Re: [Xen-devel] [PATCH 05/22] xen/arm: p2m: Clean-up mfn_to_p2m_entry

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 20 Jul 2016, Julien Grall wrote:
> The physical address is computed from the machine frame number, so
> checking if the physical address is page aligned is pointless.
> 
> Furthermore, directly assigned the MFN to the corresponding field in the
> entry rather than converting to a physical address and orring the value.
> It will avoid to rely on the field position and make the code clearer.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


>  xen/arch/arm/p2m.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 79095f1..d82349c 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -327,7 +327,6 @@ static void p2m_set_permission(lpae_t *e, p2m_type_t t, 
> p2m_access_t a)
>  static lpae_t mfn_to_p2m_entry(unsigned long mfn, unsigned int mattr,
>                                 p2m_type_t t, p2m_access_t a)
>  {
> -    paddr_t pa = ((paddr_t) mfn) << PAGE_SHIFT;
>      /*
>       * sh, xn and write bit will be defined in the following switches
>       * based on mattr and t.
> @@ -359,10 +358,9 @@ static lpae_t mfn_to_p2m_entry(unsigned long mfn, 
> unsigned int mattr,
>  
>      p2m_set_permission(&e, t, a);
>  
> -    ASSERT(!(pa & ~PAGE_MASK));
> -    ASSERT(!(pa & ~PADDR_MASK));
> +    ASSERT(!(pfn_to_paddr(mfn) & ~PADDR_MASK));
>  
> -    e.bits |= pa;
> +    e.p2m.base = mfn;
>  
>      return e;
>  }
> -- 
> 1.9.1
> 

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