diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 5234b627d0..e5785d2d96 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -688,7 +688,7 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
         return -EINVAL;
     }

-    if ( config->altp2m.opts )
+    if ( config->altp2m.opts || config->altp2m.nr )
     {
         dprintk(XENLOG_INFO, "Altp2m not supported\n");
         return -EINVAL;
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index bb5ba8fc1e..011cffb07e 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -724,16 +724,42 @@ int arch_sanitise_domain_config(struct xen_domctl_createdomain *config)
         return -EINVAL;
     }

-    if ( altp2m_mode && nested_virt )
+    if ( altp2m_mode )
     {
-        dprintk(XENLOG_INFO,
-                "Nested virt and altp2m are not supported together\n");
-        return -EINVAL;
-    }
+        if ( nested_virt )
+        {
+            dprintk(XENLOG_INFO,
+                    "Nested virt and altp2m are not supported together\n");
+            return -EINVAL;
+        }
+
+        if ( !hap )
+        {
+            dprintk(XENLOG_INFO, "altp2m is only supported with HAP\n");
+            return -EINVAL;
+        }
+
+        if ( !hvm_altp2m_supported() )
+        {
+            dprintk(XENLOG_INFO, "altp2m is not supported\n");
+            return -EINVAL;
+        }
+
+        if ( !config->altp2m.nr )
+        {
+            /* Fix the value to the legacy default */
+            config->altp2m.nr = 10;
+        }

-    if ( altp2m_mode && !hap )
+        if ( config->altp2m.nr > MAX_NR_ALTP2M )
+        {
+            dprintk(XENLOG_INFO, "altp2m.nr must be <= %lu\n", MAX_NR_ALTP2M);
+            return -EINVAL;
+        }
+    }
+    else if ( config->altp2m.nr )
     {
-        dprintk(XENLOG_INFO, "altp2m is only supported with HAP\n");
+        dprintk(XENLOG_INFO, "altp2m.nr must be zero when altp2m is off\n");
         return -EINVAL;
     }

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index a66ebaaceb..3d0357a0f8 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4657,6 +4657,12 @@ static int do_altp2m_op(
         goto out;
     }

+    if ( d->nr_altp2m == 0 )
+    {
+        rc = -EINVAL;
+        goto out;
+    }
+
     if ( (rc = xsm_hvm_altp2mhvm_op(XSM_OTHER, d, mode, a.cmd)) )
         goto out;

@@ -5245,7 +5251,7 @@ void hvm_fast_singlestep(struct vcpu *v, uint16_t p2midx)
     if ( !hvm_is_singlestep_supported() )
         return;

-    if ( p2midx >= MAX_ALTP2M )
+    if ( p2midx >= v->domain->nr_altp2m )
         return;

     v->arch.hvm.single_step = true;
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index a420d452b3..9292a2c8d8 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -4885,7 +4885,7 @@ bool asmlinkage vmx_vmenter_helper(const struct cpu_user_regs *regs)
         {
             unsigned int i;

-            for ( i = 0; i < MAX_ALTP2M; ++i )
+            for ( i = 0; i < currd->nr_altp2m; ++i )
             {
                 if ( altp2m_get_eptp(currd, i) == mfn_x(INVALID_MFN) )
                     continue;
diff --git a/xen/arch/x86/include/asm/altp2m.h b/xen/arch/x86/include/asm/altp2m.h
index 2f064c61a2..a4cc3d3ffc 100644
--- a/xen/arch/x86/include/asm/altp2m.h
+++ b/xen/arch/x86/include/asm/altp2m.h
@@ -22,7 +22,7 @@ static inline bool altp2m_active(const struct domain *d)
 static inline struct p2m_domain *altp2m_get_p2m(const struct domain* d,
                                                 unsigned int idx)
 {
-    return d->arch.altp2m_p2m[array_index_nospec(idx, MAX_ALTP2M)];
+    return d->arch.altp2m_p2m[array_index_nospec(idx, d->nr_altp2m)];
 }

 static inline uint64_t altp2m_get_eptp(const struct domain* d,
diff --git a/xen/arch/x86/include/asm/domain.h b/xen/arch/x86/include/asm/domain.h
index f5daeb182b..855e844bed 100644
--- a/xen/arch/x86/include/asm/domain.h
+++ b/xen/arch/x86/include/asm/domain.h
@@ -258,11 +258,12 @@ struct paging_vcpu {
     struct shadow_vcpu shadow;
 };

-#define MAX_NESTEDP2M 10
+#define MAX_EPTP        (PAGE_SIZE / sizeof(uint64_t))
+#define MAX_NR_ALTP2M   MAX_EPTP
+#define MAX_NESTEDP2M   10

-#define MAX_ALTP2M      10 /* arbitrary */
 #define INVALID_ALTP2M  0xffff
-#define MAX_EPTP        (PAGE_SIZE / sizeof(uint64_t))
+
 struct p2m_domain;
 struct time_scale {
     int shift;
@@ -353,7 +354,7 @@ struct arch_domain

     /* altp2m: allow multiple copies of host p2m */
     bool altp2m_active;
-    struct p2m_domain *altp2m_p2m[MAX_ALTP2M];
+    struct p2m_domain **altp2m_p2m;
     mm_lock_t altp2m_list_lock;
     uint64_t *altp2m_eptp;
     uint64_t *altp2m_visible_eptp;
diff --git a/xen/arch/x86/include/asm/hvm/hvm.h b/xen/arch/x86/include/asm/hvm/hvm.h
index 1c01e22c8e..277648dd18 100644
--- a/xen/arch/x86/include/asm/hvm/hvm.h
+++ b/xen/arch/x86/include/asm/hvm/hvm.h
@@ -828,6 +828,11 @@ static inline bool hvm_hap_supported(void)
     return false;
 }

+static inline bool hvm_altp2m_supported(void)
+{
+    return false;
+}
+
 static inline bool hvm_nested_virt_supported(void)
 {
     return false;
diff --git a/xen/arch/x86/include/asm/p2m.h b/xen/arch/x86/include/asm/p2m.h
index e6f7764f9f..a1094fc7b3 100644
--- a/xen/arch/x86/include/asm/p2m.h
+++ b/xen/arch/x86/include/asm/p2m.h
@@ -887,7 +887,7 @@ static inline struct p2m_domain *p2m_get_altp2m(struct vcpu *v)
     if ( index == INVALID_ALTP2M )
         return NULL;

-    BUG_ON(index >= MAX_ALTP2M);
+    BUG_ON(index >= v->domain->nr_altp2m);

     return altp2m_get_p2m(v->domain, index);
 }
@@ -898,7 +898,7 @@ static inline bool p2m_set_altp2m(struct vcpu *v, unsigned int idx)
     struct p2m_domain *orig;
     struct p2m_domain *ap2m;

-    BUG_ON(idx >= MAX_ALTP2M);
+    BUG_ON(idx >= v->domain->nr_altp2m);

     if ( idx == vcpu_altp2m(v).p2midx )
         return false;
diff --git a/xen/arch/x86/mm/altp2m.c b/xen/arch/x86/mm/altp2m.c
index 7fb1738376..d47277e5e5 100644
--- a/xen/arch/x86/mm/altp2m.c
+++ b/xen/arch/x86/mm/altp2m.c
@@ -15,6 +15,11 @@
 void
 altp2m_vcpu_initialise(struct vcpu *v)
 {
+    struct domain *d = v->domain;
+
+    if ( d->nr_altp2m == 0 )
+        return;
+
     if ( v != current )
         vcpu_pause(v);

@@ -30,8 +35,12 @@ altp2m_vcpu_initialise(struct vcpu *v)
 void
 altp2m_vcpu_destroy(struct vcpu *v)
 {
+    struct domain *d = v->domain;
     struct p2m_domain *p2m;

+    if ( d->nr_altp2m == 0 )
+        return;
+
     if ( v != current )
         vcpu_pause(v);

@@ -122,7 +131,12 @@ int p2m_init_altp2m(struct domain *d)
     struct p2m_domain *hostp2m = p2m_get_hostp2m(d);

     mm_lock_init(&d->arch.altp2m_list_lock);
-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    d->arch.altp2m_p2m = xzalloc_array(struct p2m_domain *, d->nr_altp2m);
+
+    if ( !d->arch.altp2m_p2m )
+        return -ENOMEM;
+
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         d->arch.altp2m_p2m[i] = p2m = p2m_init_one(d);
         if ( p2m == NULL )
@@ -143,7 +157,10 @@ void p2m_teardown_altp2m(struct domain *d)
     unsigned int i;
     struct p2m_domain *p2m;

-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    if ( !d->arch.altp2m_p2m )
+        return;
+
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         if ( !d->arch.altp2m_p2m[i] )
             continue;
@@ -151,6 +168,8 @@ void p2m_teardown_altp2m(struct domain *d)
         d->arch.altp2m_p2m[i] = NULL;
         p2m_free_one(p2m);
     }
+
+    XFREE(d->arch.altp2m_p2m);
 }

 int altp2m_get_effective_entry(struct p2m_domain *ap2m, gfn_t gfn, mfn_t *mfn,
@@ -200,7 +219,7 @@ bool p2m_switch_vcpu_altp2m_by_id(struct vcpu *v, unsigned int idx)
     struct domain *d = v->domain;
     bool rc = false;

-    if ( idx >= MAX_ALTP2M )
+    if ( idx >= d->nr_altp2m )
         return rc;

     altp2m_list_lock(d);
@@ -306,7 +325,7 @@ static void p2m_reset_altp2m(struct domain *d, unsigned int idx,
 {
     struct p2m_domain *p2m;

-    ASSERT(idx < MAX_ALTP2M);
+    ASSERT(idx < d->nr_altp2m);
     p2m = altp2m_get_p2m(d, idx);

     p2m_lock(p2m);
@@ -332,7 +351,7 @@ void p2m_flush_altp2m(struct domain *d)

     altp2m_list_lock(d);

-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         p2m_reset_altp2m(d, i, ALTP2M_DEACTIVATE);
         altp2m_set_eptp(d, i, mfn_x(INVALID_MFN));
@@ -348,7 +367,7 @@ static int p2m_activate_altp2m(struct domain *d, unsigned int idx,
     struct p2m_domain *hostp2m, *p2m;
     int rc;

-    ASSERT(idx < MAX_ALTP2M);
+    ASSERT(idx < d->nr_altp2m);

     p2m = altp2m_get_p2m(d, idx);
     hostp2m = p2m_get_hostp2m(d);
@@ -388,7 +407,7 @@ int p2m_init_altp2m_by_id(struct domain *d, unsigned int idx)
     int rc = -EINVAL;
     struct p2m_domain *hostp2m = p2m_get_hostp2m(d);

-    if ( idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) )
+    if ( idx >= d->nr_altp2m )
         return rc;

     altp2m_list_lock(d);
@@ -414,7 +433,7 @@ int p2m_init_next_altp2m(struct domain *d, uint16_t *idx,

     altp2m_list_lock(d);

-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         if ( altp2m_get_eptp(d, i) != mfn_x(INVALID_MFN) )
             continue;
@@ -436,7 +455,7 @@ int p2m_destroy_altp2m_by_id(struct domain *d, unsigned int idx)
     struct p2m_domain *p2m;
     int rc = -EBUSY;

-    if ( !idx || idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) )
+    if ( !idx || idx >= d->nr_altp2m )
         return rc;

     rc = domain_pause_except_self(d);
@@ -471,7 +490,7 @@ int p2m_switch_domain_altp2m_by_id(struct domain *d, unsigned int idx)
     struct vcpu *v;
     int rc = -EINVAL;

-    if ( idx >= MAX_ALTP2M )
+    if ( idx >= d->nr_altp2m )
         return rc;

     rc = domain_pause_except_self(d);
@@ -506,8 +525,7 @@ int p2m_change_altp2m_gfn(struct domain *d, unsigned int idx,
     mfn_t mfn;
     int rc = -EINVAL;

-    if ( idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
-         altp2m_get_eptp(d, idx) == mfn_x(INVALID_MFN) )
+    if ( idx >= d->nr_altp2m || altp2m_get_eptp(d, idx) == mfn_x(INVALID_MFN) )
         return rc;

     hp2m = p2m_get_hostp2m(d);
@@ -567,7 +585,7 @@ int p2m_altp2m_propagate_change(struct domain *d, gfn_t gfn,

     altp2m_list_lock(d);

-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         p2m_type_t t;
         p2m_access_t a;
@@ -590,7 +608,7 @@ int p2m_altp2m_propagate_change(struct domain *d, gfn_t gfn,
             else
             {
                 /* At least 2 altp2m's impacted, so reset everything */
-                for ( i = 0; i < MAX_ALTP2M; i++ )
+                for ( i = 0; i < d->nr_altp2m; i++ )
                 {
                     if ( i == last_reset_idx ||
                          altp2m_get_eptp(d, i) == mfn_x(INVALID_MFN) )
@@ -654,7 +672,7 @@ int p2m_set_suppress_ve_multi(struct domain *d,

     if ( sve->view > 0 )
     {
-        if ( sve->view >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+        if ( sve->view >= d->nr_altp2m ||
              altp2m_get_eptp(d, sve->view) == mfn_x(INVALID_MFN) )
             return -EINVAL;

@@ -721,7 +739,7 @@ int p2m_get_suppress_ve(struct domain *d, gfn_t gfn, bool *suppress_ve,

     if ( altp2m_idx > 0 )
     {
-        if ( altp2m_idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+        if ( altp2m_idx >= d->nr_altp2m ||
              altp2m_get_eptp(d, altp2m_idx) == mfn_x(INVALID_MFN) )
             return -EINVAL;

@@ -756,9 +774,9 @@ int p2m_set_altp2m_view_visibility(struct domain *d, unsigned int altp2m_idx,

     /*
      * Eptp index is correlated with altp2m index and should not exceed
-     * min(MAX_ALTP2M, MAX_EPTP).
+     * d->nr_altp2m.
      */
-    if ( altp2m_idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+    if ( altp2m_idx >= d->nr_altp2m ||
          altp2m_get_eptp(d, altp2m_idx) == mfn_x(INVALID_MFN) )
         rc = -EINVAL;
     else if ( visible )
diff --git a/xen/arch/x86/mm/hap/hap.c b/xen/arch/x86/mm/hap/hap.c
index 8fc8348152..8b23792a0d 100644
--- a/xen/arch/x86/mm/hap/hap.c
+++ b/xen/arch/x86/mm/hap/hap.c
@@ -515,7 +515,7 @@ int hap_enable(struct domain *d, u32 mode)
             altp2m_set_visible_eptp(d, i, mfn_x(INVALID_MFN));
         }

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             rv = p2m_alloc_table(altp2m_get_p2m(d, i));
             if ( rv != 0 )
@@ -538,8 +538,8 @@ void hap_final_teardown(struct domain *d)
     unsigned int i;

     if ( hvm_altp2m_supported() )
-        for ( i = 0; i < MAX_ALTP2M; i++ )
-            p2m_teardown(d->arch.altp2m_p2m[i], true, NULL);
+        for ( i = 0; i < d->nr_altp2m; i++ )
+            p2m_teardown(altp2m_get_p2m(d, i), true, NULL);

     /* Destroy nestedp2m's first */
     for (i = 0; i < MAX_NESTEDP2M; i++) {
@@ -590,7 +590,7 @@ void hap_teardown(struct domain *d, bool *preempted)
         FREE_XENHEAP_PAGE(d->arch.altp2m_eptp);
         FREE_XENHEAP_PAGE(d->arch.altp2m_visible_eptp);

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             p2m_teardown(altp2m_get_p2m(d, i), false, preempted);
             if ( preempted && *preempted )
diff --git a/xen/arch/x86/mm/mem_access.c b/xen/arch/x86/mm/mem_access.c
index 43f3a8c2aa..669a0d0a54 100644
--- a/xen/arch/x86/mm/mem_access.c
+++ b/xen/arch/x86/mm/mem_access.c
@@ -347,7 +347,7 @@ long p2m_set_mem_access(struct domain *d, gfn_t gfn, uint32_t nr,
     /* altp2m view 0 is treated as the hostp2m */
     if ( altp2m_idx )
     {
-        if ( altp2m_idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+        if ( altp2m_idx >= d->nr_altp2m ||
              altp2m_get_eptp(d, altp2m_idx) == mfn_x(INVALID_MFN) )
             return -EINVAL;

@@ -402,7 +402,7 @@ long p2m_set_mem_access_multi(struct domain *d,
     /* altp2m view 0 is treated as the hostp2m */
     if ( altp2m_idx )
     {
-        if ( altp2m_idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+        if ( altp2m_idx >= d->nr_altp2m ||
              altp2m_get_eptp(d, altp2m_idx) == mfn_x(INVALID_MFN) )
             return -EINVAL;

@@ -464,7 +464,7 @@ int p2m_get_mem_access(struct domain *d, gfn_t gfn, xenmem_access_t *access,
     }
     else if ( altp2m_idx ) /* altp2m view 0 is treated as the hostp2m */
     {
-        if ( altp2m_idx >= min(ARRAY_SIZE(d->arch.altp2m_p2m), MAX_EPTP) ||
+        if ( altp2m_idx >= d->nr_altp2m ||
              altp2m_get_eptp(d, altp2m_idx) == mfn_x(INVALID_MFN) )
             return -EINVAL;

@@ -483,7 +483,7 @@ void arch_p2m_set_access_required(struct domain *d, bool access_required)
     if ( altp2m_active(d) )
     {
         unsigned int i;
-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             struct p2m_domain *p2m = altp2m_get_p2m(d, i);

diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index 21ac361111..2139d13009 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -912,7 +912,7 @@ static int nominate_page(struct domain *d, gfn_t gfn,

         altp2m_list_lock(d);

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             ap2m = altp2m_get_p2m(d, i);
             if ( !ap2m )
diff --git a/xen/arch/x86/mm/p2m-ept.c b/xen/arch/x86/mm/p2m-ept.c
index ed4252822e..f90c82f89b 100644
--- a/xen/arch/x86/mm/p2m-ept.c
+++ b/xen/arch/x86/mm/p2m-ept.c
@@ -1293,7 +1293,7 @@ static void ept_set_ad_sync(struct domain *d, bool value)
     {
         unsigned int i;

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             struct p2m_domain *p2m;

@@ -1519,7 +1519,7 @@ unsigned int p2m_find_altp2m_by_eptp(struct domain *d, uint64_t eptp)

     altp2m_list_lock(d);

-    for ( i = 0; i < MAX_ALTP2M; i++ )
+    for ( i = 0; i < d->nr_altp2m; i++ )
     {
         if ( altp2m_get_eptp(d, i) == mfn_x(INVALID_MFN) )
             continue;
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 30a44441ba..380b7ece9c 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -105,7 +105,7 @@ void p2m_change_entry_type_global(struct domain *d,
     {
         unsigned int i;

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             if ( altp2m_get_eptp(d, i) != mfn_x(INVALID_MFN) )
             {
@@ -140,7 +140,7 @@ void p2m_memory_type_changed(struct domain *d)
     {
         unsigned int i;

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             if ( altp2m_get_eptp(d, i) != mfn_x(INVALID_MFN) )
             {
@@ -913,7 +913,7 @@ void p2m_change_type_range(struct domain *d,
     {
         unsigned int i;

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             if ( altp2m_get_eptp(d, i) != mfn_x(INVALID_MFN) )
             {
@@ -986,7 +986,7 @@ int p2m_finish_type_change(struct domain *d,
     {
         unsigned int i;

-        for ( i = 0; i < MAX_ALTP2M; i++ )
+        for ( i = 0; i < d->nr_altp2m; i++ )
         {
             if ( altp2m_get_eptp(d, i) != mfn_x(INVALID_MFN) )
             {
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 67cadb7c3f..776442cec0 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -610,6 +610,7 @@ struct domain *domain_create(domid_t domid,
     if ( config )
     {
         d->options = config->flags;
+        d->nr_altp2m = config->altp2m.nr;
         d->vmtrace_size = config->vmtrace_size;
     }

diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index dea399aa8e..056bbc82a2 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -103,7 +103,10 @@ struct xen_domctl_createdomain {
 /* Altp2m mode signaling uses bits [0, 1]. */
 #define XEN_DOMCTL_ALTP2M_mode_mask  (0x3U)
 #define XEN_DOMCTL_ALTP2M_mode(m)    ((m) & XEN_DOMCTL_ALTP2M_mode_mask)
-        uint32_t opts;
+        uint16_t opts;
+
+        /* Number of altp2ms to allocate. */
+        uint16_t nr;
     } altp2m;

     /* Per-vCPU buffer size in bytes.  0 to disable. */
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 2dcd1d1a4f..7119f3c44f 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -610,6 +610,8 @@ struct domain
         unsigned int guest_request_sync          : 1;
     } monitor;

+    unsigned int nr_altp2m;    /* Number of altp2m tables */
+
     unsigned int vmtrace_size; /* Buffer size in bytes, or 0 to disable. */

 #ifdef CONFIG_ARGO
