Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756377Ab0BXKEm (ORCPT ); Wed, 24 Feb 2010 05:04:42 -0500 Received: from mx1.redhat.com ([209.132.183.28]:41721 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756265Ab0BXKEk (ORCPT ); Wed, 24 Feb 2010 05:04:40 -0500 Message-ID: <4B84F9AF.8060804@redhat.com> Date: Wed, 24 Feb 2010 12:04:31 +0200 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.7) Gecko/20100120 Fedora/3.0.1-1.fc12 Thunderbird/3.0.1 MIME-Version: 1.0 To: Jan Kiszka 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> In-Reply-To: <4B84F765.5040209@siemens.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1314 Lines: 46 On 02/24/2010 11:54 AM, Jan Kiszka wrote: > Avi Kivity wrote: > >> On 02/24/2010 11:41 AM, Jan Kiszka wrote: >> >>> Thomas Gleixner wrote: >>> >>> >>>> On Tue, 23 Feb 2010, Jan Kiszka wrote: >>>> >>>> >>>> >>>>> Thomas Gleixner wrote: >>>>> >>>>> >>>>>> The i8254/i8259 locks need to be real spinlocks on preempt-rt. Convert >>>>>> them to raw_spinlock. No change for !RT kernels. >>>>>> >>>>>> >>>>> Doesn't fly for -rt anymore: pic_irq_update runs under this raw lock and >>>>> calls kvm_vcpu_kick which tries to wake_up some thread -> scheduling >>>>> while atomic. >>>>> >>>>> >>>> Hmm, a wakeup itself is fine. Is that code waking a wake queue ? >>>> >>>> >>> Yes, it's a wake queue. >>> >>> >> So what's the core issue? Is the lock_t in the wait_queue a sleeping mutex? >> > Yep. > I see. Won't we hit the same issue when we call pic functions from atomic context during the guest entry sequence? -- error compiling committee.c: too many arguments to function -- 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/