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[23.128.96.18]) by mx.google.com with ESMTP id w22si3956333ejc.517.2021.03.12.04.33.38; Fri, 12 Mar 2021 04:34:02 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230272AbhCLMcm (ORCPT + 99 others); Fri, 12 Mar 2021 07:32:42 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:13504 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231349AbhCLMcJ (ORCPT ); Fri, 12 Mar 2021 07:32:09 -0500 Received: from DGGEMS403-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DxlWs2tZfzrTqr; Fri, 12 Mar 2021 20:30:17 +0800 (CST) Received: from [10.174.184.135] (10.174.184.135) by DGGEMS403-HUB.china.huawei.com (10.3.19.203) with Microsoft SMTP Server id 14.3.498.0; Fri, 12 Mar 2021 20:31:56 +0800 Subject: Re: [PATCH v3 3/4] KVM: arm64: GICv4.1: Restore VLPI's pending state to physical side To: Marc Zyngier CC: Eric Auger , Will Deacon , , , , , Alex Williamson , Cornelia Huck , "Lorenzo Pieralisi" , , References: <20210127121337.1092-1-lushenming@huawei.com> <20210127121337.1092-4-lushenming@huawei.com> <87tupif3x3.wl-maz@kernel.org> <0820f429-4c29-acd6-d9e0-af9f6deb68e4@huawei.com> <87k0qcg2s6.wl-maz@kernel.org> <87h7lgfwzu.wl-maz@kernel.org> <87ft10fulr.wl-maz@kernel.org> From: Shenming Lu Message-ID: <40f40432-63b4-cceb-a9bd-09c6ef91f34d@huawei.com> Date: Fri, 12 Mar 2021 20:31:45 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.2.2 MIME-Version: 1.0 In-Reply-To: <87ft10fulr.wl-maz@kernel.org> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.184.135] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/3/12 20:02, Marc Zyngier wrote: > On Fri, 12 Mar 2021 11:34:07 +0000, > Shenming Lu wrote: >> >> On 2021/3/12 19:10, Marc Zyngier wrote: >>> On Fri, 12 Mar 2021 10:48:29 +0000, >>> Shenming Lu wrote: >>>> >>>> On 2021/3/12 17:05, Marc Zyngier wrote: >>>>> On Thu, 11 Mar 2021 12:32:07 +0000, >>>>> Shenming Lu wrote: >>>>>> >>>>>> On 2021/3/11 17:14, Marc Zyngier wrote: >>>>>>> On Wed, 27 Jan 2021 12:13:36 +0000, >>>>>>> Shenming Lu wrote: >>>>>>>> >>>>>>>> From: Zenghui Yu >>>>>>>> >>>>>>>> When setting the forwarding path of a VLPI (switch to the HW mode), >>>>>>>> we could also transfer the pending state from irq->pending_latch to >>>>>>>> VPT (especially in migration, the pending states of VLPIs are restored >>>>>>>> into kvm’s vgic first). And we currently send "INT+VSYNC" to trigger >>>>>>>> a VLPI to pending. >>>>>>>> >>>>>>>> Signed-off-by: Zenghui Yu >>>>>>>> Signed-off-by: Shenming Lu >>>>>>>> --- >>>>>>>> arch/arm64/kvm/vgic/vgic-v4.c | 14 ++++++++++++++ >>>>>>>> 1 file changed, 14 insertions(+) >>>>>>>> >>>>>>>> diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c >>>>>>>> index ac029ba3d337..a3542af6f04a 100644 >>>>>>>> --- a/arch/arm64/kvm/vgic/vgic-v4.c >>>>>>>> +++ b/arch/arm64/kvm/vgic/vgic-v4.c >>>>>>>> @@ -449,6 +449,20 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int virq, >>>>>>>> irq->host_irq = virq; >>>>>>>> atomic_inc(&map.vpe->vlpi_count); >>>>>>>> >>>>>>>> + /* Transfer pending state */ >>>>>>>> + if (irq->pending_latch) { >>>>>>>> + ret = irq_set_irqchip_state(irq->host_irq, >>>>>>>> + IRQCHIP_STATE_PENDING, >>>>>>>> + irq->pending_latch); >>>>>>>> + WARN_RATELIMIT(ret, "IRQ %d", irq->host_irq); >>>>>>>> + >>>>>>>> + /* >>>>>>>> + * Let it be pruned from ap_list later and don't bother >>>>>>>> + * the List Register. >>>>>>>> + */ >>>>>>>> + irq->pending_latch = false; >>>>>>> >>>>>>> NAK. If the interrupt is on the AP list, it must be pruned from it >>>>>>> *immediately*. The only case where it can be !pending and still on the >>>>>>> AP list is in interval between sync and prune. If we start messing >>>>>>> with this, we can't reason about the state of this list anymore. >>>>>>> >>>>>>> Consider calling vgic_queue_irq_unlock() here. >>>>>> >>>>>> Thanks for giving a hint, but it seems that vgic_queue_irq_unlock() only >>>>>> queues an IRQ after checking, did you mean vgic_prune_ap_list() instead? >>>>> >>>>> No, I really mean vgic_queue_irq_unlock(). It can be used to remove >>>>> the pending state from an interrupt, and drop it from the AP >>>>> list. This is exactly what happens when clearing the pending state of >>>>> a level interrupt, for example. >>>> >>>> Hi, I have gone through vgic_queue_irq_unlock more than once, but >>>> still can't find the place in it to drop an IRQ from the AP >>>> list... Did I miss something ?... Or could you help to point it >>>> out? Thanks very much for this! >>> >>> NO, you are right. I think this is a missing optimisation. Please call >>> the function anyway, as that's what is required to communicate a >>> change of state in general.> >>> I'll have a think about it. >> >> Maybe we could call vgic_prune_ap_list() if (irq->vcpu && >> !vgic_target_oracle(irq)) in vgic_queue_irq_unlock()... > > The locking is pretty ugly in this case, and I don't want to reparse > the whole AP list. It is basically doing the same work as the > insertion, but with a list_del() instead of a list_add()... make sense.. Thanks, Shenming > > We can live without it for now. > >> OK, I will retest this series and send a v4 soon. :-) > > Thanks, > > M. >