Re: [Xen-devel] [PATCH 08/15] xen/x86: p2m: Use typesafe gfn for the P2M callbacks get_entry and set_entry

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 13/09/2017 18:59, Julien Grall wrote:
> diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c
> index 0e63d6ed11..57878b1886 100644
> --- a/xen/arch/x86/mm/p2m-pt.c
> +++ b/xen/arch/x86/mm/p2m-pt.c
> @@ -479,12 +479,13 @@ int p2m_pt_handle_deferred_changes(uint64_t gpa)
>  
>  /* Returns: 0 for success, -errno for failure */
>  static int
> -p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long gfn, mfn_t mfn,
> +p2m_pt_set_entry(struct p2m_domain *p2m, gfn_t gfn_t, mfn_t mfn,
>                   unsigned int page_order, p2m_type_t p2mt, p2m_access_t p2ma,
>                   int sve)
>  {
>      /* XXX -- this might be able to be faster iff current->domain == d */
>      void *table;
> +    unsigned long gfn = gfn_x(gfn_t);
>      unsigned long i, gfn_remainder = gfn;
>      l1_pgentry_t *p2m_entry, entry_content;
>      /* Intermediate table to free if we're replacing it with a superpage. */
> @@ -731,11 +732,12 @@ p2m_pt_set_entry(struct p2m_domain *p2m, unsigned long 
> gfn, mfn_t mfn,
>  }
>  
>  static mfn_t
> -p2m_pt_get_entry(struct p2m_domain *p2m, unsigned long gfn,
> +p2m_pt_get_entry(struct p2m_domain *p2m, gfn_t gfn_t,
>                   p2m_type_t *t, p2m_access_t *a, p2m_query_t q,
>                   unsigned int *page_order, bool_t *sve)
>  {
>      mfn_t mfn;
> +    unsigned long gfn = gfn_x(gfn_t);

These two are rather risky, because you shadow the gfn_t type with a
variable named gfn_t.  I know its ugly, but how about just gfn_ ?

~Andrew

>      paddr_t addr = ((paddr_t)gfn) << PAGE_SHIFT;
>      l2_pgentry_t *l2e;
>      l1_pgentry_t *l1e;
>

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