From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v2] core, x86: Add user return notifiers Date: Thu, 01 Oct 2009 17:21:22 +0200 Message-ID: <4AC4C8F2.5050708@redhat.com> References: <4AB3CDEC.5050902@zytor.com> <1253342422-13811-1-git-send-email-avi@redhat.com> <4AB8980D.5070803@redhat.com> <20090922143223.GA31702@elte.hu> <4AB8EAF2.1030204@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Ingo Molnar , Peter Zijlstra , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Marcelo Tosatti To: "H. Peter Anvin" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:47148 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752714AbZJAPVj (ORCPT ); Thu, 1 Oct 2009 11:21:39 -0400 In-Reply-To: <4AB8EAF2.1030204@zytor.com> Sender: kvm-owner@vger.kernel.org List-ID: On 09/22/2009 06:19 PM, H. Peter Anvin wrote: > Ingo Molnar wrote: >> * Avi Kivity wrote: >> >>> On 09/19/2009 09:40 AM, Avi Kivity wrote: >>>> Add a general per-cpu notifier that is called whenever the kernel is >>>> about to return to userspace. The notifier uses a thread_info flag >>>> and existing checks, so there is no impact on user return or context >>>> switch fast paths. >>> Ingo/Peter? >> >> Would be nice to convert some existing open-coded >> return-to-user-space logic to this facility. One such candidate would >> be lockdep_sys_exit? >> >> Ingo > > Sorry, limited bandwidth due to LinuxCon, but I like the concept, and > the previous (partial) patch was really clean. I agree with Ingo that > arch support so we can use this as a general facility would be nice, > but I don't consider that as a prerequisite for merging. Re-ping? If accepted, please merge just the core patch and I will carry all of them in parallel. Once tip is merged I'll drop my copy of the first patch. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.