Now that the size of struct vcpu is smaller than PAGE_SIZE,
MAX_PAGES_PER_VCPU is no longer needed and is removed.

This change also updates {alloc,free}_vcpu_struct().

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
---
Changes in v2:
 - New patch.
---
 xen/arch/arm/domain.c | 25 +++++--------------------
 1 file changed, 5 insertions(+), 20 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 47973f99d9..e566023340 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -473,36 +473,21 @@ void dump_pageframe_info(struct domain *d)
 
 }
 
-/*
- * The new VGIC has a bigger per-IRQ structure, so we need more than one
- * page on ARM64. Cowardly increase the limit in this case.
- */
-#if defined(CONFIG_NEW_VGIC) && defined(CONFIG_ARM_64)
-#define MAX_PAGES_PER_VCPU  2
-#else
-#define MAX_PAGES_PER_VCPU  1
-#endif
-
 struct vcpu *alloc_vcpu_struct(const struct domain *d)
 {
     struct vcpu *v;
 
-    BUILD_BUG_ON(sizeof(*v) > MAX_PAGES_PER_VCPU * PAGE_SIZE);
-    v = alloc_xenheap_pages(get_order_from_bytes(sizeof(*v)), 0);
-    if ( v != NULL )
-    {
-        unsigned int i;
-
-        for ( i = 0; i < DIV_ROUND_UP(sizeof(*v), PAGE_SIZE); i++ )
-            clear_page((void *)v + i * PAGE_SIZE);
-    }
+    BUILD_BUG_ON(sizeof(*v) > PAGE_SIZE);
+    v = alloc_xenheap_pages(0, 0);
+    if ( v )
+        clear_page(v);
 
     return v;
 }
 
 void free_vcpu_struct(struct vcpu *v)
 {
-    free_xenheap_pages(v, get_order_from_bytes(sizeof(*v)));
+    free_xenheap_page(v);
 }
 
 int arch_vcpu_create(struct vcpu *v)
-- 
2.52.0

On 18/12/2025 5:28 pm, Oleksii Kurochko wrote:
> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> index 47973f99d9..e566023340 100644
> --- a/xen/arch/arm/domain.c
> +++ b/xen/arch/arm/domain.c
> @@ -473,36 +473,21 @@ void dump_pageframe_info(struct domain *d)
>  
>  }
>  
> -/*
> - * The new VGIC has a bigger per-IRQ structure, so we need more than one
> - * page on ARM64. Cowardly increase the limit in this case.
> - */
> -#if defined(CONFIG_NEW_VGIC) && defined(CONFIG_ARM_64)
> -#define MAX_PAGES_PER_VCPU  2
> -#else
> -#define MAX_PAGES_PER_VCPU  1
> -#endif
> -
>  struct vcpu *alloc_vcpu_struct(const struct domain *d)
>  {
>      struct vcpu *v;
>  
> -    BUILD_BUG_ON(sizeof(*v) > MAX_PAGES_PER_VCPU * PAGE_SIZE);
> -    v = alloc_xenheap_pages(get_order_from_bytes(sizeof(*v)), 0);
> -    if ( v != NULL )
> -    {
> -        unsigned int i;
> -
> -        for ( i = 0; i < DIV_ROUND_UP(sizeof(*v), PAGE_SIZE); i++ )
> -            clear_page((void *)v + i * PAGE_SIZE);
> -    }
> +    BUILD_BUG_ON(sizeof(*v) > PAGE_SIZE);
> +    v = alloc_xenheap_pages(0, 0);

I know this is only interim until the next patch, but
alloc_xenheap_page() to match the free function used.

Personally, I'd merge patches 2 and 3 together, because everything you
touch in this patch is deleted by the next one.

But, whatever the ARM maintainers prefer.

~Andrew

On 18/12/2025 19:19, Andrew Cooper wrote:
> On 18/12/2025 5:28 pm, Oleksii Kurochko wrote:
>> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
>> index 47973f99d9..e566023340 100644
>> --- a/xen/arch/arm/domain.c
>> +++ b/xen/arch/arm/domain.c
>> @@ -473,36 +473,21 @@ void dump_pageframe_info(struct domain *d)
>>  
>>  }
>>  
>> -/*
>> - * The new VGIC has a bigger per-IRQ structure, so we need more than one
>> - * page on ARM64. Cowardly increase the limit in this case.
>> - */
>> -#if defined(CONFIG_NEW_VGIC) && defined(CONFIG_ARM_64)
>> -#define MAX_PAGES_PER_VCPU  2
>> -#else
>> -#define MAX_PAGES_PER_VCPU  1
>> -#endif
>> -
>>  struct vcpu *alloc_vcpu_struct(const struct domain *d)
>>  {
>>      struct vcpu *v;
>>  
>> -    BUILD_BUG_ON(sizeof(*v) > MAX_PAGES_PER_VCPU * PAGE_SIZE);
>> -    v = alloc_xenheap_pages(get_order_from_bytes(sizeof(*v)), 0);
>> -    if ( v != NULL )
>> -    {
>> -        unsigned int i;
>> -
>> -        for ( i = 0; i < DIV_ROUND_UP(sizeof(*v), PAGE_SIZE); i++ )
>> -            clear_page((void *)v + i * PAGE_SIZE);
>> -    }
>> +    BUILD_BUG_ON(sizeof(*v) > PAGE_SIZE);
>> +    v = alloc_xenheap_pages(0, 0);
> 
> I know this is only interim until the next patch, but
> alloc_xenheap_page() to match the free function used.
> 
> Personally, I'd merge patches 2 and 3 together, because everything you
> touch in this patch is deleted by the next one.
> 
> But, whatever the ARM maintainers prefer.
I'm in favor of Andrew's suggestion. There's no point in introducing something
in one patch and dropping it in the very next one.

~Michal

On 12/19/25 9:22 AM, Orzel, Michal wrote:
>
> On 18/12/2025 19:19, Andrew Cooper wrote:
>> On 18/12/2025 5:28 pm, Oleksii Kurochko wrote:
>>> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
>>> index 47973f99d9..e566023340 100644
>>> --- a/xen/arch/arm/domain.c
>>> +++ b/xen/arch/arm/domain.c
>>> @@ -473,36 +473,21 @@ void dump_pageframe_info(struct domain *d)
>>>   
>>>   }
>>>   
>>> -/*
>>> - * The new VGIC has a bigger per-IRQ structure, so we need more than one
>>> - * page on ARM64. Cowardly increase the limit in this case.
>>> - */
>>> -#if defined(CONFIG_NEW_VGIC) && defined(CONFIG_ARM_64)
>>> -#define MAX_PAGES_PER_VCPU  2
>>> -#else
>>> -#define MAX_PAGES_PER_VCPU  1
>>> -#endif
>>> -
>>>   struct vcpu *alloc_vcpu_struct(const struct domain *d)
>>>   {
>>>       struct vcpu *v;
>>>   
>>> -    BUILD_BUG_ON(sizeof(*v) > MAX_PAGES_PER_VCPU * PAGE_SIZE);
>>> -    v = alloc_xenheap_pages(get_order_from_bytes(sizeof(*v)), 0);
>>> -    if ( v != NULL )
>>> -    {
>>> -        unsigned int i;
>>> -
>>> -        for ( i = 0; i < DIV_ROUND_UP(sizeof(*v), PAGE_SIZE); i++ )
>>> -            clear_page((void *)v + i * PAGE_SIZE);
>>> -    }
>>> +    BUILD_BUG_ON(sizeof(*v) > PAGE_SIZE);
>>> +    v = alloc_xenheap_pages(0, 0);
>> I know this is only interim until the next patch, but
>> alloc_xenheap_page() to match the free function used.
>>
>> Personally, I'd merge patches 2 and 3 together, because everything you
>> touch in this patch is deleted by the next one.
>>
>> But, whatever the ARM maintainers prefer.
> I'm in favor of Andrew's suggestion. There's no point in introducing something
> in one patch and dropping it in the very next one.

Then I will merge patch 2 and 3.

~ Oleksii