+    if ( copy_field_to_guest(arg, &exch, nr_exchanged) )
+        rc = -EFAULT;
+    return rc;
+
+    /*
+     * Failed a chunk! Free any partial chunk work. Tell caller how many
+     * chunks succeeded.
+     */
+ fail:
+    /* Reassign any input pages we managed to steal. */
+    while ( !list_empty(&in_chunk_list) )
+    {
+        page = list_entry(in_chunk_list.next, struct page_info, list);
+        list_del(&page->list);
+        if ( assign_pages(d, page, 0, MEMF_no_refcount) )
+            BUG();
+    }
+
+    /* Free any output pages we managed to allocate. */
+    while ( !list_empty(&out_chunk_list) )
+    {
+        page = list_entry(out_chunk_list.next, struct page_info, list);
+        list_del(&page->list);
+        free_domheap_pages(page, exch.out.extent_order);
+    }
+
+    exch.nr_exchanged += i << in_chunk_order;
+
+ fail_early:
+    if ( copy_field_to_guest(arg, &exch, nr_exchanged) )
+        rc = -EFAULT;
+    return rc;
+}
+
 long do_memory_op(unsigned long cmd, XEN_GUEST_HANDLE(void) arg)
 {
     struct domain *d;
-    int rc, op, flags = 0, preempted = 0;
+    int rc, op, preempted = 0;
+    unsigned int memflags = 0;
     unsigned long start_extent, progress;
     struct xen_memory_reservation reservation;
     domid_t domid;
@@ -291,16 +514,17 @@ long do_memory_op(unsigned long cmd, XEN
     case XENMEM_increase_reservation:
     case XENMEM_decrease_reservation:
     case XENMEM_populate_physmap:
+        start_extent = cmd >> START_EXTENT_SHIFT;
+
         if ( copy_from_guest(&reservation, arg, 1) )
-            return -EFAULT;
+            return start_extent;
 
         /* Is size too large for us to encode a continuation? */
         if ( reservation.nr_extents > (ULONG_MAX >> START_EXTENT_SHIFT) )
-            return -EINVAL;
-
-        start_extent = cmd >> START_EXTENT_SHIFT;
+            return start_extent;
+
         if ( unlikely(start_extent > reservation.nr_extents) )
-            return -EINVAL;
+            return start_extent;
 
         if ( !guest_handle_is_null(reservation.extent_start) )
             guest_handle_add_offset(reservation.extent_start, start_extent);
@@ -311,16 +535,15 @@ long do_memory_op(unsigned long cmd, XEN
               (get_order_from_pages(max_page) + PAGE_SHIFT)) )
         {
             if ( reservation.address_bits < 31 )
-                return -ENOMEM;
-            flags = ALLOC_DOM_DMA;
+                return start_extent;
+            memflags = MEMF_dma;
         }
 
         if ( likely(reservation.domid == DOMID_SELF) )
             d = current->domain;
-        else if ( !IS_PRIV(current->domain) )
-            return -EPERM;
-        else if ( (d = find_domain_by_id(reservation.domid)) == NULL )
-            return -ESRCH;
+        else if ( !IS_PRIV(current->domain) ||
+                  ((d = find_domain_by_id(reservation.domid)) == NULL) )
+            return start_extent;
 
         switch ( op )
         {
@@ -330,7 +553,7 @@ long do_memory_op(unsigned long cmd, XEN
                 reservation.extent_start,
                 reservation.nr_extents,
                 reservation.extent_order,
-                flags,
+                memflags,
                 &preempted);
             break;
         case XENMEM_decrease_reservation:
@@ -339,7 +562,6 @@ long do_memory_op(unsigned long cmd, XEN
                 reservation.extent_start,
                 reservation.nr_extents,
                 reservation.extent_order,
-                flags,
                 &preempted);
             break;
         case XENMEM_populate_physmap:
@@ -349,7 +571,7 @@ long do_memory_op(unsigned long cmd, XEN
                 reservation.extent_start,
                 reservation.nr_extents,
                 reservation.extent_order,
-                flags,
+                memflags,
                 &preempted);
             break;
         }
@@ -364,6 +586,10 @@ long do_memory_op(unsigned long cmd, XEN
                 __HYPERVISOR_memory_op, "lh",
                 op | (rc << START_EXTENT_SHIFT), arg);
 
+        break;
+
+    case XENMEM_exchange:
+        rc = memory_exchange(guest_handle_cast(arg, xen_memory_exchange_t));
         break;
 
     case XENMEM_maximum_ram_page:
diff -r 231e07e22f9c -r ee3d10828937 xen/common/page_alloc.c
--- a/xen/common/page_alloc.c   Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/common/page_alloc.c   Fri Jun 16 14:43:54 2006 +0100
@@ -531,16 +531,66 @@ void init_domheap_pages(paddr_t ps, padd
 }
 
 
+int assign_pages(
+    struct domain *d,
+    struct page_info *pg,
+    unsigned int order,
+    unsigned int memflags)
+{
+    unsigned long i;
+
+    spin_lock(&d->page_alloc_lock);
+
+    if ( unlikely(test_bit(_DOMF_dying, &d->domain_flags)) )
+    {
+        DPRINTK("Cannot assign page to domain%d -- dying.\n", d->domain_id);
+        goto fail;
+    }
+
+    if ( !(memflags & MEMF_no_refcount) )
+    {
+        if ( unlikely((d->tot_pages + (1 << order)) > d->max_pages) )
+        {
+            DPRINTK("Over-allocation for domain %u: %u > %u\n",
+                    d->domain_id, d->tot_pages + (1 << order), d->max_pages);
+            goto fail;
+        }
+
+        if ( unlikely(d->tot_pages == 0) )
+            get_knownalive_domain(d);
+
+        d->tot_pages += 1 << order;
+    }
+
+    for ( i = 0; i < (1 << order); i++ )
+    {
+        ASSERT(page_get_owner(&pg[i]) == NULL);
+        ASSERT((pg[i].count_info & ~(PGC_allocated | 1)) == 0);
+        page_set_owner(&pg[i], d);
+        wmb(); /* Domain pointer must be visible before updating refcnt. */
+        pg[i].count_info = PGC_allocated | 1;
+        list_add_tail(&pg[i].list, &d->page_list);
+    }
+
+    spin_unlock(&d->page_alloc_lock);
+    return 0;
+
+ fail:
+    spin_unlock(&d->page_alloc_lock);
+    return -1;
+}
+
+
 struct page_info *alloc_domheap_pages(
-    struct domain *d, unsigned int order, unsigned int flags)
+    struct domain *d, unsigned int order, unsigned int memflags)
 {
     struct page_info *pg = NULL;
     cpumask_t mask;
-    int i;
+    unsigned long i;
 
     ASSERT(!in_irq());
 
-    if ( !(flags & ALLOC_DOM_DMA) )
+    if ( !(memflags & MEMF_dma) )
     {
         pg = alloc_heap_pages(MEMZONE_DOM, order);
         /* Failure? Then check if we can fall back to the DMA pool. */
@@ -582,37 +632,11 @@ struct page_info *alloc_domheap_pages(
         flush_tlb_mask(mask);
     }
 
-    if ( d == NULL )
-        return pg;
-
-    spin_lock(&d->page_alloc_lock);
-
-    if ( unlikely(test_bit(_DOMF_dying, &d->domain_flags)) ||
-         unlikely((d->tot_pages + (1 << order)) > d->max_pages) )
-    {
-        DPRINTK("Over-allocation for domain %u: %u > %u\n",
-                d->domain_id, d->tot_pages + (1 << order), d->max_pages);
-        DPRINTK("...or the domain is dying (%d)\n", 
-                !!test_bit(_DOMF_dying, &d->domain_flags));
-        spin_unlock(&d->page_alloc_lock);
+    if ( (d != NULL) && assign_pages(d, pg, order, memflags) )
+    {
         free_heap_pages(pfn_dom_zone_type(page_to_mfn(pg)), pg, order);
         return NULL;
     }
-
-    if ( unlikely(d->tot_pages == 0) )
-        get_knownalive_domain(d);
-
-    d->tot_pages += 1 << order;
-
-    for ( i = 0; i < (1 << order); i++ )
-    {
-        page_set_owner(&pg[i], d);
-        wmb(); /* Domain pointer must be visible before updating refcnt. */
-        pg[i].count_info |= PGC_allocated | 1;
-        list_add_tail(&pg[i].list, &d->page_list);
-    }
-
-    spin_unlock(&d->page_alloc_lock);
     
     return pg;
 }
diff -r 231e07e22f9c -r ee3d10828937 xen/include/asm-ia64/grant_table.h
--- a/xen/include/asm-ia64/grant_table.h        Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/include/asm-ia64/grant_table.h        Fri Jun 16 14:43:54 2006 +0100
@@ -12,16 +12,12 @@
 #define create_grant_host_mapping(a, f, fl)  0
 #define destroy_grant_host_mapping(a, f, fl) 0
 
-// for grant transfer
-#define steal_page_for_grant_transfer(d, p)  0
-
 #else
 // for grant map/unmap
 int create_grant_host_mapping(unsigned long gpaddr, unsigned long mfn, 
unsigned int flags);
 int destroy_grant_host_mapping(unsigned long gpaddr, unsigned long mfn, 
unsigned int flags);
 
 // for grant transfer
-int steal_page_for_grant_transfer(struct domain *d, struct page_info *page);
 void guest_physmap_add_page(struct domain *d, unsigned long gpfn, unsigned 
long mfn);
 
 #endif
diff -r 231e07e22f9c -r ee3d10828937 xen/include/asm-ia64/mm.h
--- a/xen/include/asm-ia64/mm.h Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/include/asm-ia64/mm.h Fri Jun 16 14:43:54 2006 +0100
@@ -474,4 +474,11 @@ extern unsigned long ____lookup_domain_m
 /* Arch-specific portion of memory_op hypercall. */
 #define arch_memory_op(op, arg) (-ENOSYS)
 
+#ifndef CONFIG_XEN_IA64_DOM0_VP
+#define steal_page(d, p, f)  0
+#else
+int steal_page(
+    struct domain *d, struct page_info *page, unsigned int memflags);
+#endif
+
 #endif /* __ASM_IA64_MM_H__ */
diff -r 231e07e22f9c -r ee3d10828937 xen/include/asm-x86/grant_table.h
--- a/xen/include/asm-x86/grant_table.h Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/include/asm-x86/grant_table.h Fri Jun 16 14:43:54 2006 +0100
@@ -18,9 +18,6 @@ int destroy_grant_host_mapping(
 int destroy_grant_host_mapping(
     unsigned long addr, unsigned long frame, unsigned int flags);
 
-int steal_page_for_grant_transfer(
-    struct domain *d, struct page_info *page);
-
 #define gnttab_create_shared_page(d, t, i)                               \
     do {                                                                 \
         share_xen_page_with_guest(                                       \
diff -r 231e07e22f9c -r ee3d10828937 xen/include/asm-x86/mm.h
--- a/xen/include/asm-x86/mm.h  Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/include/asm-x86/mm.h  Fri Jun 16 14:43:54 2006 +0100
@@ -389,4 +389,7 @@ long arch_memory_op(int op, XEN_GUEST_HA
 long arch_memory_op(int op, XEN_GUEST_HANDLE(void) arg);
 long subarch_memory_op(int op, XEN_GUEST_HANDLE(void) arg);
 
+int steal_page(
+    struct domain *d, struct page_info *page, unsigned int memflags);
+
 #endif /* __ASM_X86_MM_H__ */
diff -r 231e07e22f9c -r ee3d10828937 xen/include/public/memory.h
--- a/xen/include/public/memory.h       Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/include/public/memory.h       Fri Jun 16 14:43:54 2006 +0100
@@ -10,8 +10,8 @@
 #define __XEN_PUBLIC_MEMORY_H__
 
 /*
- * Increase or decrease the specified domain's memory reservation. Returns a
- * -ve errcode on failure, or the # extents successfully allocated or freed.
+ * Increase or decrease the specified domain's memory reservation. Returns the
+ * number of extents successfully allocated or freed.
  * arg == addr of struct xen_memory_reservation.
  */
 #define XENMEM_increase_reservation 0
@@ -48,10 +48,52 @@ struct xen_memory_reservation {
      * Unprivileged domains can specify only DOMID_SELF.
      */
     domid_t        domid;
-
 };
 typedef struct xen_memory_reservation xen_memory_reservation_t;
 DEFINE_XEN_GUEST_HANDLE(xen_memory_reservation_t);
+
+/*
+ * An atomic exchange of memory pages. If return code is zero then
+ * @out.extent_list provides GMFNs of the newly-allocated memory.
+ * Returns zero on complete success, otherwise a negative error code.
+ * On complete success then always @nr_exchanged == @in.nr_extents.
+ * On partial success @nr_exchanged indicates how much work was done.
+ */
+#define XENMEM_exchange             11
+struct xen_memory_exchange {
+    /*
+     * [IN] Details of memory extents to be exchanged (GMFN bases).
+     * Note that @in.address_bits is ignored and unused.
+     */
+    struct xen_memory_reservation in;
+
+    /*
+     * [IN/OUT] Details of new memory extents.
+     * We require that:
+     *  1. @in.domid == @out.domid
+     *  2. @in.nr_extents  << @in.extent_order == 
+     *     @out.nr_extents << @out.extent_order
+     *  3. @in.extent_start and @out.extent_start lists must not overlap
+     *  4. @out.extent_start lists GPFN bases to be populated
+     *  5. @out.extent_start is overwritten with allocated GMFN bases
+     */
+    struct xen_memory_reservation out;
+
+    /*
+     * [OUT] Number of input extents that were successfully exchanged:
+     *  1. The first @nr_exchanged input extents were successfully
+     *     deallocated.
+     *  2. The corresponding first entries in the output extent list correctly
+     *     indicate the GMFNs that were successfully exchanged.
+     *  3. All other input and output extents are untouched.
+     *  4. If not all input exents are exchanged then the return code of this
+     *     command will be non-zero.
+     *  5. THIS FIELD MUST BE INITIALISED TO ZERO BY THE CALLER!
+     */
+    unsigned long nr_exchanged;
+};
+typedef struct xen_memory_exchange xen_memory_exchange_t;
+DEFINE_XEN_GUEST_HANDLE(xen_memory_exchange_t);
 
 /*
  * Returns the maximum machine frame number of mapped RAM in this system.
diff -r 231e07e22f9c -r ee3d10828937 xen/include/xen/mm.h
--- a/xen/include/xen/mm.h      Fri Jun 16 10:52:49 2006 +0100
+++ b/xen/include/xen/mm.h      Fri Jun 16 14:43:54 2006 +0100
@@ -60,13 +60,23 @@ void free_xenheap_pages(void *v, unsigne
 /* Domain suballocator. These functions are *not* interrupt-safe.*/
 void init_domheap_pages(paddr_t ps, paddr_t pe);
 struct page_info *alloc_domheap_pages(
-    struct domain *d, unsigned int order, unsigned int flags);
+    struct domain *d, unsigned int order, unsigned int memflags);
 void free_domheap_pages(struct page_info *pg, unsigned int order);
 unsigned long avail_domheap_pages(void);
 #define alloc_domheap_page(d) (alloc_domheap_pages(d,0,0))
 #define free_domheap_page(p)  (free_domheap_pages(p,0))
 
-#define ALLOC_DOM_DMA 1
+int assign_pages(
+    struct domain *d,
+    struct page_info *pg,
+    unsigned int order,
+    unsigned int memflags);
+
+/* memflags: */
+#define _MEMF_dma         0
+#define  MEMF_dma         (1U<<_MEMF_dma)
+#define _MEMF_no_refcount 1
+#define  MEMF_no_refcount (1U<<_MEMF_no_refcount)
 
 #ifdef CONFIG_PAGEALLOC_MAX_ORDER
 #define MAX_ORDER CONFIG_PAGEALLOC_MAX_ORDER

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