Re: [PATCH v2 1/4] xen: arm: Add a new helper update_boot_mapping()

[Michal Orzel <michal.orzel@xxxxxxx>]

Hi Ayan,

On 08/08/2024 14:09, Ayan Kumar Halder wrote:
> update_boot_mapping() invokes update_identity_mapping() for the MMU specific
> code.
> Later when the MPU code is added, update_boot_mapping() would invoke the
> equivalent.
> 
> The common code now invokes update_boot_mapping() instead of
> update_identity_mapping(). So, that there is clear abstraction between the
> common and MMU/MPU specific logic.
> 
> This is in continuation to commit
> f661a20aa880: "Extract MMU-specific MM code".
> 
> Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
> ---
> Changes from :-
> 
> v1 - 1. Introduced update_boot_mapping() which invokes
> update_identity_mapping() in MMU specific code.
> 
>  xen/arch/arm/arm64/mmu/mm.c   | 5 +++++
>  xen/arch/arm/arm64/smpboot.c  | 6 +++---
>  xen/arch/arm/include/asm/mm.h | 2 ++
>  3 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/xen/arch/arm/arm64/mmu/mm.c b/xen/arch/arm/arm64/mmu/mm.c
> index 293acb67e0..72e089a339 100644
> --- a/xen/arch/arm/arm64/mmu/mm.c
> +++ b/xen/arch/arm/arm64/mmu/mm.c
> @@ -125,6 +125,11 @@ void update_identity_mapping(bool enable)
>      BUG_ON(rc);
>  }
>  
> +void update_boot_mapping(bool enable)
> +{
> +    update_identity_mapping(enable);
With your approach, update_identity_mapping() would only be called from within 
this file,
therefore it should be marked as static and the prototype removed.

> +}
> +
>  extern void switch_ttbr_id(uint64_t ttbr);
>  
>  typedef void (switch_ttbr_fn)(uint64_t ttbr);
> diff --git a/xen/arch/arm/arm64/smpboot.c b/xen/arch/arm/arm64/smpboot.c
> index a225fae64d..789f352ab6 100644
> --- a/xen/arch/arm/arm64/smpboot.c
> +++ b/xen/arch/arm/arm64/smpboot.c
> @@ -112,18 +112,18 @@ int arch_cpu_up(int cpu)
>      if ( !smp_enable_ops[cpu].prepare_cpu )
>          return -ENODEV;
>  
> -    update_identity_mapping(true);
> +    update_boot_mapping(true);
>  
>      rc = smp_enable_ops[cpu].prepare_cpu(cpu);
>      if ( rc )
> -        update_identity_mapping(false);
> +        update_boot_mapping(false);
>  
>      return rc;
>  }
>  
>  void arch_cpu_up_finish(void)
>  {
> -    update_identity_mapping(false);
> +    update_boot_mapping(false);
>  }
>  
>  /*
> diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h
> index f6ba611f01..e769d2d3b3 100644
> --- a/xen/arch/arm/include/asm/mm.h
> +++ b/xen/arch/arm/include/asm/mm.h
> @@ -426,6 +426,8 @@ static inline void page_set_xenheap_gfn(struct page_info 
> *p, gfn_t gfn)
>      } while ( (y = cmpxchg(&p->u.inuse.type_info, x, nx)) != x );
>  }
>  
> +void update_boot_mapping(bool enable);
The definition is only present for arm64. Shouldn't the prototype be moved to 
arm64 header?

~Michal