[v2,1/2] introduce GFN notification for translated domains
diff mbox series

Message ID f2232cd2-4786-2b8e-d649-0635309edb92@suse.com
State Superseded
Headers show
Series
  • AMD/IOMMU: re-work mode updating
Related show

Commit Message

Jan Beulich Nov. 14, 2019, 4:43 p.m. UTC
In order for individual IOMMU drivers (and from an abstract pov also
architectures) to be able to adjust, ahead of actual mapping requests,
their data structures when they might cover only a sub-range of all
possible GFNs, introduce a notification call used by various code paths
potentially installing a fresh mapping of a never used GFN (for a
particular domain).

Note that before this patch, in gnttab_transfer(), once past
assign_pages(), further errors modifying the physmap are ignored
(presumably because it would be too complicated to try to roll back at
that point). This patch follows suit by ignoring failed notify_gfn()s or
races due to the need to intermediately drop locks, simply printing out
a warning that the gfn may not be accessible due to the failure.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v2: Introduce arch_notify_gfn(), to invoke gfn_valid() on x86 (this
    unfortunately means it and notify_gfn() now need to be macros, or
    else include file dependencies get in the way, as gfn_valid() lives
    in paging.h, which we shouldn't include from xen/sched.h). Improve
    description.

TBD: Does Arm actually have anything to check against in its
     arch_notify_gfn()?

Comments

Julien Grall Nov. 20, 2019, 8:22 p.m. UTC | #1
Hi Jan,

On 14/11/2019 16:43, Jan Beulich wrote:
> In order for individual IOMMU drivers (and from an abstract pov also
> architectures) to be able to adjust, ahead of actual mapping requests,
> their data structures when they might cover only a sub-range of all
> possible GFNs, introduce a notification call used by various code paths
> potentially installing a fresh mapping of a never used GFN (for a
> particular domain).

If I understand this correctly, this is mostly targeting IOMMNU driver 
where page-table are not shared with the processor. Right?

> 
> Note that before this patch, in gnttab_transfer(), once past
> assign_pages(), further errors modifying the physmap are ignored
> (presumably because it would be too complicated to try to roll back at
> that point). This patch follows suit by ignoring failed notify_gfn()s or
> races due to the need to intermediately drop locks, simply printing out
> a warning that the gfn may not be accessible due to the failure.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> ---
> v2: Introduce arch_notify_gfn(), to invoke gfn_valid() on x86 (this
>      unfortunately means it and notify_gfn() now need to be macros, or
>      else include file dependencies get in the way, as gfn_valid() lives
>      in paging.h, which we shouldn't include from xen/sched.h). Improve
>      description.
> 
> TBD: Does Arm actually have anything to check against in its
>       arch_notify_gfn()?

I understand that we want to keep the code mostly generic, but I am a 
bit concerned of the extra cost to use notify_gfn() (and indirectly 
iommu_notify_gfn()) for doing nothing.

I can't see any direct use of this for the foreseable future on Arm. So 
could we gate this under a config option?

> 
> --- a/xen/arch/x86/hvm/dom0_build.c
> +++ b/xen/arch/x86/hvm/dom0_build.c
> @@ -173,7 +173,8 @@ static int __init pvh_populate_memory_ra
>               continue;
>           }
>   
> -        rc = guest_physmap_add_page(d, _gfn(start), page_to_mfn(page),
> +        rc = notify_gfn(d, _gfn(start + (1UL << order) - 1)) ?:
> +             guest_physmap_add_page(d, _gfn(start), page_to_mfn(page),
>                                       order);
>           if ( rc != 0 )
>           {
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -4304,9 +4304,17 @@ static int hvmop_set_param(
>           if ( a.value > SHUTDOWN_MAX )
>               rc = -EINVAL;
>           break;
> +
>       case HVM_PARAM_IOREQ_SERVER_PFN:
> -        d->arch.hvm.ioreq_gfn.base = a.value;
> +        if ( d->arch.hvm.params[HVM_PARAM_NR_IOREQ_SERVER_PAGES] )
> +            rc = notify_gfn(
> +                     d,
> +                     _gfn(a.value + d->arch.hvm.params
> +                                    [HVM_PARAM_NR_IOREQ_SERVER_PAGES] - 1));
> +        if ( !rc )
> +             d->arch.hvm.ioreq_gfn.base = a.value;
>           break;
> +
>       case HVM_PARAM_NR_IOREQ_SERVER_PAGES:
>       {
>           unsigned int i;
> @@ -4317,6 +4325,9 @@ static int hvmop_set_param(
>               rc = -EINVAL;
>               break;
>           }
> +        rc = notify_gfn(d, _gfn(d->arch.hvm.ioreq_gfn.base + a.value - 1));
> +        if ( rc )
> +            break;
>           for ( i = 0; i < a.value; i++ )
>               set_bit(i, &d->arch.hvm.ioreq_gfn.mask);
>   
> @@ -4330,7 +4341,11 @@ static int hvmop_set_param(
>           BUILD_BUG_ON(HVM_PARAM_BUFIOREQ_PFN >
>                        sizeof(d->arch.hvm.ioreq_gfn.legacy_mask) * 8);
>           if ( a.value )
> -            set_bit(a.index, &d->arch.hvm.ioreq_gfn.legacy_mask);
> +        {
> +            rc = notify_gfn(d, _gfn(a.value));
> +            if ( !rc )
> +                set_bit(a.index, &d->arch.hvm.ioreq_gfn.legacy_mask);
> +        }
>           break;
>   
>       case HVM_PARAM_X87_FIP_WIDTH:
> --- a/xen/common/grant_table.c
> +++ b/xen/common/grant_table.c
> @@ -946,6 +946,16 @@ map_grant_ref(
>           return;
>       }
>   
> +    if ( paging_mode_translate(ld) /* && (op->flags & GNTMAP_host_map) */ &&

I think this wants an explanation in the code why the check is commented.

Cheers,
Jan Beulich Nov. 21, 2019, 9:04 a.m. UTC | #2
On 20.11.2019 21:22, Julien Grall wrote:
> On 14/11/2019 16:43, Jan Beulich wrote:
>> In order for individual IOMMU drivers (and from an abstract pov also
>> architectures) to be able to adjust, ahead of actual mapping requests,
>> their data structures when they might cover only a sub-range of all
>> possible GFNs, introduce a notification call used by various code paths
>> potentially installing a fresh mapping of a never used GFN (for a
>> particular domain).
> 
> If I understand this correctly, this is mostly targeting IOMMNU driver 
> where page-table are not shared with the processor. Right?

Yes - with shared page tables there's no separate handling of
IOMMU (un)mappings in the first place.

>> TBD: Does Arm actually have anything to check against in its
>>       arch_notify_gfn()?
> 
> I understand that we want to keep the code mostly generic, but I am a 
> bit concerned of the extra cost to use notify_gfn() (and indirectly 
> iommu_notify_gfn()) for doing nothing.
> 
> I can't see any direct use of this for the foreseable future on Arm. So 
> could we gate this under a config option?

This is an option, sure. Alternatively I could see about making this
an inline function, but iirc there were header dependency issues.
Then again - is a call to a function doing almost nothing really so
much extra overhead on Arm?

>> --- a/xen/common/grant_table.c
>> +++ b/xen/common/grant_table.c
>> @@ -946,6 +946,16 @@ map_grant_ref(
>>           return;
>>       }
>>   
>> +    if ( paging_mode_translate(ld) /* && (op->flags & GNTMAP_host_map) */ &&
> 
> I think this wants an explanation in the code why the check is commented.

Hmm, in such a case I'd rather omit the commented condition. It
being commented has the purpose of documenting itself.

Jan
Julien Grall Nov. 21, 2019, 10:07 a.m. UTC | #3
On 21/11/2019 09:04, Jan Beulich wrote:
> On 20.11.2019 21:22, Julien Grall wrote:
>> On 14/11/2019 16:43, Jan Beulich wrote:
>>> In order for individual IOMMU drivers (and from an abstract pov also
>>> architectures) to be able to adjust, ahead of actual mapping requests,
>>> their data structures when they might cover only a sub-range of all
>>> possible GFNs, introduce a notification call used by various code paths
>>> potentially installing a fresh mapping of a never used GFN (for a
>>> particular domain).
>>
>> If I understand this correctly, this is mostly targeting IOMMNU driver
>> where page-table are not shared with the processor. Right?
> 
> Yes - with shared page tables there's no separate handling of
> IOMMU (un)mappings in the first place.
> 
>>> TBD: Does Arm actually have anything to check against in its
>>>        arch_notify_gfn()?
>>
>> I understand that we want to keep the code mostly generic, but I am a
>> bit concerned of the extra cost to use notify_gfn() (and indirectly
>> iommu_notify_gfn()) for doing nothing.
>>
>> I can't see any direct use of this for the foreseable future on Arm. So
>> could we gate this under a config option?
> 
> This is an option, sure. Alternatively I could see about making this
> an inline function, but iirc there were header dependency issues.
> Then again - is a call to a function doing almost nothing really so
> much extra overhead on Arm.

AFAICT, this is a workaround for AMD driver. So any impact (no matter 
the size) feels not right for Arm.

In this particular case, the only thing I request is to protect the 
notify_gfn & callback with !CONFIG_IOMMU_FORCE_SHARE.

> 
>>> --- a/xen/common/grant_table.c
>>> +++ b/xen/common/grant_table.c
>>> @@ -946,6 +946,16 @@ map_grant_ref(
>>>            return;
>>>        }
>>>    
>>> +    if ( paging_mode_translate(ld) /* && (op->flags & GNTMAP_host_map) */ &&
>>
>> I think this wants an explanation in the code why the check is commented.
> 
> Hmm, in such a case I'd rather omit the commented condition. It
> being commented has the purpose of documenting itself.

I fail to understand why GNTMAP_host_map would always be true in the case.

AFAIU the code, this is only correct for paging_mode_external(ld) == 1. 
Does it mean that paging_mode_translate(ld) and paging_mode_external(ld) 
are always equal? If so, what's the point of having two macro (and two 
flags)?

Cheers,
Jan Beulich Nov. 21, 2019, 10:41 a.m. UTC | #4
On 21.11.2019 11:07, Julien Grall wrote:
> 
> 
> On 21/11/2019 09:04, Jan Beulich wrote:
>> On 20.11.2019 21:22, Julien Grall wrote:
>>> On 14/11/2019 16:43, Jan Beulich wrote:
>>>> TBD: Does Arm actually have anything to check against in its
>>>>        arch_notify_gfn()?
>>>
>>> I understand that we want to keep the code mostly generic, but I am a
>>> bit concerned of the extra cost to use notify_gfn() (and indirectly
>>> iommu_notify_gfn()) for doing nothing.
>>>
>>> I can't see any direct use of this for the foreseable future on Arm. So
>>> could we gate this under a config option?
>>
>> This is an option, sure. Alternatively I could see about making this
>> an inline function, but iirc there were header dependency issues.
>> Then again - is a call to a function doing almost nothing really so
>> much extra overhead on Arm.
> 
> AFAICT, this is a workaround for AMD driver. So any impact (no matter 
> the size) feels not right for Arm.
> 
> In this particular case, the only thing I request is to protect the 
> notify_gfn & callback with !CONFIG_IOMMU_FORCE_SHARE.

Oh, there already is a suitable config option. Will do (and
cover share_p2m_table() at the same time).

>>>> --- a/xen/common/grant_table.c
>>>> +++ b/xen/common/grant_table.c
>>>> @@ -946,6 +946,16 @@ map_grant_ref(
>>>>            return;
>>>>        }
>>>>    
>>>> +    if ( paging_mode_translate(ld) /* && (op->flags & GNTMAP_host_map) */ &&
>>>
>>> I think this wants an explanation in the code why the check is commented.
>>
>> Hmm, in such a case I'd rather omit the commented condition. It
>> being commented has the purpose of documenting itself.
> 
> I fail to understand why GNTMAP_host_map would always be true in the case.
> 
> AFAIU the code, this is only correct for paging_mode_external(ld) == 1. 
> Does it mean that paging_mode_translate(ld) and paging_mode_external(ld) 
> are always equal? If so, what's the point of having two macro (and two 
> flags)?

Historical reasons. Nowadays translate == external == refcounts on
x86. But since this is common code, perhaps I better un-comment that
part of the conditional.

Jan
Julien Grall Nov. 23, 2019, 5:55 p.m. UTC | #5
Hi Jan,

On 21/11/2019 10:41, Jan Beulich wrote:
> On 21.11.2019 11:07, Julien Grall wrote:
>>
>>
>> On 21/11/2019 09:04, Jan Beulich wrote:
>>> On 20.11.2019 21:22, Julien Grall wrote:
>>>> On 14/11/2019 16:43, Jan Beulich wrote:
>>>>> TBD: Does Arm actually have anything to check against in its
>>>>>         arch_notify_gfn()?
>>>>
>>>> I understand that we want to keep the code mostly generic, but I am a
>>>> bit concerned of the extra cost to use notify_gfn() (and indirectly
>>>> iommu_notify_gfn()) for doing nothing.
>>>>
>>>> I can't see any direct use of this for the foreseable future on Arm. So
>>>> could we gate this under a config option?
>>>
>>> This is an option, sure. Alternatively I could see about making this
>>> an inline function, but iirc there were header dependency issues.
>>> Then again - is a call to a function doing almost nothing really so
>>> much extra overhead on Arm.
>>
>> AFAICT, this is a workaround for AMD driver. So any impact (no matter
>> the size) feels not right for Arm.
>>
>> In this particular case, the only thing I request is to protect the
>> notify_gfn & callback with !CONFIG_IOMMU_FORCE_SHARE.
> 
> Oh, there already is a suitable config option. Will do (and
> cover share_p2m_table() at the same time).
> 
>>>>> --- a/xen/common/grant_table.c
>>>>> +++ b/xen/common/grant_table.c
>>>>> @@ -946,6 +946,16 @@ map_grant_ref(
>>>>>             return;
>>>>>         }
>>>>>     
>>>>> +    if ( paging_mode_translate(ld) /* && (op->flags & GNTMAP_host_map) */ &&
>>>>
>>>> I think this wants an explanation in the code why the check is commented.
>>>
>>> Hmm, in such a case I'd rather omit the commented condition. It
>>> being commented has the purpose of documenting itself.
>>
>> I fail to understand why GNTMAP_host_map would always be true in the case.
>>
>> AFAIU the code, this is only correct for paging_mode_external(ld) == 1.
>> Does it mean that paging_mode_translate(ld) and paging_mode_external(ld)
>> are always equal? If so, what's the point of having two macro (and two
>> flags)?
> 
> Historical reasons. Nowadays translate == external == refcounts on
> x86. But since this is common code, perhaps I better un-comment that
> part of the conditional.

For this patch, this would be the ideal solution.

We might want to consider to reduce to one macro (maybe 
paging_mode_translate()) if we don't expect new architecture to return a 
different value for those 3 macros.

Cheers,

Patch
diff mbox series

--- a/xen/arch/x86/hvm/dom0_build.c
+++ b/xen/arch/x86/hvm/dom0_build.c
@@ -173,7 +173,8 @@  static int __init pvh_populate_memory_ra
             continue;
         }
 
-        rc = guest_physmap_add_page(d, _gfn(start), page_to_mfn(page),
+        rc = notify_gfn(d, _gfn(start + (1UL << order) - 1)) ?:
+             guest_physmap_add_page(d, _gfn(start), page_to_mfn(page),
                                     order);
         if ( rc != 0 )
         {
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4304,9 +4304,17 @@  static int hvmop_set_param(
         if ( a.value > SHUTDOWN_MAX )
             rc = -EINVAL;
         break;
+
     case HVM_PARAM_IOREQ_SERVER_PFN:
-        d->arch.hvm.ioreq_gfn.base = a.value;
+        if ( d->arch.hvm.params[HVM_PARAM_NR_IOREQ_SERVER_PAGES] )
+            rc = notify_gfn(
+                     d,
+                     _gfn(a.value + d->arch.hvm.params
+                                    [HVM_PARAM_NR_IOREQ_SERVER_PAGES] - 1));
+        if ( !rc )
+             d->arch.hvm.ioreq_gfn.base = a.value;
         break;
+
     case HVM_PARAM_NR_IOREQ_SERVER_PAGES:
     {
         unsigned int i;
@@ -4317,6 +4325,9 @@  static int hvmop_set_param(
             rc = -EINVAL;
             break;
         }
+        rc = notify_gfn(d, _gfn(d->arch.hvm.ioreq_gfn.base + a.value - 1));
+        if ( rc )
+            break;
         for ( i = 0; i < a.value; i++ )
             set_bit(i, &d->arch.hvm.ioreq_gfn.mask);
 
@@ -4330,7 +4341,11 @@  static int hvmop_set_param(
         BUILD_BUG_ON(HVM_PARAM_BUFIOREQ_PFN >
                      sizeof(d->arch.hvm.ioreq_gfn.legacy_mask) * 8);
         if ( a.value )
-            set_bit(a.index, &d->arch.hvm.ioreq_gfn.legacy_mask);
+        {
+            rc = notify_gfn(d, _gfn(a.value));
+            if ( !rc )
+                set_bit(a.index, &d->arch.hvm.ioreq_gfn.legacy_mask);
+        }
         break;
 
     case HVM_PARAM_X87_FIP_WIDTH:
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -946,6 +946,16 @@  map_grant_ref(
         return;
     }
 
+    if ( paging_mode_translate(ld) /* && (op->flags & GNTMAP_host_map) */ &&
+         (rc = notify_gfn(ld, gaddr_to_gfn(op->host_addr))) )
+    {
+        gdprintk(XENLOG_INFO, "notify(%"PRI_gfn") -> %d\n",
+                 gfn_x(gaddr_to_gfn(op->host_addr)), rc);
+        op->status = GNTST_general_error;
+        return;
+        BUILD_BUG_ON(GNTST_okay);
+    }
+
     if ( unlikely((rd = rcu_lock_domain_by_id(op->dom)) == NULL) )
     {
         gdprintk(XENLOG_INFO, "Could not find domain %d\n", op->dom);
@@ -2123,6 +2133,7 @@  gnttab_transfer(
     {
         bool_t okay;
         int rc;
+        gfn_t gfn;
 
         if ( i && hypercall_preempt_check() )
             return i;
@@ -2300,21 +2311,52 @@  gnttab_transfer(
         act = active_entry_acquire(e->grant_table, gop.ref);
 
         if ( evaluate_nospec(e->grant_table->gt_version == 1) )
+            gfn = _gfn(shared_entry_v1(e->grant_table, gop.ref).frame);
+        else
+            gfn = _gfn(shared_entry_v2(e->grant_table, gop.ref).full_page.frame);
+
+        if ( paging_mode_translate(e) )
         {
-            grant_entry_v1_t *sha = &shared_entry_v1(e->grant_table, gop.ref);
+            gfn_t gfn2;
+
+            active_entry_release(act);
+            grant_read_unlock(e->grant_table);
+
+            rc = notify_gfn(e, gfn);
+            if ( rc )
+                printk(XENLOG_G_WARNING
+                       "%pd: gref %u: xfer GFN %"PRI_gfn" may be inaccessible (%d)\n",
+                       e, gop.ref, gfn_x(gfn), rc);
+
+            grant_read_lock(e->grant_table);
+            act = active_entry_acquire(e->grant_table, gop.ref);
 
-            guest_physmap_add_page(e, _gfn(sha->frame), mfn, 0);
-            if ( !paging_mode_translate(e) )
-                sha->frame = mfn_x(mfn);
+            if ( evaluate_nospec(e->grant_table->gt_version == 1) )
+                gfn2 = _gfn(shared_entry_v1(e->grant_table, gop.ref).frame);
+            else
+                gfn2 = _gfn(shared_entry_v2(e->grant_table, gop.ref).
+                    full_page.frame);
+
+            if ( !gfn_eq(gfn, gfn2) )
+            {
+                printk(XENLOG_G_WARNING
+                       "%pd: gref %u: xfer GFN went %"PRI_gfn" -> %"PRI_gfn"\n",
+                       e, gop.ref, gfn_x(gfn), gfn_x(gfn2));
+                gfn = gfn2;
+            }
         }
-        else
-        {
-            grant_entry_v2_t *sha = &shared_entry_v2(e->grant_table, gop.ref);
 
-            guest_physmap_add_page(e, _gfn(sha->full_page.frame), mfn, 0);
-            if ( !paging_mode_translate(e) )
-                sha->full_page.frame = mfn_x(mfn);
+        guest_physmap_add_page(e, gfn, mfn, 0);
+
+        if ( !paging_mode_translate(e) )
+        {
+            if ( evaluate_nospec(e->grant_table->gt_version == 1) )
+                shared_entry_v1(e->grant_table, gop.ref).frame = mfn_x(mfn);
+            else
+                shared_entry_v2(e->grant_table, gop.ref).full_page.frame =
+                    mfn_x(mfn);
         }
+
         smp_wmb();
         shared_entry_header(e->grant_table, gop.ref)->flags |=
             GTF_transfer_completed;
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -203,6 +203,10 @@  static void populate_physmap(struct memo
         if ( unlikely(__copy_from_guest_offset(&gpfn, a->extent_list, i, 1)) )
             goto out;
 
+        if ( paging_mode_translate(d) &&
+             notify_gfn(d, _gfn(gpfn + (1U << a->extent_order) - 1)) )
+            goto out;
+
         if ( a->memflags & MEMF_populate_on_demand )
         {
             /* Disallow populating PoD pages on oneself. */
@@ -745,6 +749,10 @@  static long memory_exchange(XEN_GUEST_HA
                 continue;
             }
 
+            if ( paging_mode_translate(d) )
+                rc = notify_gfn(d,
+                                _gfn(gpfn + (1U << exch.out.extent_order) - 1));
+
             mfn = page_to_mfn(page);
             guest_physmap_add_page(d, _gfn(gpfn), mfn,
                                    exch.out.extent_order);
@@ -813,12 +821,20 @@  int xenmem_add_to_physmap(struct domain
         extra.foreign_domid = DOMID_INVALID;
 
     if ( xatp->space != XENMAPSPACE_gmfn_range )
-        return xenmem_add_to_physmap_one(d, xatp->space, extra,
+        return notify_gfn(d, _gfn(xatp->gpfn)) ?:
+               xenmem_add_to_physmap_one(d, xatp->space, extra,
                                          xatp->idx, _gfn(xatp->gpfn));
 
     if ( xatp->size < start )
         return -EILSEQ;
 
+    if ( !start && xatp->size )
+    {
+        rc = notify_gfn(d, _gfn(xatp->gpfn + xatp->size - 1));
+        if ( rc )
+            return rc;
+    }
+
     xatp->idx += start;
     xatp->gpfn += start;
     xatp->size -= start;
@@ -891,7 +907,8 @@  static int xenmem_add_to_physmap_batch(s
                                                extent, 1)) )
             return -EFAULT;
 
-        rc = xenmem_add_to_physmap_one(d, xatpb->space,
+        rc = notify_gfn(d, _gfn(gpfn)) ?:
+             xenmem_add_to_physmap_one(d, xatpb->space,
                                        xatpb->u,
                                        idx, _gfn(gpfn));
 
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -530,6 +530,14 @@  void iommu_share_p2m_table(struct domain
         iommu_get_ops()->share_p2m(d);
 }
 
+int iommu_notify_gfn(struct domain *d, gfn_t gfn)
+{
+    const struct iommu_ops *ops = dom_iommu(d)->platform_ops;
+
+    return need_iommu_pt_sync(d) && ops->notify_dfn
+           ? iommu_call(ops, notify_dfn, d, _dfn(gfn_x(gfn))) : 0;
+}
+
 void iommu_crash_shutdown(void)
 {
     if ( !iommu_crash_disable )
--- a/xen/include/asm-arm/domain.h
+++ b/xen/include/asm-arm/domain.h
@@ -272,6 +272,8 @@  static inline void free_vcpu_guest_conte
 
 static inline void arch_vcpu_block(struct vcpu *v) {}
 
+#define arch_notify_gfn(d, gfn) ((void)(d), (void)(gfn), 0)
+
 #endif /* __ASM_DOMAIN_H__ */
 
 /*
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -647,6 +647,8 @@  static inline void free_vcpu_guest_conte
 
 void arch_vcpu_regs_init(struct vcpu *v);
 
+#define arch_notify_gfn(d, gfn) (gfn_valid(d, gfn) ? 0 : -EADDRNOTAVAIL)
+
 struct vcpu_hvm_context;
 int arch_set_info_hvm_guest(struct vcpu *v, const struct vcpu_hvm_context *ctx);
 
--- a/xen/include/xen/iommu.h
+++ b/xen/include/xen/iommu.h
@@ -237,6 +237,8 @@  struct iommu_ops {
     int __must_check (*lookup_page)(struct domain *d, dfn_t dfn, mfn_t *mfn,
                                     unsigned int *flags);
 
+    int __must_check (*notify_dfn)(struct domain *d, dfn_t dfn);
+
     void (*free_page_table)(struct page_info *);
 
 #ifdef CONFIG_X86
@@ -331,6 +333,7 @@  void iommu_crash_shutdown(void);
 int iommu_get_reserved_device_memory(iommu_grdm_t *, void *);
 
 void iommu_share_p2m_table(struct domain *d);
+int __must_check iommu_notify_gfn(struct domain *d, gfn_t gfn);
 
 #ifdef CONFIG_HAS_PCI
 int iommu_do_pci_domctl(struct xen_domctl *, struct domain *d,
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -1039,6 +1039,8 @@  static always_inline bool is_iommu_enabl
     return evaluate_nospec(d->options & XEN_DOMCTL_CDF_iommu);
 }
 
+#define notify_gfn(d, gfn) (arch_notify_gfn(d, gfn) ?: iommu_notify_gfn(d, gfn))
+
 extern bool sched_smt_power_savings;
 extern bool sched_disable_smt_switching;