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[23.128.96.18]) by mx.google.com with ESMTP id z5si3860658edp.368.2021.03.12.02.52.54; Fri, 12 Mar 2021 02:53:17 -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 S233399AbhCLKt5 (ORCPT + 99 others); Fri, 12 Mar 2021 05:49:57 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:13156 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233633AbhCLKt1 (ORCPT ); Fri, 12 Mar 2021 05:49:27 -0500 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.60]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4DxjCv5Q4pzmWPx; Fri, 12 Mar 2021 18:46:19 +0800 (CST) Received: from [10.174.184.135] (10.174.184.135) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.498.0; Fri, 12 Mar 2021 18:48:29 +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> From: Shenming Lu Message-ID: Date: Fri, 12 Mar 2021 18:48:29 +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: <87k0qcg2s6.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 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! Shenming > > M. >