From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gerd Hoffmann Subject: Re: Re: Next steps with pv_ops for Xen Date: Wed, 05 Dec 2007 21:06:08 +0100 Message-ID: <475704B0.1000701@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 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: Derek Murray , "xen-devel@lists.xensource.com" , Eduardo Habkost , Juan Quintela , "Stephen C. Tweedie" , Jan Beulich , Glauber de Oliveira Costa , Chris Wright , "virtualization@lists.osdl.org" List-Id: virtualization@lists.linuxfoundation.org >> Alternatively, could we use the _PAGE_GNTTAB PTE flag that is used for >> debugging? Indeed, if we did this, could be obviate the need for the >> PTE-zapping hook, by instead catching the case where this flag is set, >> and unmapping the grant implicitly? > > Well, in the general case you don't have enough info to know which grant to > release (a single page can be granted multiple times). You'll also get the mm and the addr which should make it sufficiently unique, so this looks like a doable approach to me. ptep_get_and_clear_full() in include/asm-x86/pgtable_32.h needs to be changed take care, but that should be possible to do and the change is local to x86 paravirt_ops, which looks much better to me than touching generic mm code. cheers, Gerd