Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756554Ab0BXKbb (ORCPT ); Wed, 24 Feb 2010 05:31:31 -0500 Received: from goliath.siemens.de ([192.35.17.28]:20496 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756442Ab0BXKb3 (ORCPT ); Wed, 24 Feb 2010 05:31:29 -0500 Message-ID: <4B84FFEE.9020706@siemens.com> Date: Wed, 24 Feb 2010 11:31:10 +0100 From: Jan Kiszka User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 MIME-Version: 1.0 To: Avi Kivity CC: Thomas Gleixner , KVM , Gleb Natapov , RT , Linux Kernel Mailing List Subject: Re: [PATCH] KVM: x86: Kick VCPU outside PIC lock again References: <20100217135901.331576359@linutronix.de> <4B842A1F.50601@siemens.com> <4B84F466.2080009@siemens.com> <4B84F5D4.5020202@redhat.com> <4B84F765.5040209@siemens.com> <4B84F9AF.8060804@redhat.com> <4B84FBDB.1070006@siemens.com> <4B84FCBB.8070702@redhat.com> <4B84FDF5.5080106@siemens.com> <4B84FF2F.5040705@redhat.com> In-Reply-To: <4B84FF2F.5040705@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1404 Lines: 46 Avi Kivity wrote: > On 02/24/2010 12:22 PM, Jan Kiszka wrote: >> Avi Kivity wrote: >> >>> On 02/24/2010 12:13 PM, Jan Kiszka wrote: >>> >>>> >>>>> I see. Won't we hit the same issue when we call pic functions from >>>>> atomic context during the guest entry sequence? >>>>> >>>>> >>>>> >>>> If there are such call paths, for sure. What concrete path(s) do you >>>> have in mind? >>>> >>>> >>>> >>> vcpu_enter_guest() -> inject_pending_event() -> >>> kvm_cpu_{has,get}_interrupt() -> various pic functions if you're unlucky. >>> >> But do they kick anyone or just check/pull information? > > Probably not, kicking should be a side effect (or rather the main > effect) of queueing an interrupt, not dequeuing it. > >> Never saw any >> warnings during my tests last year (granted: with older -rt and kvm >> versions). >> > > Well, most guests kill the pic early on. Will apply the patch. > I think it needs some extension: pic_irq_request should only schedule a wake up on a rising edge of the PIC output. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/