From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH 0/8] use jump labels to streamline common APIC configuration Date: Sun, 5 Aug 2012 16:35:49 +0300 Message-ID: <20120805133549.GL27579@redhat.com> References: <1344171513-4659-1-git-send-email-gleb@redhat.com> <501E760E.9050109@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org, mtosatti@redhat.com To: Avi Kivity Return-path: Received: from mx1.redhat.com ([209.132.183.28]:53753 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754402Ab2HENfw (ORCPT ); Sun, 5 Aug 2012 09:35:52 -0400 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q75DZpS2012312 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Sun, 5 Aug 2012 09:35:51 -0400 Content-Disposition: inline In-Reply-To: <501E760E.9050109@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Sun, Aug 05, 2012 at 04:33:02PM +0300, Avi Kivity wrote: > On 08/05/2012 03:58 PM, Gleb Natapov wrote: > > APIC code has a lot of checks for apic presence and apic HW/SW enable > > state. Most common configuration is when each vcpu has in kernel apic > > and it is fully enabled. This path series uses jump labels to turn checks > > to nops in the common case. > > > > Gleb Natapov (8): > > KVM: clean up kvm_(set|get)_apic_base > > KVM: use kvm_lapic_set_base() to change apic_base > > KVM: mark apic enabled on start up. > > Export jump_label_rate_limit() > > KVM: use jump label to optimize checking for HW enabled APIC in > > APIC_BASE MSR. > > KVM: use jump label to optimize checking for SW enabled apic in > > spurious interrupt register > > KVM: use jump label to optimize checking for in kernel local apic > > presence. > > KVM: inline kvm_apic_present() and kvm_lapic_enabled() > > Neat. > > During guest boot up, some of these jump keys will change, no? Does > this mean a stop_machine() or equivalent? I'm worried about real-time > response or one guest being affected by another. > Yes, SW enable bit changes during boot. The jump label triggerable by a guest are rate limited though. So stop machine will not happen more then once per second even with malicious guests. -- Gleb.