Re: [PATCH 2/3] x86/xen: add extra memory for remapped frames during setup

[Juergen Gross <jgross@suse.com>]

On 01/07/2015 03:47 PM, David Vrabel wrote:
> If the non-RAM regions in the e820 memory map are larger than the size
> of the initial balloon, a BUG was triggered as the frames are remaped
> beyond the limit of the linear p2m.  The frames are remapped into the
> initial balloon area (xen_extra_mem) but not enough of this is
> available.
>
> Ensure enough extra memory regions are added for these remapped
> frames.
>
> Signed-off-by: David Vrabel <david.vrabel@citrix.com>

Reviewed-by: Juergen Gross <jgross@suse.com>

> ---
>   arch/x86/xen/setup.c |   13 +++++++++----
>   1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
> index 664dffc..feb6d86 100644
> --- a/arch/x86/xen/setup.c
> +++ b/arch/x86/xen/setup.c
> @@ -366,7 +366,7 @@ static void __init xen_do_set_identity_and_remap_chunk(
>   static unsigned long __init xen_set_identity_and_remap_chunk(
>           const struct e820entry *list, size_t map_size, unsigned long start_pfn,
>   	unsigned long end_pfn, unsigned long nr_pages, unsigned long remap_pfn,
> -	unsigned long *released)
> +	unsigned long *released, unsigned long *remapped)
>   {
>   	unsigned long pfn;
>   	unsigned long i = 0;
> @@ -404,6 +404,7 @@ static unsigned long __init xen_set_identity_and_remap_chunk(
>   		/* Update variables to reflect new mappings. */
>   		i += size;
>   		remap_pfn += size;
> +		*remapped += size;
>   	}
>
>   	/*
> @@ -420,12 +421,13 @@ static unsigned long __init xen_set_identity_and_remap_chunk(
>
>   static void __init xen_set_identity_and_remap(
>   	const struct e820entry *list, size_t map_size, unsigned long nr_pages,
> -	unsigned long *released)
> +	unsigned long *released, unsigned long *remapped)
>   {
>   	phys_addr_t start = 0;
>   	unsigned long last_pfn = nr_pages;
>   	const struct e820entry *entry;
>   	unsigned long num_released = 0;
> +	unsigned long num_remapped = 0;
>   	int i;
>
>   	/*
> @@ -452,12 +454,13 @@ static void __init xen_set_identity_and_remap(
>   				last_pfn = xen_set_identity_and_remap_chunk(
>   						list, map_size, start_pfn,
>   						end_pfn, nr_pages, last_pfn,
> -						&num_released);
> +						&num_released, &num_remapped);
>   			start = end;
>   		}
>   	}
>
>   	*released = num_released;
> +	*remapped = num_remapped;
>
>   	pr_info("Released %ld page(s)\n", num_released);
>   }
> @@ -577,6 +580,7 @@ char * __init xen_memory_setup(void)
>   	struct xen_memory_map memmap;
>   	unsigned long max_pages;
>   	unsigned long extra_pages = 0;
> +	unsigned long remapped_pages;
>   	int i;
>   	int op;
>
> @@ -626,9 +630,10 @@ char * __init xen_memory_setup(void)
>   	 * underlying RAM.
>   	 */
>   	xen_set_identity_and_remap(map, memmap.nr_entries, max_pfn,
> -				   &xen_released_pages);
> +				   &xen_released_pages, &remapped_pages);
>
>   	extra_pages += xen_released_pages;
> +	extra_pages += remapped_pages;
>
>   	/*
>   	 * Clamp the amount of extra memory to a EXTRA_MEM_RATIO
>