[PATCH] [VTD] Separate VT-d page table from P2M table

[PATCH] [VTD] Separate VT-d page table from P2M table

[Han, Weidong]

[-- Attachment #1: Type: text/plain, Size: 679 bytes --]

Currently VT-d page table shares with P2M table, this patch supports
separate VT-d page table. 
1) add an option (vtd_share) to control whether VT-d page table shares
with P2M table or not.
2) in p2m_set_entry(), map/unmap page in VT-d page table. And also add a
function to free VT-d page table when tear down. 
3) allocate extra memory for VT-d page table when allocate memory for
doamin. 

In addition, when VT-d page table shares with P2M table,  remove the if
conditional judgement for iommu_flush(). Or there is opential issue when
using balloon driver. 

Signed-off-by: Weidong Han <weidong.han@intel.com>
Signed-off-by: Anthony Xu <anthony.xu@intel.com>


[-- Attachment #2: vtd-sep.patch --]
[-- Type: application/octet-stream, Size: 4917 bytes --]

diff -r a4136cb2e23f tools/python/xen/xend/XendDomainInfo.py
--- a/tools/python/xen/xend/XendDomainInfo.py	Tue Apr 22 13:39:29 2008 +0800
+++ b/tools/python/xen/xend/XendDomainInfo.py	Tue Apr 22 14:14:04 2008 +0800
@@ -2132,8 +2132,13 @@ class XendDomainInfo:
             # set memory limit
             xc.domain_setmaxmem(self.domid, maxmem)
 
+            # Reserve 1 page per MiB of RAM for separate VT-d page table.
+            vtd_mem = 4 * (self.info['memory_static_max'] / 1024 / 1024)
+            # Round vtd_mem up to a multiple of a MiB.
+            vtd_mem = ((vtd_mem + 1023) / 1024) * 1024
+
             # Make sure there's enough RAM available for the domain
-            balloon.free(memory + shadow)
+            balloon.free(memory + shadow + vtd_mem)
 
             # Set up the shadow memory
             shadow_cur = xc.shadow_mem_control(self.domid, shadow / 1024)
diff -r a4136cb2e23f xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c	Tue Apr 22 13:39:29 2008 +0800
+++ b/xen/arch/x86/mm/p2m.c	Tue Apr 22 14:19:23 2008 +0800
@@ -259,12 +259,9 @@ p2m_set_entry(struct domain *d, unsigned
 
     if ( iommu_enabled && is_hvm_domain(d) )
     {
-        if ( boot_cpu_data.x86_vendor == X86_VENDOR_INTEL )
-        {
-            if ( (p2mt == p2m_mmio_direct) )
-                iommu_flush(d, gfn, (u64*)p2m_entry);
-        }
-        else if ( boot_cpu_data.x86_vendor == X86_VENDOR_AMD )
+        if ( vtd_share )
+            iommu_flush(d, gfn, (u64*)p2m_entry);
+        else
         {
             if ( p2mt == p2m_ram_rw )
                 iommu_map_page(d, gfn, mfn_x(mfn));
@@ -530,7 +527,7 @@ int p2m_alloc_table(struct domain *d,
     }
 
 #if CONFIG_PAGING_LEVELS >= 3
-    if (vtd_enabled && is_hvm_domain(d))
+    if ( vtd_share && vtd_enabled && is_hvm_domain(d) )
         iommu_set_pgd(d);
 #endif
 
diff -r a4136cb2e23f xen/drivers/passthrough/vtd/dmar.c
--- a/xen/drivers/passthrough/vtd/dmar.c	Tue Apr 22 13:39:29 2008 +0800
+++ b/xen/drivers/passthrough/vtd/dmar.c	Tue Apr 22 14:14:04 2008 +0800
@@ -32,6 +32,10 @@
 
 int vtd_enabled = 1;
 
+/* Specify whether VT-d page table shares with P2M table or not. */
+int vtd_share;
+boolean_param("vtd_share", vtd_share);
+
 #undef PREFIX
 #define PREFIX VTDPREFIX "ACPI DMAR:"
 #define DEBUG
diff -r a4136cb2e23f xen/drivers/passthrough/vtd/iommu.c
--- a/xen/drivers/passthrough/vtd/iommu.c	Tue Apr 22 13:39:29 2008 +0800
+++ b/xen/drivers/passthrough/vtd/iommu.c	Tue Apr 22 14:14:04 2008 +0800
@@ -676,6 +676,58 @@ void dma_pte_free_pagetable(struct domai
     {
         free_pgtable_maddr(hd->pgd_maddr);
         hd->pgd_maddr = 0;
+    }
+}
+
+/* If VT-d page table doesn't share with p2m table, need to free
+ * VT-d page table explicitely when shut down or destroy domain.
+ */
+static void iommu_free_pagetable(struct domain *domain)
+{
+    struct hvm_iommu *hd = domain_hvm_iommu(domain);
+    int addr_width = agaw_to_width(hd->agaw);
+    int total_level = agaw_to_level(hd->agaw);
+    struct acpi_drhd_unit *drhd;
+    struct iommu *iommu;
+    int level;
+    struct dma_pte *page, *pte;
+    u64 pg_maddr, tmp;
+    u64 start, end;
+
+    if ( !vtd_share )
+    {
+        drhd = list_entry(acpi_drhd_units.next, typeof(*drhd), list);
+        iommu = drhd->iommu;
+
+        start = 0;
+        end = (((u64)1) << addr_width) - 1;
+
+        level = 2;
+        while ( level <= total_level )
+        {
+            tmp = align_to_level(start, level);
+            if ( (tmp >= end) || ((tmp + level_size(level)) > end) )
+                break;
+
+            while ( tmp < end )
+            {
+                pg_maddr = dma_addr_level_page_maddr(domain, tmp, level);
+                if ( pg_maddr == 0 )
+                {
+                    tmp += level_size(level);
+                    continue;
+                }
+                page = (struct dma_pte *)map_vtd_domain_page(pg_maddr);
+                pte = page + address_level_offset(tmp, level);
+                dma_clear_pte(*pte);
+                iommu_flush_cache_entry(iommu, pte);
+                unmap_vtd_domain_page(page);
+                free_pgtable_maddr(pg_maddr);
+
+                tmp += level_size(level);
+            }
+            level++;
+        }
     }
 }
 
@@ -1529,9 +1581,10 @@ void iommu_domain_teardown(struct domain
     if ( list_empty(&acpi_drhd_units) )
         return;
 
-    iommu_domid_release(d);
+    iommu_free_pagetable(d);
     iommu_free_pgd(d);
     return_devices_to_dom0(d);
+    iommu_domid_release(d);
 }
 
 static int domain_context_mapped(struct pci_dev *pdev)
diff -r a4136cb2e23f xen/include/xen/iommu.h
--- a/xen/include/xen/iommu.h	Tue Apr 22 13:39:29 2008 +0800
+++ b/xen/include/xen/iommu.h	Tue Apr 22 14:14:04 2008 +0800
@@ -26,6 +26,7 @@
 #include <public/hvm/ioreq.h>
 #include <public/domctl.h>
 
+extern int vtd_share;
 extern int vtd_enabled;
 extern int iommu_enabled;
 

[-- Attachment #3: Type: text/plain, Size: 138 bytes --]

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Re: [PATCH] [VTD] Separate VT-d page table from P2M table

[Keir Fraser]

On 22/4/08 09:36, "Han, Weidong" <weidong.han@intel.com> wrote:

> Currently VT-d page table shares with P2M table, this patch supports
> separate VT-d page table.
> 1) add an option (vtd_share) to control whether VT-d page table shares
> with P2M table or not.

Why? Is this just another option that noone will understand.

 -- Keir

RE: [PATCH] [VTD] Separate VT-d page table from P2M table

[Han, Weidong]

Separate VT-d page table is by default. Shared VT-d page table may be
easy and good in some cases. So we let them co-exist now. If shared VT-d
page table is not necessary and useless, we can remove it easily in
future.

Randy (weidong)

Keir Fraser wrote:
> On 22/4/08 09:36, "Han, Weidong" <weidong.han@intel.com> wrote:
> 
>> Currently VT-d page table shares with P2M table, this patch supports
>> separate VT-d page table. 1) add an option (vtd_share) to control
>> whether VT-d page table shares with P2M table or not.
> 
> Why? Is this just another option that noone will understand.
> 
>  -- Keir

Re: [PATCH] [VTD] Separate VT-d page table from P2M table

[Keir Fraser]

What are the tradeoffs? One obvious tradeoff is that separate tables doubles
the memory overhead. What are the advantages of separate tables? I believe
currently we share the pagetables (right?). If so, why would we even
consider moving to separate tables?

 -- Keir

On 22/4/08 10:34, "Han, Weidong" <weidong.han@intel.com> wrote:

> Separate VT-d page table is by default. Shared VT-d page table may be
> easy and good in some cases. So we let them co-exist now. If shared VT-d
> page table is not necessary and useless, we can remove it easily in
> future.
> 
> Randy (weidong)
> 
> Keir Fraser wrote:
>> On 22/4/08 09:36, "Han, Weidong" <weidong.han@intel.com> wrote:
>> 
>>> Currently VT-d page table shares with P2M table, this patch supports
>>> separate VT-d page table. 1) add an option (vtd_share) to control
>>> whether VT-d page table shares with P2M table or not.
>> 
>> Why? Is this just another option that noone will understand.
>> 
>>  -- Keir
> 

RE: [PATCH] [VTD] Separate VT-d page table from P2M table

[Han, Weidong]

If EPT supports 2MB page, we need separate VT-d table to let them work
together. What's more, sharing makes coupling between VT-d page table
and p2m table. In case VT-d spec changes or p2m structure changes,
shared table will be broken.

Randy (Weidong)

Keir Fraser wrote:
> What are the tradeoffs? One obvious tradeoff is that separate tables
> doubles the memory overhead. What are the advantages of separate
> tables? I believe currently we share the pagetables (right?). If so,
> why would we even consider moving to separate tables?
> 
>  -- Keir
> 
> On 22/4/08 10:34, "Han, Weidong" <weidong.han@intel.com> wrote:
> 
>> Separate VT-d page table is by default. Shared VT-d page table may be
>> easy and good in some cases. So we let them co-exist now. If shared
>> VT-d page table is not necessary and useless, we can remove it
>> easily in future. 
>> 
>> Randy (weidong)
>> 
>> Keir Fraser wrote:
>>> On 22/4/08 09:36, "Han, Weidong" <weidong.han@intel.com> wrote:
>>> 
>>>> Currently VT-d page table shares with P2M table, this patch
>>>> supports separate VT-d page table. 1) add an option (vtd_share) to
>>>> control whether VT-d page table shares with P2M table or not.
>>> 
>>> Why? Is this just another option that noone will understand.
>>> 
>>>  -- Keir

RE: [PATCH] [VTD] Separate VT-d page table from P2M table

[Ian Pratt]

> If EPT supports 2MB page, we need separate VT-d table to let them work
> together. 

Are you saying that the VT-d 2MB page format is different from the EPT
2MB page format? Or that VTd does not support 2MB pages?

Ian

> What's more, sharing makes coupling between VT-d page table
> and p2m table. In case VT-d spec changes or p2m structure changes,
> shared table will be broken.

> Randy (Weidong)
> 
> Keir Fraser wrote:
> > What are the tradeoffs? One obvious tradeoff is that separate tables
> > doubles the memory overhead. What are the advantages of separate
> > tables? I believe currently we share the pagetables (right?). If so,
> > why would we even consider moving to separate tables?
> >
> >  -- Keir
> >
> > On 22/4/08 10:34, "Han, Weidong" <weidong.han@intel.com> wrote:
> >
> >> Separate VT-d page table is by default. Shared VT-d page table may
> be
> >> easy and good in some cases. So we let them co-exist now. If shared
> >> VT-d page table is not necessary and useless, we can remove it
> >> easily in future.
> >>
> >> Randy (weidong)
> >>
> >> Keir Fraser wrote:
> >>> On 22/4/08 09:36, "Han, Weidong" <weidong.han@intel.com> wrote:
> >>>
> >>>> Currently VT-d page table shares with P2M table, this patch
> >>>> supports separate VT-d page table. 1) add an option (vtd_share)
to
> >>>> control whether VT-d page table shares with P2M table or not.
> >>>
> >>> Why? Is this just another option that noone will understand.
> >>>
> >>>  -- Keir
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

RE: [PATCH] [VTD] Separate VT-d page table from P2M table

[Han, Weidong]

Ian Pratt wrote:
>> If EPT supports 2MB page, we need separate VT-d table to let them
>> work together.
> 
> Are you saying that the VT-d 2MB page format is different from the EPT
> 2MB page format? Or that VTd does not support 2MB pages?
> 

Now VTd does not support 2MB pages.

> Ian
> 
>> What's more, sharing makes coupling between VT-d page table
>> and p2m table. In case VT-d spec changes or p2m structure changes,
>> shared table will be broken.
> 
>> Randy (Weidong)
>> 
>> Keir Fraser wrote:
>>> What are the tradeoffs? One obvious tradeoff is that separate tables
>>> doubles the memory overhead. What are the advantages of separate
>>> tables? I believe currently we share the pagetables (right?). If so,
>>> why would we even consider moving to separate tables?
>>> 
>>>  -- Keir
>>> 
>>> On 22/4/08 10:34, "Han, Weidong" <weidong.han@intel.com> wrote:
>>> 
>>>> Separate VT-d page table is by default. Shared VT-d page table may
>>>> be easy and good in some cases. So we let them co-exist now. If
>>>> shared VT-d page table is not necessary and useless, we can remove
>>>> it easily in future. 
>>>> 
>>>> Randy (weidong)
>>>> 
>>>> Keir Fraser wrote:
>>>>> On 22/4/08 09:36, "Han, Weidong" <weidong.han@intel.com> wrote:
>>>>> 
>>>>>> Currently VT-d page table shares with P2M table, this patch
>>>>>> supports separate VT-d page table. 1) add an option (vtd_share)
>>>>>> to control whether VT-d page table shares with P2M table or not.
>>>>> 
>>>>> Why? Is this just another option that noone will understand.
>>>>> 
>>>>>  -- Keir
>> 
>> 
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@lists.xensource.com
>> http://lists.xensource.com/xen-devel

Re: [PATCH] [VTD] Separate VT-d page table from P2M table

[Keir Fraser]

On 22/4/08 13:17, "Han, Weidong" <weidong.han@intel.com> wrote:

>> Are you saying that the VT-d 2MB page format is different from the EPT
>> 2MB page format? Or that VTd does not support 2MB pages?
>> 
> 
> Now VTd does not support 2MB pages.

Then don't allow EPT 2MB mappings for domains which have passthru devices?

 -- Keir

RE: [PATCH] [VTD] Separate VT-d page table from P2M table

[Han, Weidong]

Keir Fraser wrote:
> On 22/4/08 13:17, "Han, Weidong" <weidong.han@intel.com> wrote:
> 
>>> Are you saying that the VT-d 2MB page format is different from the
>>> EPT 2MB page format? Or that VTd does not support 2MB pages?
>>> 
>> 
>> Now VTd does not support 2MB pages.
> 
> Then don't allow EPT 2MB mappings for domains which have passthru
> devices? 
> 

No, EPT is 2MB, VT-d page table is 4KB.

Randy (Weidong)

RE: [PATCH] [VTD] Separate VT-d page table from P2M table

[Espen Skoglund]

[Weidong Han]
> Keir Fraser wrote:
>> On 22/4/08 13:17, "Han, Weidong" <weidong.han@intel.com> wrote:
>> 
>>>> Are you saying that the VT-d 2MB page format is different from
>>>> the EPT 2MB page format? Or that VTd does not support 2MB pages?
>>>> 
>>> 
>>> Now VTd does not support 2MB pages.
>> 
>> Then don't allow EPT 2MB mappings for domains which have passthru
>> devices?
>> 

> No, EPT is 2MB, VT-d page table is 4KB.

So EPT only supports 2MB mappings?  Not 4KB?  That doesn't sound right.

Another possible inompatibility: The VT-d chipset I'm using only
allows 4-level page tables.  Not sure if similar restrictions might
apply to EPT.  Also, in another project I worked on I found it
advantageous to emulate superpages in the guest even if this was not
supported by the VT hardware --- lower memory footprint, quicker table
lookups.  Such optimizations might be another reason for separating
the tables.

That said, I would really disfavor separating the tables.  There are
enough memory management structures as it is right now.  If the tables
really, really, really need to be separated then don't make it a boot
time option.  The capabilities of VT-d (and probably also EPT) is
readily available at initialization time, and that's where the
decision for sharing or not should be done.

	eSk

RE: [PATCH] [VTD] Separate VT-d page table fromP2M table

[Han, Weidong]

Espen Skoglund wrote:
> [Weidong Han]
>> Keir Fraser wrote:
>>> On 22/4/08 13:17, "Han, Weidong" <weidong.han@intel.com> wrote:
>>> 
>>>>> Are you saying that the VT-d 2MB page format is different from
>>>>> the EPT 2MB page format? Or that VTd does not support 2MB pages?
>>>>> 
>>>> 
>>>> Now VTd does not support 2MB pages.
>>> 
>>> Then don't allow EPT 2MB mappings for domains which have passthru
>>> devices? 
>>> 
> 
>> No, EPT is 2MB, VT-d page table is 4KB.
> 
> So EPT only supports 2MB mappings?  Not 4KB?  That doesn't sound
> right. 

No, EPT can support both 4KB and 2MB pages. 


> 
> Another possible inompatibility: The VT-d chipset I'm using only
> allows 4-level page tables.  Not sure if similar restrictions might
> apply to EPT.  Also, in another project I worked on I found it
> advantageous to emulate superpages in the guest even if this was not
> supported by the VT hardware --- lower memory footprint, quicker table
> lookups.  Such optimizations might be another reason for separating
> the tables.
> 
> That said, I would really disfavor separating the tables.  There are
> enough memory management structures as it is right now.  If the tables
> really, really, really need to be separated then don't make it a boot
> time option.  The capabilities of VT-d (and probably also EPT) is
> readily available at initialization time, and that's where the
> decision for sharing or not should be done.

I think the option for sharing or not will be a temporary thing. If
community considers shared table or separate table is useless, we can
remove the one easily.

Randy (Weidong)

RE: [PATCH] [VTD] Separate VT-d page table from P2M table

[Li, Xin B]

>On 22/4/08 13:17, "Han, Weidong" <weidong.han@intel.com> wrote:
>
>>> Are you saying that the VT-d 2MB page format is different from the
EPT
>>> 2MB page format? Or that VTd does not support 2MB pages?
>>> 
>> 
>> Now VTd does not support 2MB pages.
>
>Then don't allow EPT 2MB mappings for domains which have 
>passthru devices?
>

EPT 2M page is already supported while VT-d 2M not, so for we have to
seperate the 2 guys if we want to use 2M page in EPT.
and of course we share the page tables if both sides use 4K pages.
-Xin

Re: [PATCH] [VTD] Separate VT-d page table from P2M table

[Keir Fraser]

On 22/4/08 16:43, "Li, Xin B" <xin.b.li@intel.com> wrote:

>> Then don't allow EPT 2MB mappings for domains which have
>> passthru devices?
>> 
> 
> EPT 2M page is already supported while VT-d 2M not, so for we have to
> seperate the 2 guys if we want to use 2M page in EPT.
> and of course we share the page tables if both sides use 4K pages.

Just share the tables and put up with not having 2MB mappings available to
you if a guest has devices passed through to it? Doesn't sound so bad to me,
and you can get the performance back down the line by fixing the VT-d
hardware to understand superpage mappings. We're going to end up with a
silly number of p2m structures otherwise.

 -- Keir

Re: [PATCH] [VTD] Separate VT-d page table from P2M table

[Samuel Thibault]

Han, Weidong, le Tue 22 Apr 2008 17:34:11 +0800, a écrit :
> Separate VT-d page table is by default. Shared VT-d page table may be
> easy and good in some cases. So we let them co-exist now. If shared VT-d
> page table is not necessary and useless, we can remove it easily in
> future.

But why unsharing it at all?  Is there any bonus except using more
memory? :)

Samuel

RE: [PATCH] [VTD] Separate VT-d page table from P2M table

[Han, Weidong]

[-- Attachment #1: Type: text/plain, Size: 875 bytes --]

Keir,

Attached patch removes the shared option, and only supports separated
VT-d page table.

Randy (Weidong)

Keir Fraser wrote:
> On 22/4/08 16:43, "Li, Xin B" <xin.b.li@intel.com> wrote:
> 
>>> Then don't allow EPT 2MB mappings for domains which have passthru
>>> devices? 
>>> 
>> 
>> EPT 2M page is already supported while VT-d 2M not, so for we have to
>> seperate the 2 guys if we want to use 2M page in EPT.
>> and of course we share the page tables if both sides use 4K pages.
> 
> Just share the tables and put up with not having 2MB mappings
> available to you if a guest has devices passed through to it? Doesn't
> sound so bad to me, and you can get the performance back down the
> line by fixing the VT-d hardware to understand superpage mappings.
> We're going to end up with a silly number of p2m structures otherwise.
> 
>  -- Keir

[-- Attachment #2: vtd-sep-2.patch --]
[-- Type: application/octet-stream, Size: 3373 bytes --]

diff -r 483d006cc607 tools/python/xen/xend/XendDomainInfo.py
--- a/tools/python/xen/xend/XendDomainInfo.py	Fri Apr 25 13:46:27 2008 +0100
+++ b/tools/python/xen/xend/XendDomainInfo.py	Mon Apr 28 15:23:10 2008 +0800
@@ -2135,8 +2135,13 @@ class XendDomainInfo:
             # set memory limit
             xc.domain_setmaxmem(self.domid, maxmem)
 
+            # Reserve 1 page per MiB of RAM for separate VT-d page table.
+            vtd_mem = 4 * (self.info['memory_static_max'] / 1024 / 1024)
+            # Round vtd_mem up to a multiple of a MiB.
+            vtd_mem = ((vtd_mem + 1023) / 1024) * 1024
+
             # Make sure there's enough RAM available for the domain
-            balloon.free(memory + shadow)
+            balloon.free(memory + shadow + vtd_mem)
 
             # Set up the shadow memory
             shadow_cur = xc.shadow_mem_control(self.domid, shadow / 1024)
diff -r 483d006cc607 xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c	Fri Apr 25 13:46:27 2008 +0100
+++ b/xen/arch/x86/mm/p2m.c	Mon Apr 28 15:23:10 2008 +0800
@@ -259,18 +259,10 @@ p2m_set_entry(struct domain *d, unsigned
 
     if ( iommu_enabled && is_hvm_domain(d) )
     {
-        if ( boot_cpu_data.x86_vendor == X86_VENDOR_INTEL )
-        {
-            if ( (p2mt == p2m_mmio_direct) )
-                iommu_flush(d, gfn, (u64*)p2m_entry);
-        }
-        else if ( boot_cpu_data.x86_vendor == X86_VENDOR_AMD )
-        {
-            if ( p2mt == p2m_ram_rw )
-                iommu_map_page(d, gfn, mfn_x(mfn));
-            else
-                iommu_unmap_page(d, gfn);
-        }
+        if ( p2mt == p2m_ram_rw )
+            iommu_map_page(d, gfn, mfn_x(mfn));
+        else
+            iommu_unmap_page(d, gfn);
     }
 
     /* Success */
@@ -528,11 +520,6 @@ int p2m_alloc_table(struct domain *d,
             && !set_p2m_entry(d, gfn, mfn, p2m_ram_rw) )
             goto error;
     }
-
-#if CONFIG_PAGING_LEVELS >= 3
-    if (vtd_enabled && is_hvm_domain(d))
-        iommu_set_pgd(d);
-#endif
 
     P2M_PRINTK("p2m table initialised (%u pages)\n", page_count);
     p2m_unlock(p2m);
diff -r 483d006cc607 xen/drivers/passthrough/vtd/iommu.c
--- a/xen/drivers/passthrough/vtd/iommu.c	Fri Apr 25 13:46:27 2008 +0100
+++ b/xen/drivers/passthrough/vtd/iommu.c	Mon Apr 28 15:43:58 2008 +0800
@@ -671,11 +671,24 @@ void dma_pte_free_pagetable(struct domai
     }
 
     /* free pgd */
-    if ( start == 0 && end == ((((u64)1) << addr_width) - 1) )
+    if ( start == 0 && end >= ((((u64)1) << addr_width) - 1) )
     {
         free_pgtable_maddr(hd->pgd_maddr);
         hd->pgd_maddr = 0;
     }
+}
+
+ /* free all VT-d page tables when shut down or destroy domain. */
+static void iommu_free_pagetable(struct domain *domain)
+{
+    struct hvm_iommu *hd = domain_hvm_iommu(domain);
+    int addr_width = agaw_to_width(hd->agaw);
+    u64 start, end;
+
+    start = 0;
+    end = (((u64)1) << addr_width) - 1;
+
+    dma_pte_free_pagetable(domain, start, end);
 }
 
 static int iommu_set_root_entry(struct iommu *iommu)
@@ -1472,9 +1485,9 @@ void iommu_domain_teardown(struct domain
     if ( list_empty(&acpi_drhd_units) )
         return;
 
+    iommu_free_pagetable(d);
+    return_devices_to_dom0(d);
     iommu_domid_release(d);
-    iommu_free_pgd(d);
-    return_devices_to_dom0(d);
 }
 
 static int domain_context_mapped(struct pci_dev *pdev)

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