x86/ioreq server: Asynchronously reset outstanding p2m_ioreq_server entries.

Commit Message

Yu Zhang April 7, 2017, 2:44 p.m. UTC

After an ioreq server has unmapped, the remaining p2m_ioreq_server
entries need to be reset back to p2m_ram_rw. This patch does this
asynchronously with the current p2m_change_entry_type_global()
interface.

New field entry_count is introduced in struct p2m_domain, to record
the number of p2m_ioreq_server p2m page table entries. One nature of
these entries is that they only point to 4K sized page frames, because
all p2m_ioreq_server entries are originated from p2m_ram_rw ones in
p2m_change_type_one(). We do not need to worry about the counting for
2M/1G sized pages.

This patch disallows mapping of an ioreq server, when there's still
p2m_ioreq_server entry left, in case another mapping occurs right after
the current one being unmapped, releases its lock, with p2m table not
synced yet.

This patch also disallows live migration, when there's remaining
p2m_ioreq_server entry in p2m table. The core reason is our current
implementation of p2m_change_entry_type_global() lacks information
to resync p2m_ioreq_server entries correctly if global_logdirty is
on.

We still need to handle other recalculations, however; which means
that when doing a recalculation, if the current type is
p2m_ioreq_server, we check to see if p2m->ioreq.server is valid or
not.  If it is, we leave it as type p2m_ioreq_server; if not, we reset
it to p2m_ram as appropriate.

To avoid code duplication, lift recalc_type() out of p2m-pt.c and use
it for all type recalculations (both in p2m-pt.c and p2m-ept.c).

Signed-off-by: Yu Zhang <[e-mail]>
Signed-off-by: George Dunlap <[e-mail]>
Reviewed-by: Paul Durrant <[e-mail]>
---
Cc: Paul Durrant <[e-mail]>
Cc: Jan Beulich <[e-mail]>
Cc: Andrew Cooper <[e-mail]>
Cc: George Dunlap <[e-mail]>
Cc: Jun Nakajima <[e-mail]>
Cc: Kevin Tian <[e-mail]>

Note: this is the 5/6 patch for the ioreq server patch series v12.
with other patches got reviewed-by/acked-by, I just resend this one.

changes in v8:
  - According to comments from Jan: do not reset p2m_ioreq_server
    back when an ioreq server is mapped.
  - According to comments from Jan: added a helper function to do
    the p2m type calculation.
  - According to comments from Jan: add ASSERT for 1G and 2M page
    size.
  - According to comments from George: comment changes.
  - Added "Signed-off-by: George Dunlap <[e-mail]>".

changes in v7:
  - According to comments from George: add code to increase the
    entry_count.
  - Comment changes in {ept,p2m_pt}_set_entry.

changes in v6:
  - According to comments from Jan & George: move the count from
    p2m_change_type_one() to {ept,p2m_pt}_set_entry.
  - According to comments from George: comments change.

changes in v5: 
  - According to comments from Jan: use unsigned long for entry_count;
  - According to comments from Jan: refuse mapping requirement when
    there's p2m_ioreq_server remained in p2m table.
  - Added "Reviewed-by: Paul Durrant <[e-mail]>"

changes in v4: 
  - According to comments from Jan: use ASSERT() instead of 'if'
    condition in p2m_change_type_one().
  - According to comments from Jan: commit message changes to mention
    the p2m_ioreq_server are all based on 4K sized pages.

changes in v3: 
  - Move the synchronously resetting logic into patch 5.
  - According to comments from Jan: introduce p2m_check_changeable()
    to clarify the p2m type change code.
  - According to comments from George: use locks in the same order
    to avoid deadlock, call p2m_change_entry_type_global() after unmap
    of the ioreq server is finished.

changes in v2:
  - Move the calculation of ioreq server page entry_cout into
    p2m_change_type_one() so that we do not need a seperate lock.
    Note: entry_count is also calculated in resolve_misconfig()/
    do_recalc(), fortunately callers of both routines have p2m
    lock protected already.
  - Simplify logic in hvmop_set_mem_type().
  - Introduce routine p2m_finish_type_change() to walk the p2m
    table and do the p2m reset.
---
 xen/arch/x86/hvm/ioreq.c  |  8 +++++
 xen/arch/x86/mm/hap/hap.c |  9 ++++++
 xen/arch/x86/mm/p2m-ept.c | 75 +++++++++++++++++++++++++++++++----------------
 xen/arch/x86/mm/p2m-pt.c  | 62 ++++++++++++++++++++++++++-------------
 xen/arch/x86/mm/p2m.c     |  9 ++++++
 xen/include/asm-x86/p2m.h | 25 +++++++++++++++-
 6 files changed, 140 insertions(+), 48 deletions(-)

Comments

Jan Beulich April 7, 2017, 3:20 p.m. UTC | #1

>>> On 07.04.17 at 16:44, <[e-mail]> wrote:
> After an ioreq server has unmapped, the remaining p2m_ioreq_server
> entries need to be reset back to p2m_ram_rw. This patch does this
> asynchronously with the current p2m_change_entry_type_global()
> interface.
> 
> New field entry_count is introduced in struct p2m_domain, to record
> the number of p2m_ioreq_server p2m page table entries. One nature of
> these entries is that they only point to 4K sized page frames, because
> all p2m_ioreq_server entries are originated from p2m_ram_rw ones in
> p2m_change_type_one(). We do not need to worry about the counting for
> 2M/1G sized pages.
> 
> This patch disallows mapping of an ioreq server, when there's still
> p2m_ioreq_server entry left, in case another mapping occurs right after
> the current one being unmapped, releases its lock, with p2m table not
> synced yet.
> 
> This patch also disallows live migration, when there's remaining
> p2m_ioreq_server entry in p2m table. The core reason is our current
> implementation of p2m_change_entry_type_global() lacks information
> to resync p2m_ioreq_server entries correctly if global_logdirty is
> on.
> 
> We still need to handle other recalculations, however; which means
> that when doing a recalculation, if the current type is
> p2m_ioreq_server, we check to see if p2m->ioreq.server is valid or
> not.  If it is, we leave it as type p2m_ioreq_server; if not, we reset
> it to p2m_ram as appropriate.
> 
> To avoid code duplication, lift recalc_type() out of p2m-pt.c and use
> it for all type recalculations (both in p2m-pt.c and p2m-ept.c).
> 
> Signed-off-by: Yu Zhang <[e-mail]>
> Signed-off-by: George Dunlap <[e-mail]>
> Reviewed-by: Paul Durrant <[e-mail]>

Reviewed-by: Jan Beulich <[e-mail]>
with two (cosmetic) remarks (may be addressed while committing):

> @@ -542,10 +544,17 @@ static int resolve_misconfig(struct p2m_domain *p2m, unsigned long gfn)
>                                                 _mfn(e.mfn), 0, &ipat,
>                                                 e.sa_p2mt == p2m_mmio_direct);
>                      e.ipat = ipat;
> -                    if ( e.recalc && p2m_is_changeable(e.sa_p2mt) )
> +
> +                    nt = p2m_recalc_type(e.recalc, e.sa_p2mt, p2m, gfn + i);
> +                    if ( nt != e.sa_p2mt )
>                      {
> -                         e.sa_p2mt = p2m_is_logdirty_range(p2m, gfn + i, gfn + i)
> -                                     ? p2m_ram_logdirty : p2m_ram_rw;
> +                         if ( e.sa_p2mt == p2m_ioreq_server )
> +                         {
> +                             ASSERT(p2m->ioreq.entry_count > 0);
> +                             p2m->ioreq.entry_count--;
> +                         }
> +
> +                         e.sa_p2mt = nt;
>                           ept_p2m_type_to_flags(p2m, &e, e.sa_p2mt, e.access);
>                      }

Indentation in that scope is till wrong (and hence the badness is
being extended).

> @@ -744,6 +746,27 @@ static inline p2m_type_t p2m_flags_to_type(unsigned long flags)
>      return (flags >> 12) & 0x7f;
>  }
>  
> +static inline p2m_type_t p2m_recalc_type_range(bool recalc, p2m_type_t t,

While this is bool now, ...

> +                                               struct p2m_domain *p2m,
> +                                               unsigned long gfn_start,
> +                                               unsigned long gfn_end)
> +{
> +    if ( !recalc || !p2m_is_changeable(t) )
> +        return t;
> +
> +    if ( t == p2m_ioreq_server && p2m->ioreq.server != NULL )
> +        return t;
> +
> +    return p2m_is_logdirty_range(p2m, gfn_start, gfn_end) ? p2m_ram_logdirty
> +                                                          : p2m_ram_rw;
> +}
> +
> +static inline p2m_type_t p2m_recalc_type(bool_t recalc, p2m_type_t t,

... this one still isn't.

Jan

Patch

diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
index 5bf3b6d..07a6c26 100644
--- a/xen/arch/x86/hvm/ioreq.c
+++ b/xen/arch/x86/hvm/ioreq.c
@@ -955,6 +955,14 @@  int hvm_map_mem_type_to_ioreq_server(struct domain *d, ioservid_t id,
 
     spin_unlock_recursive(&d->arch.hvm_domain.ioreq_server.lock);
 
+    if ( rc == 0 && flags == 0 )
+    {
+        struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+        if ( read_atomic(&p2m->ioreq.entry_count) )
+            p2m_change_entry_type_global(d, p2m_ioreq_server, p2m_ram_rw);
+    }
+
     return rc;
 }
 
diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c
index c0610c5..b981432 100644
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -187,6 +187,15 @@  out:
  */
 static int hap_enable_log_dirty(struct domain *d, bool_t log_global)
 {
+    struct p2m_domain *p2m = p2m_get_hostp2m(d);
+
+    /*
+     * Refuse to turn on global log-dirty mode if
+     * there are outstanding p2m_ioreq_server pages.
+     */
+    if ( log_global && read_atomic(&p2m->ioreq.entry_count) )
+        return -EBUSY;
+
     /* turn on PG_log_dirty bit in paging mode */
     paging_lock(d);
     d->arch.paging.mode |= PG_log_dirty;
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index cc1eb21..478e7e8 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -533,6 +533,8 @@  static int resolve_misconfig(struct p2m_domain *p2m, unsigned long gfn)
             {
                 for ( gfn -= i, i = 0; i < EPT_PAGETABLE_ENTRIES; ++i )
                 {
+                    p2m_type_t nt;
+
                     e = atomic_read_ept_entry(&epte[i]);
                     if ( e.emt == MTRR_NUM_TYPES )
                         e.emt = 0;
@@ -542,10 +544,17 @@  static int resolve_misconfig(struct p2m_domain *p2m, unsigned long gfn)
                                                _mfn(e.mfn), 0, &ipat,
                                                e.sa_p2mt == p2m_mmio_direct);
                     e.ipat = ipat;
-                    if ( e.recalc && p2m_is_changeable(e.sa_p2mt) )
+
+                    nt = p2m_recalc_type(e.recalc, e.sa_p2mt, p2m, gfn + i);
+                    if ( nt != e.sa_p2mt )
                     {
-                         e.sa_p2mt = p2m_is_logdirty_range(p2m, gfn + i, gfn + i)
-                                     ? p2m_ram_logdirty : p2m_ram_rw;
+                         if ( e.sa_p2mt == p2m_ioreq_server )
+                         {
+                             ASSERT(p2m->ioreq.entry_count > 0);
+                             p2m->ioreq.entry_count--;
+                         }
+
+                         e.sa_p2mt = nt;
                          ept_p2m_type_to_flags(p2m, &e, e.sa_p2mt, e.access);
                     }
                     e.recalc = 0;
@@ -562,23 +571,24 @@  static int resolve_misconfig(struct p2m_domain *p2m, unsigned long gfn)
 
                 if ( recalc && p2m_is_changeable(e.sa_p2mt) )
                 {
-                     unsigned long mask = ~0UL << (level * EPT_TABLE_ORDER);
-
-                     switch ( p2m_is_logdirty_range(p2m, gfn & mask,
-                                                    gfn | ~mask) )
-                     {
-                     case 0:
-                          e.sa_p2mt = p2m_ram_rw;
-                          e.recalc = 0;
-                          break;
-                     case 1:
-                          e.sa_p2mt = p2m_ram_logdirty;
-                          e.recalc = 0;
-                          break;
-                     default: /* Force split. */
-                          emt = -1;
-                          break;
-                     }
+                    unsigned long mask = ~0UL << (level * EPT_TABLE_ORDER);
+
+                    ASSERT(e.sa_p2mt != p2m_ioreq_server);
+                    switch ( p2m_is_logdirty_range(p2m, gfn & mask,
+                                                   gfn | ~mask) )
+                    {
+                    case 0:
+                         e.sa_p2mt = p2m_ram_rw;
+                         e.recalc = 0;
+                         break;
+                    case 1:
+                         e.sa_p2mt = p2m_ram_logdirty;
+                         e.recalc = 0;
+                         break;
+                    default: /* Force split. */
+                         emt = -1;
+                         break;
+                    }
                 }
                 if ( unlikely(emt < 0) )
                 {
@@ -816,6 +826,23 @@  ept_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
         new_entry.suppress_ve = is_epte_valid(&old_entry) ?
                                     old_entry.suppress_ve : 1;
 
+    /*
+     * p2m_ioreq_server is only used for 4K pages, so the
+     * count is only done on ept page table entries.
+     */
+    if ( p2mt == p2m_ioreq_server )
+    {
+        ASSERT(i == 0);
+        p2m->ioreq.entry_count++;
+    }
+
+    if ( ept_entry->sa_p2mt == p2m_ioreq_server )
+    {
+        ASSERT(i == 0);
+        ASSERT(p2m->ioreq.entry_count > 0);
+        p2m->ioreq.entry_count--;
+    }
+
     rc = atomic_write_ept_entry(ept_entry, new_entry, target);
     if ( unlikely(rc) )
         old_entry.epte = 0;
@@ -964,12 +991,8 @@  static mfn_t ept_get_entry(struct p2m_domain *p2m,
 
     if ( is_epte_valid(ept_entry) )
     {
-        if ( (recalc || ept_entry->recalc) &&
-             p2m_is_changeable(ept_entry->sa_p2mt) )
-            *t = p2m_is_logdirty_range(p2m, gfn, gfn) ? p2m_ram_logdirty
-                                                      : p2m_ram_rw;
-        else
-            *t = ept_entry->sa_p2mt;
+        *t = p2m_recalc_type(recalc || ept_entry->recalc,
+                             ept_entry->sa_p2mt, p2m, gfn);
         *a = ept_entry->access;
         if ( sve )
             *sve = ept_entry->suppress_ve;
diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c
index c0055f3..5079b59 100644
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -389,6 +389,7 @@  static int do_recalc(struct p2m_domain *p2m, unsigned long gfn)
         {
             unsigned long mask = ~0UL << (level * PAGETABLE_ORDER);
 
+            ASSERT(p2m_flags_to_type(l1e_get_flags(*pent)) != p2m_ioreq_server);
             if ( !needs_recalc(l1, *pent) ||
                  !p2m_is_changeable(p2m_flags_to_type(l1e_get_flags(*pent))) ||
                  p2m_is_logdirty_range(p2m, gfn & mask, gfn | ~mask) >= 0 )
@@ -436,17 +437,18 @@  static int do_recalc(struct p2m_domain *p2m, unsigned long gfn)
          needs_recalc(l1, *pent) )
     {
         l1_pgentry_t e = *pent;
+        p2m_type_t ot, nt;
+        unsigned long mask = ~0UL << (level * PAGETABLE_ORDER);
 
         if ( !valid_recalc(l1, e) )
             P2M_DEBUG("bogus recalc leaf at d%d:%lx:%u\n",
                       p2m->domain->domain_id, gfn, level);
-        if ( p2m_is_changeable(p2m_flags_to_type(l1e_get_flags(e))) )
+        ot = p2m_flags_to_type(l1e_get_flags(e));
+        nt = p2m_recalc_type_range(true, ot, p2m, gfn & mask, gfn | ~mask);
+        if ( nt != ot )
         {
-            unsigned long mask = ~0UL << (level * PAGETABLE_ORDER);
-            p2m_type_t p2mt = p2m_is_logdirty_range(p2m, gfn & mask, gfn | ~mask)
-                              ? p2m_ram_logdirty : p2m_ram_rw;
             unsigned long mfn = l1e_get_pfn(e);
-            unsigned long flags = p2m_type_to_flags(p2m, p2mt,
+            unsigned long flags = p2m_type_to_flags(p2m, nt,
                                                     _mfn(mfn), level);
 
             if ( level )
@@ -460,9 +462,17 @@  static int do_recalc(struct p2m_domain *p2m, unsigned long gfn)
                      mfn &= ~((unsigned long)_PAGE_PSE_PAT >> PAGE_SHIFT);
                 flags |= _PAGE_PSE;
             }
+
+            if ( ot == p2m_ioreq_server )
+            {
+                ASSERT(p2m->ioreq.entry_count > 0);
+                ASSERT(level == 0);
+                p2m->ioreq.entry_count--;
+            }
+
             e = l1e_from_pfn(mfn, flags);
             p2m_add_iommu_flags(&e, level,
-                                (p2mt == p2m_ram_rw)
+                                (nt == p2m_ram_rw)
                                 ? IOMMUF_readable|IOMMUF_writable : 0);
             ASSERT(!needs_recalc(l1, e));
         }
@@ -582,6 +592,7 @@  p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
             }
         }
 
+        ASSERT(p2m_flags_to_type(flags) != p2m_ioreq_server);
         ASSERT(!mfn_valid(mfn) || p2mt != p2m_mmio_direct);
         l3e_content = mfn_valid(mfn) || p2m_allows_invalid_mfn(p2mt)
             ? l3e_from_pfn(mfn_x(mfn),
@@ -606,6 +617,8 @@  p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
 
     if ( page_order == PAGE_ORDER_4K )
     {
+        p2m_type_t p2mt_old;
+
         rc = p2m_next_level(p2m, &table, &gfn_remainder, gfn,
                             L2_PAGETABLE_SHIFT - PAGE_SHIFT,
                             L2_PAGETABLE_ENTRIES, PGT_l1_page_table, 1);
@@ -629,6 +642,21 @@  p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
         if ( entry_content.l1 != 0 )
             p2m_add_iommu_flags(&entry_content, 0, iommu_pte_flags);
 
+        p2mt_old = p2m_flags_to_type(l1e_get_flags(*p2m_entry));
+
+        /*
+         * p2m_ioreq_server is only used for 4K pages, so
+         * the count is only done for level 1 entries.
+         */
+        if ( p2mt == p2m_ioreq_server )
+            p2m->ioreq.entry_count++;
+
+        if ( p2mt_old == p2m_ioreq_server )
+        {
+            ASSERT(p2m->ioreq.entry_count > 0);
+            p2m->ioreq.entry_count--;
+        }
+
         /* level 1 entry */
         p2m->write_p2m_entry(p2m, gfn, p2m_entry, entry_content, 1);
         /* NB: paging_write_p2m_entry() handles tlb flushes properly */
@@ -655,7 +683,8 @@  p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
                 intermediate_entry = *p2m_entry;
             }
         }
-        
+
+        ASSERT(p2m_flags_to_type(flags) != p2m_ioreq_server);
         ASSERT(!mfn_valid(mfn) || p2mt != p2m_mmio_direct);
         if ( mfn_valid(mfn) || p2m_allows_invalid_mfn(p2mt) )
             l2e_content = l2e_from_pfn(mfn_x(mfn),
@@ -726,15 +755,6 @@  p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
     return rc;
 }
 
-static inline p2m_type_t recalc_type(bool_t recalc, p2m_type_t t,
-                                     struct p2m_domain *p2m, unsigned long gfn)
-{
-    if ( !recalc || !p2m_is_changeable(t) )
-        return t;
-    return p2m_is_logdirty_range(p2m, gfn, gfn) ? p2m_ram_logdirty
-                                                : p2m_ram_rw;
-}
-
 static mfn_t
 p2m_pt_get_entry(struct p2m_domain *p2m, unsigned long gfn,
                  p2m_type_t *t, p2m_access_t *a, p2m_query_t q,
@@ -820,8 +840,8 @@  pod_retry_l3:
             mfn = _mfn(l3e_get_pfn(*l3e) +
                        l2_table_offset(addr) * L1_PAGETABLE_ENTRIES +
                        l1_table_offset(addr));
-            *t = recalc_type(recalc || _needs_recalc(flags),
-                             p2m_flags_to_type(flags), p2m, gfn);
+            *t = p2m_recalc_type(recalc || _needs_recalc(flags),
+                                 p2m_flags_to_type(flags), p2m, gfn);
             unmap_domain_page(l3e);
 
             ASSERT(mfn_valid(mfn) || !p2m_is_ram(*t));
@@ -859,8 +879,8 @@  pod_retry_l2:
     if ( flags & _PAGE_PSE )
     {
         mfn = _mfn(l2e_get_pfn(*l2e) + l1_table_offset(addr));
-        *t = recalc_type(recalc || _needs_recalc(flags),
-                         p2m_flags_to_type(flags), p2m, gfn);
+        *t = p2m_recalc_type(recalc || _needs_recalc(flags),
+                             p2m_flags_to_type(flags), p2m, gfn);
         unmap_domain_page(l2e);
         
         ASSERT(mfn_valid(mfn) || !p2m_is_ram(*t));
@@ -896,7 +916,7 @@  pod_retry_l1:
         return INVALID_MFN;
     }
     mfn = _mfn(l1e_get_pfn(*l1e));
-    *t = recalc_type(recalc || _needs_recalc(flags), l1t, p2m, gfn);
+    *t = p2m_recalc_type(recalc || _needs_recalc(flags), l1t, p2m, gfn);
     unmap_domain_page(l1e);
 
     ASSERT(mfn_valid(mfn) || !p2m_is_ram(*t) || p2m_is_paging(*t));
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index b84add0..4169d18 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -317,6 +317,15 @@  int p2m_set_ioreq_server(struct domain *d,
         if ( p2m->ioreq.server != NULL )
             goto out;
 
+        /*
+         * It is possible that an ioreq server has just been unmapped,
+         * released the spin lock, with some p2m_ioreq_server entries
+         * in p2m table remained. We shall refuse another ioreq server
+         * mapping request in such case.
+         */
+        if ( read_atomic(&p2m->ioreq.entry_count) )
+            goto out;
+
         p2m->ioreq.server = s;
         p2m->ioreq.flags = flags;
     }
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 4521620..7d39113 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -120,7 +120,8 @@  typedef unsigned int p2m_query_t;
 
 /* Types that can be subject to bulk transitions. */
 #define P2M_CHANGEABLE_TYPES (p2m_to_mask(p2m_ram_rw) \
-                              | p2m_to_mask(p2m_ram_logdirty) )
+                              | p2m_to_mask(p2m_ram_logdirty) \
+                              | p2m_to_mask(p2m_ioreq_server) )
 
 #define P2M_POD_TYPES (p2m_to_mask(p2m_populate_on_demand))
 
@@ -349,6 +350,7 @@  struct p2m_domain {
           * are to be emulated by an ioreq server.
           */
          unsigned int flags;
+         unsigned long entry_count;
      } ioreq;
 };
 
@@ -744,6 +746,27 @@  static inline p2m_type_t p2m_flags_to_type(unsigned long flags)
     return (flags >> 12) & 0x7f;
 }
 
+static inline p2m_type_t p2m_recalc_type_range(bool recalc, p2m_type_t t,
+                                               struct p2m_domain *p2m,
+                                               unsigned long gfn_start,
+                                               unsigned long gfn_end)
+{
+    if ( !recalc || !p2m_is_changeable(t) )
+        return t;
+
+    if ( t == p2m_ioreq_server && p2m->ioreq.server != NULL )
+        return t;
+
+    return p2m_is_logdirty_range(p2m, gfn_start, gfn_end) ? p2m_ram_logdirty
+                                                          : p2m_ram_rw;
+}
+
+static inline p2m_type_t p2m_recalc_type(bool_t recalc, p2m_type_t t,
+                                         struct p2m_domain *p2m, unsigned long gfn)
+{
+    return p2m_recalc_type_range(recalc, t, p2m, gfn, gfn);
+}
+
 int p2m_pt_handle_deferred_changes(uint64_t gpa);
 
 /*