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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 973BCC32771 for ; Wed, 15 Jan 2020 03:49:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 758E4222C3 for ; Wed, 15 Jan 2020 03:49:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729045AbgAODt6 (ORCPT ); Tue, 14 Jan 2020 22:49:58 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:8721 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728884AbgAODt6 (ORCPT ); Tue, 14 Jan 2020 22:49:58 -0500 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 42F61B4ECE60620A8E73; Wed, 15 Jan 2020 11:49:56 +0800 (CST) Received: from [127.0.0.1] (10.173.222.27) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.439.0; Wed, 15 Jan 2020 11:49:46 +0800 Subject: Re: [PATCH v3 29/32] KVM: arm64: GICv4.1: Allow SGIs to switch between HW and SW interrupts To: Shaokun Zhang , Marc Zyngier , , CC: Eric Auger , James Morse , Julien Thierry , Suzuki K Poulose , Thomas Gleixner , Jason Cooper , Lorenzo Pieralisi , "Andrew Murray" , Robert Richter , "Tangnianyao (ICT)" References: <20191224111055.11836-1-maz@kernel.org> <20191224111055.11836-30-maz@kernel.org> From: Zenghui Yu Message-ID: <6e24d53e-64d9-a682-6753-9e16155c7fde@huawei.com> Date: Wed, 15 Jan 2020 11:49:44 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.173.222.27] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 2020/1/15 10:49, Shaokun Zhang wrote: > Hi Marc, [This is from Nianyao] > > On 2019/12/24 19:10, Marc Zyngier wrote: >> In order to let a guest buy in the new, active-less SGIs, we >> need to be able to switch between the two modes. >> >> Handle this by stopping all guest activity, transfer the state >> from one mode to the other, and resume the guest. >> >> Signed-off-by: Marc Zyngier >> --- [...] >> diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c >> index c2fcde104ea2..063785fd2dc7 100644 >> --- a/virt/kvm/arm/vgic/vgic-v4.c >> +++ b/virt/kvm/arm/vgic/vgic-v4.c >> @@ -97,6 +97,102 @@ static irqreturn_t vgic_v4_doorbell_handler(int irq, void *info) >> return IRQ_HANDLED; >> } >> >> +static void vgic_v4_sync_sgi_config(struct its_vpe *vpe, struct vgic_irq *irq) >> +{ >> + vpe->sgi_config[irq->intid].enabled = irq->enabled; >> + vpe->sgi_config[irq->intid].group = irq->group; >> + vpe->sgi_config[irq->intid].priority = irq->priority; >> +} >> + >> +static void vgic_v4_enable_vsgis(struct kvm_vcpu *vcpu) >> +{ >> + struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe; >> + int i; >> + >> + /* >> + * With GICv4.1, every virtual SGI can be directly injected. So >> + * let's pretend that they are HW interrupts, tied to a host >> + * IRQ. The SGI code will do its magic. >> + */ >> + for (i = 0; i < VGIC_NR_SGIS; i++) { >> + struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, i); >> + struct irq_desc *desc; >> + int ret; >> + >> + if (irq->hw) { >> + vgic_put_irq(vcpu->kvm, irq); >> + continue; >> + } >> + >> + irq->hw = true; >> + irq->host_irq = irq_find_mapping(vpe->sgi_domain, i); > > I think we need to check whether irq_find_mapping returns 0. > >> + vgic_v4_sync_sgi_config(vpe, irq); >> + /* >> + * SGIs are initialised as disabled. Enable them if >> + * required by the rest of the VGIC init code. >> + */ >> + desc = irq_to_desc(irq->host_irq); >> + ret = irq_domain_activate_irq(irq_desc_get_irq_data(desc), >> + false); > > If irq->host_irq is not valid , in irq_domain_activate_irq, it will trigger NULL pointer > dereference in host kernel. > I meet a problem here. When hw support GIC4.1, and host kernel is started with > kvm-arm.vgic_v4_enable=0, starting a virtual machine will trigger NULL pointer > dereference in host. I think the thing is that we should _not_ try to configure vSGIs at all if kvm-arm.vgic_v4_enable=0 (which indicates we don't allow use of the GICv4 of direct injection). We currently set kvm_vgic_global_state.has_gicv4_1 to true if HW support GICv4.1, regardless whatever the gicv4_enable is (see patch#23 - vgic_v3_probe). I think this is what actually needs fixing. Thanks, Zenghui