Xen devel - Nov 2013 - [PATCH] xen/arm: Allow balooning working with 1:1 memory mapping

With the lake of iommu, dom0 must have a 1:1 memory mapping for all
these guest physical address. When the ballon decides to give back a
page to the kernel, this page must have the same address as previously.
Otherwise, we will loose the 1:1 mapping and will break DMA-capable
device.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
CC: Keir Fraser <keir@xen.org>
CC: Jan Beulich <jbeulich@suse.com>
---
 xen/common/memory.c | 42 ++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 40 insertions(+), 2 deletions(-)

diff --git a/xen/common/memory.c b/xen/common/memory.c
index 50b740f..df36d43 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -28,6 +28,9 @@
 #include <public/memory.h>
 #include <xsm/xsm.h>
 #include <xen/trace.h>
+#ifdef CONFIG_ARM
+#include <asm/platform.h>
+#endif
 
 struct memop_args {
     /* INPUT */
@@ -90,7 +93,7 @@ static void increase_reservation(struct memop_args *a)
 
 static void populate_physmap(struct memop_args *a)
 {
-    struct page_info *page;
+    struct page_info *page = NULL;
     unsigned long i, j;
     xen_pfn_t gpfn, mfn;
     struct domain *d = a->domain;
@@ -122,7 +125,33 @@ static void populate_physmap(struct memop_args *a)
         }
         else
         {
-            page = alloc_domheap_pages(d, a->extent_order, a->memflags);
+#ifdef CONFIG_ARM
+            if ( d == dom0 &&
platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11) )
+            {
+                mfn = gpfn;
+                if (!mfn_valid(mfn))
+                {
+                    gdprintk(XENLOG_INFO, "Invalid mfn
0x%"PRI_xen_pfn"\n",
+                             mfn);
+                    goto out;
+                }
+
+                page = mfn_to_page(mfn);
+                if ( !get_page(page, d) )
+                {
+                    gdprintk(XENLOG_INFO,
+                             "mfn 0x%"PRI_xen_pfn"
doesn''t belong to dom0\n",
+                             mfn);
+                    goto out;
+                }
+                put_page(page);
+            }
+            else
+#endif
+            {
+                page = alloc_domheap_pages(d, a->extent_order,
a->memflags);
+            }
+
             if ( unlikely(page == NULL) ) 
             {
                 if ( !opt_tmem || (a->extent_order != 0) )
@@ -270,6 +299,15 @@ static void decrease_reservation(struct memop_args *a)
              && p2m_pod_decrease_reservation(a->domain, gmfn,
a->extent_order) )
             continue;
 
+#ifdef CONFIG_ARM
+        /* With the lake for iommu, dom0 must retrieve the same pfn when
+         * the hypercall populate_physmap is called.
+         */
+        if ( a->domain == dom0 &&
+             platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11) )
+            continue;
+#endif
+
         for ( j = 0; j < (1 << a->extent_order); j++ )
             if ( !guest_remove_page(a->domain, gmfn + j) )
                 goto out;
-- 
1.8.3.1

On Thu, 14 Nov 2013, Julien Grall wrote:
> With the lake of iommu, dom0 must have a 1:1 memory mapping for all
> these guest physical address. When the ballon decides to give back a
> page to the kernel, this page must have the same address as previously.
> Otherwise, we will loose the 1:1 mapping and will break DMA-capable
> device.
> 
> Signed-off-by: Julien Grall <julien.grall@linaro.org>
> CC: Keir Fraser <keir@xen.org>
> CC: Jan Beulich <jbeulich@suse.com>
> ---
>  xen/common/memory.c | 42 ++++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 40 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/common/memory.c b/xen/common/memory.c
> index 50b740f..df36d43 100644
> --- a/xen/common/memory.c
> +++ b/xen/common/memory.c
> @@ -28,6 +28,9 @@
>  #include <public/memory.h>
>  #include <xsm/xsm.h>
>  #include <xen/trace.h>
> +#ifdef CONFIG_ARM
> +#include <asm/platform.h>
> +#endif
>  
>  struct memop_args {
>      /* INPUT */
> @@ -90,7 +93,7 @@ static void increase_reservation(struct memop_args *a)
>  
>  static void populate_physmap(struct memop_args *a)
>  {
> -    struct page_info *page;
> +    struct page_info *page = NULL;
>      unsigned long i, j;
>      xen_pfn_t gpfn, mfn;
>      struct domain *d = a->domain;
> @@ -122,7 +125,33 @@ static void populate_physmap(struct memop_args *a)
>          }
>          else
>          {
> -            page = alloc_domheap_pages(d, a->extent_order,
a->memflags);
> +#ifdef CONFIG_ARM
> +            if ( d == dom0 &&
platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11) )
> +            {
> +                mfn = gpfn;
> +                if (!mfn_valid(mfn))
> +                {
> +                    gdprintk(XENLOG_INFO, "Invalid mfn
0x%"PRI_xen_pfn"\n",
> +                             mfn);
> +                    goto out;
> +                }
> +
> +                page = mfn_to_page(mfn);
> +                if ( !get_page(page, d) )
> +                {
> +                    gdprintk(XENLOG_INFO,
> +                             "mfn 0x%"PRI_xen_pfn"
doesn''t belong to dom0\n",
> +                             mfn);
> +                    goto out;
> +                }
> +                put_page(page);
> +            }
> +            else
> +#endif
I don''t know if the x86 maintainers would like that, but I would prefer
to remove the ifdef CONFIG_ARM.
You just need to define a new function called is_dom0_mapped_11, that
always returns false on x86 and on ARM is implemented by d == dom0 &&
platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11).
Then you can use it on common code.

> +            {
> +                page = alloc_domheap_pages(d, a->extent_order,
a->memflags);
> +            }
> +
>              if ( unlikely(page == NULL) ) 
>              {
>                  if ( !opt_tmem || (a->extent_order != 0) )
> @@ -270,6 +299,15 @@ static void decrease_reservation(struct memop_args *a)
>               && p2m_pod_decrease_reservation(a->domain, gmfn,
a->extent_order) )
>              continue;
>  
> +#ifdef CONFIG_ARM
> +        /* With the lake for iommu, dom0 must retrieve the same pfn when
> +         * the hypercall populate_physmap is called.
> +         */
> +        if ( a->domain == dom0 &&
> +             platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11) )
> +            continue;
> +#endif
> +
>          for ( j = 0; j < (1 << a->extent_order); j++ )
>              if ( !guest_remove_page(a->domain, gmfn + j) )
>                  goto out;
> -- 
> 1.8.3.1
>

On 11/14/2013 03:34 PM, Stefano Stabellini wrote:
> On Thu, 14 Nov 2013, Julien Grall wrote:
>> With the lake of iommu, dom0 must have a 1:1 memory mapping for all
>> these guest physical address. When the ballon decides to give back a
>> page to the kernel, this page must have the same address as previously.
>> Otherwise, we will loose the 1:1 mapping and will break DMA-capable
>> device.
>>
>> Signed-off-by: Julien Grall <julien.grall@linaro.org>
>> CC: Keir Fraser <keir@xen.org>
>> CC: Jan Beulich <jbeulich@suse.com>
>> ---
>>   xen/common/memory.c | 42 ++++++++++++++++++++++++++++++++++++++++--
>>   1 file changed, 40 insertions(+), 2 deletions(-)
>>
>> diff --git a/xen/common/memory.c b/xen/common/memory.c
>> index 50b740f..df36d43 100644
>> --- a/xen/common/memory.c
>> +++ b/xen/common/memory.c
>> @@ -28,6 +28,9 @@
>>   #include <public/memory.h>
>>   #include <xsm/xsm.h>
>>   #include <xen/trace.h>
>> +#ifdef CONFIG_ARM
>> +#include <asm/platform.h>
>> +#endif
>>
>>   struct memop_args {
>>       /* INPUT */
>> @@ -90,7 +93,7 @@ static void increase_reservation(struct memop_args
*a)
>>
>>   static void populate_physmap(struct memop_args *a)
>>   {
>> -    struct page_info *page;
>> +    struct page_info *page = NULL;
>>       unsigned long i, j;
>>       xen_pfn_t gpfn, mfn;
>>       struct domain *d = a->domain;
>> @@ -122,7 +125,33 @@ static void populate_physmap(struct memop_args *a)
>>           }
>>           else
>>           {
>> -            page = alloc_domheap_pages(d, a->extent_order,
a->memflags);
>> +#ifdef CONFIG_ARM
>> +            if ( d == dom0 &&
platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11) )
>> +            {
>> +                mfn = gpfn;
>> +                if (!mfn_valid(mfn))
>> +                {
>> +                    gdprintk(XENLOG_INFO, "Invalid mfn
0x%"PRI_xen_pfn"\n",
>> +                             mfn);
>> +                    goto out;
>> +                }
>> +
>> +                page = mfn_to_page(mfn);
>> +                if ( !get_page(page, d) )
>> +                {
>> +                    gdprintk(XENLOG_INFO,
>> +                             "mfn 0x%"PRI_xen_pfn"
doesn''t belong to dom0\n",
>> +                             mfn);
>> +                    goto out;
>> +                }
>> +                put_page(page);
>> +            }
>> +            else
>> +#endif
>
> I don''t know if the x86 maintainers would like that, but I would
prefer
> to remove the ifdef CONFIG_ARM.
> You just need to define a new function called is_dom0_mapped_11, that
> always returns false on x86 and on ARM is implemented by d == dom0
&&
> platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11).
> Then you can use it on common code.
With this solution, it''s less clear that it''s ARM specific
code. We are
introducing a workaround that will never be used on x86.

I would wait an opinion from other maintainers before sending a new 
version of this patch.

-- 
Julien Grall

On 11/14/2013 04:18 PM, Julien Grall wrote:
> 
> 
> On 11/14/2013 03:34 PM, Stefano Stabellini wrote:
>> On Thu, 14 Nov 2013, Julien Grall wrote:
>>> With the lake of iommu, dom0 must have a 1:1 memory mapping for all
>>> these guest physical address. When the ballon decides to give back
a
>>> page to the kernel, this page must have the same address as
previously.
>>> Otherwise, we will loose the 1:1 mapping and will break DMA-capable
>>> device.
>>>
>>> Signed-off-by: Julien Grall <julien.grall@linaro.org>
>>> CC: Keir Fraser <keir@xen.org>
>>> CC: Jan Beulich <jbeulich@suse.com>
>>> ---
>>>   xen/common/memory.c | 42
++++++++++++++++++++++++++++++++++++++++--
>>>   1 file changed, 40 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/xen/common/memory.c b/xen/common/memory.c
>>> index 50b740f..df36d43 100644
>>> --- a/xen/common/memory.c
>>> +++ b/xen/common/memory.c
>>> @@ -28,6 +28,9 @@
>>>   #include <public/memory.h>
>>>   #include <xsm/xsm.h>
>>>   #include <xen/trace.h>
>>> +#ifdef CONFIG_ARM
>>> +#include <asm/platform.h>
>>> +#endif
>>>
>>>   struct memop_args {
>>>       /* INPUT */
>>> @@ -90,7 +93,7 @@ static void increase_reservation(struct
memop_args *a)
>>>
>>>   static void populate_physmap(struct memop_args *a)
>>>   {
>>> -    struct page_info *page;
>>> +    struct page_info *page = NULL;
>>>       unsigned long i, j;
>>>       xen_pfn_t gpfn, mfn;
>>>       struct domain *d = a->domain;
>>> @@ -122,7 +125,33 @@ static void populate_physmap(struct memop_args
*a)
>>>           }
>>>           else
>>>           {
>>> -            page = alloc_domheap_pages(d, a->extent_order,
>>> a->memflags);
>>> +#ifdef CONFIG_ARM
>>> +            if ( d == dom0 &&
>>> platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11) )
>>> +            {
>>> +                mfn = gpfn;
>>> +                if (!mfn_valid(mfn))
>>> +                {
>>> +                    gdprintk(XENLOG_INFO, "Invalid mfn
>>> 0x%"PRI_xen_pfn"\n",
>>> +                             mfn);
>>> +                    goto out;
>>> +                }
>>> +
>>> +                page = mfn_to_page(mfn);
>>> +                if ( !get_page(page, d) )
>>> +                {
>>> +                    gdprintk(XENLOG_INFO,
>>> +                             "mfn 0x%"PRI_xen_pfn"
doesn''t belong to
>>> dom0\n",
>>> +                             mfn);
>>> +                    goto out;
>>> +                }
>>> +                put_page(page);
>>> +            }
>>> +            else
>>> +#endif
>>
>> I don''t know if the x86 maintainers would like that, but I
would prefer
>> to remove the ifdef CONFIG_ARM.
>> You just need to define a new function called is_dom0_mapped_11, that
>> always returns false on x86 and on ARM is implemented by d == dom0
&&
>> platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11).
>> Then you can use it on common code.
> 
> With this solution, it''s less clear that it''s ARM
specific code. We are
> introducing a workaround that will never be used on x86.
> 
> I would wait an opinion from other maintainers before sending a new
> version of this patch.
> 
Ping, any input for X86 maintainers (Keir, Jan)?

-- 
Julien Grall

Ping, any input for X86 maintainers (Keir, Jan)?

On 11/14/2013 04:18 PM, Julien Grall wrote:
>
>
> On 11/14/2013 03:34 PM, Stefano Stabellini wrote:
>> On Thu, 14 Nov 2013, Julien Grall wrote:
>>> With the lake of iommu, dom0 must have a 1:1 memory mapping for all
>>> these guest physical address. When the ballon decides to give back
a
>>> page to the kernel, this page must have the same address as
previously.
>>> Otherwise, we will loose the 1:1 mapping and will break DMA-capable
>>> device.
>>>
>>> Signed-off-by: Julien Grall <julien.grall@linaro.org>
>>> CC: Keir Fraser <keir@xen.org>
>>> CC: Jan Beulich <jbeulich@suse.com>
>>> ---
>>>   xen/common/memory.c | 42
++++++++++++++++++++++++++++++++++++++++--
>>>   1 file changed, 40 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/xen/common/memory.c b/xen/common/memory.c
>>> index 50b740f..df36d43 100644
>>> --- a/xen/common/memory.c
>>> +++ b/xen/common/memory.c
>>> @@ -28,6 +28,9 @@
>>>   #include <public/memory.h>
>>>   #include <xsm/xsm.h>
>>>   #include <xen/trace.h>
>>> +#ifdef CONFIG_ARM
>>> +#include <asm/platform.h>
>>> +#endif
>>>
>>>   struct memop_args {
>>>       /* INPUT */
>>> @@ -90,7 +93,7 @@ static void increase_reservation(struct
memop_args *a)
>>>
>>>   static void populate_physmap(struct memop_args *a)
>>>   {
>>> -    struct page_info *page;
>>> +    struct page_info *page = NULL;
>>>       unsigned long i, j;
>>>       xen_pfn_t gpfn, mfn;
>>>       struct domain *d = a->domain;
>>> @@ -122,7 +125,33 @@ static void populate_physmap(struct memop_args
*a)
>>>           }
>>>           else
>>>           {
>>> -            page = alloc_domheap_pages(d, a->extent_order,
>>> a->memflags);
>>> +#ifdef CONFIG_ARM
>>> +            if ( d == dom0 &&
>>> platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11) )
>>> +            {
>>> +                mfn = gpfn;
>>> +                if (!mfn_valid(mfn))
>>> +                {
>>> +                    gdprintk(XENLOG_INFO, "Invalid mfn
>>> 0x%"PRI_xen_pfn"\n",
>>> +                             mfn);
>>> +                    goto out;
>>> +                }
>>> +
>>> +                page = mfn_to_page(mfn);
>>> +                if ( !get_page(page, d) )
>>> +                {
>>> +                    gdprintk(XENLOG_INFO,
>>> +                             "mfn 0x%"PRI_xen_pfn"
doesn''t belong to
>>> dom0\n",
>>> +                             mfn);
>>> +                    goto out;
>>> +                }
>>> +                put_page(page);
>>> +            }
>>> +            else
>>> +#endif
>>
>> I don''t know if the x86 maintainers would like that, but I
would prefer
>> to remove the ifdef CONFIG_ARM.
>> You just need to define a new function called is_dom0_mapped_11, that
>> always returns false on x86 and on ARM is implemented by d == dom0
&&
>> platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11).
>> Then you can use it on common code.
>
> With this solution, it''s less clear that it''s ARM
specific code. We are
> introducing a workaround that will never be used on x86.
>
> I would wait an opinion from other maintainers before sending a new
> version of this patch.
>
-- 
Julien Grall