Re: [Xen-devel] [PATCH V3 4/8] xen: Delay invalidating extra memory

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

> @@ -376,12 +374,14 @@ void __init xen_build_dynamic_phys_to_machine(void)
>       unsigned long max_pfn;
>       unsigned long pfn;
>  
> -      if (xen_feature(XENFEAT_auto_translated_physmap))
> +     if (xen_feature(XENFEAT_auto_translated_physmap))

Spurious change.

.. snip..
> diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
> index 0e5f9b6..8d5985b 100644
> --- a/arch/x86/xen/setup.c
> +++ b/arch/x86/xen/setup.c
> @@ -75,7 +75,6 @@ static unsigned long xen_remap_mfn __initdata = 
> INVALID_P2M_ENTRY;
>  
>  static void __init xen_add_extra_mem(u64 start, u64 size)
>  {
> -     unsigned long pfn;
>       int i;
>  
>       for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
> @@ -95,17 +94,74 @@ static void __init xen_add_extra_mem(u64 start, u64 size)
>               printk(KERN_WARNING "Warning: not enough extra memory 
> regions\n");
>  
>       memblock_reserve(start, size);
> +}
>  
> -     xen_max_p2m_pfn = PFN_DOWN(start + size);
> -     for (pfn = PFN_DOWN(start); pfn < xen_max_p2m_pfn; pfn++) {
> -             unsigned long mfn = pfn_to_mfn(pfn);
> +static void __init xen_del_extra_mem(u64 start, u64 size)
> +{
> +     int i;
> +     u64 start_r, size_r;
>  
> -             if (WARN_ONCE(mfn == pfn, "Trying to over-write 1-1 mapping 
> (pfn: %lx)\n", pfn))
> -                     continue;
> -             WARN_ONCE(mfn != INVALID_P2M_ENTRY, "Trying to remove %lx which 
> has %lx mfn!\n",
> -                       pfn, mfn);
> +     for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
> +             start_r = xen_extra_mem[i].start;
> +             size_r = xen_extra_mem[i].size;
> +
> +             /* Start of region. */
> +             if (start_r == start) {
> +                     BUG_ON(size > size_r);
> +                     xen_extra_mem[i].start += size;
> +                     xen_extra_mem[i].size -= size;
> +                     break;
> +             }
> +             /* End of region. */
> +             if (start_r + size_r == start + size) {
> +                     BUG_ON(size > size_r);
> +                     xen_extra_mem[i].size -= size;
> +                     break;
> +             }
> +             /* Mid of region. */
> +             if (start > start_r && start < start_r + size_r) {
> +                     BUG_ON(start + size > start_r + size_r);
> +                     xen_extra_mem[i].size = start - start_r;
> +                     xen_add_extra_mem(start + size, start_r + size_r -
> +                                       (start + size));

Which ends up calling 'memblock_reserve' for an region it already has
reserved. Should we call memblock_free(start_r, size_r - size) before calling 
this?

Or is that not neccessary as memblock_* is pretty smart about this sort of 
thing?

> +                     break;
> +             }
> +     }
> +     memblock_free(start, size);
> +}
> +

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