diff mbox

[v3] common/vm_event: Initialize vm_event lists on domain creation

Message ID 1503655056-26620-1-git-send-email-aisaila@bitdefender.com (mailing list archive)
State New, archived
Headers show

Commit Message

Alexandru Stefan ISAILA Aug. 25, 2017, 9:57 a.m. UTC
The patch splits the vm_event into three structures:vm_event_share,
vm_event_paging, vm_event_monitor. The allocation for the
structure is moved to vm_event_enable so that it can be
allocated/init when needed and freed in vm_event_disable.

Signed-off-by: Alexandru Isaila <aisaila@bitdefender.com>

---
Changes since V2:
	- Removed parentheses from around *ved in vm_event_enable
	- Moved both ifs in on if in vm_event_disable
	- Moved the xfree in vm_event_disable out of the if
	- Changed the return value in __vm_event_claim_slot
	- Added a local var for v->domain
	- Moved the !d->vm_event_paging to the if above in the
	assign_device function
---
 xen/arch/arm/mem_access.c     |   2 +-
 xen/arch/x86/mm/mem_access.c  |   2 +-
 xen/arch/x86/mm/mem_paging.c  |   2 +-
 xen/arch/x86/mm/mem_sharing.c |   4 +-
 xen/arch/x86/mm/p2m.c         |  10 +--
 xen/common/domain.c           |  13 ++--
 xen/common/mem_access.c       |   2 +-
 xen/common/monitor.c          |   4 +-
 xen/common/vm_event.c         | 156 +++++++++++++++++++++++++-----------------
 xen/drivers/passthrough/pci.c |   4 +-
 xen/include/xen/sched.h       |  18 ++---
 11 files changed, 125 insertions(+), 92 deletions(-)

Comments

Jan Beulich Aug. 25, 2017, 10:26 a.m. UTC | #1
>>> On 25.08.17 at 11:57, <aisaila@bitdefender.com> wrote:
> --- a/xen/drivers/passthrough/pci.c
> +++ b/xen/drivers/passthrough/pci.c
> @@ -1358,14 +1358,14 @@ static int assign_device(struct domain *d, u16 seg, u8 bus, u8 devfn, u32 flag)
>      struct pci_dev *pdev;
>      int rc = 0;
>  
> -    if ( !iommu_enabled || !hd->platform_ops )
> +    if ( !iommu_enabled || !hd->platform_ops || !d->vm_event_paging )
>          return 0;

So without paging enabled assigning a device does nothing and
succeeds? I think you want to add the extra condition ...

>      /* Prevent device assign if mem paging or mem sharing have been 
>       * enabled for this domain */
>      if ( unlikely(!need_iommu(d) &&
>              (d->arch.hvm_domain.mem_sharing_enabled ||
> -             d->vm_event->paging.ring_page ||
> +             d->vm_event_paging->ring_page ||

... here. And please make sure you test your change (or indicate
you can't below the commit message, so appropriate care can be
taken by consumers of your patch).

Jan
diff mbox

Patch

diff --git a/xen/arch/arm/mem_access.c b/xen/arch/arm/mem_access.c
index e0888bb..a7f0cae 100644
--- a/xen/arch/arm/mem_access.c
+++ b/xen/arch/arm/mem_access.c
@@ -256,7 +256,7 @@  bool_t p2m_mem_access_check(paddr_t gpa, vaddr_t gla, const struct npfec npfec)
     }
 
     /* Otherwise, check if there is a vm_event monitor subscriber */
-    if ( !vm_event_check_ring(&v->domain->vm_event->monitor) )
+    if ( !vm_event_check_ring(v->domain->vm_event_monitor) )
     {
         /* No listener */
         if ( p2m->access_required )
diff --git a/xen/arch/x86/mm/mem_access.c b/xen/arch/x86/mm/mem_access.c
index 5adaf6d..414e38f 100644
--- a/xen/arch/x86/mm/mem_access.c
+++ b/xen/arch/x86/mm/mem_access.c
@@ -179,7 +179,7 @@  bool_t p2m_mem_access_check(paddr_t gpa, unsigned long gla,
     gfn_unlock(p2m, gfn, 0);
 
     /* Otherwise, check if there is a memory event listener, and send the message along */
-    if ( !vm_event_check_ring(&d->vm_event->monitor) || !req_ptr )
+    if ( !vm_event_check_ring(d->vm_event_monitor) || !req_ptr )
     {
         /* No listener */
         if ( p2m->access_required )
diff --git a/xen/arch/x86/mm/mem_paging.c b/xen/arch/x86/mm/mem_paging.c
index a049e0d..20214ac 100644
--- a/xen/arch/x86/mm/mem_paging.c
+++ b/xen/arch/x86/mm/mem_paging.c
@@ -43,7 +43,7 @@  int mem_paging_memop(XEN_GUEST_HANDLE_PARAM(xen_mem_paging_op_t) arg)
         goto out;
 
     rc = -ENODEV;
-    if ( unlikely(!d->vm_event->paging.ring_page) )
+    if ( !d->vm_event_paging || unlikely(!d->vm_event_paging->ring_page) )
         goto out;
 
     switch( mpo.op )
diff --git a/xen/arch/x86/mm/mem_sharing.c b/xen/arch/x86/mm/mem_sharing.c
index 1f20ce7..12fb9cc 100644
--- a/xen/arch/x86/mm/mem_sharing.c
+++ b/xen/arch/x86/mm/mem_sharing.c
@@ -563,7 +563,7 @@  int mem_sharing_notify_enomem(struct domain *d, unsigned long gfn,
     };
 
     if ( (rc = __vm_event_claim_slot(d, 
-                        &d->vm_event->share, allow_sleep)) < 0 )
+                        d->vm_event_share, allow_sleep)) < 0 )
         return rc;
 
     if ( v->domain == d )
@@ -572,7 +572,7 @@  int mem_sharing_notify_enomem(struct domain *d, unsigned long gfn,
         vm_event_vcpu_pause(v);
     }
 
-    vm_event_put_request(d, &d->vm_event->share, &req);
+    vm_event_put_request(d, d->vm_event_share, &req);
 
     return 0;
 }
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index e8a57d1..6ae23be 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -1454,7 +1454,7 @@  void p2m_mem_paging_drop_page(struct domain *d, unsigned long gfn,
      * correctness of the guest execution at this point.  If this is the only
      * page that happens to be paged-out, we'll be okay..  but it's likely the
      * guest will crash shortly anyways. */
-    int rc = vm_event_claim_slot(d, &d->vm_event->paging);
+    int rc = vm_event_claim_slot(d, d->vm_event_paging);
     if ( rc < 0 )
         return;
 
@@ -1468,7 +1468,7 @@  void p2m_mem_paging_drop_page(struct domain *d, unsigned long gfn,
         /* Evict will fail now, tag this request for pager */
         req.u.mem_paging.flags |= MEM_PAGING_EVICT_FAIL;
 
-    vm_event_put_request(d, &d->vm_event->paging, &req);
+    vm_event_put_request(d, d->vm_event_paging, &req);
 }
 
 /**
@@ -1505,7 +1505,7 @@  void p2m_mem_paging_populate(struct domain *d, unsigned long gfn)
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
 
     /* We're paging. There should be a ring */
-    int rc = vm_event_claim_slot(d, &d->vm_event->paging);
+    int rc = vm_event_claim_slot(d, d->vm_event_paging);
     if ( rc == -ENOSYS )
     {
         gdprintk(XENLOG_ERR, "Domain %hu paging gfn %lx yet no ring "
@@ -1543,7 +1543,7 @@  void p2m_mem_paging_populate(struct domain *d, unsigned long gfn)
     else if ( p2mt != p2m_ram_paging_out && p2mt != p2m_ram_paged )
     {
         /* gfn is already on its way back and vcpu is not paused */
-        vm_event_cancel_slot(d, &d->vm_event->paging);
+        vm_event_cancel_slot(d, d->vm_event_paging);
         return;
     }
 
@@ -1551,7 +1551,7 @@  void p2m_mem_paging_populate(struct domain *d, unsigned long gfn)
     req.u.mem_paging.p2mt = p2mt;
     req.vcpu_id = v->vcpu_id;
 
-    vm_event_put_request(d, &d->vm_event->paging, &req);
+    vm_event_put_request(d, d->vm_event_paging, &req);
 }
 
 /**
diff --git a/xen/common/domain.c b/xen/common/domain.c
index b22aacc..30f507b 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -363,9 +363,6 @@  struct domain *domain_create(domid_t domid, unsigned int domcr_flags,
         poolid = 0;
 
         err = -ENOMEM;
-        d->vm_event = xzalloc(struct vm_event_per_domain);
-        if ( !d->vm_event )
-            goto fail;
 
         d->pbuf = xzalloc_array(char, DOMAIN_PBUF_SIZE);
         if ( !d->pbuf )
@@ -403,7 +400,6 @@  struct domain *domain_create(domid_t domid, unsigned int domcr_flags,
     if ( hardware_domain == d )
         hardware_domain = old_hwdom;
     atomic_set(&d->refcnt, DOMAIN_DESTROYED);
-    xfree(d->vm_event);
     xfree(d->pbuf);
     if ( init_status & INIT_arch )
         arch_domain_destroy(d);
@@ -820,7 +816,14 @@  static void complete_domain_destroy(struct rcu_head *head)
     free_xenoprof_pages(d);
 #endif
 
-    xfree(d->vm_event);
+#ifdef CONFIG_HAS_MEM_PAGING
+    xfree(d->vm_event_paging);
+#endif
+    xfree(d->vm_event_monitor);
+#ifdef CONFIG_HAS_MEM_SHARING
+    xfree(d->vm_event_share);
+#endif
+
     xfree(d->pbuf);
 
     for ( i = d->max_vcpus - 1; i >= 0; i-- )
diff --git a/xen/common/mem_access.c b/xen/common/mem_access.c
index 19f63bb..10ea4ae 100644
--- a/xen/common/mem_access.c
+++ b/xen/common/mem_access.c
@@ -52,7 +52,7 @@  int mem_access_memop(unsigned long cmd,
         goto out;
 
     rc = -ENODEV;
-    if ( unlikely(!d->vm_event->monitor.ring_page) )
+    if ( !d->vm_event_monitor || unlikely(!d->vm_event_monitor->ring_page) )
         goto out;
 
     switch ( mao.op )
diff --git a/xen/common/monitor.c b/xen/common/monitor.c
index 451f42f..70d38d4 100644
--- a/xen/common/monitor.c
+++ b/xen/common/monitor.c
@@ -92,7 +92,7 @@  int monitor_traps(struct vcpu *v, bool_t sync, vm_event_request_t *req)
     int rc;
     struct domain *d = v->domain;
 
-    rc = vm_event_claim_slot(d, &d->vm_event->monitor);
+    rc = vm_event_claim_slot(d, d->vm_event_monitor);
     switch ( rc )
     {
     case 0:
@@ -123,7 +123,7 @@  int monitor_traps(struct vcpu *v, bool_t sync, vm_event_request_t *req)
     }
 
     vm_event_fill_regs(req);
-    vm_event_put_request(d, &d->vm_event->monitor, req);
+    vm_event_put_request(d, d->vm_event_monitor, req);
 
     return rc;
 }
diff --git a/xen/common/vm_event.c b/xen/common/vm_event.c
index 9291db6..e8bba1e 100644
--- a/xen/common/vm_event.c
+++ b/xen/common/vm_event.c
@@ -42,7 +42,7 @@ 
 static int vm_event_enable(
     struct domain *d,
     xen_domctl_vm_event_op_t *vec,
-    struct vm_event_domain *ved,
+    struct vm_event_domain **ved,
     int pause_flag,
     int param,
     xen_event_channel_notification_t notification_fn)
@@ -50,32 +50,37 @@  static int vm_event_enable(
     int rc;
     unsigned long ring_gfn = d->arch.hvm_domain.params[param];
 
+    if ( !*ved )
+        (*ved) = xzalloc(struct vm_event_domain);
+    if ( !*ved )
+        return -ENOMEM;
+
     /* Only one helper at a time. If the helper crashed,
      * the ring is in an undefined state and so is the guest.
      */
-    if ( ved->ring_page )
-        return -EBUSY;
+    if ( (*ved)->ring_page )
+        return -EBUSY;;
 
     /* The parameter defaults to zero, and it should be
      * set to something */
     if ( ring_gfn == 0 )
         return -ENOSYS;
 
-    vm_event_ring_lock_init(ved);
-    vm_event_ring_lock(ved);
+    vm_event_ring_lock_init(*ved);
+    vm_event_ring_lock(*ved);
 
     rc = vm_event_init_domain(d);
 
     if ( rc < 0 )
         goto err;
 
-    rc = prepare_ring_for_helper(d, ring_gfn, &ved->ring_pg_struct,
-                                    &ved->ring_page);
+    rc = prepare_ring_for_helper(d, ring_gfn, &(*ved)->ring_pg_struct,
+                                    &(*ved)->ring_page);
     if ( rc < 0 )
         goto err;
 
     /* Set the number of currently blocked vCPUs to 0. */
-    ved->blocked = 0;
+    (*ved)->blocked = 0;
 
     /* Allocate event channel */
     rc = alloc_unbound_xen_event_channel(d, 0, current->domain->domain_id,
@@ -83,26 +88,28 @@  static int vm_event_enable(
     if ( rc < 0 )
         goto err;
 
-    ved->xen_port = vec->port = rc;
+    (*ved)->xen_port = vec->port = rc;
 
     /* Prepare ring buffer */
-    FRONT_RING_INIT(&ved->front_ring,
-                    (vm_event_sring_t *)ved->ring_page,
+    FRONT_RING_INIT(&(*ved)->front_ring,
+                    (vm_event_sring_t *)(*ved)->ring_page,
                     PAGE_SIZE);
 
     /* Save the pause flag for this particular ring. */
-    ved->pause_flag = pause_flag;
+    (*ved)->pause_flag = pause_flag;
 
     /* Initialize the last-chance wait queue. */
-    init_waitqueue_head(&ved->wq);
+    init_waitqueue_head(&(*ved)->wq);
 
-    vm_event_ring_unlock(ved);
+    vm_event_ring_unlock((*ved));
     return 0;
 
  err:
-    destroy_ring_for_helper(&ved->ring_page,
-                            ved->ring_pg_struct);
-    vm_event_ring_unlock(ved);
+    destroy_ring_for_helper(&(*ved)->ring_page,
+                            (*ved)->ring_pg_struct);
+    vm_event_ring_unlock((*ved));
+    xfree(*ved);
+    *ved = NULL;
 
     return rc;
 }
@@ -187,41 +194,44 @@  void vm_event_wake(struct domain *d, struct vm_event_domain *ved)
         vm_event_wake_blocked(d, ved);
 }
 
-static int vm_event_disable(struct domain *d, struct vm_event_domain *ved)
+static int vm_event_disable(struct domain *d, struct vm_event_domain **ved)
 {
-    if ( ved->ring_page )
+    if ( *ved && (*ved)->ring_page )
     {
         struct vcpu *v;
 
-        vm_event_ring_lock(ved);
+        vm_event_ring_lock(*ved);
 
-        if ( !list_empty(&ved->wq.list) )
+        if ( !list_empty(&(*ved)->wq.list) )
         {
-            vm_event_ring_unlock(ved);
+            vm_event_ring_unlock(*ved);
             return -EBUSY;
         }
 
         /* Free domU's event channel and leave the other one unbound */
-        free_xen_event_channel(d, ved->xen_port);
+        free_xen_event_channel(d, (*ved)->xen_port);
 
         /* Unblock all vCPUs */
         for_each_vcpu ( d, v )
         {
-            if ( test_and_clear_bit(ved->pause_flag, &v->pause_flags) )
+            if ( test_and_clear_bit((*ved)->pause_flag, &v->pause_flags) )
             {
                 vcpu_unpause(v);
-                ved->blocked--;
+                (*ved)->blocked--;
             }
         }
 
-        destroy_ring_for_helper(&ved->ring_page,
-                                ved->ring_pg_struct);
+        destroy_ring_for_helper(&(*ved)->ring_page,
+                                (*ved)->ring_pg_struct);
 
         vm_event_cleanup_domain(d);
 
-        vm_event_ring_unlock(ved);
+        vm_event_ring_unlock(*ved);
     }
 
+    xfree(*ved);
+    *ved = NULL;
+
     return 0;
 }
 
@@ -267,6 +277,9 @@  void vm_event_put_request(struct domain *d,
     RING_IDX req_prod;
     struct vcpu *curr = current;
 
+    if( !ved )
+        return;
+
     if ( curr->domain != d )
     {
         req->flags |= VM_EVENT_FLAG_FOREIGN;
@@ -434,6 +447,9 @@  void vm_event_resume(struct domain *d, struct vm_event_domain *ved)
 
 void vm_event_cancel_slot(struct domain *d, struct vm_event_domain *ved)
 {
+    if( !ved )
+        return;
+
     vm_event_ring_lock(ved);
     vm_event_release_slot(d, ved);
     vm_event_ring_unlock(ved);
@@ -500,6 +516,9 @@  bool_t vm_event_check_ring(struct vm_event_domain *ved)
 int __vm_event_claim_slot(struct domain *d, struct vm_event_domain *ved,
                           bool_t allow_sleep)
 {
+    if ( !ved )
+        return -EOPNOTSUPP;
+
     if ( (current->domain == d) && allow_sleep )
         return vm_event_wait_slot(ved);
     else
@@ -510,24 +529,30 @@  int __vm_event_claim_slot(struct domain *d, struct vm_event_domain *ved,
 /* Registered with Xen-bound event channel for incoming notifications. */
 static void mem_paging_notification(struct vcpu *v, unsigned int port)
 {
-    if ( likely(v->domain->vm_event->paging.ring_page != NULL) )
-        vm_event_resume(v->domain, &v->domain->vm_event->paging);
+    struct domain *domain = v->domain;
+
+    if ( likely(domain->vm_event_paging->ring_page != NULL) )
+        vm_event_resume(domain, domain->vm_event_paging);
 }
 #endif
 
 /* Registered with Xen-bound event channel for incoming notifications. */
 static void monitor_notification(struct vcpu *v, unsigned int port)
 {
-    if ( likely(v->domain->vm_event->monitor.ring_page != NULL) )
-        vm_event_resume(v->domain, &v->domain->vm_event->monitor);
+    struct domain *domain = v->domain;
+
+    if ( likely(domain->vm_event_monitor->ring_page != NULL) )
+        vm_event_resume(domain, domain->vm_event_monitor);
 }
 
 #ifdef CONFIG_HAS_MEM_SHARING
 /* Registered with Xen-bound event channel for incoming notifications. */
 static void mem_sharing_notification(struct vcpu *v, unsigned int port)
 {
-    if ( likely(v->domain->vm_event->share.ring_page != NULL) )
-        vm_event_resume(v->domain, &v->domain->vm_event->share);
+    struct domain *domain = v->domain;
+
+    if ( likely(domain->vm_event_share->ring_page != NULL) )
+        vm_event_resume(domain, domain->vm_event_share);
 }
 #endif
 
@@ -535,7 +560,7 @@  static void mem_sharing_notification(struct vcpu *v, unsigned int port)
 void vm_event_cleanup(struct domain *d)
 {
 #ifdef CONFIG_HAS_MEM_PAGING
-    if ( d->vm_event->paging.ring_page )
+    if ( d->vm_event_paging && d->vm_event_paging->ring_page )
     {
         /* Destroying the wait queue head means waking up all
          * queued vcpus. This will drain the list, allowing
@@ -544,20 +569,20 @@  void vm_event_cleanup(struct domain *d)
          * Finally, because this code path involves previously
          * pausing the domain (domain_kill), unpausing the
          * vcpus causes no harm. */
-        destroy_waitqueue_head(&d->vm_event->paging.wq);
-        (void)vm_event_disable(d, &d->vm_event->paging);
+        destroy_waitqueue_head(&d->vm_event_paging->wq);
+        (void)vm_event_disable(d, &d->vm_event_paging);
     }
 #endif
-    if ( d->vm_event->monitor.ring_page )
+    if ( d->vm_event_monitor && d->vm_event_monitor->ring_page )
     {
-        destroy_waitqueue_head(&d->vm_event->monitor.wq);
-        (void)vm_event_disable(d, &d->vm_event->monitor);
+        destroy_waitqueue_head(&d->vm_event_monitor->wq);
+        (void)vm_event_disable(d, &d->vm_event_monitor);
     }
 #ifdef CONFIG_HAS_MEM_SHARING
-    if ( d->vm_event->share.ring_page )
+    if ( d->vm_event_share && d->vm_event_share->ring_page )
     {
-        destroy_waitqueue_head(&d->vm_event->share.wq);
-        (void)vm_event_disable(d, &d->vm_event->share);
+        destroy_waitqueue_head(&d->vm_event_share->wq);
+        (void)vm_event_disable(d, &d->vm_event_share);
     }
 #endif
 }
@@ -599,7 +624,6 @@  int vm_event_domctl(struct domain *d, xen_domctl_vm_event_op_t *vec,
 #ifdef CONFIG_HAS_MEM_PAGING
     case XEN_DOMCTL_VM_EVENT_OP_PAGING:
     {
-        struct vm_event_domain *ved = &d->vm_event->paging;
         rc = -EINVAL;
 
         switch( vec->op )
@@ -629,24 +653,28 @@  int vm_event_domctl(struct domain *d, xen_domctl_vm_event_op_t *vec,
                 break;
 
             /* domain_pause() not required here, see XSA-99 */
-            rc = vm_event_enable(d, vec, ved, _VPF_mem_paging,
+            rc = vm_event_enable(d, vec, &d->vm_event_paging, _VPF_mem_paging,
                                  HVM_PARAM_PAGING_RING_PFN,
                                  mem_paging_notification);
         }
         break;
 
         case XEN_VM_EVENT_DISABLE:
-            if ( ved->ring_page )
+            if ( !d->vm_event_paging )
+                break;
+            if ( d->vm_event_paging->ring_page )
             {
                 domain_pause(d);
-                rc = vm_event_disable(d, ved);
+                rc = vm_event_disable(d, &d->vm_event_paging);
                 domain_unpause(d);
             }
             break;
 
         case XEN_VM_EVENT_RESUME:
-            if ( ved->ring_page )
-                vm_event_resume(d, ved);
+            if ( !d->vm_event_paging )
+                break;
+            if ( d->vm_event_paging->ring_page )
+                vm_event_resume(d, d->vm_event_paging);
             else
                 rc = -ENODEV;
             break;
@@ -661,7 +689,6 @@  int vm_event_domctl(struct domain *d, xen_domctl_vm_event_op_t *vec,
 
     case XEN_DOMCTL_VM_EVENT_OP_MONITOR:
     {
-        struct vm_event_domain *ved = &d->vm_event->monitor;
         rc = -EINVAL;
 
         switch( vec->op )
@@ -671,24 +698,28 @@  int vm_event_domctl(struct domain *d, xen_domctl_vm_event_op_t *vec,
             rc = arch_monitor_init_domain(d);
             if ( rc )
                 break;
-            rc = vm_event_enable(d, vec, ved, _VPF_mem_access,
+            rc = vm_event_enable(d, vec, &d->vm_event_monitor, _VPF_mem_access,
                                  HVM_PARAM_MONITOR_RING_PFN,
                                  monitor_notification);
             break;
 
         case XEN_VM_EVENT_DISABLE:
-            if ( ved->ring_page )
+            if ( !d->vm_event_monitor )
+                break;
+            if ( d->vm_event_monitor->ring_page )
             {
                 domain_pause(d);
-                rc = vm_event_disable(d, ved);
+                rc = vm_event_disable(d, &d->vm_event_monitor);
                 arch_monitor_cleanup_domain(d);
                 domain_unpause(d);
             }
             break;
 
         case XEN_VM_EVENT_RESUME:
-            if ( ved->ring_page )
-                vm_event_resume(d, ved);
+            if ( !d->vm_event_monitor )
+                break;
+            if ( d->vm_event_monitor->ring_page )
+                vm_event_resume(d, d->vm_event_monitor);
             else
                 rc = -ENODEV;
             break;
@@ -703,7 +734,6 @@  int vm_event_domctl(struct domain *d, xen_domctl_vm_event_op_t *vec,
 #ifdef CONFIG_HAS_MEM_SHARING
     case XEN_DOMCTL_VM_EVENT_OP_SHARING:
     {
-        struct vm_event_domain *ved = &d->vm_event->share;
         rc = -EINVAL;
 
         switch( vec->op )
@@ -720,23 +750,27 @@  int vm_event_domctl(struct domain *d, xen_domctl_vm_event_op_t *vec,
                 break;
 
             /* domain_pause() not required here, see XSA-99 */
-            rc = vm_event_enable(d, vec, ved, _VPF_mem_sharing,
+            rc = vm_event_enable(d, vec, &d->vm_event_share, _VPF_mem_sharing,
                                  HVM_PARAM_SHARING_RING_PFN,
                                  mem_sharing_notification);
             break;
 
         case XEN_VM_EVENT_DISABLE:
-            if ( ved->ring_page )
+            if ( !d->vm_event_share )
+                break;
+            if ( d->vm_event_share->ring_page )
             {
                 domain_pause(d);
-                rc = vm_event_disable(d, ved);
+                rc = vm_event_disable(d, &d->vm_event_share);
                 domain_unpause(d);
             }
             break;
 
         case XEN_VM_EVENT_RESUME:
-            if ( ved->ring_page )
-                vm_event_resume(d, ved);
+            if ( !d->vm_event_share )
+                break;
+            if ( d->vm_event_share->ring_page )
+                vm_event_resume(d, d->vm_event_share);
             else
                 rc = -ENODEV;
             break;
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index 27bdb71..cd1eec5 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -1358,14 +1358,14 @@  static int assign_device(struct domain *d, u16 seg, u8 bus, u8 devfn, u32 flag)
     struct pci_dev *pdev;
     int rc = 0;
 
-    if ( !iommu_enabled || !hd->platform_ops )
+    if ( !iommu_enabled || !hd->platform_ops || !d->vm_event_paging )
         return 0;
 
     /* Prevent device assign if mem paging or mem sharing have been 
      * enabled for this domain */
     if ( unlikely(!need_iommu(d) &&
             (d->arch.hvm_domain.mem_sharing_enabled ||
-             d->vm_event->paging.ring_page ||
+             d->vm_event_paging->ring_page ||
              p2m_get_hostp2m(d)->global_logdirty)) )
         return -EXDEV;
 
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 6673b27..e48487c 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -295,16 +295,6 @@  struct vm_event_domain
     unsigned int last_vcpu_wake_up;
 };
 
-struct vm_event_per_domain
-{
-    /* Memory sharing support */
-    struct vm_event_domain share;
-    /* Memory paging support */
-    struct vm_event_domain paging;
-    /* VM event monitor support */
-    struct vm_event_domain monitor;
-};
-
 struct evtchn_port_ops;
 
 enum guest_type {
@@ -464,7 +454,13 @@  struct domain
     struct lock_profile_qhead profile_head;
 
     /* Various vm_events */
-    struct vm_event_per_domain *vm_event;
+
+    /* Memory sharing support */
+    struct vm_event_domain *vm_event_share;
+    /* Memory paging support */
+    struct vm_event_domain *vm_event_paging;
+    /* VM event monitor support */
+    struct vm_event_domain *vm_event_monitor;
 
     /*
      * Can be specified by the user. If that is not the case, it is