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[PATCH v3 5/5] xen/arm32: mpu: Stubs to build MPU for arm32

Ayan Kumar Halder posted 5 patches 10 months, 2 weeks ago
There is a newer version of this series
[PATCH v3 5/5] xen/arm32: mpu: Stubs to build MPU for arm32
Posted by Ayan Kumar Halder 10 months, 2 weeks ago 
Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
---
Changes from :-

v1, v2 -
1. New patch introduced in v3.
2. Should be applied on top of
https://patchwork.kernel.org/project/xen-devel/cover/20250316192445.2376484-1-luca.fancellu@arm.com/

 xen/arch/arm/Kconfig             |  2 +-
 xen/arch/arm/arm32/mpu/Makefile  |  2 ++
 xen/arch/arm/arm32/mpu/p2m.c     | 18 ++++++++++++++++++
 xen/arch/arm/arm32/mpu/smpboot.c | 23 +++++++++++++++++++++++
 xen/arch/arm/include/asm/mm.h    |  5 +++++
 5 files changed, 49 insertions(+), 1 deletion(-)
 create mode 100644 xen/arch/arm/arm32/mpu/p2m.c
 create mode 100644 xen/arch/arm/arm32/mpu/smpboot.c

diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
index 565f288331..a1dd942091 100644
--- a/xen/arch/arm/Kconfig
+++ b/xen/arch/arm/Kconfig
@@ -1,7 +1,7 @@
 config ARM_32
 	def_bool y
 	depends on "$(ARCH)" = "arm32"
-	select ARCH_MAP_DOMAIN_PAGE
+	select ARCH_MAP_DOMAIN_PAGE if MMU
 
 config ARM_64
 	def_bool y
diff --git a/xen/arch/arm/arm32/mpu/Makefile b/xen/arch/arm/arm32/mpu/Makefile
index 3340058c08..38797f28af 100644
--- a/xen/arch/arm/arm32/mpu/Makefile
+++ b/xen/arch/arm/arm32/mpu/Makefile
@@ -1 +1,3 @@
 obj-y += head.o
+obj-y += smpboot.o
+obj-y += p2m.o
diff --git a/xen/arch/arm/arm32/mpu/p2m.c b/xen/arch/arm/arm32/mpu/p2m.c
new file mode 100644
index 0000000000..df8de5c7d8
--- /dev/null
+++ b/xen/arch/arm/arm32/mpu/p2m.c
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <xen/init.h>
+#include <asm/p2m.h>
+
+void __init setup_virt_paging(void)
+{
+    BUG_ON("unimplemented");
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/arm/arm32/mpu/smpboot.c b/xen/arch/arm/arm32/mpu/smpboot.c
new file mode 100644
index 0000000000..3f3e54294e
--- /dev/null
+++ b/xen/arch/arm/arm32/mpu/smpboot.c
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <xen/mm.h>
+
+int prepare_secondary_mm(int cpu)
+{
+    BUG_ON("unimplemented");
+    return -EINVAL;
+}
+
+void update_boot_mapping(bool enable)
+{
+    BUG_ON("unimplemented");
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h
index fbffaccef4..a894e28ac9 100644
--- a/xen/arch/arm/include/asm/mm.h
+++ b/xen/arch/arm/include/asm/mm.h
@@ -171,12 +171,17 @@ struct page_info
 #define PGC_need_scrub    PGC_allocated
 
 #ifdef CONFIG_ARM_32
+#ifdef CONFIG_MPU
+#define is_xen_heap_page(page) false
+#define is_xen_heap_mfn(mfn) false
+#else
 #define is_xen_heap_page(page) is_xen_heap_mfn(page_to_mfn(page))
 #define is_xen_heap_mfn(mfn) ({                                 \
     unsigned long mfn_ = mfn_x(mfn);                            \
     (mfn_ >= mfn_x(directmap_mfn_start) &&                      \
      mfn_ < mfn_x(directmap_mfn_end));                          \
 })
+#endif
 #else
 #define is_xen_heap_page(page) ((page)->count_info & PGC_xen_heap)
 #define is_xen_heap_mfn(mfn) \
-- 
2.25.1
Re: [PATCH v3 5/5] xen/arm32: mpu: Stubs to build MPU for arm32
Posted by Julien Grall 10 months, 2 weeks ago 
Hi Ayan,

On 30/03/2025 19:03, Ayan Kumar Halder wrote:
> Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
> ---
> Changes from :-
> 
> v1, v2 -
> 1. New patch introduced in v3.
> 2. Should be applied on top of
> https://patchwork.kernel.org/project/xen-devel/cover/20250316192445.2376484-1-luca.fancellu@arm.com/
> 
>   xen/arch/arm/Kconfig             |  2 +-
>   xen/arch/arm/arm32/mpu/Makefile  |  2 ++
>   xen/arch/arm/arm32/mpu/p2m.c     | 18 ++++++++++++++++++
>   xen/arch/arm/arm32/mpu/smpboot.c | 23 +++++++++++++++++++++++
>   xen/arch/arm/include/asm/mm.h    |  5 +++++
>   5 files changed, 49 insertions(+), 1 deletion(-)
>   create mode 100644 xen/arch/arm/arm32/mpu/p2m.c
>   create mode 100644 xen/arch/arm/arm32/mpu/smpboot.c
> 
> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
> index 565f288331..a1dd942091 100644
> --- a/xen/arch/arm/Kconfig
> +++ b/xen/arch/arm/Kconfig
> @@ -1,7 +1,7 @@
>   config ARM_32
>   	def_bool y
>   	depends on "$(ARCH)" = "arm32"
> -	select ARCH_MAP_DOMAIN_PAGE
> +	select ARCH_MAP_DOMAIN_PAGE if MMU

If ARCH_MAP_DOMAIN_PAGE is not present, then the assumption is Xen will 
be able to access all the memory. Is this what we want long term?

If not, then I would consider providing stubs rather than disable 
ARCH_MAP_DOMAIN_PAGE.

>   
>   config ARM_64
>   	def_bool y
> diff --git a/xen/arch/arm/arm32/mpu/Makefile b/xen/arch/arm/arm32/mpu/Makefile
> index 3340058c08..38797f28af 100644
> --- a/xen/arch/arm/arm32/mpu/Makefile
> +++ b/xen/arch/arm/arm32/mpu/Makefile
> @@ -1 +1,3 @@
>   obj-y += head.o
> +obj-y += smpboot.o
> +obj-y += p2m.o
> diff --git a/xen/arch/arm/arm32/mpu/p2m.c b/xen/arch/arm/arm32/mpu/p2m.c
> new file mode 100644
> index 0000000000..df8de5c7d8
> --- /dev/null
> +++ b/xen/arch/arm/arm32/mpu/p2m.c
> @@ -0,0 +1,18 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#include <xen/init.h>
> +#include <asm/p2m.h>
> +
> +void __init setup_virt_paging(void)
> +{
> +    BUG_ON("unimplemented");
> +}
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/arch/arm/arm32/mpu/smpboot.c b/xen/arch/arm/arm32/mpu/smpboot.c
> new file mode 100644
> index 0000000000..3f3e54294e
> --- /dev/null
> +++ b/xen/arch/arm/arm32/mpu/smpboot.c
> @@ -0,0 +1,23 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#include <xen/mm.h>
> +
> +int prepare_secondary_mm(int cpu)
> +{
> +    BUG_ON("unimplemented");
> +    return -EINVAL;
> +}
> +
> +void update_boot_mapping(bool enable)
> +{
> +    BUG_ON("unimplemented");
> +}
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-file-style: "BSD"
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h
> index fbffaccef4..a894e28ac9 100644
> --- a/xen/arch/arm/include/asm/mm.h
> +++ b/xen/arch/arm/include/asm/mm.h
> @@ -171,12 +171,17 @@ struct page_info
>   #define PGC_need_scrub    PGC_allocated
>   
>   #ifdef CONFIG_ARM_32
> +#ifdef CONFIG_MPU
> +#define is_xen_heap_page(page) false
> +#define is_xen_heap_mfn(mfn) false

Can you clarify whether this is the intended implementation? If not then 
we can be use BUG_ON("unimplemented")?

Also...

> +#else
>   #define is_xen_heap_page(page) is_xen_heap_mfn(page_to_mfn(page))
>   #define is_xen_heap_mfn(mfn) ({                                 \
>       unsigned long mfn_ = mfn_x(mfn);                            \
>       (mfn_ >= mfn_x(directmap_mfn_start) &&                      \
>        mfn_ < mfn_x(directmap_mfn_end));                          \
>   })
> +#endif

... is the implementation will be similar to is_xen_heap_page() for MMU?

>   #else
>   #define is_xen_heap_page(page) ((page)->count_info & PGC_xen_heap)
>   #define is_xen_heap_mfn(mfn) \

Cheers,

-- 
Julien Grall
Re: [PATCH v3 5/5] xen/arm32: mpu: Stubs to build MPU for arm32
Posted by Ayan Kumar Halder 10 months, 1 week ago 
On 30/03/2025 22:11, Julien Grall wrote:
> Hi Ayan,
Hi Julien,
>
> On 30/03/2025 19:03, Ayan Kumar Halder wrote:
>> Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@amd.com>
>> ---
>> Changes from :-
>>
>> v1, v2 -
>> 1. New patch introduced in v3.
>> 2. Should be applied on top of
>> https://patchwork.kernel.org/project/xen-devel/cover/20250316192445.2376484-1-luca.fancellu@arm.com/ 
>>
>>
>>   xen/arch/arm/Kconfig             |  2 +-
>>   xen/arch/arm/arm32/mpu/Makefile  |  2 ++
>>   xen/arch/arm/arm32/mpu/p2m.c     | 18 ++++++++++++++++++
>>   xen/arch/arm/arm32/mpu/smpboot.c | 23 +++++++++++++++++++++++
>>   xen/arch/arm/include/asm/mm.h    |  5 +++++
>>   5 files changed, 49 insertions(+), 1 deletion(-)
>>   create mode 100644 xen/arch/arm/arm32/mpu/p2m.c
>>   create mode 100644 xen/arch/arm/arm32/mpu/smpboot.c
>>
>> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
>> index 565f288331..a1dd942091 100644
>> --- a/xen/arch/arm/Kconfig
>> +++ b/xen/arch/arm/Kconfig
>> @@ -1,7 +1,7 @@
>>   config ARM_32
>>       def_bool y
>>       depends on "$(ARCH)" = "arm32"
>> -    select ARCH_MAP_DOMAIN_PAGE
>> +    select ARCH_MAP_DOMAIN_PAGE if MMU
>
> If ARCH_MAP_DOMAIN_PAGE is not present, then the assumption is Xen 
> will be able to access all the memory. Is this what we want long term?
>
> If not, then I would consider providing stubs rather than disable 
> ARCH_MAP_DOMAIN_PAGE.
I will provide the stubs.
>
>>     config ARM_64
>>       def_bool y
>> diff --git a/xen/arch/arm/arm32/mpu/Makefile 
>> b/xen/arch/arm/arm32/mpu/Makefile
>> index 3340058c08..38797f28af 100644
>> --- a/xen/arch/arm/arm32/mpu/Makefile
>> +++ b/xen/arch/arm/arm32/mpu/Makefile
>> @@ -1 +1,3 @@
>>   obj-y += head.o
>> +obj-y += smpboot.o
>> +obj-y += p2m.o
>> diff --git a/xen/arch/arm/arm32/mpu/p2m.c b/xen/arch/arm/arm32/mpu/p2m.c
>> new file mode 100644
>> index 0000000000..df8de5c7d8
>> --- /dev/null
>> +++ b/xen/arch/arm/arm32/mpu/p2m.c
>> @@ -0,0 +1,18 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +
>> +#include <xen/init.h>
>> +#include <asm/p2m.h>
>> +
>> +void __init setup_virt_paging(void)
>> +{
>> +    BUG_ON("unimplemented");
>> +}
>> +
>> +/*
>> + * Local variables:
>> + * mode: C
>> + * c-file-style: "BSD"
>> + * c-basic-offset: 4
>> + * indent-tabs-mode: nil
>> + * End:
>> + */
>> diff --git a/xen/arch/arm/arm32/mpu/smpboot.c 
>> b/xen/arch/arm/arm32/mpu/smpboot.c
>> new file mode 100644
>> index 0000000000..3f3e54294e
>> --- /dev/null
>> +++ b/xen/arch/arm/arm32/mpu/smpboot.c
>> @@ -0,0 +1,23 @@
>> +/* SPDX-License-Identifier: GPL-2.0-only */
>> +
>> +#include <xen/mm.h>
>> +
>> +int prepare_secondary_mm(int cpu)
>> +{
>> +    BUG_ON("unimplemented");
>> +    return -EINVAL;
>> +}
>> +
>> +void update_boot_mapping(bool enable)
>> +{
>> +    BUG_ON("unimplemented");
>> +}
>> +
>> +/*
>> + * Local variables:
>> + * mode: C
>> + * c-file-style: "BSD"
>> + * c-basic-offset: 4
>> + * indent-tabs-mode: nil
>> + * End:
>> + */
>> diff --git a/xen/arch/arm/include/asm/mm.h 
>> b/xen/arch/arm/include/asm/mm.h
>> index fbffaccef4..a894e28ac9 100644
>> --- a/xen/arch/arm/include/asm/mm.h
>> +++ b/xen/arch/arm/include/asm/mm.h
>> @@ -171,12 +171,17 @@ struct page_info
>>   #define PGC_need_scrub    PGC_allocated
>>     #ifdef CONFIG_ARM_32
>> +#ifdef CONFIG_MPU
>> +#define is_xen_heap_page(page) false
>> +#define is_xen_heap_mfn(mfn) false
>
> Can you clarify whether this is the intended implementation? If not 
> then we can be use BUG_ON("unimplemented")?
yes, we will use BUG_ON("unimplemented").
>
> Also...
>
>> +#else
>>   #define is_xen_heap_page(page) is_xen_heap_mfn(page_to_mfn(page))
>>   #define is_xen_heap_mfn(mfn) ({                                 \
>>       unsigned long mfn_ = mfn_x(mfn);                            \
>>       (mfn_ >= mfn_x(directmap_mfn_start) &&                      \
>>        mfn_ < mfn_x(directmap_mfn_end));                          \
>>   })
>> +#endif
>
> ... is the implementation will be similar to is_xen_heap_page() for MMU?
>
>>   #else
>>   #define is_xen_heap_page(page) ((page)->count_info & PGC_xen_heap)
>>   #define is_xen_heap_mfn(mfn) \
>
- Ayan
> Cheers,
>

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