Re: [Xen-devel] [PATCH v3 03/16] xen/arm: p2m: Redefine mfn_to_page and page_to_mfn to use typesafe

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 30 Jun 2017, Julien Grall wrote:
> The file xen/arch/arm/p2m.c is using typesafe MFN in most of the place.
> This requires caller to mfn_to_page and page_to_mfn to use _mfn/mfn_x.
> 
> To avoid extra _mfn/mfn_x, re-define mfn_to_page and page_to_mfn within
> xen/arch/arm/p2m.c to handle typesafe MFN.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>     The idea behind redefining locally mfn_to_page and page_to_mfn is
>     splitting the introduction of typesafe MFN in smaller series and
>     between multiple people. We know the file is typesafe ready and if
>     we decide to make the main helper typesafe, we would just need to
>     drop the definition at the top of the file.
> 
>     Changes in v3:
>         - Use __page_to_mfn(...) rather than mfn_x(page_to_mfn(...))
> ---
>  xen/arch/arm/p2m.c | 20 +++++++++++++-------
>  1 file changed, 13 insertions(+), 7 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 05eb584e89..3e20a1ec82 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -38,6 +38,12 @@ static unsigned int __read_mostly max_vmid = 
> MAX_VMID_8_BIT;
>  
>  #define P2M_ROOT_PAGES    (1<<P2M_ROOT_ORDER)
>  
> +/* Override macros from asm/mm.h to make them work with mfn_t */
> +#undef mfn_to_page
> +#define mfn_to_page(mfn) __mfn_to_page(mfn_x(mfn))
> +#undef page_to_mfn
> +#define page_to_mfn(pg) _mfn(__page_to_mfn(pg))
> +
>  unsigned int __read_mostly p2m_ipa_bits;
>  
>  /* Helpers to lookup the properties of each level */
> @@ -115,7 +121,7 @@ void dump_p2m_lookup(struct domain *d, paddr_t addr)
>      printk("dom%d IPA 0x%"PRIpaddr"\n", d->domain_id, addr);
>  
>      printk("P2M @ %p mfn:0x%lx\n",
> -           p2m->root, page_to_mfn(p2m->root));
> +           p2m->root, __page_to_mfn(p2m->root));
>  
>      dump_pt_walk(page_to_maddr(p2m->root), addr,
>                   P2M_ROOT_LEVEL, P2M_ROOT_PAGES);
> @@ -591,7 +597,7 @@ static int p2m_create_table(struct p2m_domain *p2m, 
> lpae_t *entry)
>       * The access value does not matter because the hardware will ignore
>       * the permission fields for table entry.
>       */
> -    pte = mfn_to_p2m_entry(_mfn(page_to_mfn(page)), p2m_invalid,
> +    pte = mfn_to_p2m_entry(page_to_mfn(page), p2m_invalid,
>                             p2m->default_access);
>  
>      p2m_write_pte(entry, pte, p2m->clean_pte);
> @@ -650,9 +656,9 @@ static void p2m_put_l3_page(const lpae_t pte)
>       */
>      if ( p2m_is_foreign(pte.p2m.type) )
>      {
> -        unsigned long mfn = pte.p2m.base;
> +        mfn_t mfn = _mfn(pte.p2m.base);
>  
> -        ASSERT(mfn_valid(_mfn(mfn)));
> +        ASSERT(mfn_valid(mfn));
>          put_page(mfn_to_page(mfn));
>      }
>  }
> @@ -702,7 +708,7 @@ static void p2m_free_entry(struct p2m_domain *p2m,
>      mfn = _mfn(entry.p2m.base);
>      ASSERT(mfn_valid(mfn));
>  
> -    pg = mfn_to_page(mfn_x(mfn));
> +    pg = mfn_to_page(mfn);
>  
>      page_list_del(pg, &p2m->pages);
>      free_domheap_page(pg);
> @@ -780,7 +786,7 @@ static bool p2m_split_superpage(struct p2m_domain *p2m, 
> lpae_t *entry,
>  
>      unmap_domain_page(table);
>  
> -    pte = mfn_to_p2m_entry(_mfn(page_to_mfn(page)), p2m_invalid,
> +    pte = mfn_to_p2m_entry(page_to_mfn(page), p2m_invalid,
>                             p2m->default_access);
>  
>      /*
> @@ -1442,7 +1448,7 @@ struct page_info *get_page_from_gva(struct vcpu *v, 
> vaddr_t va,
>      if ( !mfn_valid(maddr_to_mfn(maddr)) )
>          goto err;
>  
> -    page = mfn_to_page(mfn_x(maddr_to_mfn(maddr)));
> +    page = mfn_to_page(maddr_to_mfn(maddr));
>      ASSERT(page);
>  
>      if ( unlikely(!get_page(page, d)) )
> -- 
> 2.11.0
> 

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