From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH] virtio-balloon spec: provide a version of the "silent deflate" feature that works Date: Fri, 7 Sep 2012 13:43:06 +0300 Message-ID: <20120907104306.GA17211@redhat.com> References: <1346917610-14568-1-git-send-email-pbonzini@redhat.com> <20120906084736.GF17656@redhat.com> <50486BB2.7070108@redhat.com> <20120906094442.GA22816@redhat.com> <50487382.8030303@redhat.com> <20120906105301.GC32325@redhat.com> <5048935A.8090308@redhat.com> <87wr06hg0l.fsf@rustcorp.com.au> <20120907054202.GA3452@redhat.com> <87vcfqfia1.fsf@rustcorp.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <87vcfqfia1.fsf@rustcorp.com.au> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Rusty Russell Cc: fes@google.com, aarcange@redhat.com, riel@redhat.com, kvm@vger.kernel.org, yvugenfi@redhat.com, linux-kernel@vger.kernel.org, mikew@google.com, yinghan@google.com, Paolo Bonzini , virtualization@lists.linux-foundation.org List-Id: virtualization@lists.linuxfoundation.org On Fri, Sep 07, 2012 at 04:09:50PM +0930, Rusty Russell wrote: > > So it looks like a bug: we should teach driver to tell host first on leak? > > Yan, Vadim, can you comment please? > > > > Also if true, looks like this bit will be useful to detect a fixed driver on > > the hypervisor side - to avoid unmapping such pages? Rusty what do you > > think? > > So, feature is unimplemented in qemu, and broken in drivers. I starting > to share Paolo's dislike of it. What is broken in drivers? To me it looks like it works exactly as advertized: linux and bsd ack TELL_HOST and tells host first. windows does not do either. Do windows drivers currently are not broken: they just do not support the feature. The claim that drivers and hyprevisors do not support it is false: qemu does not support it but drivers do and in non trivial way. > Don't understand why we'd care about fixed drivers though, if we remove > the feature bit.... > > Cheers, > Rusty. Do we really know there are no hypervisors implementing it? As I said above drivers do have support. -- MST From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760307Ab2IGKlw (ORCPT ); Fri, 7 Sep 2012 06:41:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:38580 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752949Ab2IGKlu (ORCPT ); Fri, 7 Sep 2012 06:41:50 -0400 Date: Fri, 7 Sep 2012 13:43:06 +0300 From: "Michael S. Tsirkin" To: Rusty Russell Cc: Paolo Bonzini , fes@google.com, aarcange@redhat.com, riel@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, mikew@google.com, yinghan@google.com, virtualization@lists.linux-foundation.org, yvugenfi@redhat.com, vrozenfe@redhat.com Subject: Re: [PATCH] virtio-balloon spec: provide a version of the "silent deflate" feature that works Message-ID: <20120907104306.GA17211@redhat.com> References: <1346917610-14568-1-git-send-email-pbonzini@redhat.com> <20120906084736.GF17656@redhat.com> <50486BB2.7070108@redhat.com> <20120906094442.GA22816@redhat.com> <50487382.8030303@redhat.com> <20120906105301.GC32325@redhat.com> <5048935A.8090308@redhat.com> <87wr06hg0l.fsf@rustcorp.com.au> <20120907054202.GA3452@redhat.com> <87vcfqfia1.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87vcfqfia1.fsf@rustcorp.com.au> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 07, 2012 at 04:09:50PM +0930, Rusty Russell wrote: > > So it looks like a bug: we should teach driver to tell host first on leak? > > Yan, Vadim, can you comment please? > > > > Also if true, looks like this bit will be useful to detect a fixed driver on > > the hypervisor side - to avoid unmapping such pages? Rusty what do you > > think? > > So, feature is unimplemented in qemu, and broken in drivers. I starting > to share Paolo's dislike of it. What is broken in drivers? To me it looks like it works exactly as advertized: linux and bsd ack TELL_HOST and tells host first. windows does not do either. Do windows drivers currently are not broken: they just do not support the feature. The claim that drivers and hyprevisors do not support it is false: qemu does not support it but drivers do and in non trivial way. > Don't understand why we'd care about fixed drivers though, if we remove > the feature bit.... > > Cheers, > Rusty. Do we really know there are no hypervisors implementing it? As I said above drivers do have support. -- MST