Re: [Xen-devel] [PATCH v13 05/19] xen/mmu/p2m: Refactor the xen_pagetable_init code (v2).

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 3 Jan 2014, Konrad Rzeszutek Wilk wrote:
> The revector and copying of the P2M only happens when
> !auto-xlat and on 64-bit builds. It is not obvious from
> the code, so lets have seperate 32 and 64-bit functions.
> 
> We also invert the check for auto-xlat to make the code
> flow simpler.
> 
> Suggested-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

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


>  arch/x86/xen/mmu.c | 70 
> +++++++++++++++++++++++++++++-------------------------
>  1 file changed, 37 insertions(+), 33 deletions(-)
> 
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index ce563be..c140eff 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -1198,44 +1198,40 @@ static void __init xen_cleanhighmap(unsigned long 
> vaddr,
>        * instead of somewhere later and be confusing. */
>       xen_mc_flush();
>  }
> -#endif
> -static void __init xen_pagetable_init(void)
> +static void __init xen_pagetable_p2m_copy(void)
>  {
> -#ifdef CONFIG_X86_64
>       unsigned long size;
>       unsigned long addr;
> -#endif
> -     paging_init();
> -     xen_setup_shared_info();
> -#ifdef CONFIG_X86_64
> -     if (!xen_feature(XENFEAT_auto_translated_physmap)) {
> -             unsigned long new_mfn_list;
> +     unsigned long new_mfn_list;
> +
> +     if (xen_feature(XENFEAT_auto_translated_physmap))
> +             return;
> +
> +     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
> +             return;
>  
> -             /* 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
> -                     goto skip;
> -     }
>       /* 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
> @@ -1255,7 +1251,15 @@ static void __init xen_pagetable_init(void)
>        * anything at this stage. */
>       xen_cleanhighmap(MODULES_VADDR, roundup(MODULES_VADDR, PUD_SIZE) - 1);
>  #endif
> -skip:
> +}
> +#endif
> +
> +static void __init xen_pagetable_init(void)
> +{
> +     paging_init();
> +     xen_setup_shared_info();
> +#ifdef CONFIG_X86_64
> +     xen_pagetable_p2m_copy();
>  #endif
>       xen_post_allocator_init();
>  }
> -- 
> 1.8.3.1
> 

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