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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7FFBCC3DA4A for ; Mon, 19 Aug 2024 12:49:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: References:In-Reply-To:Subject:Cc:To:From:Message-ID:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=1/7F3rn/IWPJV0INM8TbMsb+fny/oMHjxdbp0hsMn/U=; b=4Aa9E7mAf+7+dl3IqZNPZYlOTo FIuQLRIMiTT8EN2+TlOIh4fEUJ4b8wJkgrMvX5FbBJcL2d1H9Nr+k6XgIFRweDjLAwpN7Ecg2Y8xv FfHBGtNJQfmEd74fMCkDwcnkfcw0IZ84HooSkJaNP/my7XUeD7bL/SQqApvhXBU9VjFIcg2l7z5sc XI72tXKJbMAn9jEe36Nez1NycAw4rE4gXvDflhQ99tPuXIq6iM8mDGxlxJRVc8ReMPYVeDcSxm4db 5/I+MLluEkNSLPBQPnpVi6nkmwlXSqlXNx+52guvhD6TMoBE4i9HbY57J8eEfhydl/ocud2hVjKSe VOKj0/2Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1sg1p7-00000001U8d-3ht3; Mon, 19 Aug 2024 12:49:25 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1sg1oQ-00000001U1f-2UC8 for linux-arm-kernel@lists.infradead.org; Mon, 19 Aug 2024 12:48:44 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id B18CD60C31; Mon, 19 Aug 2024 12:48:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 820E4C4AF11; Mon, 19 Aug 2024 12:48:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1724071721; bh=rJ00fmlX3u2TZClBGgRz2pCSLIEUy/YzfF3e903e8yk=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=WlqT2UHVJ11bw9efaSi7HxgJLTWhqxkIFhqsx9WYw5Q/hOW5hsDTYsFPICwt6HP92 2G3wt/bYWIKkTFB7Ee/gKPFy0wKYUtfEUMIkv4CAoLpo3SqBR08Fu9vuWqRQh9bI+1 EmtoufYqKz4fu71fDrVB2hCBacwtJfmZjJn0FtcMkddnNyvaPXeB0t4gbihgC3QPwn O/EY2mvKRnPdQiH3YEsBlpefXW5RX9vb+CGpMIGU3jhglhy0EmvZuSyv5tOGGwCw+D r4ejylHd8UWIbrV/TDFs2V5CZ5hhTTZyYh6BAXQfqqwPEserpB+T4jYKKmHkPOzzl8 6NIa3IMzVZshg== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1sg1oN-004uuX-41; Mon, 19 Aug 2024 13:48:39 +0100 Date: Mon, 19 Aug 2024 13:48:38 +0100 Message-ID: <861q2kznix.wl-maz@kernel.org> From: Marc Zyngier To: Zenghui Yu Cc: , , James Morse , Suzuki K Poulose , Oliver Upton , Alexander Potapenko Subject: Re: [PATCH] KVM: arm64: vgic: Hold config_lock while tearing down a CPU interface In-Reply-To: <40d0a14b-b501-aef6-a168-1c1acd5448e7@huawei.com> References: <20240808091546.3262111-1-maz@kernel.org> <8634n0zsu0.wl-maz@kernel.org> <40d0a14b-b501-aef6-a168-1c1acd5448e7@huawei.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.4 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: yuzenghui@huawei.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, glider@google.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240819_054842_787572_AEA73C73 X-CRM114-Status: GOOD ( 29.02 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, 19 Aug 2024 13:31:59 +0100, Zenghui Yu wrote: > > On 2024/8/19 18:53, Marc Zyngier wrote: > > On Mon, 19 Aug 2024 10:39:50 +0100, > > Zenghui Yu wrote: > > > > > > Hi Marc, > > > > > > On 2024/8/8 17:15, Marc Zyngier wrote: > > > > Tearing down a vcpu CPU interface involves freeing the private interrupt > > > > array. If we don't hold the lock, we may race against another thread > > > > trying to configure it. Yeah, fuzzers do wonderful things... > > > > > > > > Taking the lock early solves this particular problem. > > > > > > > > Fixes: 03b3d00a70b5 ("KVM: arm64: vgic: Allocate private interrupts on demand") > > > > Reported-by: Alexander Potapenko > > > > Tested-by: Alexander Potapenko > > > > Signed-off-by: Marc Zyngier > > > > --- > > > > arch/arm64/kvm/vgic/vgic-init.c | 3 +-- > > > > 1 file changed, 1 insertion(+), 2 deletions(-) > > > > > > > > diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c > > > > index 7f68cf58b978..41feb858ff9a 100644 > > > > --- a/arch/arm64/kvm/vgic/vgic-init.c > > > > +++ b/arch/arm64/kvm/vgic/vgic-init.c > > > > @@ -438,14 +438,13 @@ void kvm_vgic_destroy(struct kvm *kvm) > > > > unsigned long i; > > > > > > > > mutex_lock(&kvm->slots_lock); > > > > + mutex_lock(&kvm->arch.config_lock); > > > > > > > > vgic_debug_destroy(kvm); > > > > > > > > kvm_for_each_vcpu(i, vcpu, kvm) > > > > __kvm_vgic_vcpu_destroy(vcpu); > > > > > > > > - mutex_lock(&kvm->arch.config_lock); > > > > - > > > > kvm_vgic_dist_destroy(kvm); > > > > > > > > mutex_unlock(&kvm->arch.config_lock); > > > > > > The following splat was triggered when running the vgic_init selftest on > > > a lockdep kernel (I use rc4, with defconfig + PROVE_LOCKING). > > > > > > I'm not entirely sure that the splat is related to this change. Just > > > haven't got time to dig further so post it out early for record. > > > > Arghh. Thanks for reporting this. Can you try the following patch? It > > does the trick for me, but I don't trust myself anymore... > > I tested it with defconfig+PROVE_LOCKING and my own config, both worked > for me (the WARNING disappeared). I think the locking order should be > correct now. Awesome. Let me post a proper patch right away. Thanks again, M. -- Without deviation from the norm, progress is not possible.