Re: [Xen-devel] [PATCH 2/5] xen mapcache: Check if a memory space has moved.

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 24 Nov 2011, Anthony PERARD wrote:
> diff --git a/xen-mapcache.c b/xen-mapcache.c
> index 7bcb86e..73927ab 100644
> --- a/xen-mapcache.c
> +++ b/xen-mapcache.c
> @@ -191,10 +191,14 @@ uint8_t *xen_map_cache(target_phys_addr_t phys_addr, 
> target_phys_addr_t size,
>                         uint8_t lock)
>  {
>      MapCacheEntry *entry, *pentry = NULL;
> -    target_phys_addr_t address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;
> -    target_phys_addr_t address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
> +    target_phys_addr_t address_index;
> +    target_phys_addr_t address_offset;
>      target_phys_addr_t __size = size;
>  
> +    phys_addr = xen_addr_actually_is(phys_addr, size);
> +    address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;
> +    address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
> +
>      trace_xen_map_cache(phys_addr);
>  
>      if (address_index == mapcache->last_address_index && !lock && !__size) {

it is probably a good idea to call xen_addr_actually_is only in case
the normal mapping failed, for performance reasons

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