From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965102AbcCOIwG (ORCPT ); Tue, 15 Mar 2016 04:52:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46193 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934392AbcCOIvz (ORCPT ); Tue, 15 Mar 2016 04:51:55 -0400 Subject: Re: [PATCH 3/3] x86: context_tracking: avoid irq_save/irq_restore on kernel entry and exit To: Andy Lutomirski References: <1445996397-32703-1-git-send-email-pbonzini@redhat.com> <1445996397-32703-4-git-send-email-pbonzini@redhat.com> Cc: "linux-kernel@vger.kernel.org" , kvm list , Andy Lutomirski , Frederic Weisbecker , Rik van Riel , Paul McKenney From: Paolo Bonzini Message-ID: <56E7CD25.8070507@redhat.com> Date: Tue, 15 Mar 2016 09:51:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/03/2016 20:23, Andy Lutomirski wrote: > On Tue, Oct 27, 2015 at 10:22 PM, Andy Lutomirski wrote: >> On Tue, Oct 27, 2015 at 6:39 PM, Paolo Bonzini wrote: >>> x86 always calls user_enter and user_exit with interrupt disabled. >>> Therefore, it is not necessary to check for exceptions, nor to >>> save/restore the IRQ state, when context tracking functions are >>> called by guest_enter and guest_exit. >>> >>> Use the previously introduced __context_tracking_entry and >>> __context_tracking_exit. >> >> x86 isn't ready for this yet. We could do a quick-and-dirty fix with >> explicit IRQs-on-and-off much protected by the static key, or we could >> just wait until I finish the syscall cleanup. I favor the latter, but >> you're all welcome to do the former and I'll review it. >> > > Once Linus pulls tip:x86/asm, x86 should be ready for this. Want to try again? Yup, it's on my todo list. :) Paolo