Re: [Xen-devel] Bug on shadow page mode

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 04.04.13 at 12:34, Tim Deegan <tim@xxxxxxx> wrote:
> OTOH, looking at map_domain_page_global, there doesn't seem to be any 
> locking preventing two CPUs from populating a page of global-map l1es at
> the same time.  So, here's a different patch to test -- it would be good
> to know if this patch by itself fixes the crash.

With Xudong having verified the fix, I would convert it into full
patch form and commit it, but I'd need your confirmation that I
can put your S-o-b on it.

Jan

> --- a/xen/arch/x86/domain_page.c
> +++ b/xen/arch/x86/domain_page.c
> @@ -354,9 +354,10 @@ void *map_domain_page_global(unsigned long mfn)
>      set_bit(idx, inuse);
>      inuse_cursor = idx + 1;
>  
> +    pl1e = virt_to_xen_l1e(va);
> +
>      spin_unlock(&globalmap_lock);
>  
> -    pl1e = virt_to_xen_l1e(va);
>      if ( !pl1e )
>          return NULL;
>      l1e_write(pl1e, l1e_from_pfn(mfn, __PAGE_HYPERVISOR));




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