Re: [Xen-devel] [PATCH v2 1/2] XEN, X86: Improve semantic support for pagetable_reserve PVOPS

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 14 Aug 2012, Attilio Rao wrote:
> - Allow xen_mapping_pagetable_reserve() to handle a start different from
>   pgt_buf_start, but still bigger than it.
> - Add checks to xen_mapping_pagetable_reserve() and native_pagetable_reserve()
>   for verifying start and end are contained in the range
>   [pgt_buf_start, pgt_buf_top].
> - In xen_mapping_pagetable_reserve(), change printk into pr_debug.
> - In xen_mapping_pagetable_reserve(), print out diagnostic only if there is
>   an actual need to do that (or, in other words, if there are actually some
>   pages going to switch from RO to RW).
> 
> Signed-off-by: Attilio Rao <attilio.rao@xxxxxxxxxx>
> ---
>  arch/x86/mm/init.c |    4 ++++
>  arch/x86/xen/mmu.c |   22 ++++++++++++++++++++--
>  2 files changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
> index e0e6990..c5849b6 100644
> --- a/arch/x86/mm/init.c
> +++ b/arch/x86/mm/init.c
> @@ -92,6 +92,10 @@ static void __init find_early_table_space(struct map_range 
> *mr, unsigned long en
>  
>  void __init native_pagetable_reserve(u64 start, u64 end)
>  {
> +     if (start < PFN_PHYS(pgt_buf_start) || end > PFN_PHYS(pgt_buf_top))
> +             panic("Invalid address range: [%llu - %llu] should be a subset 
> of [%llu - %llu]\n"

code style (you can check whether your patch breaks the code style with
scripts/checkpatch.pl)

> +                     start, end, PFN_PHYS(pgt_buf_start),
> +                     PFN_PHYS(pgt_buf_top));
>       memblock_reserve(start, end - start);
>  }
>  
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index b65a761..66d73a2 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -1180,12 +1180,30 @@ static void __init xen_pagetable_setup_start(pgd_t 
> *base)
>  
>  static __init void xen_mapping_pagetable_reserve(u64 start, u64 end)
>  {
> +     u64 begin;
> +
> +     begin = PFN_PHYS(pgt_buf_start);
> +
> +     if (start < begin || end > PFN_PHYS(pgt_buf_top))
> +             panic("Invalid address range: [%llu - %llu] should be a subset 
> of [%llu - %llu]\n"

code style

> +                     start, end, begin, PFN_PHYS(pgt_buf_top));
> +
> +     /* set RW the initial range */
> +     if  (start != begin)
> +             pr_debug("xen: setting RW the range %llx - %llx\n",
> +                     begin, start);
> +     while (begin < start) {
> +             make_lowmem_page_readwrite(__va(begin));
> +             begin += PAGE_SIZE;
> +     }
> +
>       /* reserve the range used */
>       native_pagetable_reserve(start, end);
>  
>       /* set as RW the rest */
> -     printk(KERN_DEBUG "xen: setting RW the range %llx - %llx\n", end,
> -                     PFN_PHYS(pgt_buf_top));
> +     if (end != PFN_PHYS(pgt_buf_top))
> +             pr_debug("xen: setting RW the range %llx - %llx\n",
> +                     end, PFN_PHYS(pgt_buf_top));
>       while (end < PFN_PHYS(pgt_buf_top)) {
>               make_lowmem_page_readwrite(__va(end));
>               end += PAGE_SIZE;
> -- 
> 1.7.2.5
> 

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