[PATCH v2] boot allocator: Use arch helper for virt_to_mfn on DIRECTMAP

[PATCH v2] boot allocator: Use arch helper for virt_to_mfn on DIRECTMAP

[vijay.kilari]

From: Vijaya Kumar K <Vijaya.Kumar@cavium.com>

On ARM, virt_to_mfn uses the hardware for address
translation. So if the virtual address is not mapped translation
fault is raised.On ARM, DIRECTMAP_VIRT region is direct mapped.

On ARM with NUMA, While initializing second memory node,
panic is triggered from init_node_heap() when virt_to_mfn()
is called for DIRECTMAP_VIRT region address.
Here the check is made to ensure that MFN less than max MFN mapped.
The max MFN is found by calling virt_to_mfn of DIRECTMAP_VIRT_END
region. Since DIRECMAP_VIRT region is not mapped to any virtual address
on ARM, it fails.

In this patch, instead of calling virt_to_mfn(), arch helper
arch_mfn_below_directmap_max_mfn() is introduced. On ARM this arch helper
will return 1 always and for x86 this helper does virt_to_mfn.

Signed-off-by: Vijaya Kumar K <Vijaya.Kumar@cavium.com>
---
 xen/common/page_alloc.c    |  7 ++-----
 xen/include/asm-arm/mm.h   |  7 +++++++
 xen/include/asm-x86/page.h | 16 ++++++++++++++++
 3 files changed, 25 insertions(+), 5 deletions(-)

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 42c20cb..85322cd 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -520,9 +520,6 @@ static unsigned long init_node_heap(int node, unsigned long mfn,
     unsigned long needed = (sizeof(**_heap) +
                             sizeof(**avail) * NR_ZONES +
                             PAGE_SIZE - 1) >> PAGE_SHIFT;
-#ifdef DIRECTMAP_VIRT_END
-    unsigned long eva = min(DIRECTMAP_VIRT_END, HYPERVISOR_VIRT_END);
-#endif
     int i, j;
 
     if ( !first_node_initialised )
@@ -534,7 +531,7 @@ static unsigned long init_node_heap(int node, unsigned long mfn,
     }
 #ifdef DIRECTMAP_VIRT_END
     else if ( *use_tail && nr >= needed &&
-              (mfn + nr) <= (virt_to_mfn(eva - 1) + 1) &&
+              arch_mfn_below_directmap_max_mfn(mfn + nr) &&
               (!xenheap_bits ||
                !((mfn + nr - 1) >> (xenheap_bits - PAGE_SHIFT))) )
     {
@@ -543,7 +540,7 @@ static unsigned long init_node_heap(int node, unsigned long mfn,
                       PAGE_SIZE - sizeof(**avail) * NR_ZONES;
     }
     else if ( nr >= needed &&
-              (mfn + needed) <= (virt_to_mfn(eva - 1) + 1) &&
+              arch_mfn_below_directmap_max_mfn(mfn + needed) &&
               (!xenheap_bits ||
                !((mfn + needed - 1) >> (xenheap_bits - PAGE_SHIFT))) )
     {
diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
index 60ccbf3..f0c90c2 100644
--- a/xen/include/asm-arm/mm.h
+++ b/xen/include/asm-arm/mm.h
@@ -260,6 +260,13 @@ static inline int gvirt_to_maddr(vaddr_t va, paddr_t *pa, unsigned int flags)
 #define virt_to_mfn(va)   (virt_to_maddr(va) >> PAGE_SHIFT)
 #define mfn_to_virt(mfn)  (maddr_to_virt((paddr_t)(mfn) << PAGE_SHIFT))
 
+/*
+ * On ARM DIRECTMAP_VIRT region is directly mapped. Hence return true;
+ */
+static inline bool_t arch_mfn_below_directmap_max_mfn(unsigned long mfn)
+{
+    return 1;
+}
 
 /* Convert between Xen-heap virtual addresses and page-info structures. */
 static inline struct page_info *virt_to_page(const void *v)
diff --git a/xen/include/asm-x86/page.h b/xen/include/asm-x86/page.h
index 46faffc..3ea5310 100644
--- a/xen/include/asm-x86/page.h
+++ b/xen/include/asm-x86/page.h
@@ -18,6 +18,7 @@
 #ifndef __ASSEMBLY__
 # include <asm/types.h>
 # include <xen/lib.h>
+# include <xen/kernel.h>
 #endif
 
 #include <asm/x86_64/page.h>
@@ -374,6 +375,21 @@ perms_strictly_increased(uint32_t old_flags, uint32_t new_flags)
     return ((of | (of ^ nf)) == nf);
 }
 
+/*
+ * x86 maps DIRECTMAP_VIRT to physical memory. Get the mfn for directmap
+ * memory region.
+ */
+static inline bool_t arch_mfn_below_directmap_max_mfn(unsigned long mfn)
+{
+#ifdef DIRECTMAP_VIRT_END
+    unsigned long eva = min(DIRECTMAP_VIRT_END, HYPERVISOR_VIRT_END);
+
+    return mfn <= (virt_to_mfn(eva - 1) + 1);
+#else
+    return 0;
+#endif
+}
+
 #endif /* !__ASSEMBLY__ */
 
 #define PAGE_ALIGN(x) (((x) + PAGE_SIZE - 1) & PAGE_MASK)
-- 
2.7.4


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Re: [PATCH v2] boot allocator: Use arch helper for virt_to_mfn on DIRECTMAP

[Jan Beulich]

>>> On 13.03.17 at 12:43, <vijay.kilari@gmail.com> wrote:
> --- a/xen/include/asm-arm/mm.h
> +++ b/xen/include/asm-arm/mm.h
> @@ -260,6 +260,13 @@ static inline int gvirt_to_maddr(vaddr_t va, paddr_t *pa, unsigned int flags)
>  #define virt_to_mfn(va)   (virt_to_maddr(va) >> PAGE_SHIFT)
>  #define mfn_to_virt(mfn)  (maddr_to_virt((paddr_t)(mfn) << PAGE_SHIFT))
>  
> +/*
> + * On ARM DIRECTMAP_VIRT region is directly mapped. Hence return true;
> + */
> +static inline bool_t arch_mfn_below_directmap_max_mfn(unsigned long mfn)
> +{
> +    return 1;
> +}

bool and true respectively, please (also on the x86 side).

> --- a/xen/include/asm-x86/page.h
> +++ b/xen/include/asm-x86/page.h
> @@ -18,6 +18,7 @@
>  #ifndef __ASSEMBLY__
>  # include <asm/types.h>
>  # include <xen/lib.h>
> +# include <xen/kernel.h>

Why?

> @@ -374,6 +375,21 @@ perms_strictly_increased(uint32_t old_flags, uint32_t new_flags)
>      return ((of | (of ^ nf)) == nf);
>  }
>  
> +/*
> + * x86 maps DIRECTMAP_VIRT to physical memory. Get the mfn for directmap
> + * memory region.
> + */
> +static inline bool_t arch_mfn_below_directmap_max_mfn(unsigned long mfn)
> +{
> +#ifdef DIRECTMAP_VIRT_END

The symbol is always defined on x86 afaics - no need for the #ifdef.

Jan


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Re: [PATCH v2] boot allocator: Use arch helper for virt_to_mfn on DIRECTMAP

[Vijay Kilari]

On Mon, Mar 13, 2017 at 7:12 PM, Jan Beulich <JBeulich@suse.com> wrote:
>>>> On 13.03.17 at 12:43, <vijay.kilari@gmail.com> wrote:
>> --- a/xen/include/asm-arm/mm.h
>> +++ b/xen/include/asm-arm/mm.h
>> @@ -260,6 +260,13 @@ static inline int gvirt_to_maddr(vaddr_t va, paddr_t *pa, unsigned int flags)
>>  #define virt_to_mfn(va)   (virt_to_maddr(va) >> PAGE_SHIFT)
>>  #define mfn_to_virt(mfn)  (maddr_to_virt((paddr_t)(mfn) << PAGE_SHIFT))
>>
>> +/*
>> + * On ARM DIRECTMAP_VIRT region is directly mapped. Hence return true;
>> + */
>> +static inline bool_t arch_mfn_below_directmap_max_mfn(unsigned long mfn)
>> +{
>> +    return 1;
>> +}
>
> bool and true respectively, please (also on the x86 side).

OK
>
>> --- a/xen/include/asm-x86/page.h
>> +++ b/xen/include/asm-x86/page.h
>> @@ -18,6 +18,7 @@
>>  #ifndef __ASSEMBLY__
>>  # include <asm/types.h>
>>  # include <xen/lib.h>
>> +# include <xen/kernel.h>
>
> Why?

Compilation fails saying min() is not defined

>
>> @@ -374,6 +375,21 @@ perms_strictly_increased(uint32_t old_flags, uint32_t new_flags)
>>      return ((of | (of ^ nf)) == nf);
>>  }
>>
>> +/*
>> + * x86 maps DIRECTMAP_VIRT to physical memory. Get the mfn for directmap
>> + * memory region.
>> + */
>> +static inline bool_t arch_mfn_below_directmap_max_mfn(unsigned long mfn)
>> +{
>> +#ifdef DIRECTMAP_VIRT_END
>
> The symbol is always defined on x86 afaics - no need for the #ifdef.
ok.
>
> Jan
>

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Re: [PATCH v2] boot allocator: Use arch helper for virt_to_mfn on DIRECTMAP

[Julien Grall]

Hello Vijay,

On 13/03/17 11:43, vijay.kilari@gmail.com wrote:
> From: Vijaya Kumar K <Vijaya.Kumar@cavium.com>
>
> On ARM, virt_to_mfn uses the hardware for address
> translation. So if the virtual address is not mapped translation
> fault is raised.On ARM, DIRECTMAP_VIRT region is direct mapped.

This is not true. As I said before, all the memory will be direct mapped 
on ARM64 but not on ARM32.

For ARM32, only xenheap will be direct mapped. So you may want to return 
is_xenheap_mfn(...). Or even return false in all the case. Either is 
fine by me, but it would need to be explained in the code.

Regards,

-- 
Julien Grall

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Re: [PATCH v2] boot allocator: Use arch helper for virt_to_mfn on DIRECTMAP

[Vijay Kilari]

On Tue, Mar 14, 2017 at 9:02 PM, Julien Grall <julien.grall@arm.com> wrote:
> Hello Vijay,
>
> On 13/03/17 11:43, vijay.kilari@gmail.com wrote:
>>
>> From: Vijaya Kumar K <Vijaya.Kumar@cavium.com>
>>
>> On ARM, virt_to_mfn uses the hardware for address
>> translation. So if the virtual address is not mapped translation
>> fault is raised.On ARM, DIRECTMAP_VIRT region is direct mapped.
>
>
> This is not true. As I said before, all the memory will be direct mapped on
> ARM64 but not on ARM32.
>
> For ARM32, only xenheap will be direct mapped. So you may want to return
> is_xenheap_mfn(...). Or even return false in all the case. Either is fine by
> me, but it would need to be explained in the code.

Is this ok?.

/*
 * On ARM64 DIRECTMAP_VIRT region is directly mapped. Hence return true;
 * On ARM only xenheap memory is directly mapped. Hence return false.
 */
static inline bool_t arch_mfn_below_directmap_max_mfn(unsigned long mfn)
{
#ifdef CONFIG_ARM_64
    return true;
#else
    return false;
#endif
}

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Re: [PATCH v2] boot allocator: Use arch helper for virt_to_mfn on DIRECTMAP

[Julien Grall]

Hi Vijay,

On 03/15/2017 05:11 AM, Vijay Kilari wrote:
> On Tue, Mar 14, 2017 at 9:02 PM, Julien Grall <julien.grall@arm.com> wrote:
>> Hello Vijay,
>>
>> On 13/03/17 11:43, vijay.kilari@gmail.com wrote:
>>>
>>> From: Vijaya Kumar K <Vijaya.Kumar@cavium.com>
>>>
>>> On ARM, virt_to_mfn uses the hardware for address
>>> translation. So if the virtual address is not mapped translation
>>> fault is raised.On ARM, DIRECTMAP_VIRT region is direct mapped.
>>
>>
>> This is not true. As I said before, all the memory will be direct mapped on
>> ARM64 but not on ARM32.
>>
>> For ARM32, only xenheap will be direct mapped. So you may want to return
>> is_xenheap_mfn(...). Or even return false in all the case. Either is fine by
>> me, but it would need to be explained in the code.
>
> Is this ok?.
>
> /*
>  * On ARM64 DIRECTMAP_VIRT region is directly mapped. Hence return true;
>  * On ARM only xenheap memory is directly mapped. Hence return false.
>  */
> static inline bool_t arch_mfn_below_directmap_max_mfn(unsigned long mfn)
> {
> #ifdef CONFIG_ARM_64
>     return true;
> #else
>     return false;
> #endif
> }

I would implement the helper in {arm32,arm64}/mm.h and avoid the #ifdef 
in the implementation.

Cheers,

-- 
Julien Grall

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