Re: [Xen-devel] [PATCH v13 06/19] xen/mmu: Cleanup xen_pagetable_p2m_copy a bit.

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 3 Jan 2014, Konrad Rzeszutek Wilk wrote:
> Stefano noticed that the code runs only under 64-bit so
> the comments about 32-bit are pointless.
> 
> Also we change the condition for xen_revector_p2m_tree
> returning the same value (because it could not allocate
> a swath of space to put the new P2M in) or it had been
> called once already. In such we return early from the
> function.
> 
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>


>  arch/x86/xen/mmu.c | 40 ++++++++++++++++++++--------------------
>  1 file changed, 20 insertions(+), 20 deletions(-)
> 
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index c140eff..9d74249 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -1209,29 +1209,29 @@ static void __init xen_pagetable_p2m_copy(void)
>  
>       size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));
>  
> -     /* On 32-bit, we get zero so this never gets executed. */
>       new_mfn_list = xen_revector_p2m_tree();
> -     if (new_mfn_list && new_mfn_list != xen_start_info->mfn_list) {
> -             /* using __ka address and sticking INVALID_P2M_ENTRY! */
> -             memset((void *)xen_start_info->mfn_list, 0xff, size);
> -
> -             /* We should be in __ka space. */
> -             BUG_ON(xen_start_info->mfn_list < __START_KERNEL_map);
> -             addr = xen_start_info->mfn_list;
> -             /* We roundup to the PMD, which means that if anybody at this 
> stage is
> -              * using the __ka address of xen_start_info or 
> xen_start_info->shared_info
> -              * they are in going to crash. Fortunatly we have already 
> revectored
> -              * in xen_setup_kernel_pagetable and in xen_setup_shared_info. 
> */
> -             size = roundup(size, PMD_SIZE);
> -             xen_cleanhighmap(addr, addr + size);
> -
> -             size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned 
> long));
> -             memblock_free(__pa(xen_start_info->mfn_list), size);
> -             /* And revector! Bye bye old array */
> -             xen_start_info->mfn_list = new_mfn_list;
> -     } else
> +     /* No memory or already called. */
> +     if (!new_mfn_list || new_mfn_list == xen_start_info->mfn_list)
>               return;
>  
> +     /* using __ka address and sticking INVALID_P2M_ENTRY! */
> +     memset((void *)xen_start_info->mfn_list, 0xff, size);
> +
> +     /* We should be in __ka space. */
> +     BUG_ON(xen_start_info->mfn_list < __START_KERNEL_map);
> +     addr = xen_start_info->mfn_list;
> +     /* We roundup to the PMD, which means that if anybody at this stage is
> +      * using the __ka address of xen_start_info or 
> xen_start_info->shared_info
> +      * they are in going to crash. Fortunatly we have already revectored
> +      * in xen_setup_kernel_pagetable and in xen_setup_shared_info. */
> +     size = roundup(size, PMD_SIZE);
> +     xen_cleanhighmap(addr, addr + size);
> +
> +     size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));
> +     memblock_free(__pa(xen_start_info->mfn_list), size);
> +     /* And revector! Bye bye old array */
> +     xen_start_info->mfn_list = new_mfn_list;
> +
>       /* At this stage, cleanup_highmap has already cleaned __ka space
>        * from _brk_limit way up to the max_pfn_mapped (which is the end of
>        * the ramdisk). We continue on, erasing PMD entries that point to page
> -- 
> 1.8.3.1
> 

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