From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DE68C433DB for ; Fri, 12 Mar 2021 11:35:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 36C5664F6F for ; Fri, 12 Mar 2021 11:35:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232217AbhCLLey (ORCPT ); Fri, 12 Mar 2021 06:34:54 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:13525 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230062AbhCLLe2 (ORCPT ); Fri, 12 Mar 2021 06:34:28 -0500 Received: from DGGEMS409-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DxkDk5yxmzNlm9; Fri, 12 Mar 2021 19:32:06 +0800 (CST) Received: from [10.174.184.135] (10.174.184.135) by DGGEMS409-HUB.china.huawei.com (10.3.19.209) with Microsoft SMTP Server id 14.3.498.0; Fri, 12 Mar 2021 19:34:18 +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> From: Shenming Lu Message-ID: Date: Fri, 12 Mar 2021 19:34:07 +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: <87h7lgfwzu.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 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()... OK, I will retest this series and send a v4 soon. :-) Thanks, Shenming > > Thanks, > > M. >