Re: [Xen-devel] [PATCHv2 09/10] x86/xen: export xen_alloc_p2m_entry()

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Fri, Jul 24, 2015 at 12:47:47PM +0100, David Vrabel wrote:
> Rename alloc_p2m() to xen_alloc_p2m_entry() and export it.
> 
> This is useful for ensuring that a p2m entry is allocated (i.e., not a
> shared missing or identity entry) so that subsequent set_phys_to_machine()
> calls will require no further allocations.
> 
> Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> ---
>  arch/x86/include/asm/xen/page.h |  2 ++
>  arch/x86/xen/p2m.c              | 16 ++++++++++------
>  2 files changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
> index c44a5d5..960b380 100644
> --- a/arch/x86/include/asm/xen/page.h
> +++ b/arch/x86/include/asm/xen/page.h
> @@ -45,6 +45,8 @@ extern unsigned long *xen_p2m_addr;
>  extern unsigned long  xen_p2m_size;
>  extern unsigned long  xen_max_p2m_pfn;
>  
> +extern int xen_alloc_p2m_entry(unsigned long pfn);
> +
>  extern unsigned long get_phys_to_machine(unsigned long pfn);
>  extern bool set_phys_to_machine(unsigned long pfn, unsigned long mfn);
>  extern bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
> diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
> index 8b7f18e..ef93ccf 100644
> --- a/arch/x86/xen/p2m.c
> +++ b/arch/x86/xen/p2m.c
> @@ -503,7 +503,7 @@ static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t 
> *pte_pg)
>   * the new pages are installed with cmpxchg; if we lose the race then
>   * simply free the page we allocated and use the one that's there.
>   */
> -static bool alloc_p2m(unsigned long pfn)
> +int xen_alloc_p2m_entry(unsigned long pfn)
>  {
>       unsigned topidx, mididx;
>       unsigned long *top_mfn_p, *mid_mfn;
> @@ -524,7 +524,7 @@ static bool alloc_p2m(unsigned long pfn)
>               /* PMD level is missing, allocate a new one */
>               ptep = alloc_p2m_pmd(addr, pte_pg);
>               if (!ptep)
> -                     return false;
> +                     return -ENOMEM;
>       }
>  
>       if (p2m_top_mfn) {
> @@ -541,7 +541,7 @@ static bool alloc_p2m(unsigned long pfn)
>  
>                       mid_mfn = alloc_p2m_page();
>                       if (!mid_mfn)
> -                             return false;
> +                             return -ENOMEM;
>  
>                       p2m_mid_mfn_init(mid_mfn, p2m_missing);
>  
> @@ -567,7 +567,7 @@ static bool alloc_p2m(unsigned long pfn)
>  
>               p2m = alloc_p2m_page();
>               if (!p2m)
> -                     return false;
> +                     return -ENOMEM;
>  
>               if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
>                       p2m_init(p2m);
> @@ -590,8 +590,9 @@ static bool alloc_p2m(unsigned long pfn)
>                       free_p2m_page(p2m);
>       }
>  
> -     return true;
> +     return 0;
>  }
> +EXPORT_SYMBOL(xen_alloc_p2m);
>  
>  unsigned long __init set_phys_range_identity(unsigned long pfn_s,
>                                     unsigned long pfn_e)
> @@ -648,7 +649,10 @@ bool __set_phys_to_machine(unsigned long pfn, unsigned 
> long mfn)
>  bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
>  {
>       if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
> -             if (!alloc_p2m(pfn))
> +             int ret;
> +
> +             ret = xen_alloc_p2m_entry(pfn);
> +             if (ret < 0)
>                       return false;
>  
>               return __set_phys_to_machine(pfn, mfn);
> -- 
> 2.1.4
> 

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