From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Jones Subject: Re: [PATCH v3 0/2] KVM: ARM: Enable vtimers with user space gic Date: Mon, 19 Sep 2016 09:52:17 +0200 Message-ID: <20160919075217.nlxdmoicjhmc2hy6@kamzik.localdomain> References: <1474007187-18673-1-git-send-email-agraf@suse.de> <57DBC782.7080305@arm.com> <7beb406b-6194-8451-2d92-9a4394ef91dd@redhat.com> <20160916123039.GB14140@cbox> <20160916133027.GA27036@cbox> <20160916134619.jjiaplhxgkkl5qri@kamzik.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoffer Dall , Paolo Bonzini , Marc Zyngier , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org To: Alexander Graf Return-path: Received: from mx1.redhat.com ([209.132.183.28]:39732 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754088AbcISHwW (ORCPT ); Mon, 19 Sep 2016 03:52:22 -0400 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Fri, Sep 16, 2016 at 09:36:42PM +0200, Alexander Graf wrote: > > > > Am 16.09.2016 um 15:46 schrieb Andrew Jones : > > > >> On Fri, Sep 16, 2016 at 03:30:27PM +0200, Christoffer Dall wrote: > >>> On Fri, Sep 16, 2016 at 02:31:42PM +0200, Paolo Bonzini wrote: > >>> > >>> > >>> On 16/09/2016 14:30, Christoffer Dall wrote: > >>>>>>> This patch set allows user space to receive vtimer events as well as mask > >>>>>>> them, so that we can handle all vtimer related interrupt injection from user > >>>>>>> space, enabling us to use architected timer with user space gic emulation. > >>>>>> > >>>>>> I have already voiced my concerns in the past, including face to face, > >>>>>> and I'm going to repeat it: I not keen at all on adding a new userspace > >>>>>> interface that is going to bitrot extremely quickly. > >>>>> > >>>>> You don't have automated tests set up? It's not going to bitrot if you > >>>>> test it, either with kvm-unit-tests or just by smoke-testing Linux. > >>>>> It's _for_ the raspi, but it's not limited to it. > >>>> > >>>> Our automated testing situation is not great, no. Something we're > >>>> looking at, but have resource problems with. > >>> > >>> But it's not a good reason to hold back a feature... > >> > >> I didn't say that exactly, but choosing not to merge something we cannot > >> maintain and which we're not paid to look after and where there's a > >> minimal interest, is not entirely unreasonable. > >> > >> That being said, I'm not categorically against these patches, but I > >> share Marc's view that we've already seen that non-vgic support had been > >> broken for multiple versions without anyone complaining, and without > >> automated testing or substantial interest in the work, the patches > >> really are likely to bit-rot. > >> > >> But I haven't even looked at the patches in detail, I was just replying > >> to the comment about testing. > > > > This may be a great time to start encouraging feature writers to submit > > kvm-unit-tests patches at the same time as the feature (Hi Alex :-) > > I actually started off implementing this with the help of kvm-unit-tests. It's awesome! > > I'm lacking actual irq support to make the test reasonable though and wanted to get the kernel bits out first :). But I'll sit down on that again soon I hope. I'm glad it looks like a good base for you. I need to get this series https://github.com/rhdrjones/kvm-unit-tests/commits/arm/gic refreshed and merged, and also it's time to start looking into adding interrupt injection to chr-testdev. With those in place I hope it'll be an even better base for you. Thanks, drew From mboxrd@z Thu Jan 1 00:00:00 1970 From: drjones@redhat.com (Andrew Jones) Date: Mon, 19 Sep 2016 09:52:17 +0200 Subject: [PATCH v3 0/2] KVM: ARM: Enable vtimers with user space gic In-Reply-To: References: <1474007187-18673-1-git-send-email-agraf@suse.de> <57DBC782.7080305@arm.com> <7beb406b-6194-8451-2d92-9a4394ef91dd@redhat.com> <20160916123039.GB14140@cbox> <20160916133027.GA27036@cbox> <20160916134619.jjiaplhxgkkl5qri@kamzik.localdomain> Message-ID: <20160919075217.nlxdmoicjhmc2hy6@kamzik.localdomain> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Sep 16, 2016 at 09:36:42PM +0200, Alexander Graf wrote: > > > > Am 16.09.2016 um 15:46 schrieb Andrew Jones : > > > >> On Fri, Sep 16, 2016 at 03:30:27PM +0200, Christoffer Dall wrote: > >>> On Fri, Sep 16, 2016 at 02:31:42PM +0200, Paolo Bonzini wrote: > >>> > >>> > >>> On 16/09/2016 14:30, Christoffer Dall wrote: > >>>>>>> This patch set allows user space to receive vtimer events as well as mask > >>>>>>> them, so that we can handle all vtimer related interrupt injection from user > >>>>>>> space, enabling us to use architected timer with user space gic emulation. > >>>>>> > >>>>>> I have already voiced my concerns in the past, including face to face, > >>>>>> and I'm going to repeat it: I not keen at all on adding a new userspace > >>>>>> interface that is going to bitrot extremely quickly. > >>>>> > >>>>> You don't have automated tests set up? It's not going to bitrot if you > >>>>> test it, either with kvm-unit-tests or just by smoke-testing Linux. > >>>>> It's _for_ the raspi, but it's not limited to it. > >>>> > >>>> Our automated testing situation is not great, no. Something we're > >>>> looking at, but have resource problems with. > >>> > >>> But it's not a good reason to hold back a feature... > >> > >> I didn't say that exactly, but choosing not to merge something we cannot > >> maintain and which we're not paid to look after and where there's a > >> minimal interest, is not entirely unreasonable. > >> > >> That being said, I'm not categorically against these patches, but I > >> share Marc's view that we've already seen that non-vgic support had been > >> broken for multiple versions without anyone complaining, and without > >> automated testing or substantial interest in the work, the patches > >> really are likely to bit-rot. > >> > >> But I haven't even looked at the patches in detail, I was just replying > >> to the comment about testing. > > > > This may be a great time to start encouraging feature writers to submit > > kvm-unit-tests patches at the same time as the feature (Hi Alex :-) > > I actually started off implementing this with the help of kvm-unit-tests. It's awesome! > > I'm lacking actual irq support to make the test reasonable though and wanted to get the kernel bits out first :). But I'll sit down on that again soon I hope. I'm glad it looks like a good base for you. I need to get this series https://github.com/rhdrjones/kvm-unit-tests/commits/arm/gic refreshed and merged, and also it's time to start looking into adding interrupt injection to chr-testdev. With those in place I hope it'll be an even better base for you. Thanks, drew