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[Xen-devel] [PATCH] Provide support for multiple frame buffers in Xen



Support is provided for both shadow and hardware assisted paging (HAP) modes.
This code bookkeeps the set of video frame buffers (vram),
detects when the guest has modified any of those buffers and, upon request,
returns a bitmap of the modified pages.
This lets other software components re-paint the portions of the monitor (or 
monitors) that have changed.
Each monitor has a frame buffer of some size at some position in guest physical 
memory.
The set of frame buffers being tracked can change over time as monitors are 
plugged and unplugged.
(Version 2 of this patch.)

Signed-Off-By: Robert Phillips <robert.phillips@xxxxxxxxxx>
---
 tools/libxc/xenctrl.h            |   17 +-
 xen/arch/x86/hvm/Makefile        |    2 +-
 xen/arch/x86/hvm/hvm.c           |    4 +-
 xen/arch/x86/mm/Makefile         |    1 +
 xen/arch/x86/mm/dirty_vram.c     |  951 ++++++++++++++++++++++++++++++++++++++
 xen/arch/x86/mm/hap/hap.c        |  140 +-----
 xen/arch/x86/mm/paging.c         |  236 ++++------
 xen/arch/x86/mm/shadow/common.c  |  335 ++++++++------
 xen/arch/x86/mm/shadow/multi.c   |  174 ++++---
 xen/arch/x86/mm/shadow/multi.h   |    7 +-
 xen/arch/x86/mm/shadow/types.h   |    1 +
 xen/include/asm-x86/dirty_vram.h |  196 ++++++++
 xen/include/asm-x86/hap.h        |    4 -
 xen/include/asm-x86/hvm/domain.h |    2 +-
 xen/include/asm-x86/paging.h     |   22 +-
 xen/include/asm-x86/shadow.h     |    6 -
 16 files changed, 1535 insertions(+), 563 deletions(-)
 create mode 100644 xen/arch/x86/mm/dirty_vram.c
 create mode 100644 xen/include/asm-x86/dirty_vram.h

diff --git a/tools/libxc/xenctrl.h b/tools/libxc/xenctrl.h
index 7eb5743..693d7fe 100644
--- a/tools/libxc/xenctrl.h
+++ b/tools/libxc/xenctrl.h
@@ -1552,15 +1552,20 @@ int xc_hvm_inject_msi(
     xc_interface *xch, domid_t dom, uint64_t addr, uint32_t data);
 
 /*
- * Track dirty bit changes in the VRAM area
+ * Track dirty bit changes in a VRAM region defined by
+ * [ first_pfn : first_pfn + nr - 1 ]
  *
  * All of this is done atomically:
- * - get the dirty bitmap since the last call
- * - set up dirty tracking area for period up to the next call
- * - clear the dirty tracking area.
+ * - gets the dirty bitmap since the last call, all zeroes for
+ *   the first call with some new region
+ * - sets up a dirty tracking region for period up to the next call
+ * - clears the specified dirty tracking region.
  *
- * Returns -ENODATA and does not fill bitmap if the area has changed since the
- * last call.
+ * Creating a new region causes any existing regions that it overlaps
+ * to be discarded.
+ *
+ * Specifying nr == 0 causes all regions to be discarded and
+ * disables dirty bit tracking.
  */
 int xc_hvm_track_dirty_vram(
     xc_interface *xch, domid_t dom,
diff --git a/xen/arch/x86/hvm/Makefile b/xen/arch/x86/hvm/Makefile
index eea5555..e374aac 100644
--- a/xen/arch/x86/hvm/Makefile
+++ b/xen/arch/x86/hvm/Makefile
@@ -22,4 +22,4 @@ obj-y += vlapic.o
 obj-y += vmsi.o
 obj-y += vpic.o
 obj-y += vpt.o
-obj-y += vpmu.o
\ No newline at end of file
+obj-y += vpmu.o
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 34da2f5..b12e3b6 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -57,6 +57,7 @@
 #include <asm/hvm/cacheattr.h>
 #include <asm/hvm/trace.h>
 #include <asm/hvm/nestedhvm.h>
+#include <asm/dirty_vram.h>
 #include <asm/mtrr.h>
 #include <asm/apic.h>
 #include <public/sched.h>
@@ -1433,8 +1434,7 @@ int hvm_hap_nested_page_fault(paddr_t gpa,
          */
         if ( access_w )
         {
-            paging_mark_dirty(v->domain, mfn_x(mfn));
-            p2m_change_type(v->domain, gfn, p2m_ram_logdirty, p2m_ram_rw);
+            paging_mark_dirty_hap(v->domain, gfn, mfn_x(mfn));
         }
         rc = 1;
         goto out_put_gfn;
diff --git a/xen/arch/x86/mm/Makefile b/xen/arch/x86/mm/Makefile
index 73dcdf4..becd0c9 100644
--- a/xen/arch/x86/mm/Makefile
+++ b/xen/arch/x86/mm/Makefile
@@ -5,6 +5,7 @@ obj-y += paging.o
 obj-y += p2m.o p2m-pt.o p2m-ept.o p2m-pod.o
 obj-y += guest_walk_2.o
 obj-y += guest_walk_3.o
+obj-y += dirty_vram.o
 obj-$(x86_64) += guest_walk_4.o
 obj-$(x86_64) += mem_event.o
 obj-$(x86_64) += mem_paging.o
diff --git a/xen/arch/x86/mm/dirty_vram.c b/xen/arch/x86/mm/dirty_vram.c
new file mode 100644
index 0000000..72bcf4e
--- /dev/null
+++ b/xen/arch/x86/mm/dirty_vram.c
@@ -0,0 +1,951 @@
+/*
+ * arch/x86/mm/dirty_vram.c: Bookkeep/query dirty VRAM pages
+ * with support for multiple frame buffers.
+ *
+ * Copyright (c) 2012, Citrix Systems, Inc. (Robert Phillips)
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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 <xen/types.h>
+#include <xen/sched.h>
+#include <xen/guest_access.h>
+#include <asm/shadow.h>
+#include <asm/dirty_vram.h>
+#include "mm-locks.h"
+
+#define DEBUG_stop_tracking_all_vram          1
+#define DEBUG_allocating_dirty_vram_range     1
+#define DEBUG_high_water_mark_for_vram_ranges 1
+#define DEBUG_freeing_dirty_vram_range        1
+#define DEBUG_allocate_paddr_links_page       0
+#define DEBUG_update_vram_mapping             0
+
+/* Allocates domain's dirty_vram structure */
+dv_dirty_vram_t *
+dirty_vram_alloc(struct domain *d)
+{
+    dv_dirty_vram_t *dirty_vram;
+    ASSERT( paging_locked_by_me(d) );
+    dirty_vram = d->arch.hvm_domain.dirty_vram = xzalloc(dv_dirty_vram_t);
+    if ( dirty_vram )
+    {
+        INIT_LIST_HEAD(&dirty_vram->range_head);
+        INIT_LIST_HEAD(&dirty_vram->ext_head);
+    }
+    return dirty_vram;
+}
+
+/*
+ * Returns domain's dirty_vram structure,
+ * allocating it if necessary
+ */
+dv_dirty_vram_t *
+dirty_vram_find_or_alloc(struct domain *d)
+{
+    dv_dirty_vram_t *dirty_vram = d->arch.hvm_domain.dirty_vram;
+    ASSERT( paging_locked_by_me(d) );
+    if ( !dirty_vram )
+        dirty_vram = dirty_vram_alloc(d);
+    return dirty_vram;
+}
+
+
+/* Free domain's dirty_vram structure */
+void dirty_vram_free(struct domain *d)
+{
+    dv_dirty_vram_t *dirty_vram = d->arch.hvm_domain.dirty_vram;
+    ASSERT( paging_locked_by_me(d) );
+    if ( dirty_vram )
+    {
+        struct list_head *curr, *next;
+        /* Free all the ranges */
+        list_for_each_safe(curr, next, &dirty_vram->range_head)
+        {
+            dv_range_t *range = list_entry(curr, dv_range_t, range_link);
+#if DEBUG_stop_tracking_all_vram
+            gdprintk(XENLOG_DEBUG, "[%05lx:%05lx] stop tracking all vram\n",
+                     range->begin_pfn, range->end_pfn);
+#endif
+            xfree(range->pl_tab);
+            xfree(range);
+        }
+        /* Free all the extension pages */
+        list_for_each_safe(curr, next, &dirty_vram->ext_head)
+        {
+            struct dv_paddr_link_ext *ext =
+                container_of(
+                    curr, struct dv_paddr_link_ext, ext_link);
+            struct page_info *pg = __virt_to_page(ext);
+            d->arch.paging.free_page(d, pg);
+        }
+
+        xfree(dirty_vram);
+        d->arch.hvm_domain.dirty_vram = NULL;
+    }
+}
+
+/* Returns dirty vram range containing gfn, NULL if none */
+struct dv_range *
+dirty_vram_range_find_gfn(struct domain *d,
+                          unsigned long gfn)
+{
+    struct dv_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
+    ASSERT( paging_locked_by_me(d) );
+    if ( dirty_vram )
+    {
+        struct list_head *curr;
+        list_for_each(curr, &dirty_vram->range_head)
+        {
+            dv_range_t *range = list_entry(curr, dv_range_t, range_link);
+            if ( gfn >= range->begin_pfn &&
+                 gfn <  range->end_pfn )
+                return range;
+        }
+    }
+    return NULL;
+}
+
+/*
+ * Returns pointer to dirty vram range matching [begin_pfn .. end_pfn ),
+ * NULL if none.
+ */
+dv_range_t *
+dirty_vram_range_find(struct domain *d,
+                      unsigned long begin_pfn,
+                      unsigned long nr)
+{
+    unsigned long end_pfn = begin_pfn + nr;
+    dv_dirty_vram_t *dirty_vram = d->arch.hvm_domain.dirty_vram;
+    ASSERT( paging_locked_by_me(d) );
+    if ( dirty_vram )
+    {
+        struct list_head *curr;
+        list_for_each(curr, &dirty_vram->range_head)
+        {
+            dv_range_t *range = list_entry(curr, dv_range_t, range_link);
+            if ( begin_pfn == range->begin_pfn &&
+                 end_pfn   == range->end_pfn )
+                return range;
+        }
+    }
+    return NULL;
+}
+
+/* Allocate specified dirty_vram range */
+static dv_range_t *
+_dirty_vram_range_alloc(struct domain *d,
+                        unsigned long begin_pfn,
+                        unsigned long nr)
+{
+    dv_dirty_vram_t *dirty_vram = d->arch.hvm_domain.dirty_vram;
+    dv_range_t *range = NULL;
+    unsigned long end_pfn = begin_pfn + nr;
+    dv_paddr_link_t *pl_tab = NULL;
+    int i;
+
+    ASSERT( paging_locked_by_me(d) );
+    ASSERT( dirty_vram != NULL );
+
+#if DEBUG_allocating_dirty_vram_range
+    gdprintk(XENLOG_DEBUG,
+             "[%05lx:%05lx] Allocating dirty vram range hap:%d\n",
+             begin_pfn, end_pfn,
+             d->arch.hvm_domain.hap_enabled);
+#endif
+
+    range = xzalloc(dv_range_t);
+    if ( range == NULL )
+        goto err_out;
+
+    INIT_LIST_HEAD(&range->range_link);
+
+    range->begin_pfn = begin_pfn;
+    range->end_pfn = end_pfn;
+
+    if ( !hap_enabled(d) )
+    {
+        if ( (pl_tab = xzalloc_array(dv_paddr_link_t, nr)) == NULL )
+            goto err_out;
+
+        for ( i = 0; i != nr; i++ )
+        {
+            pl_tab[i].sl1ma = INVALID_PADDR;
+        }
+    }
+
+    range->pl_tab = pl_tab;
+    range->mappings_hwm = 1;
+
+    list_add(&range->range_link, &dirty_vram->range_head);
+    if ( ++dirty_vram->nr_ranges > dirty_vram->ranges_hwm )
+    {
+        dirty_vram->ranges_hwm = dirty_vram->nr_ranges;
+#if DEBUG_high_water_mark_for_vram_ranges
+        gdprintk(XENLOG_DEBUG,
+                 "High water mark for number of vram ranges is now:%d\n",
+                 dirty_vram->ranges_hwm);
+#endif
+    }
+    return range;
+
+ err_out:
+    xfree(pl_tab);
+    xfree(range);
+    return NULL;
+}
+
+
+/* Frees specified dirty_vram range */
+void dirty_vram_range_free(struct domain *d,
+                           dv_range_t *range)
+{
+    dv_dirty_vram_t *dirty_vram = d->arch.hvm_domain.dirty_vram;
+    ASSERT( paging_locked_by_me(d) );
+    if ( dirty_vram )
+    {
+        int i, nr = range->end_pfn - range->begin_pfn;
+
+#if DEBUG_freeing_dirty_vram_range
+        gdprintk(XENLOG_DEBUG,
+                 "[%05lx:%05lx] Freeing dirty vram range\n",
+                 range->begin_pfn, range->end_pfn);
+#endif
+
+        if ( range->pl_tab )
+        {
+            for ( i = 0; i != nr; i++ )
+            {
+                dv_paddr_link_t *plx;
+                plx = range->pl_tab[i].pl_next;
+                /* Does current FB page have multiple mappings? */
+                if ( plx ) /* yes */
+                {
+                    /* Find the last element in singly-linked list */
+                    while ( plx->pl_next != NULL )
+                        plx = plx->pl_next;
+                    
+                    /* Prepend whole list to the free list */
+                    plx->pl_next = dirty_vram->pl_free;
+                    dirty_vram->pl_free = range->pl_tab[i].pl_next;
+                }
+            }
+            xfree(range->pl_tab);
+            range->pl_tab = NULL;
+        }
+
+        /* Remove range from the linked list, free it, and adjust count*/
+        list_del(&range->range_link);
+        xfree(range);
+        dirty_vram->nr_ranges--;
+    }
+}
+
+/*
+ * dirty_vram_range_alloc()
+ * This function ensures that the new range does not overlap any existing
+ * ranges -- deleting them if necessary -- and then calls
+ * _dirty_vram_range_alloc to actually allocate the new range.
+ */
+dv_range_t *
+dirty_vram_range_alloc(struct domain *d,
+                        unsigned long begin_pfn,
+                        unsigned long nr)
+{
+    unsigned long end_pfn = begin_pfn + nr;
+    dv_dirty_vram_t *dirty_vram = d->arch.hvm_domain.dirty_vram;
+    dv_range_t *range;
+    struct list_head *curr, *next;
+
+    ASSERT( paging_locked_by_me(d) );
+    ASSERT( dirty_vram != NULL );
+
+    /*
+     * Ranges cannot overlap so
+     * free any range that overlaps [ begin_pfn .. end_pfn )
+     */
+    list_for_each_safe(curr, next, &dirty_vram->range_head)
+    {
+        dv_range_t *rng = list_entry(curr, dv_range_t, range_link);
+        if ( ( ( rng->begin_pfn <= begin_pfn ) &&
+               ( begin_pfn <  rng->end_pfn   )
+                 ) ||
+             ( ( begin_pfn <= rng->begin_pfn ) &&
+               ( rng->begin_pfn < end_pfn    )
+                 ) )
+        {
+            /* Different tracking, tear the previous down. */
+            dirty_vram_range_free(d, rng);
+        }
+    }
+
+    range = _dirty_vram_range_alloc(d, begin_pfn, nr);
+    if ( !range )
+        goto out;
+
+ out:
+    return range;
+}
+
+/*
+ * dirty_vram_range_find_or_alloc()
+ * Find the range for [begin_pfn:begin_pfn+nr).
+ * If it doesn't exists, create it.
+ */
+dv_range_t *
+dirty_vram_range_find_or_alloc(struct domain *d,
+                                unsigned long begin_pfn,
+                                unsigned long nr)
+{
+    dv_range_t *range;
+    ASSERT( paging_locked_by_me(d) );
+    range = dirty_vram_range_find(d, begin_pfn, nr);
+    if ( !range )
+        range = dirty_vram_range_alloc(d, begin_pfn, nr);
+    
+    return range;
+}
+
+
+
+/* Allocate a dv_paddr_link struct */
+static dv_paddr_link_t *
+alloc_paddr_link(struct domain *d)
+{
+    dv_paddr_link_t * pl = NULL;
+    dv_dirty_vram_t *dirty_vram = d->arch.hvm_domain.dirty_vram;
+
+    ASSERT( paging_locked_by_me(d) );
+    BUILD_BUG_ON(sizeof(dv_paddr_link_ext_t) > PAGE_SIZE);
+    /* Is the list of free pl's empty? */
+    if ( dirty_vram->pl_free == NULL ) /* yes */
+    {
+        /*
+         * Allocate another page of pl's.
+         * Link them all together and point the free list head at them
+         */
+        int i;
+        struct page_info *pg = d->arch.paging.alloc_page(d);
+        dv_paddr_link_ext_t *ext = __page_to_virt(pg);
+        if ( ext == NULL )
+            goto out;
+
+#if DEBUG_allocate_paddr_links_page
+        gdprintk(XENLOG_DEBUG, "Allocated another page of paddr_links\n");
+#endif
+        list_add(&ext->ext_link, &dirty_vram->ext_head);
+
+        /* initialize and link together the new pl entries */
+        for ( i = 0; i != ARRAY_SIZE(ext->entries); i++ )
+        {
+            ext->entries[i].sl1ma = INVALID_PADDR;
+            ext->entries[i].pl_next = &ext->entries[i+1];
+        }
+        ext->entries[ARRAY_SIZE(ext->entries) - 1].pl_next = NULL;
+        dirty_vram->pl_free = &ext->entries[0];
+    }
+    pl = dirty_vram->pl_free;
+    dirty_vram->pl_free = pl->pl_next;
+
+    pl->sl1ma = INVALID_PADDR;
+    pl->pl_next = NULL;
+ out:
+    return pl;
+}
+
+
+/*
+ * Free a paddr_link struct.
+ *
+ * The caller has walked the singly-linked list of elements
+ * that have, as their head, an element in a pl_tab cell.
+ * The list walks has reached the element to be freed.
+ * (Each element is a dv_paddr_link_t struct.)
+ *
+ * @pl points to the element to be freed.
+ * @ppl points to its predecessor element's next member.
+ *
+ * After linking the precessor to the element's successor,
+ * we can free @pl by prepending it to the list of free
+ * elements.
+ *
+ * As a boundary case (which happens to be the common case),
+ * @pl points to a cell in the pl_tab rather than to some
+ * extension element danging from that cell.
+ * We recognize this case because @ppl is NULL.
+ * In that case we promote the first extension element by
+ * copying it into the pl_tab cell and free it.
+ */
+
+dv_paddr_link_t *
+free_paddr_link(struct domain *d,
+                dv_paddr_link_t **ppl,
+                dv_paddr_link_t *pl)
+{
+    dv_dirty_vram_t *dirty_vram = d->arch.hvm_domain.dirty_vram;
+    dv_paddr_link_t *npl; /* next pl */
+
+    ASSERT( paging_locked_by_me(d) );
+    /* extension mapping? */
+    if ( ppl ) /* yes. free it */
+    {
+        ASSERT(pl == (*ppl));
+        (*ppl) = npl = pl->pl_next;
+    }
+    else  /* main table */
+    {
+        /*
+         * move 2nd mapping to main table.
+         * and free 2nd mapping
+         */
+        dv_paddr_link_t * spl;
+        spl = pl->pl_next;
+        if ( spl == NULL )
+        {
+            pl->sl1ma = INVALID_PADDR;
+            return pl;
+        }
+        pl->sl1ma = spl->sl1ma;
+        pl->pl_next = spl->pl_next;
+        npl = pl; /* reprocess main table entry again */
+        pl = spl;
+    }
+    pl->sl1ma = INVALID_PADDR;
+    pl->pl_next = dirty_vram->pl_free;
+    dirty_vram->pl_free = pl;
+    return npl;
+}
+
+
+/*
+ * dirty_vram_range_update()
+ *
+ * This is called whenever a level 1 page table entry is modified.
+ * If the L1PTE is being cleared, the function removes any paddr_links
+ * that refer to it.
+ * If the L1PTE is being set to a frame buffer page, a paddr_link is
+ * created for that page's entry in pl_tab.
+ * Returns 1 iff entry found and set or cleared.
+ */
+int dirty_vram_range_update(struct domain *d,
+                            unsigned long gfn,
+                            paddr_t sl1ma,
+                            int set)
+{
+    int effective = 0;
+    dv_range_t *range;
+    unsigned long i;
+    dv_paddr_link_t *pl;
+    dv_paddr_link_t **ppl;
+    int len = 0;
+
+    ASSERT(paging_locked_by_me(d));
+    range = dirty_vram_range_find_gfn(d, gfn);
+    if ( !range )
+        return effective;
+
+    
+    i = gfn - range->begin_pfn;
+    pl = &range->pl_tab[ i ];
+    ppl = NULL;
+
+    /*
+     * find matching entry (pl), if any, and its predecessor
+     * in linked list (ppl)
+     */
+    while ( pl != NULL )
+    {
+        if ( pl->sl1ma == sl1ma || pl->sl1ma == INVALID_PADDR )
+            break;
+            
+        ppl = &pl->pl_next;
+        pl = *ppl;
+        len++;
+    }
+
+    if ( set )
+    {
+        /* Did we find sl1ma in either the main table or the linked list? */
+        if ( pl == NULL ) /* no, so we'll need to alloc a link */
+        {
+            ASSERT(ppl != NULL);
+            /*
+             * Have we reached the limit of mappings we're willing
+             * to bookkeep?
+             */
+            if (len > DV_ADDR_LINK_LIST_LIMIT) /* yes */
+                /*
+                 * The side effect of failing to record this mapping
+                 * is that we will not detect any changes to the frame
+                 * buffer made through the mapping so
+                 * areas of a monitor may not get refreshed.
+                 * In practice this should never happen.
+                 */
+                goto out;
+
+            /* alloc link and append it to list */
+            (*ppl) = pl = alloc_paddr_link(d);
+            if ( pl == NULL )
+                goto out;
+        }
+        if ( pl->sl1ma != sl1ma )
+        {
+            ASSERT(pl->sl1ma == INVALID_PADDR);
+            pl->sl1ma = sl1ma;
+            range->nr_mappings++;
+        }
+        effective = 1;
+        if ( len > range->mappings_hwm )
+        {
+            range->mappings_hwm = len;
+#if DEBUG_update_vram_mapping
+            gdprintk(XENLOG_DEBUG,
+                     "[%lx] set      sl1ma:%lx hwm:%d mappings:%d 
freepages:%d\n",
+                     gfn, sl1ma,
+                     range->mappings_hwm,
+                     range->nr_mappings,
+                     d->arch.paging.shadow.free_pages);
+#endif
+        }
+    }
+    else /* clear */
+    {
+        if ( pl && pl->sl1ma == sl1ma )
+        {
+#if DEBUG_update_vram_mapping
+            gdprintk(XENLOG_DEBUG,
+                     "[%lx] clear    sl1ma:%lx mappings:%d\n",
+                     gfn, sl1ma,
+                     range->nr_mappings - 1);
+#endif
+            free_paddr_link(d, ppl, pl);
+            if ( --range->nr_mappings == 0 )
+            {
+                dirty_vram_range_free(d, range);
+            }
+            effective = 1;
+        }
+    }
+ out:
+    return effective;
+}
+
+
+/*
+ * shadow_scan_dirty_flags()
+ * This produces a dirty bitmap for the range by examining every
+ * L1PTE referenced by some dv_paddr_link in the range's pl_tab table.
+ * It tests and clears each such L1PTE's dirty flag.
+ */
+static int shadow_scan_dirty_flags(struct domain *d,
+                                   dv_range_t *range,
+                                   uint8_t *dirty_bitmap)
+{
+    int flush_tlb = 0;
+    unsigned long i;
+    unsigned long nr = range->end_pfn - range->begin_pfn;
+
+    ASSERT( paging_locked_by_me(d) );
+    /* Iterate over VRAM to track dirty bits. */
+    for ( i = 0; i < nr; i++ )
+    {
+        int dirty = 0, len = 1;
+        dv_paddr_link_t *pl;
+        for ( pl = &range->pl_tab[i]; pl; pl = pl->pl_next, len++ )
+        {
+            l1_pgentry_t *sl1e;
+            paddr_t sl1ma = pl->sl1ma;
+            if (sl1ma == INVALID_PADDR) /* FB page is unmapped */
+                continue;
+            sl1e = maddr_to_virt(sl1ma);
+            if ( l1e_get_flags(*sl1e) & _PAGE_DIRTY )
+            {
+                dirty = 1;
+                /* Clear dirty so we can detect if page gets re-dirtied.
+                 * Note: this is atomic, so we may clear a
+                 * _PAGE_ACCESSED set by another processor.
+                 */
+                l1e_remove_flags(*sl1e, _PAGE_DIRTY);
+                flush_tlb = 1;
+            }
+        } /* for */
+        
+        if ( dirty )
+            dirty_bitmap[i >> 3] |= (1 << (i & 7));
+
+    }
+
+    return flush_tlb;
+}
+
+
+/*
+ * shadow_track_dirty_vram()
+ * This is the API called by the guest to determine which pages in the range
+ * from [begin_pfn:begin_pfn+nr) have been dirtied since the last call.
+ * It creates the domain's dv_dirty_vram on demand.
+ * It creates ranges on demand when some [begin_pfn:nr) is first encountered.
+ * To collect the dirty bitmask it calls shadow_scan_dirty_flags().
+ * It copies the dirty bitmask into guest storage.
+ */
+int shadow_track_dirty_vram(struct domain *d,
+                            unsigned long begin_pfn,
+                            unsigned long nr,
+                            XEN_GUEST_HANDLE_64(uint8) guest_dirty_bitmap)
+{
+    int rc = 0;
+    unsigned long end_pfn = begin_pfn + nr;
+    int flush_tlb = 0;
+    dv_range_t *range;
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+    /*
+     * This range test is tricky.
+     *
+     * The range [begin_pfn..end_pfn) is an open interval, so end_pfn is a pfn
+     * beyond the end of the range.
+     *
+     * p2m->max_mapped_pfn is a valid PFN so p2m->max_mapped_pfn + 1 is an
+     * invalid PFN.
+     *
+     * If end_pfn is beyond *that* then the range is invalid.
+     */
+    if ( end_pfn < begin_pfn
+         || begin_pfn > p2m->max_mapped_pfn
+         || end_pfn > p2m->max_mapped_pfn + 1 )
+        return -EINVAL;
+
+    paging_lock(d);
+
+    if (!nr)
+    {
+        dirty_vram_free(d);
+        goto out;
+    }
+
+    if ( guest_handle_is_null(guest_dirty_bitmap) )
+        goto out;
+
+    if ( !dirty_vram_find_or_alloc(d) )
+    {
+        rc = -ENOMEM;
+        goto out;
+    }
+
+    range = dirty_vram_range_find(d, begin_pfn, nr);
+    if ( !range )
+    {
+        range = dirty_vram_range_alloc(d, begin_pfn, nr);
+        if ( range )
+            sh_find_all_vram_mappings(d->vcpu[0], range);
+    }
+    if ( range )
+    {
+        int size = (nr + BITS_PER_LONG - 1) / BITS_PER_LONG;
+        unsigned long dirty_bitmap[size];
+
+        memset(dirty_bitmap, 0x00, size * BYTES_PER_LONG);
+
+       flush_tlb |= shadow_scan_dirty_flags(d, range, (uint8_t*)dirty_bitmap);
+
+        rc = -EFAULT;
+        if ( copy_to_guest(guest_dirty_bitmap,
+                           (uint8_t*)dirty_bitmap,
+                           size * BYTES_PER_LONG) == 0 )
+            rc = 0;
+    }
+    
+    if ( flush_tlb )
+        flush_tlb_mask(d->domain_dirty_cpumask);
+
+out:
+    paging_unlock(d);
+    return rc;
+}
+
+
+/************************************************/
+/*          HAP VRAM TRACKING SUPPORT           */
+/************************************************/
+
+/*
+ * hap_enable_vram_tracking()
+ * For all ranges, mark all vram pages in range as logdirty read-only.
+ */
+static int hap_enable_vram_tracking(struct domain *d)
+{
+    int rc = 0;
+    dv_dirty_vram_t *dirty_vram;
+    struct list_head *curr;
+
+    /* turn on PG_log_dirty bit in paging mode */
+    paging_lock(d);
+    d->arch.paging.mode |= PG_log_dirty;
+    paging_unlock(d);
+
+    p2m_lock(p2m_get_hostp2m(d));
+    paging_lock(d);
+
+    dirty_vram = d->arch.hvm_domain.dirty_vram;
+
+    /*
+     * dirty_vram != NULL iff we're tracking dirty vram.
+     * If we start tracking dirty pages for all memory then
+     * the dirty_vram structure is freed.
+     */
+    if ( !dirty_vram )
+    {
+        rc = -EINVAL;
+        goto out;
+    }
+
+    /* set l1e entries of P2M table to be read-only. */
+    list_for_each(curr, &dirty_vram->range_head)
+    {
+       dv_range_t *range = list_entry(curr, dv_range_t, range_link);
+       gdprintk(XENLOG_DEBUG, "[%05lx:%05lx] enable  vram tracking\n",
+                range->begin_pfn, range->end_pfn);
+       p2m_change_type_range(d, range->begin_pfn, range->end_pfn,
+                             p2m_ram_rw, p2m_ram_logdirty);
+    }
+
+    flush_tlb_mask(d->domain_dirty_cpumask);
+ out:
+    paging_unlock(d);
+    p2m_unlock(p2m_get_hostp2m(d));
+    if ( rc )
+    {
+        paging_lock(d);
+        d->arch.paging.mode &= ~PG_log_dirty;
+        paging_unlock(d);
+    }
+    return rc;
+}
+
+/*
+ * hap_disable_vram_tracking()
+ * For all ranges, mark all vram pages in range as logdirty read-write.
+ */
+static int hap_disable_vram_tracking(struct domain *d)
+{
+    int rc = 0;
+    dv_dirty_vram_t *dirty_vram;
+    struct list_head *curr;
+
+    paging_lock(d);
+    d->arch.paging.mode &= ~PG_log_dirty;
+    paging_unlock(d);
+
+    p2m_lock(p2m_get_hostp2m(d));
+    paging_lock(d);
+
+    dirty_vram = d->arch.hvm_domain.dirty_vram;
+    if ( !dirty_vram )
+    {
+        rc = -EINVAL;
+        goto out;
+    }
+
+    /* set l1e entries of P2M table with normal mode */
+    list_for_each(curr, &dirty_vram->range_head)
+    {
+       dv_range_t *range = list_entry(curr, dv_range_t, range_link);
+       gdprintk(XENLOG_DEBUG, "[%05lx:%05lx] disable vram tracking\n",
+                range->begin_pfn, range->end_pfn);
+       p2m_change_type_range(d, range->begin_pfn, range->end_pfn,
+                             p2m_ram_logdirty, p2m_ram_rw);
+    }
+    flush_tlb_mask(d->domain_dirty_cpumask);
+ out:
+    paging_unlock(d);
+    p2m_unlock(p2m_get_hostp2m(d));
+    if ( rc )
+    {
+        paging_lock(d);
+        d->arch.paging.mode |= PG_log_dirty;
+        paging_unlock(d);
+    }
+    return rc;
+}
+
+/*
+ * hap_clean_vram_tracking_range()
+ * For all the pages in the range specified by [begin_pfn,nr),
+ * note in the dirty bitmap any page that has been marked as read-write,
+ * which signifies that the page has been dirtied, and reset the page
+ * to ram_logdirty.
+ */
+void hap_clean_vram_tracking_range(struct domain *d,
+                                   unsigned long begin_pfn,
+                                   unsigned long nr,
+                                   uint8_t *dirty_bitmap)
+{
+    int i;
+    unsigned long pfn;
+    dv_dirty_vram_t *dirty_vram = d->arch.hvm_domain.dirty_vram;
+    dv_range_t *range;
+
+    ASSERT(p2m_locked_by_me(p2m_get_hostp2m(d)));
+    ASSERT(paging_locked_by_me(d));
+
+    if ( !dirty_vram )
+    {
+        gdprintk(XENLOG_DEBUG,
+                 "Should only be called while tracking dirty vram.\n");
+        return;
+    }
+
+    range = dirty_vram_range_find(d, begin_pfn, nr);
+    if ( !range )
+        return;
+
+    /* set l1e entries of P2M table to be read-only. */
+    /*
+     * On first write, it page faults, its entry is changed to read-write,
+     * its bit in the dirty bitmap is set, and on retry the write succeeds.
+     */
+    for ( i = 0, pfn = range->begin_pfn; pfn < range->end_pfn; i++, pfn++ )
+    {
+        p2m_type_t pt;
+        pt = p2m_change_type(d, pfn, p2m_ram_rw, p2m_ram_logdirty);
+        if ( pt == p2m_ram_rw )
+            dirty_bitmap[i >> 3] |= (1 << (i & 7));
+    }
+    flush_tlb_mask(d->domain_dirty_cpumask);
+}
+
+static void hap_vram_tracking_init(struct domain *d)
+{
+    paging_log_dirty_init(d, hap_enable_vram_tracking,
+                          hap_disable_vram_tracking,
+                          NULL);
+}
+
+/*
+ * hap_track_dirty_vram()
+ * Create the domain's dv_dirty_vram struct on demand.
+ * Create a dirty vram range on demand when some [begin_pfn:begin_pfn+nr] is
+ * first encountered.
+ * Collect the guest_dirty bitmask, a bit mask of the dirty vram pages, by
+ * calling paging_log_dirty_range().
+ */
+int hap_track_dirty_vram(struct domain *d,
+                         unsigned long begin_pfn,
+                         unsigned long nr,
+                         XEN_GUEST_HANDLE_64(uint8) guest_dirty_bitmap)
+{
+    long rc = 0;
+    dv_dirty_vram_t *dirty_vram;
+
+    paging_lock(d);
+    dirty_vram = d->arch.hvm_domain.dirty_vram;
+    if ( nr )
+    {
+        dv_range_t *range = NULL;
+        int size = ( nr + BITS_PER_LONG - 1 ) & ~( BITS_PER_LONG - 1 );
+        uint8_t dirty_bitmap[size];
+
+        /* Already tracking dirty vram? */
+        if ( paging_mode_log_dirty(d) && dirty_vram ) /* yes */
+        {
+            /* Handle the addition of another range */
+            range = dirty_vram_range_find(d, begin_pfn, nr);
+            if ( !range )
+            {
+                rc = -ENOMEM;
+                if ( !(range = dirty_vram_range_alloc(d, begin_pfn, nr)) )
+                    goto param_fail;
+            }
+        }
+        /* Just starting to track dirty vram? */
+        else if ( !paging_mode_log_dirty(d) && !dirty_vram ) /* yes */
+        {
+            rc = -ENOMEM;
+            if ( !(dirty_vram = dirty_vram_alloc(d)) )
+                goto param_fail;
+
+            if ( !(range = dirty_vram_range_find_or_alloc(d, begin_pfn, nr)) )
+                goto param_fail;
+
+            /* Initialize callbacks for vram tracking */
+            hap_vram_tracking_init(d);
+
+            /* Enable HAP vram tracking */
+            paging_unlock(d);
+            rc = paging_log_dirty_enable(d);
+            paging_lock(d);
+            
+            if ( rc != 0 )
+                goto param_fail;
+        }
+        else
+        {
+            /* Test for invalid combination */
+            if ( !paging_mode_log_dirty(d) && dirty_vram )
+                rc = -EINVAL;
+            else /* logging dirty of all memory, not tracking dirty vram */
+                rc = -ENODATA;
+            goto param_fail;
+        }
+
+        paging_unlock(d);
+        memset(dirty_bitmap, 0x00, size);
+       paging_log_dirty_range(d, begin_pfn, nr, dirty_bitmap);
+        rc = -EFAULT;
+        if ( copy_to_guest(guest_dirty_bitmap,
+                           dirty_bitmap,
+                           size) == 0 )
+        {
+            rc = 0;
+        }
+    }
+    else
+    {
+        /*
+         * If zero pages specified while already tracking dirty vram
+         * then stop tracking
+         */
+        if ( paging_mode_log_dirty(d) && dirty_vram )
+        {
+            /* Disable HAP vram tracking */
+            paging_unlock(d);
+            rc = paging_log_dirty_disable(d);
+            paging_lock(d);
+            
+            dirty_vram_free(d);
+        }
+        else /* benign no-op */
+        {
+            rc = 0;
+        }
+        paging_unlock(d);
+    }
+
+    return rc;
+
+param_fail:
+    dirty_vram_free(d);
+    paging_unlock(d);
+    return rc;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c
index fd99cde..09cdba2 100644
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -41,6 +41,7 @@
 #include <asm/domain.h>
 #include <xen/numa.h>
 #include <asm/hvm/nestedhvm.h>
+#include <asm/dirty_vram.h>
 
 #include "private.h"
 
@@ -53,139 +54,6 @@
 #define page_to_mfn(_pg) _mfn(__page_to_mfn(_pg))
 
 /************************************************/
-/*          HAP VRAM TRACKING SUPPORT           */
-/************************************************/
-
-static int hap_enable_vram_tracking(struct domain *d)
-{
-    struct sh_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
-
-    if ( !dirty_vram )
-        return -EINVAL;
-
-    /* turn on PG_log_dirty bit in paging mode */
-    paging_lock(d);
-    d->arch.paging.mode |= PG_log_dirty;
-    paging_unlock(d);
-
-    /* set l1e entries of P2M table to be read-only. */
-    p2m_change_type_range(d, dirty_vram->begin_pfn, dirty_vram->end_pfn, 
-                          p2m_ram_rw, p2m_ram_logdirty);
-
-    flush_tlb_mask(d->domain_dirty_cpumask);
-    return 0;
-}
-
-static int hap_disable_vram_tracking(struct domain *d)
-{
-    struct sh_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
-
-    if ( !dirty_vram )
-        return -EINVAL;
-
-    paging_lock(d);
-    d->arch.paging.mode &= ~PG_log_dirty;
-    paging_unlock(d);
-
-    /* set l1e entries of P2M table with normal mode */
-    p2m_change_type_range(d, dirty_vram->begin_pfn, dirty_vram->end_pfn, 
-                          p2m_ram_logdirty, p2m_ram_rw);
-
-    flush_tlb_mask(d->domain_dirty_cpumask);
-    return 0;
-}
-
-static void hap_clean_vram_tracking(struct domain *d)
-{
-    struct sh_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
-
-    if ( !dirty_vram )
-        return;
-
-    /* set l1e entries of P2M table to be read-only. */
-    p2m_change_type_range(d, dirty_vram->begin_pfn, dirty_vram->end_pfn, 
-                          p2m_ram_rw, p2m_ram_logdirty);
-
-    flush_tlb_mask(d->domain_dirty_cpumask);
-}
-
-static void hap_vram_tracking_init(struct domain *d)
-{
-    paging_log_dirty_init(d, hap_enable_vram_tracking,
-                          hap_disable_vram_tracking,
-                          hap_clean_vram_tracking);
-}
-
-int hap_track_dirty_vram(struct domain *d,
-                         unsigned long begin_pfn,
-                         unsigned long nr,
-                         XEN_GUEST_HANDLE_64(uint8) dirty_bitmap)
-{
-    long rc = 0;
-    struct sh_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
-
-    if ( nr )
-    {
-        if ( paging_mode_log_dirty(d) && dirty_vram )
-        {
-            if ( begin_pfn != dirty_vram->begin_pfn ||
-                 begin_pfn + nr != dirty_vram->end_pfn )
-            {
-                paging_log_dirty_disable(d);
-                dirty_vram->begin_pfn = begin_pfn;
-                dirty_vram->end_pfn = begin_pfn + nr;
-                rc = paging_log_dirty_enable(d);
-                if (rc != 0)
-                    goto param_fail;
-            }
-        }
-        else if ( !paging_mode_log_dirty(d) && !dirty_vram )
-        {
-            rc = -ENOMEM;
-            if ( (dirty_vram = xmalloc(struct sh_dirty_vram)) == NULL )
-                goto param_fail;
-
-            dirty_vram->begin_pfn = begin_pfn;
-            dirty_vram->end_pfn = begin_pfn + nr;
-            d->arch.hvm_domain.dirty_vram = dirty_vram;
-            hap_vram_tracking_init(d);
-            rc = paging_log_dirty_enable(d);
-            if (rc != 0)
-                goto param_fail;
-        }
-        else
-        {
-            if ( !paging_mode_log_dirty(d) && dirty_vram )
-                rc = -EINVAL;
-            else
-                rc = -ENODATA;
-            goto param_fail;
-        }
-        /* get the bitmap */
-        rc = paging_log_dirty_range(d, begin_pfn, nr, dirty_bitmap);
-    }
-    else
-    {
-        if ( paging_mode_log_dirty(d) && dirty_vram ) {
-            rc = paging_log_dirty_disable(d);
-            xfree(dirty_vram);
-            dirty_vram = d->arch.hvm_domain.dirty_vram = NULL;
-        } else
-            rc = 0;
-    }
-
-    return rc;
-
-param_fail:
-    if ( dirty_vram )
-    {
-        xfree(dirty_vram);
-        dirty_vram = d->arch.hvm_domain.dirty_vram = NULL;
-    }
-    return rc;
-}
-
-/************************************************/
 /*            HAP LOG DIRTY SUPPORT             */
 /************************************************/
 
@@ -223,14 +91,12 @@ static void hap_clean_dirty_bitmap(struct domain *d)
 
 void hap_logdirty_init(struct domain *d)
 {
-    struct sh_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
+    struct dv_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
     if ( paging_mode_log_dirty(d) && dirty_vram )
     {
         paging_log_dirty_disable(d);
-        xfree(dirty_vram);
-        dirty_vram = d->arch.hvm_domain.dirty_vram = NULL;
+        dirty_vram_free(d);
     }
-
     /* Reinitialize logdirty mechanism */
     paging_log_dirty_init(d, hap_enable_log_dirty,
                           hap_disable_log_dirty,
diff --git a/xen/arch/x86/mm/paging.c b/xen/arch/x86/mm/paging.c
index ea44e39..5e76609 100644
--- a/xen/arch/x86/mm/paging.c
+++ b/xen/arch/x86/mm/paging.c
@@ -27,6 +27,7 @@
 #include <asm/p2m.h>
 #include <asm/hap.h>
 #include <asm/hvm/nestedhvm.h>
+#include <asm/dirty_vram.h>
 #include <xen/numa.h>
 #include <xsm/xsm.h>
 
@@ -278,6 +279,46 @@ out:
 }
 
 
+/* paging_mark_dirty_hap()
+ * Make a hap page writeable and mark it as dirty.
+ * This done atomically under the p2m and paging locks to avoid leaving
+ * a window where the page might be modified without being counted as dirty.
+ */
+void paging_mark_dirty_hap(struct domain *d,
+                           unsigned long pfn,
+                           unsigned long guest_mfn)
+{
+    mfn_t gmfn;
+    p2m_type_t pt;
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+    
+    if ( !paging_mode_log_dirty(d) )
+        return;
+
+    gmfn = _mfn(guest_mfn);
+
+    ASSERT( mfn_valid(gmfn) &&
+            page_get_owner(mfn_to_page(gmfn)) == d );
+
+    p2m_lock(p2m);
+    pt = p2m_change_type(d, pfn, p2m_ram_logdirty, p2m_ram_rw);
+    paging_lock(d);
+    if ( pt == p2m_ram_logdirty )
+    {
+        dv_range_t *range;
+        PAGING_DEBUG(LOGDIRTY,
+                     "marked mfn %" PRI_mfn " (pfn=%lx), dom %d\n",
+                     mfn_x(gmfn), pfn, d->domain_id);
+        d->arch.paging.log_dirty.dirty_count++;
+        range = dirty_vram_range_find_gfn(d, pfn);
+        if ( range )
+            range->dirty_count++;
+    }
+    paging_mark_dirty(d, guest_mfn); 
+    paging_unlock(d);
+    p2m_unlock(p2m);
+}
+
 /* Is this guest page dirty? */
 int paging_mfn_is_dirty(struct domain *d, mfn_t gmfn)
 {
@@ -333,8 +374,11 @@ int paging_log_dirty_op(struct domain *d, struct 
xen_domctl_shadow_op *sc)
     mfn_t *l4, *l3, *l2;
     unsigned long *l1;
     int i4, i3, i2;
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
 
     domain_pause(d);
+    /* Locking hierarchy requires p2m lock to be taken first */
+    p2m_lock(p2m);
     paging_lock(d);
 
     clean = (sc->op == XEN_DOMCTL_SHADOW_OP_CLEAN);
@@ -345,6 +389,14 @@ int paging_log_dirty_op(struct domain *d, struct 
xen_domctl_shadow_op *sc)
                  d->arch.paging.log_dirty.fault_count,
                  d->arch.paging.log_dirty.dirty_count);
 
+    if ( hap_enabled(d) && d->arch.hvm_domain.dirty_vram )
+    {
+        /* If we're cleaning/peeking all guest memory, we should not be 
tracking
+         * dirty vram. */
+        rv = -EINVAL;
+        goto out;
+    }
+
     sc->stats.fault_count = d->arch.paging.log_dirty.fault_count;
     sc->stats.dirty_count = d->arch.paging.log_dirty.dirty_count;
 
@@ -424,170 +476,64 @@ int paging_log_dirty_op(struct domain *d, struct 
xen_domctl_shadow_op *sc)
 
     if ( clean )
     {
-        /* We need to further call clean_dirty_bitmap() functions of specific
-         * paging modes (shadow or hap).  Safe because the domain is paused. */
-        d->arch.paging.log_dirty.clean_dirty_bitmap(d);
+        /* Is null if tracking dirty vram */
+        if ( d->arch.paging.log_dirty.clean_dirty_bitmap )
+        {
+            /*
+             * We need to call clean_dirty_bitmap() functions of specific
+             * paging modes (shadow or hap).
+             * Safe because the domain is paused.
+             */
+            d->arch.paging.log_dirty.clean_dirty_bitmap(d);
+        }
     }
     domain_unpause(d);
     return rv;
 
  out:
     paging_unlock(d);
+    p2m_unlock(p2m);
     domain_unpause(d);
     return rv;
 }
 
-int paging_log_dirty_range(struct domain *d,
-                            unsigned long begin_pfn,
-                            unsigned long nr,
-                            XEN_GUEST_HANDLE_64(uint8) dirty_bitmap)
+void paging_log_dirty_range(struct domain *d,
+                           unsigned long begin_pfn,
+                           unsigned long nr,
+                           uint8_t *dirty_bitmap)
 {
-    int rv = 0;
-    unsigned long pages = 0;
-    mfn_t *l4, *l3, *l2;
-    unsigned long *l1;
-    int b1, b2, b3, b4;
-    int i2, i3, i4;
-
-    d->arch.paging.log_dirty.clean_dirty_bitmap(d);
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+    dv_range_t *range;
+    unsigned int range_dirty_count = 0;
+    
+    p2m_lock(p2m);
     paging_lock(d);
 
-    PAGING_DEBUG(LOGDIRTY, "log-dirty-range: dom %u faults=%u dirty=%u\n",
-                 d->domain_id,
-                 d->arch.paging.log_dirty.fault_count,
-                 d->arch.paging.log_dirty.dirty_count);
-
-    if ( unlikely(d->arch.paging.log_dirty.failed_allocs) ) {
-        printk("%s: %d failed page allocs while logging dirty pages\n",
-               __FUNCTION__, d->arch.paging.log_dirty.failed_allocs);
-        rv = -ENOMEM;
-        goto out;
-    }
-
-    if ( !d->arch.paging.log_dirty.fault_count &&
-         !d->arch.paging.log_dirty.dirty_count ) {
-        unsigned int size = BITS_TO_LONGS(nr);
-
-        if ( clear_guest(dirty_bitmap, size * BYTES_PER_LONG) != 0 )
-            rv = -EFAULT;
-        goto out;
-    }
-    d->arch.paging.log_dirty.fault_count = 0;
-    d->arch.paging.log_dirty.dirty_count = 0;
-
-    b1 = L1_LOGDIRTY_IDX(begin_pfn);
-    b2 = L2_LOGDIRTY_IDX(begin_pfn);
-    b3 = L3_LOGDIRTY_IDX(begin_pfn);
-    b4 = L4_LOGDIRTY_IDX(begin_pfn);
-    l4 = paging_map_log_dirty_bitmap(d);
-
-    for ( i4 = b4;
-          (pages < nr) && (i4 < LOGDIRTY_NODE_ENTRIES);
-          i4++ )
+    /* Only called when tracking dirty vram in HAP mode */
+    ASSERT(hap_enabled(d) && d->arch.hvm_domain.dirty_vram);
+    
+    range = dirty_vram_range_find_gfn(d, begin_pfn);
+    if ( range )
     {
-        l3 = (l4 && mfn_valid(l4[i4])) ? map_domain_page(mfn_x(l4[i4])) : NULL;
-        for ( i3 = b3;
-              (pages < nr) && (i3 < LOGDIRTY_NODE_ENTRIES);
-              i3++ )
-        {
-            l2 = ((l3 && mfn_valid(l3[i3])) ?
-                  map_domain_page(mfn_x(l3[i3])) : NULL);
-            for ( i2 = b2;
-                  (pages < nr) && (i2 < LOGDIRTY_NODE_ENTRIES);
-                  i2++ )
-            {
-                unsigned int bytes = PAGE_SIZE;
-                uint8_t *s;
-                l1 = ((l2 && mfn_valid(l2[i2])) ?
-                      map_domain_page(mfn_x(l2[i2])) : NULL);
-
-                s = ((uint8_t*)l1) + (b1 >> 3);
-                bytes -= b1 >> 3;
-
-                if ( likely(((nr - pages + 7) >> 3) < bytes) )
-                    bytes = (unsigned int)((nr - pages + 7) >> 3);
-
-                if ( !l1 )
-                {
-                    if ( clear_guest_offset(dirty_bitmap, pages >> 3,
-                                            bytes) != 0 )
-                    {
-                        rv = -EFAULT;
-                        goto out;
-                    }
-                }
-                /* begin_pfn is not 32K aligned, hence we have to bit
-                 * shift the bitmap */
-                else if ( b1 & 0x7 )
-                {
-                    int i, j;
-                    uint32_t *l = (uint32_t*) s;
-                    int bits = b1 & 0x7;
-                    int bitmask = (1 << bits) - 1;
-                    int size = (bytes + BYTES_PER_LONG - 1) / BYTES_PER_LONG;
-                    unsigned long bitmap[size];
-                    static unsigned long printed = 0;
-
-                    if ( printed != begin_pfn )
-                    {
-                        dprintk(XENLOG_DEBUG, "%s: begin_pfn %lx is not 32K 
aligned!\n",
-                                __FUNCTION__, begin_pfn);
-                        printed = begin_pfn;
-                    }
-
-                    for ( i = 0; i < size - 1; i++, l++ ) {
-                        bitmap[i] = ((*l) >> bits) |
-                            (((*((uint8_t*)(l + 1))) & bitmask) << (sizeof(*l) 
* 8 - bits));
-                    }
-                    s = (uint8_t*) l;
-                    size = BYTES_PER_LONG - ((b1 >> 3) & 0x3);
-                    bitmap[i] = 0;
-                    for ( j = 0; j < size; j++, s++ )
-                        bitmap[i] |= (*s) << (j * 8);
-                    bitmap[i] = (bitmap[i] >> bits) | (bitmask << (size * 8 - 
bits));
-                    if ( copy_to_guest_offset(dirty_bitmap, (pages >> 3),
-                                (uint8_t*) bitmap, bytes) != 0 )
-                    {
-                        rv = -EFAULT;
-                        goto out;
-                    }
-                }
-                else
-                {
-                    if ( copy_to_guest_offset(dirty_bitmap, pages >> 3,
-                                              s, bytes) != 0 )
-                    {
-                        rv = -EFAULT;
-                        goto out;
-                    }
-                }
-
-                pages += bytes << 3;
-                if ( l1 )
-                {
-                    clear_page(l1);
-                    unmap_domain_page(l1);
-                }
-                b1 = b1 & 0x7;
-            }
-            b2 = 0;
-            if ( l2 )
-                unmap_domain_page(l2);
-        }
-        b3 = 0;
-        if ( l3 )
-            unmap_domain_page(l3);
+        range_dirty_count = range->dirty_count;
+        range->dirty_count = 0;
     }
-    if ( l4 )
-        unmap_domain_page(l4);
-
-    paging_unlock(d);
+    
+    if ( !range_dirty_count)
+        goto out;
 
-    return rv;
+    PAGING_DEBUG(LOGDIRTY,
+                 "log-dirty-range: dom %u [%05lx:%05lx] range_dirty=%u\n",
+                 d->domain_id,
+                 begin_pfn,
+                 range->end_pfn,
+                 range_dirty_count);
 
+    hap_clean_vram_tracking_range(d, begin_pfn, nr, dirty_bitmap);
  out:
     paging_unlock(d);
-    return rv;
+    p2m_unlock(p2m);
+    return;
 }
 
 /* Note that this function takes three function pointers. Callers must supply
diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index ce79131..4e40f43 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -36,6 +36,7 @@
 #include <asm/current.h>
 #include <asm/flushtlb.h>
 #include <asm/shadow.h>
+#include <asm/dirty_vram.h>
 #include <xen/numa.h>
 #include "private.h"
 
@@ -3121,12 +3122,7 @@ void shadow_teardown(struct domain *d)
      * calls now that we've torn down the bitmap */
     d->arch.paging.mode &= ~PG_log_dirty;
 
-    if (d->arch.hvm_domain.dirty_vram) {
-        xfree(d->arch.hvm_domain.dirty_vram->sl1ma);
-        xfree(d->arch.hvm_domain.dirty_vram->dirty_bitmap);
-        xfree(d->arch.hvm_domain.dirty_vram);
-        d->arch.hvm_domain.dirty_vram = NULL;
-    }
+    dirty_vram_free(d);
 
     paging_unlock(d);
 
@@ -3463,179 +3459,212 @@ void shadow_clean_dirty_bitmap(struct domain *d)
 
 
 /**************************************************************************/
-/* VRAM dirty tracking support */
-int shadow_track_dirty_vram(struct domain *d,
-                            unsigned long begin_pfn,
-                            unsigned long nr,
-                            XEN_GUEST_HANDLE_64(uint8) dirty_bitmap)
-{
-    int rc;
-    unsigned long end_pfn = begin_pfn + nr;
-    unsigned long dirty_size = (nr + 7) / 8;
-    int flush_tlb = 0;
-    unsigned long i;
-    p2m_type_t t;
-    struct sh_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
-    struct p2m_domain *p2m = p2m_get_hostp2m(d);
-
-    if (end_pfn < begin_pfn
-            || begin_pfn > p2m->max_mapped_pfn
-            || end_pfn >= p2m->max_mapped_pfn)
-        return -EINVAL;
-
-    /* We perform p2m lookups, so lock the p2m upfront to avoid deadlock */
-    p2m_lock(p2m_get_hostp2m(d));
-    paging_lock(d);
+/* Support functions for shadow-based dirty VRAM code */
 
-    if ( dirty_vram && (!nr ||
-             ( begin_pfn != dirty_vram->begin_pfn
-            || end_pfn   != dirty_vram->end_pfn )) )
-    {
-        /* Different tracking, tear the previous down. */
-        gdprintk(XENLOG_INFO, "stopping tracking VRAM %lx - %lx\n", 
dirty_vram->begin_pfn, dirty_vram->end_pfn);
-        xfree(dirty_vram->sl1ma);
-        xfree(dirty_vram->dirty_bitmap);
-        xfree(dirty_vram);
-        dirty_vram = d->arch.hvm_domain.dirty_vram = NULL;
-    }
+#define DEBUG_unshadow_sl1ma                  0          
+#define DEBUG_unshadow_sl1ma_detail           0
+#define DEBUG_count_initial_mappings          1
 
-    if ( !nr )
+/* smfn is no longer a shadow page.  Remove it from any
+ * dirty vram range mapping. */
+void
+dirty_vram_delete_shadow(struct vcpu *v,
+                         unsigned long gfn,
+                         unsigned int shadow_type, 
+                         mfn_t smfn)
+{
+    static unsigned int l1_shadow_mask = 
+          1 << SH_type_l1_32_shadow
+        | 1 << SH_type_fl1_32_shadow
+        | 1 << SH_type_l1_pae_shadow
+        | 1 << SH_type_fl1_pae_shadow
+        | 1 << SH_type_l1_64_shadow
+        | 1 << SH_type_fl1_64_shadow
+        ;
+    struct domain *d = v->domain;
+    dv_dirty_vram_t *dirty_vram;
+    struct list_head *curr, *next;
+    
+    ASSERT(paging_locked_by_me(d));
+    /* Ignore all but level 1 shadows */
+    
+    if ( (l1_shadow_mask & (1 << shadow_type)) == 0 )
     {
-        rc = 0;
         goto out;
     }
 
-    /* This should happen seldomly (Video mode change),
-     * no need to be careful. */
+    dirty_vram = d->arch.hvm_domain.dirty_vram;
     if ( !dirty_vram )
     {
-        /* Throw away all the shadows rather than walking through them 
-         * up to nr times getting rid of mappings of each pfn */
-        shadow_blow_tables(d);
-
-        gdprintk(XENLOG_INFO, "tracking VRAM %lx - %lx\n", begin_pfn, end_pfn);
-
-        rc = -ENOMEM;
-        if ( (dirty_vram = xmalloc(struct sh_dirty_vram)) == NULL )
-            goto out;
-        dirty_vram->begin_pfn = begin_pfn;
-        dirty_vram->end_pfn = end_pfn;
-        d->arch.hvm_domain.dirty_vram = dirty_vram;
-
-        if ( (dirty_vram->sl1ma = xmalloc_array(paddr_t, nr)) == NULL )
-            goto out_dirty_vram;
-        memset(dirty_vram->sl1ma, ~0, sizeof(paddr_t) * nr);
-
-        if ( (dirty_vram->dirty_bitmap = xzalloc_array(uint8_t, dirty_size)) 
== NULL )
-            goto out_sl1ma;
-
-        dirty_vram->last_dirty = NOW();
-
-        /* Tell the caller that this time we could not track dirty bits. */
-        rc = -ENODATA;
-    }
-    else if (dirty_vram->last_dirty == -1)
-    {
-        /* still completely clean, just copy our empty bitmap */
-        rc = -EFAULT;
-        if ( copy_to_guest(dirty_bitmap, dirty_vram->dirty_bitmap, dirty_size) 
== 0 )
-            rc = 0;
+        goto out;
     }
-    else
+        
+    list_for_each_safe(curr, next, &dirty_vram->range_head)
     {
-        /* Iterate over VRAM to track dirty bits. */
-        for ( i = 0; i < nr; i++ ) {
-            mfn_t mfn = get_gfn_query_unlocked(d, begin_pfn + i, &t);
-            struct page_info *page;
-            int dirty = 0;
-            paddr_t sl1ma = dirty_vram->sl1ma[i];
-
-            if (mfn_x(mfn) == INVALID_MFN)
-            {
-                dirty = 1;
-            }
-            else
+        dv_range_t *range = list_entry(curr, dv_range_t, range_link);
+        unsigned long i;
+        int max_mappings = 1, mappings = 0;
+        int unshadowed = 0;
+        for ( i = 0; i != range->end_pfn - range->begin_pfn; i++ )
+        {
+            dv_paddr_link_t *pl = &range->pl_tab[ i ];
+            dv_paddr_link_t **ppl = NULL;
+            mappings = 0;
+            
+            while ( pl != NULL )
             {
-                page = mfn_to_page(mfn);
-                switch (page->u.inuse.type_info & PGT_count_mask)
-                {
-                case 0:
-                    /* No guest reference, nothing to track. */
-                    break;
-                case 1:
-                    /* One guest reference. */
-                    if ( sl1ma == INVALID_PADDR )
-                    {
-                        /* We don't know which sl1e points to this, too bad. */
-                        dirty = 1;
-                        /* TODO: Heuristics for finding the single mapping of
-                         * this gmfn */
-                        flush_tlb |= sh_remove_all_mappings(d->vcpu[0], mfn);
-                    }
-                    else
-                    {
-                        /* Hopefully the most common case: only one mapping,
-                         * whose dirty bit we can use. */
-                        l1_pgentry_t *sl1e = maddr_to_virt(sl1ma);
-
-                        if ( l1e_get_flags(*sl1e) & _PAGE_DIRTY )
-                        {
-                            dirty = 1;
-                            /* Note: this is atomic, so we may clear a
-                             * _PAGE_ACCESSED set by another processor. */
-                            l1e_remove_flags(*sl1e, _PAGE_DIRTY);
-                            flush_tlb = 1;
-                        }
-                    }
-                    break;
-                default:
-                    /* More than one guest reference,
-                     * we don't afford tracking that. */
-                    dirty = 1;
+                paddr_t sl1ma = pl->sl1ma;
+                unsigned long sl1mn;
+                
+                if ( sl1ma == INVALID_PADDR )
                     break;
+                
+                sl1mn = sl1ma >> PAGE_SHIFT;
+                if ( sl1mn == mfn_x(smfn) ) {
+#if DEBUG_unshadow_sl1ma_detail
+                    gdprintk(XENLOG_DEBUG,
+                             "[%lx] gfn[%lx] unshadow sl1ma:%lx\n",
+                             mfn_x(smfn),
+                             range->begin_pfn + i,
+                             sl1ma);
+#endif
+                    unshadowed++;
+                    pl = free_paddr_link(d, ppl, pl);
+                    --range->nr_mappings;
+                }
+                else
+                {
+                    ppl = &pl->pl_next;
+                    pl = *ppl;
+                    mappings++;
                 }
             }
-
-            if ( dirty )
+        }
+        if ( mappings > max_mappings )
+            max_mappings = mappings;
+        
+        if ( unshadowed ) {
+#if DEBUG_unshadow_sl1ma
+            gdprintk(XENLOG_DEBUG,
+                     "[%lx] gfn[%05lx:%05lx] unshadowed:%d mappings:0x%x 
max_mappings:%d\n",
+                     mfn_x(smfn),
+                     range->begin_pfn, range->end_pfn,
+                     unshadowed, range->nr_mappings, max_mappings);
+#endif
+            if ( range->nr_mappings == 0 )
             {
-                dirty_vram->dirty_bitmap[i / 8] |= 1 << (i % 8);
-                dirty_vram->last_dirty = NOW();
+                dirty_vram_range_free(d, range);                    
             }
         }
+    }
+ out:
+    return;
+}
+
+
+typedef int (*hash_pfn_callback_t)(struct vcpu *v,
+                                   mfn_t smfn,
+                                   unsigned long begin_pfn,
+                                   unsigned long end_pfn,
+                                   int *removed);
+
+static int hash_pfn_foreach(struct vcpu *v, 
+                            unsigned int callback_mask, 
+                            hash_pfn_callback_t callbacks[], 
+                            unsigned long begin_pfn,
+                            unsigned long end_pfn)
+/* Walk the hash table looking at the types of the entries and 
+ * calling the appropriate callback function for each entry. 
+ * The mask determines which shadow types we call back for, and the array
+ * of callbacks tells us which function to call.
+ * Any callback may return non-zero to let us skip the rest of the scan. 
+ *
+ * WARNING: Callbacks MUST NOT add or remove hash entries unless they 
+ * then return non-zero to terminate the scan. */
+{
+    int i, done = 0, removed = 0;
+    struct domain *d = v->domain;
+    struct page_info *x;
+
+    /* Say we're here, to stop hash-lookups reordering the chains */
+    ASSERT(paging_locked_by_me(d));
+    ASSERT(d->arch.paging.shadow.hash_walking == 0);
+    d->arch.paging.shadow.hash_walking = 1;
 
-        rc = -EFAULT;
-        if ( copy_to_guest(dirty_bitmap, dirty_vram->dirty_bitmap, dirty_size) 
== 0 ) {
-            memset(dirty_vram->dirty_bitmap, 0, dirty_size);
-            if (dirty_vram->last_dirty + SECONDS(2) < NOW())
+    for ( i = 0; i < SHADOW_HASH_BUCKETS; i++ ) 
+    {
+        /* WARNING: This is not safe against changes to the hash table.
+         * The callback *must* return non-zero if it has inserted or
+         * deleted anything from the hash (lookups are OK, though). */
+        for ( x = d->arch.paging.shadow.hash_table[i]; x; x = next_shadow(x) )
+        {
+            if ( callback_mask & (1 << x->u.sh.type) )
             {
-                /* was clean for more than two seconds, try to disable guest
-                 * write access */
-                for ( i = begin_pfn; i < end_pfn; i++ ) {
-                    mfn_t mfn = get_gfn_query_unlocked(d, i, &t);
-                    if (mfn_x(mfn) != INVALID_MFN)
-                        flush_tlb |= sh_remove_write_access(d->vcpu[0], mfn, 
1, 0);
-                }
-                dirty_vram->last_dirty = -1;
+                ASSERT(x->u.sh.type <= 15);
+                ASSERT(callbacks[x->u.sh.type] != NULL);
+                done = callbacks[x->u.sh.type](v, page_to_mfn(x), 
+                                               begin_pfn, end_pfn,
+                                               &removed);
+                if ( done ) break;
             }
-            rc = 0;
         }
+        if ( done ) break; 
     }
-    if ( flush_tlb )
-        flush_tlb_mask(d->domain_dirty_cpumask);
-    goto out;
+    d->arch.paging.shadow.hash_walking = 0;
+    return removed;
+}
 
-out_sl1ma:
-    xfree(dirty_vram->sl1ma);
-out_dirty_vram:
-    xfree(dirty_vram);
-    dirty_vram = d->arch.hvm_domain.dirty_vram = NULL;
+void sh_find_all_vram_mappings(struct vcpu *v,
+                               dv_range_t *range)
+{
+    /* Dispatch table for getting per-type functions */
+    static hash_pfn_callback_t callbacks[SH_type_unused] = {
+        NULL, /* none    */
+        SHADOW_INTERNAL_NAME(sh_find_vram_mappings_in_l1, 2), /* l1_32   */
+        SHADOW_INTERNAL_NAME(sh_find_vram_mappings_in_l1, 2), /* fl1_32  */
+        NULL, /* l2_32   */
+        SHADOW_INTERNAL_NAME(sh_find_vram_mappings_in_l1, 3), /* l1_pae  */
+        SHADOW_INTERNAL_NAME(sh_find_vram_mappings_in_l1, 3), /* fl1_pae */
+        NULL, /* l2_pae  */
+        NULL, /* l2h_pae */
+#if CONFIG_PAGING_LEVELS >= 4
+        SHADOW_INTERNAL_NAME(sh_find_vram_mappings_in_l1, 4), /* l1_64   */
+        SHADOW_INTERNAL_NAME(sh_find_vram_mappings_in_l1, 4), /* fl1_64  */
+#else
+        NULL, /* l1_64   */
+        NULL, /* fl1_64  */
+#endif
+        NULL, /* l2_64   */
+        NULL, /* l2h_64  */
+        NULL, /* l3_64   */
+        NULL, /* l4_64   */
+        NULL, /* p2m     */
+        NULL  /* unused  */
+    };
 
-out:
-    paging_unlock(d);
-    p2m_unlock(p2m_get_hostp2m(d));
-    return rc;
+    static unsigned int callback_mask = 
+          1 << SH_type_l1_32_shadow
+        | 1 << SH_type_fl1_32_shadow
+        | 1 << SH_type_l1_pae_shadow
+        | 1 << SH_type_fl1_pae_shadow
+        | 1 << SH_type_l1_64_shadow
+        | 1 << SH_type_fl1_64_shadow
+        ;
+
+    perfc_incr(shadow_mappings);
+
+    hash_pfn_foreach(v, callback_mask, callbacks,
+                     range->begin_pfn,
+                     range->end_pfn);
+
+#if DEBUG_count_initial_mappings
+    gdprintk(XENLOG_DEBUG, "[%05lx:%05lx] count of initial mappings:%d\n",
+             range->begin_pfn, range->end_pfn,
+             range->nr_mappings);
+#endif
 }
 
+
 /**************************************************************************/
 /* Shadow-control XEN_DOMCTL dispatcher */
 
diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c
index b0e6d72..9c00574 100644
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -35,6 +35,7 @@
 #include <asm/flushtlb.h>
 #include <asm/hvm/hvm.h>
 #include <asm/hvm/cacheattr.h>
+#include <asm/dirty_vram.h>
 #include <asm/mtrr.h>
 #include <asm/guest_pt.h>
 #include <public/sched.h>
@@ -149,6 +150,10 @@ delete_fl1_shadow_status(struct vcpu *v, gfn_t gfn, mfn_t 
smfn)
     SHADOW_PRINTK("gfn=%"SH_PRI_gfn", type=%08x, smfn=%05lx\n",
                    gfn_x(gfn), SH_type_fl1_shadow, mfn_x(smfn));
     ASSERT(mfn_to_page(smfn)->u.sh.head);
+
+    /* Removing any dv_paddr_links to the erstwhile shadow page */
+    dirty_vram_delete_shadow(v, gfn_x(gfn), SH_type_fl1_shadow, smfn);
+    
     shadow_hash_delete(v, gfn_x(gfn), SH_type_fl1_shadow, smfn);
 }
 
@@ -160,6 +165,10 @@ delete_shadow_status(struct vcpu *v, mfn_t gmfn, u32 
shadow_type, mfn_t smfn)
                    v->domain->domain_id, v->vcpu_id,
                    mfn_x(gmfn), shadow_type, mfn_x(smfn));
     ASSERT(mfn_to_page(smfn)->u.sh.head);
+    
+    /* Removing any dv_paddr_links to the erstwhile shadow page */
+    dirty_vram_delete_shadow(v, mfn_x(gmfn), shadow_type, smfn);
+    
     shadow_hash_delete(v, mfn_x(gmfn), shadow_type, smfn);
     /* 32-on-64 PV guests don't own their l4 pages; see set_shadow_status */
     if ( !is_pv_32on64_vcpu(v) || shadow_type != SH_type_l4_64_shadow )
@@ -516,7 +525,6 @@ _sh_propagate(struct vcpu *v,
     guest_l1e_t guest_entry = { guest_intpte };
     shadow_l1e_t *sp = shadow_entry_ptr;
     struct domain *d = v->domain;
-    struct sh_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
     gfn_t target_gfn = guest_l1e_get_gfn(guest_entry);
     u32 pass_thru_flags;
     u32 gflags, sflags;
@@ -663,17 +671,6 @@ _sh_propagate(struct vcpu *v,
         }
     }
 
-    if ( unlikely((level == 1) && dirty_vram
-            && dirty_vram->last_dirty == -1
-            && gfn_x(target_gfn) >= dirty_vram->begin_pfn
-            && gfn_x(target_gfn) < dirty_vram->end_pfn) )
-    {
-        if ( ft & FETCH_TYPE_WRITE )
-            dirty_vram->last_dirty = NOW();
-        else
-            sflags &= ~_PAGE_RW;
-    }
-
     /* Read-only memory */
     if ( p2m_is_readonly(p2mt) ||
          (p2mt == p2m_mmio_direct &&
@@ -1072,101 +1069,60 @@ static int shadow_set_l2e(struct vcpu *v,
     return flags;
 }
 
-static inline void shadow_vram_get_l1e(shadow_l1e_t new_sl1e,
+/* shadow_vram_fix_l1e()
+ *
+ * Tests L1PTEs as they are modified, looking for when they start to
+ * (or cease to) point to frame buffer pages.  If the old and new gfns differ,
+ * calls dirty_vram_range_update() to updates the dirty_vram structures.
+ */
+static inline void shadow_vram_fix_l1e(shadow_l1e_t old_sl1e,
+                                       shadow_l1e_t new_sl1e,
                                        shadow_l1e_t *sl1e,
                                        mfn_t sl1mfn,
                                        struct domain *d)
 { 
-    mfn_t mfn = shadow_l1e_get_mfn(new_sl1e);
-    int flags = shadow_l1e_get_flags(new_sl1e);
-    unsigned long gfn;
-    struct sh_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
+    mfn_t new_mfn, old_mfn;
+    unsigned long new_gfn = INVALID_M2P_ENTRY, old_gfn = INVALID_M2P_ENTRY;
+    paddr_t sl1ma;
+    dv_dirty_vram_t *dirty_vram = d->arch.hvm_domain.dirty_vram;
 
-    if ( !dirty_vram         /* tracking disabled? */
-         || !(flags & _PAGE_RW) /* read-only mapping? */
-         || !mfn_valid(mfn) )   /* mfn can be invalid in mmio_direct */
+    if ( !dirty_vram )
         return;
 
-    gfn = mfn_to_gfn(d, mfn);
-    /* Page sharing not supported on shadow PTs */
-    BUG_ON(SHARED_M2P(gfn));
+    sl1ma = pfn_to_paddr(mfn_x(sl1mfn)) | ((unsigned long)sl1e & ~PAGE_MASK);
 
-    if ( (gfn >= dirty_vram->begin_pfn) && (gfn < dirty_vram->end_pfn) )
+    old_mfn = shadow_l1e_get_mfn(old_sl1e);
+
+    if ( !sh_l1e_is_magic(old_sl1e) &&
+         (l1e_get_flags(old_sl1e) & _PAGE_PRESENT) &&
+         mfn_valid(old_mfn))
     {
-        unsigned long i = gfn - dirty_vram->begin_pfn;
-        struct page_info *page = mfn_to_page(mfn);
-        
-        if ( (page->u.inuse.type_info & PGT_count_mask) == 1 )
-            /* Initial guest reference, record it */
-            dirty_vram->sl1ma[i] = pfn_to_paddr(mfn_x(sl1mfn))
-                | ((unsigned long)sl1e & ~PAGE_MASK);
+        old_gfn = mfn_to_gfn(d, old_mfn);
     }
-}
-
-static inline void shadow_vram_put_l1e(shadow_l1e_t old_sl1e,
-                                       shadow_l1e_t *sl1e,
-                                       mfn_t sl1mfn,
-                                       struct domain *d)
-{
-    mfn_t mfn = shadow_l1e_get_mfn(old_sl1e);
-    int flags = shadow_l1e_get_flags(old_sl1e);
-    unsigned long gfn;
-    struct sh_dirty_vram *dirty_vram = d->arch.hvm_domain.dirty_vram;
-
-    if ( !dirty_vram         /* tracking disabled? */
-         || !(flags & _PAGE_RW) /* read-only mapping? */
-         || !mfn_valid(mfn) )   /* mfn can be invalid in mmio_direct */
-        return;
-
-    gfn = mfn_to_gfn(d, mfn);
-    /* Page sharing not supported on shadow PTs */
-    BUG_ON(SHARED_M2P(gfn));
-
-    if ( (gfn >= dirty_vram->begin_pfn) && (gfn < dirty_vram->end_pfn) )
+    
+    new_mfn = shadow_l1e_get_mfn(new_sl1e);
+    if ( !sh_l1e_is_magic(new_sl1e) &&
+         (l1e_get_flags(new_sl1e) & _PAGE_PRESENT) &&
+         mfn_valid(new_mfn))
     {
-        unsigned long i = gfn - dirty_vram->begin_pfn;
-        struct page_info *page = mfn_to_page(mfn);
-        int dirty = 0;
-        paddr_t sl1ma = pfn_to_paddr(mfn_x(sl1mfn))
-            | ((unsigned long)sl1e & ~PAGE_MASK);
+        new_gfn = mfn_to_gfn(d, new_mfn);
+    }
 
-        if ( (page->u.inuse.type_info & PGT_count_mask) == 1 )
-        {
-            /* Last reference */
-            if ( dirty_vram->sl1ma[i] == INVALID_PADDR ) {
-                /* We didn't know it was that one, let's say it is dirty */
-                dirty = 1;
-            }
-            else
-            {
-                ASSERT(dirty_vram->sl1ma[i] == sl1ma);
-                dirty_vram->sl1ma[i] = INVALID_PADDR;
-                if ( flags & _PAGE_DIRTY )
-                    dirty = 1;
-            }
-        }
-        else
+    if ( old_gfn == new_gfn ) return;
+
+    if ( VALID_M2P(old_gfn) )
+        if ( dirty_vram_range_update(d, old_gfn, sl1ma, 0/*clear*/) )
         {
-            /* We had more than one reference, just consider the page dirty. */
-            dirty = 1;
-            /* Check that it's not the one we recorded. */
-            if ( dirty_vram->sl1ma[i] == sl1ma )
-            {
-                /* Too bad, we remembered the wrong one... */
-                dirty_vram->sl1ma[i] = INVALID_PADDR;
-            }
-            else
-            {
-                /* Ok, our recorded sl1e is still pointing to this page, let's
-                 * just hope it will remain. */
-            }
+            SHADOW_PRINTK("gfn %lx (mfn %lx) cleared vram pte\n",
+                          old_gfn, mfn_x(old_mfn));
         }
-        if ( dirty )
+
+    if ( VALID_M2P(new_gfn) )
+        if ( dirty_vram_range_update(d, new_gfn, sl1ma, 1/*set*/) )
         {
-            dirty_vram->dirty_bitmap[i / 8] |= 1 << (i % 8);
-            dirty_vram->last_dirty = NOW();
+            SHADOW_PRINTK("gfn %lx (mfn %lx) set vram pte\n",
+                          new_gfn, mfn_x(new_mfn));
         }
-    }
 }
 
 static int shadow_set_l1e(struct vcpu *v, 
@@ -1211,12 +1167,13 @@ static int shadow_set_l1e(struct vcpu *v,
                 shadow_l1e_remove_flags(new_sl1e, _PAGE_RW);
                 /* fall through */
             case 0:
-                shadow_vram_get_l1e(new_sl1e, sl1e, sl1mfn, d);
                 break;
             }
         }
     } 
 
+    shadow_vram_fix_l1e(old_sl1e, new_sl1e, sl1e, sl1mfn, d);
+
     /* Write the new entry */
     shadow_write_entries(sl1e, &new_sl1e, 1, sl1mfn);
     flags |= SHADOW_SET_CHANGED;
@@ -1231,7 +1188,6 @@ static int shadow_set_l1e(struct vcpu *v,
          * trigger a flush later. */
         if ( shadow_mode_refcounts(d) ) 
         {
-            shadow_vram_put_l1e(old_sl1e, sl1e, sl1mfn, d);
             shadow_put_page_from_l1e(old_sl1e, d);
             TRACE_SHADOW_PATH_FLAG(TRCE_SFLAG_SHADOW_L1_PUT_REF);
         } 
@@ -2018,7 +1974,6 @@ void sh_destroy_l1_shadow(struct vcpu *v, mfn_t smfn)
         SHADOW_FOREACH_L1E(sl1mfn, sl1e, 0, 0, {
             if ( (shadow_l1e_get_flags(*sl1e) & _PAGE_PRESENT)
                  && !sh_l1e_is_magic(*sl1e) ) {
-                shadow_vram_put_l1e(*sl1e, sl1e, sl1mfn, d);
                 shadow_put_page_from_l1e(*sl1e, d);
             }
         });
@@ -4336,6 +4291,37 @@ int sh_rm_mappings_from_l1(struct vcpu *v, mfn_t sl1mfn, 
mfn_t target_mfn)
     return done;
 }
 
+
+int sh_find_vram_mappings_in_l1(struct vcpu *v,
+                                mfn_t sl1mfn,
+                                unsigned long begin_pfn,
+                                unsigned long end_pfn,
+                                int *removed)
+/* Find all VRAM mappings in this shadow l1 table */
+{
+    struct domain *d = v->domain;
+    shadow_l1e_t *sl1e;
+    int done = 0;
+
+    /* only returns _PAGE_PRESENT entries */
+    SHADOW_FOREACH_L1E(sl1mfn, sl1e, 0, done, 
+    {
+        unsigned long gfn;
+        mfn_t gmfn = shadow_l1e_get_mfn(*sl1e);
+        if ( !mfn_valid(gmfn) )
+            continue;
+        gfn = mfn_to_gfn(d, gmfn);
+        if ( VALID_M2P(gfn) && (begin_pfn <= gfn) && (gfn < end_pfn) ) 
+        {
+            paddr_t sl1ma =
+                pfn_to_paddr(mfn_x(sl1mfn)) |
+                ( (unsigned long)sl1e & ~PAGE_MASK );
+            dirty_vram_range_update(v->domain, gfn, sl1ma, 1/*set*/);
+        }
+    });
+    return 0;
+}
+
 /**************************************************************************/
 /* Functions to excise all pointers to shadows from higher-level shadows. */
 
diff --git a/xen/arch/x86/mm/shadow/multi.h b/xen/arch/x86/mm/shadow/multi.h
index 835121e..436a4ac 100644
--- a/xen/arch/x86/mm/shadow/multi.h
+++ b/xen/arch/x86/mm/shadow/multi.h
@@ -66,7 +66,12 @@ SHADOW_INTERNAL_NAME(sh_rm_write_access_from_l1, 
GUEST_LEVELS)
 extern int
 SHADOW_INTERNAL_NAME(sh_rm_mappings_from_l1, GUEST_LEVELS)
     (struct vcpu *v, mfn_t sl1mfn, mfn_t target_mfn);
-
+extern int
+SHADOW_INTERNAL_NAME(sh_find_vram_mappings_in_l1, GUEST_LEVELS)
+     (struct vcpu *v, mfn_t sl1mfn, 
+      unsigned long begin_pfn,
+      unsigned long end_pfn,
+      int *removed);
 extern void
 SHADOW_INTERNAL_NAME(sh_clear_shadow_entry, GUEST_LEVELS)
     (struct vcpu *v, void *ep, mfn_t smfn);
diff --git a/xen/arch/x86/mm/shadow/types.h b/xen/arch/x86/mm/shadow/types.h
index 43ce1db..5b0f9f7 100644
--- a/xen/arch/x86/mm/shadow/types.h
+++ b/xen/arch/x86/mm/shadow/types.h
@@ -229,6 +229,7 @@ static inline shadow_l4e_t shadow_l4e_from_mfn(mfn_t mfn, 
u32 flags)
 #define sh_update_cr3              INTERNAL_NAME(sh_update_cr3)
 #define sh_rm_write_access_from_l1 INTERNAL_NAME(sh_rm_write_access_from_l1)
 #define sh_rm_mappings_from_l1     INTERNAL_NAME(sh_rm_mappings_from_l1)
+#define sh_find_vram_mappings_in_l1 INTERNAL_NAME(sh_find_vram_mappings_in_l1)
 #define sh_remove_l1_shadow        INTERNAL_NAME(sh_remove_l1_shadow)
 #define sh_remove_l2_shadow        INTERNAL_NAME(sh_remove_l2_shadow)
 #define sh_remove_l3_shadow        INTERNAL_NAME(sh_remove_l3_shadow)
diff --git a/xen/include/asm-x86/dirty_vram.h b/xen/include/asm-x86/dirty_vram.h
new file mode 100644
index 0000000..7f3ccf9
--- /dev/null
+++ b/xen/include/asm-x86/dirty_vram.h
@@ -0,0 +1,196 @@
+/******************************************************************************
+ * include/asm-x86/dirty_vram.h
+ *
+ * Interface for tracking dirty VRAM pages
+ *
+ * Copyright (c) 2012 Citrix Systems, Inc. (Robert Phillips)
+ * 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
+ */
+
+#ifndef _DIRTY_VRAM_H
+#define _DIRTY_VRAM_H
+
+/*
+ * In shadow mode we need to bookkeep all the L1 page table entries that
+ * map a frame buffer page.  Struct dv_paddr_link does this
+ * by recording the address of a L1 page table entry for some frame buffer 
page.
+ * Also has a link to additional pl entries if the frame buffer page
+ * has multiple mappings.
+ * In practice very few pages have multiple mappings.
+ * But to rule out some pathological situation, we limit the number of
+ * mappings we're willing to bookkeep.
+ */
+
+#define DV_ADDR_LINK_LIST_LIMIT 20
+
+typedef struct dv_paddr_link {
+    paddr_t sl1ma;
+    struct dv_paddr_link *pl_next;
+} dv_paddr_link_t;
+
+/*
+ * This defines an extension page of pl entries for FB pages with multiple
+ * mappings. All such pages (of a domain) are linked together.
+ */
+typedef struct dv_paddr_link_ext {
+    struct list_head ext_link;
+    dv_paddr_link_t entries[ ( PAGE_SIZE - sizeof( struct list_head ) ) /
+                             sizeof( dv_paddr_link_t ) ];
+} dv_paddr_link_ext_t;
+
+/*
+ * This defines a single frame buffer range.  It bookkeeps all the level 1 PTEs
+ * that map guest pages within that range.
+ * All such ranges (of a domain) are linked together.
+ */
+typedef struct dv_range {
+    struct list_head range_link; /* the several ranges form a linked list */
+    unsigned long begin_pfn;
+    unsigned long end_pfn;
+    dv_paddr_link_t *pl_tab; /* table has 1 pl entry per pfn in range */
+    int nr_mappings;  /* total number of mappings in this range */
+    int mappings_hwm; /* high water mark of max mapping count */
+    unsigned int dirty_count;
+} dv_range_t;
+
+/*
+ * This contains all the data structures required by a domain to
+ * bookkeep the dirty pages within its frame buffers.
+ */
+typedef struct dv_dirty_vram {
+    struct list_head range_head; /* head of the linked list of ranges */
+    struct list_head ext_head; /* head of list of extension pages */
+    dv_paddr_link_t *pl_free; /* free list of pl's within extension pages */
+    int nr_ranges; /* bookkeeps number of ranges */
+    int ranges_hwm; /* high water mark of max number of ranges */
+} dv_dirty_vram_t;
+
+/* Allocates domain's dirty_vram structure */
+dv_dirty_vram_t *
+dirty_vram_alloc(struct domain *d);
+
+/*
+ * Returns domain's dirty_vram structure,
+ * allocating it if necessary
+ */
+dv_dirty_vram_t *
+dirty_vram_find_or_alloc(struct domain *d);
+
+/* Frees domain's dirty_vram structure */
+void dirty_vram_free(struct domain *d);
+
+/* Returns dirty vram range containing gfn, NULL if none */
+struct dv_range *
+dirty_vram_range_find_gfn(struct domain *d,
+                          unsigned long gfn);
+
+/*
+ * Returns dirty vram range matching [ begin_pfn .. begin_pfn+nr ),
+ * NULL if none
+ */
+dv_range_t *
+dirty_vram_range_find(struct domain *d,
+                      unsigned long begin_pfn,
+                      unsigned long nr);
+
+/*
+ * Allocate dirty vram range containing [ begin_pfn .. begin_pfn+nr ),
+ * freeing any existing range that overlaps the new range.
+ */
+dv_range_t *
+dirty_vram_range_alloc(struct domain *d,
+                       unsigned long begin_pfn,
+                       unsigned long nr);
+
+/*
+ * Returns dirty vram range matching [ begin_pfn .. begin_pfn+nr ),
+ * creating a range if none already exists and
+ * freeing any existing range that overlaps the new range.
+ */
+dv_range_t *
+dirty_vram_range_find_or_alloc(struct domain *d,
+                               unsigned long begin_pfn,
+                               unsigned long nr);
+
+void dirty_vram_range_free(struct domain *d,
+                           dv_range_t *range);
+
+/* Bookkeep PTE address of a frame buffer page */
+int dirty_vram_range_update(struct domain *d,
+                            unsigned long gfn,
+                            paddr_t sl1ma,
+                            int set);
+
+/*
+ * smfn is no longer a shadow page.  Remove it from any
+ * dirty vram range mapping.
+ */
+void
+dirty_vram_delete_shadow(struct vcpu *v,
+                         unsigned long gfn,
+                         unsigned int shadow_type,
+                         mfn_t smfn);
+
+
+/*
+ * Scan all the L1 tables looking for VRAM mappings.
+ * Record them in the domain's dv_dirty_vram structure
+ */
+void sh_find_all_vram_mappings(struct vcpu *v,
+                               dv_range_t *range);
+
+/*
+ * Free a paddr_link struct, given address of its
+ * predecessor in singly-linked list
+ */
+dv_paddr_link_t *
+free_paddr_link(struct domain *d,
+                dv_paddr_link_t **ppl,
+                dv_paddr_link_t *pl);
+
+
+/* Enable VRAM dirty tracking. */
+int
+shadow_track_dirty_vram(struct domain *d,
+                       unsigned long first_pfn,
+                       unsigned long nr,
+                       XEN_GUEST_HANDLE_64(uint8) dirty_bitmap);
+
+int
+hap_track_dirty_vram(struct domain *d,
+                    unsigned long begin_pfn,
+                    unsigned long nr,
+                    XEN_GUEST_HANDLE_64(uint8) dirty_bitmap);
+
+void
+hap_clean_vram_tracking_range(struct domain *d,
+                             unsigned long begin_pfn,
+                             unsigned long nr,
+                             uint8_t *dirty_bitmap);
+
+#endif /* _DIRTY_VRAM_H */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/include/asm-x86/hap.h b/xen/include/asm-x86/hap.h
index 916a35b..3e3a1f5 100644
--- a/xen/include/asm-x86/hap.h
+++ b/xen/include/asm-x86/hap.h
@@ -57,10 +57,6 @@ void  hap_final_teardown(struct domain *d);
 void  hap_teardown(struct domain *d);
 void  hap_vcpu_init(struct vcpu *v);
 void  hap_logdirty_init(struct domain *d);
-int   hap_track_dirty_vram(struct domain *d,
-                           unsigned long begin_pfn,
-                           unsigned long nr,
-                           XEN_GUEST_HANDLE_64(uint8) dirty_bitmap);
 
 extern const struct paging_mode *hap_paging_get_mode(struct vcpu *);
 
diff --git a/xen/include/asm-x86/hvm/domain.h b/xen/include/asm-x86/hvm/domain.h
index 27b3de5..6146542 100644
--- a/xen/include/asm-x86/hvm/domain.h
+++ b/xen/include/asm-x86/hvm/domain.h
@@ -74,7 +74,7 @@ struct hvm_domain {
     struct list_head       pinned_cacheattr_ranges;
 
     /* VRAM dirty support. */
-    struct sh_dirty_vram *dirty_vram;
+    struct dv_dirty_vram * dirty_vram;
 
     /* If one of vcpus of this domain is in no_fill_mode or
      * mtrr/pat between vcpus is not the same, set is_in_uc_mode
diff --git a/xen/include/asm-x86/paging.h b/xen/include/asm-x86/paging.h
index 9a40f2c..f804104 100644
--- a/xen/include/asm-x86/paging.h
+++ b/xen/include/asm-x86/paging.h
@@ -137,10 +137,10 @@ struct paging_mode {
 void paging_free_log_dirty_bitmap(struct domain *d);
 
 /* get the dirty bitmap for a specific range of pfns */
-int paging_log_dirty_range(struct domain *d,
-                           unsigned long begin_pfn,
-                           unsigned long nr,
-                           XEN_GUEST_HANDLE_64(uint8) dirty_bitmap);
+void paging_log_dirty_range(struct domain *d,
+                            unsigned long begin_pfn,
+                            unsigned long nr,
+                            uint8_t *dirty_bitmap);
 
 /* enable log dirty */
 int paging_log_dirty_enable(struct domain *d);
@@ -161,6 +161,11 @@ void paging_mark_dirty(struct domain *d, unsigned long 
guest_mfn);
  * This is called from inside paging code, with the paging lock held. */
 int paging_mfn_is_dirty(struct domain *d, mfn_t gmfn);
 
+/* mark a page as dirty, from hap page fault handler */
+void paging_mark_dirty_hap(struct domain *d,
+                           unsigned long pfn,
+                           unsigned long guest_mfn);
+
 /*
  * Log-dirty radix tree indexing:
  *   All tree nodes are PAGE_SIZE bytes, mapped on-demand.
@@ -183,15 +188,6 @@ int paging_mfn_is_dirty(struct domain *d, mfn_t gmfn);
 #define L4_LOGDIRTY_IDX(pfn) 0
 #endif
 
-/* VRAM dirty tracking support */
-struct sh_dirty_vram {
-    unsigned long begin_pfn;
-    unsigned long end_pfn;
-    paddr_t *sl1ma;
-    uint8_t *dirty_bitmap;
-    s_time_t last_dirty;
-};
-
 /*****************************************************************************
  * Entry points into the paging-assistance code */
 
diff --git a/xen/include/asm-x86/shadow.h b/xen/include/asm-x86/shadow.h
index 2eb6efc..940d7fd 100644
--- a/xen/include/asm-x86/shadow.h
+++ b/xen/include/asm-x86/shadow.h
@@ -62,12 +62,6 @@ void shadow_vcpu_init(struct vcpu *v);
 /* Enable an arbitrary shadow mode.  Call once at domain creation. */
 int shadow_enable(struct domain *d, u32 mode);
 
-/* Enable VRAM dirty bit tracking. */
-int shadow_track_dirty_vram(struct domain *d,
-                            unsigned long first_pfn,
-                            unsigned long nr,
-                            XEN_GUEST_HANDLE_64(uint8) dirty_bitmap);
-
 /* Handler for shadow control ops: operations from user-space to enable
  * and disable ephemeral shadow modes (test mode and log-dirty mode) and
  * manipulate the log-dirty bitmap. */
-- 
1.7.9.5


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