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Re: [PATCH 04/10] arm/mpu: Implement virt/maddr conversion in MPU system
- To: Luca Fancellu <Luca.Fancellu@xxxxxxx>
- From: "Orzel, Michal" <michal.orzel@xxxxxxx>
- Date: Thu, 13 Mar 2025 10:11:12 +0100
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- Cc: "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Penny Zheng <Penny.Zheng@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>, Wei Chen <Wei.Chen@xxxxxxx>
- Delivery-date: Thu, 13 Mar 2025 09:11:24 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 13/03/2025 10:04, Luca Fancellu wrote:
>
>
> Hi Michal,
>
> thanks for your review,
>
>>> diff --git a/xen/arch/arm/include/asm/mpu/mm.h
>>> b/xen/arch/arm/include/asm/mpu/mm.h
>>> new file mode 100644
>>> index 000000000000..57f1e558fd44
>>> --- /dev/null
>>> +++ b/xen/arch/arm/include/asm/mpu/mm.h
>>> @@ -0,0 +1,27 @@
>>> +/* SPDX-License-Identifier: GPL-2.0-only */
>>> +
>>> +#ifndef __ARM_MPU_MM__
>> Missing _H? Should be: __ARM_MPU_MM_H__
>>
>>> +#define __ARM_MPU_MM__
>>> +
>>> +#include <xen/macros.h>
>> I guess you also need xen/types.h
>>
>>> +
>>> +#define virt_to_maddr(va) ({ \
>>> + (paddr_t)va; \
>>> +})
>> Why multiline? Also, shouldn't we take PA bits into account?
>> I'd imagine:
>> ((paddr_t)((vaddr_t)(va) & PADDR_MASK))
>>
>>> +
>>> +/* On MPU systems there is no translation, ma == va. */
>>> +static inline void *maddr_to_virt(paddr_t ma)
>>> +{
>>> + return _p(ma);
>> Why do we need to cast paddr_t to unsigned long before casting to void?
>> Why not:
>> return (void *)(ma);
>
> So it was pointed out on a previous review that it’s ok to use _p() instead
> of doing straight the cast:
> https://patchwork.kernel.org/project/xen-devel/patch/20230626033443.2943270-29-Penny.Zheng@xxxxxxx/#25404105
>
> please let me know your thought about it.
I'm ok with that.
~Michal
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