From mboxrd@z Thu Jan 1 00:00:00 1970 From: Radim =?utf-8?B?S3LEjW3DocWZ?= Subject: Re: kvm_pv_unhalt and kernel_irqchip=off Date: Wed, 10 Aug 2016 21:04:13 +0200 Message-ID: <20160810190412.GA8001@potion> References: <20160810182704.GE5627@thinpad.lan.raisama.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Marcelo Tosatti , Paolo Bonzini , peterx@redhat.com, Andrew Jones , kvm@vger.kernel.org To: Eduardo Habkost Return-path: Received: from mx1.redhat.com ([209.132.183.28]:59722 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932483AbcHJTER (ORCPT ); Wed, 10 Aug 2016 15:04:17 -0400 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9D2294E32B for ; Wed, 10 Aug 2016 19:04:16 +0000 (UTC) Content-Disposition: inline In-Reply-To: <20160810182704.GE5627@thinpad.lan.raisama.net> Sender: kvm-owner@vger.kernel.org List-ID: 2016-08-10 15:27-0300, Eduardo Habkost: > Hi, > > I got a bug report[1] that seems to be caused by kvm_pv_unhalt > not working with kernel_irqchip=off. > > Is kvm_pv_unhalt supposed to work at all without kernel_irqchip? No. Guest interface of current PV unhalt is based on APIC ID and KVM does not ask userspace to handle the unknown mapping to VCPU. The code in kernel just somehow managed not to BUG. :) > Should QEMU prevent it from being enabled if kernel_irqchip=off? Yes. We'd need a new guest or userspace interface to make it work. KVM should not pretend that the feature works without kernel_irqchip. > Related question: is there any kvm-unit-test test for > kvm_pv_unhalt? Not that I know of, thanks for the request. > [1] https://bugzilla.redhat.com/show_bug.cgi?id=1363679