Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41551C61DA3 for ; Fri, 27 Jan 2023 15:58:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231952AbjA0P6j (ORCPT ); Fri, 27 Jan 2023 10:58:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52634 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230313AbjA0P6h (ORCPT ); Fri, 27 Jan 2023 10:58:37 -0500 Received: from out0.migadu.com (out0.migadu.com [IPv6:2001:41d0:2:267::]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8FDC180173; Fri, 27 Jan 2023 07:58:33 -0800 (PST) Message-ID: <713a3e22-6327-875e-072d-e916f75d5239@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1674835111; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=LilgKmKEflCZfQlcQYFPLEHnFe8sGUdWiFuvFJpiBQE=; b=W1h1/95tW4oi19mOTrCL4z3lTFY8WnS1D5JQdlCzgj3W/8QulHUVnFCJLQrkC+WNPqCc47 rjsHDgp33JKmjFdkuV7f2w+Tvq9wVSksD8V1gMzpBeUH3UoXQOMnhfMW/yBZFXt6NGDQ2G 6akvkrV+vSX/NkAKfmFonoHFUCrl15c= Date: Fri, 27 Jan 2023 23:57:57 +0800 MIME-Version: 1.0 Subject: Re: [PATCH v3 4/4] KVM: arm64: Allow no running vcpu on saving vgic3 pending table Content-Language: en-US To: Gavin Shan , kvmarm@lists.linux.dev Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, pbonzini@redhat.com, corbet@lwn.net, maz@kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, yuzhe@nfschina.com, isaku.yamahata@intel.com, seanjc@google.com, ricarkol@google.com, eric.auger@redhat.com, renzhengeek@gmail.com, reijiw@google.com, shan.gavin@gmail.com References: <20230126235451.469087-1-gshan@redhat.com> <20230126235451.469087-5-gshan@redhat.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Zenghui Yu In-Reply-To: <20230126235451.469087-5-gshan@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/1/27 07:54, Gavin Shan wrote: > We don't have a running VCPU context to save vgic3 pending table due > to KVM_DEV_ARM_VGIC_{GRP_CTRL, SAVE_PENDING_TABLES} command on KVM > device "kvm-arm-vgic-v3". The unknown case is caught by kvm-unit-tests. > > # ./kvm-unit-tests/tests/its-pending-migration > WARNING: CPU: 120 PID: 7973 at arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3325 \ > mark_page_dirty_in_slot+0x60/0xe0 > : > mark_page_dirty_in_slot+0x60/0xe0 > __kvm_write_guest_page+0xcc/0x100 > kvm_write_guest+0x7c/0xb0 > vgic_v3_save_pending_tables+0x148/0x2a0 > vgic_set_common_attr+0x158/0x240 > vgic_v3_set_attr+0x4c/0x5c > kvm_device_ioctl+0x100/0x160 > __arm64_sys_ioctl+0xa8/0xf0 > invoke_syscall.constprop.0+0x7c/0xd0 > el0_svc_common.constprop.0+0x144/0x160 > do_el0_svc+0x34/0x60 > el0_svc+0x3c/0x1a0 > el0t_64_sync_handler+0xb4/0x130 > el0t_64_sync+0x178/0x17c > > Use vgic_write_guest_lock() to save vgic3 pending table. > > Reported-by: Zenghui Yu > Signed-off-by: Gavin Shan > Reviewed-by: Oliver Upton > --- > Documentation/virt/kvm/api.rst | 4 +++- > arch/arm64/kvm/vgic/vgic-v3.c | 2 +- > 2 files changed, 4 insertions(+), 2 deletions(-) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index 40ada313faa3..07f07668995e 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -8074,7 +8074,9 @@ NOTE: Multiple examples of using the backup bitmap: (1) save vgic/its > tables through command KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_SAVE_TABLES} on > KVM device "kvm-arm-vgic-its". (2) restore vgic/its tables through > command KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_RESTORE_TABLES} on KVM device > -"kvm-arm-vgic-its". vgic3 LPI pending status is restored. > +"kvm-arm-vgic-its". vgic3 LPI pending status is restored. (3) save > +vgic3 pending table through KVM_DEV_ARM_VGIC_{GRP_CTRL, SAVE_PENDING_TABLES} > +command on KVM device "kvm-arm-vgic-v3". Can we summarize these 3 examples with something like: "when the guest memory (pending tables, ITS tables, etc) is dirtied by the virtual GIC or ITS, which is typically triggered by a userspace request (e.g., KVM_DEV_ARM_ITS_SAVE_TABLES) and doesn't require a running VCPU context"? In case there will be more no-running-vcpu kvm_write_guest_lock() cases in the VGIC emulation code in future and we have to extend the documentation.. But I don't have objection to your writing and the whole series looks good. Thanks, Zenghui