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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=unavailable 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 4A9FCC2BA19 for ; Tue, 14 Apr 2020 13:16:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 236762063A for ; Tue, 14 Apr 2020 13:16:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586870169; bh=v0a5YinYfPspIVz+q0NHgE/kUU23yUEY3inKhdoX4tU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=hqwycVqx/SEXfcn2+QOy3A0DuAkdId2x2NaXyFEdLQteLlMfDHKtCc0SQ7BWBYMrP DpmqcXFk2BpLJIH2oQjZTqgXPseKt6Tepujj1zBz1nbSPq/wiFJpzCuiA9WDJxP8kO Xo174ZX6PV6CzZi74MyrjT17IgO2XEYQJ4yKiK6U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2502893AbgDNNQE (ORCPT ); Tue, 14 Apr 2020 09:16:04 -0400 Received: from mail.kernel.org ([198.145.29.99]:42792 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2502768AbgDNNPL (ORCPT ); Tue, 14 Apr 2020 09:15:11 -0400 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 993552075E; Tue, 14 Apr 2020 13:15:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586870110; bh=v0a5YinYfPspIVz+q0NHgE/kUU23yUEY3inKhdoX4tU=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=w3390RS3SR8v6HZfOEkZCrpHMCPLgbTFJk2j24PRa75T/76LECBlHWumjlVFr0KQt IOQF4ZkQGozqEMqhJMSKG1XR3b5udb0nV9muqMutN7bn/yOq95DbwY8+nEVqhJ4uLm d3glyW9gRNB4lcZpGcAtrdqQrBuS2VORrG3uSas0= Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why) by disco-boy.misterjones.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jOLPA-0039rd-KC; Tue, 14 Apr 2020 14:15:08 +0100 Date: Tue, 14 Apr 2020 14:15:07 +0100 From: Marc Zyngier To: Zenghui Yu Cc: , , , , , , , Subject: Re: [PATCH 1/2] KVM: arm64: vgic-v3: Retire all pending LPIs on vcpu destroy Message-ID: <20200414141507.0d0a0f93@why> In-Reply-To: References: <20200414030349.625-1-yuzenghui@huawei.com> <20200414030349.625-2-yuzenghui@huawei.com> <20200414115417.451f8b66@why> Organization: Approximate X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: yuzenghui@huawei.com, kvmarm@lists.cs.columbia.edu, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, wanghaibin.wang@huawei.com, yezengruan@huawei.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 14 Apr 2020 19:17:49 +0800 Zenghui Yu wrote: > Hi Marc, > > On 2020/4/14 18:54, Marc Zyngier wrote: > > On Tue, 14 Apr 2020 11:03:47 +0800 > > Zenghui Yu wrote: > > > > Hi Zenghui, > > > >> It's likely that the vcpu fails to handle all virtual interrupts if > >> userspace decides to destroy it, leaving the pending ones stay in the > >> ap_list. If the un-handled one is a LPI, its vgic_irq structure will > >> be eventually leaked because of an extra refcount increment in > >> vgic_queue_irq_unlock(). > >> > >> This was detected by kmemleak on almost every guest destroy, the > >> backtrace is as follows: > >> > >> unreferenced object 0xffff80725aed5500 (size 128): > >> comm "CPU 5/KVM", pid 40711, jiffies 4298024754 (age 166366.512s) > >> hex dump (first 32 bytes): > >> 00 00 00 00 00 00 00 00 08 01 a9 73 6d 80 ff ff ...........sm... > >> c8 61 ee a9 00 20 ff ff 28 1e 55 81 6c 80 ff ff .a... ..(.U.l... > >> backtrace: > >> [<000000004bcaa122>] kmem_cache_alloc_trace+0x2dc/0x418 > >> [<0000000069c7dabb>] vgic_add_lpi+0x88/0x418 > >> [<00000000bfefd5c5>] vgic_its_cmd_handle_mapi+0x4dc/0x588 > >> [<00000000cf993975>] vgic_its_process_commands.part.5+0x484/0x1198 > >> [<000000004bd3f8e3>] vgic_its_process_commands+0x50/0x80 > >> [<00000000b9a65b2b>] vgic_mmio_write_its_cwriter+0xac/0x108 > >> [<0000000009641ebb>] dispatch_mmio_write+0xd0/0x188 > >> [<000000008f79d288>] __kvm_io_bus_write+0x134/0x240 > >> [<00000000882f39ac>] kvm_io_bus_write+0xe0/0x150 > >> [<0000000078197602>] io_mem_abort+0x484/0x7b8 > >> [<0000000060954e3c>] kvm_handle_guest_abort+0x4cc/0xa58 > >> [<00000000e0d0cd65>] handle_exit+0x24c/0x770 > >> [<00000000b44a7fad>] kvm_arch_vcpu_ioctl_run+0x460/0x1988 > >> [<0000000025fb897c>] kvm_vcpu_ioctl+0x4f8/0xee0 > >> [<000000003271e317>] do_vfs_ioctl+0x160/0xcd8 > >> [<00000000e7f39607>] ksys_ioctl+0x98/0xd8 > >> > >> Fix it by retiring all pending LPIs in the ap_list on the destroy path. > >> > >> p.s. I can also reproduce it on a normal guest shutdown. It is because > >> userspace still send LPIs to vcpu (through KVM_SIGNAL_MSI ioctl) while > >> the guest is being shutdown and unable to handle it. A little strange > >> though and haven't dig further... > > > > What userspace are you using? You'd hope that the VMM would stop > > processing I/Os when destroying the guest. But we still need to handle > > it anyway, and I thing this fix makes sense. > > I'm using Qemu (master) for debugging. Looks like an interrupt > corresponding to a virtio device configuration change, triggered after > all other devices had freed their irqs. Not sure if it's expected. > > >> > >> Signed-off-by: Zenghui Yu > >> --- > >> virt/kvm/arm/vgic/vgic-init.c | 6 ++++++ > >> 1 file changed, 6 insertions(+) > >> > >> diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c > >> index a963b9d766b7..53ec9b9d9bc4 100644 > >> --- a/virt/kvm/arm/vgic/vgic-init.c > >> +++ b/virt/kvm/arm/vgic/vgic-init.c > >> @@ -348,6 +348,12 @@ void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu) > >> { > >> struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu; > >> >> + /* > >> + * Retire all pending LPIs on this vcpu anyway as we're > >> + * going to destroy it. > >> + */ > >> + vgic_flush_pending_lpis(vcpu); > >> + > >> INIT_LIST_HEAD(&vgic_cpu->ap_list_head); > >> } > >> > > I guess that at this stage, the INIT_LIST_HEAD() is superfluous, right? > > I was just thinking that the ap_list_head may not be empty (besides LPI, > with other active or pending interrupts), so leave it unchanged. It isn't clear what purpose this serves (the vcpus are about to be freed, and so are the ap_lists), but I guess it doesn't hurt either. I'll queue both patches. Thanks, M. -- Jazz is not dead. It just smells funny...