From mboxrd@z Thu Jan 1 00:00:00 1970 From: Derek Murray Subject: Re: Re: Next steps with pv_ops for Xen Date: Thu, 06 Dec 2007 10:00:06 +0000 Message-ID: <4757C826.10506@cl.cam.ac.uk> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Keir Fraser Cc: Jeremy Fitzhardinge , "xen-devel@lists.xensource.com" , Eduardo Habkost , Juan Quintela , Jan Beulich , Glauber de Oliveira Costa , Chris Wright , "virtualization@lists.osdl.org" , Gerd Hoffmann List-Id: virtualization@lists.linuxfoundation.org Keir Fraser wrote: > You'd need to track pte->grant_handle mappings somewhere, but it could > certainly be done this way, yes. At the moment, blktap and gntdev provide struct pages to get_user_pages by smuggling them in the vm_private_data field of the relevant vm_area_struct. Could we use this field to get the handles to ptep_get_and_clear_full as well? Only downside that I can see is that we would need to find the vma for each PTE that needs to be cleared this way (since we don't get this passed to ptep_get_and_clear_full), but this is mitigated by (i) it only happening in the erroneous, unclean-shutdown case, and (ii) getting a hit in the mm->mmap_cache for consecutive runs of mapped grants. Regards, Derek.