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 9D551C88E50 for ; Fri, 11 Sep 2026 08:44:19 +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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From: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=vg4F0k6m+4+kzUXRLBavhu3U7lVZddOyXeiUGCg25js=; b=1/u2RKd8lPinq5DjgGP9UqJsOW cBccb2JzHST3b8qrLrN3qK+HW72f5UHGW8vxOaMdZFIDohU8IzwOx0Fx1JEhAO8tyuTpMNHbZc4RF gQ58+AfjfO/s284Ln0sRxg1gZPFDQ24zhTiW5iYWkOVKop+42KNY5TALs+do9tD2vJ79vhI/TxQG9 jl96d8iPWHAvFVwAxA59ZSCoyrZxI5ptODqpbjMgzufhMV+6mniQpejk08bbjpoK1/2/GV4btMPPe 2j1XZaDVsKkiPBo1/yzpjZee4QrEIMhXDuJnPx93K8DyUVTsMyOer+YvQntCJMsUpt1prPG81VxoR DGduUarw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x4wrl-0000000GAQi-1k2l; Fri, 11 Sep 2026 08:44:13 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x4wrk-0000000GAQS-0k0c for linux-arm-kernel@lists.infradead.org; Fri, 11 Sep 2026 08:44:12 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id BEFB940C1E; Fri, 11 Sep 2026 08:44:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 493C41F000FF; Fri, 11 Sep 2026 08:44:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789116251; bh=vg4F0k6m+4+kzUXRLBavhu3U7lVZddOyXeiUGCg25js=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=O8LgwFy42EhGdTvVn3EhBaT0y7CkuGzg0ms4nYS/vmCIFDDimi6eIzv4AkEWKgqms NqGCc+KcmrlqlgNtlz+n2ZAn4mt+1d8Bp4pARgvV6UsRPlOL3iAudNnMeciIWjKC2g 486vaVWTK2vW3Ce1Dm30Xl8nAZ/wEBCEXjyK94T711Dc/0VHsFU/6aSgynNNqRxpf3 jUhoSBJLZ+TLgVKvf4VfidcqsZ5rYg5XPEDJQ+S6G75ShYzOAq41nS1ot45lnbwUV9 hu0hOO4mEzBDl9SIyLCAAQzW4jVsQwHfyNqVmRRU3S1ewkAB5uqLuUA2BaFjAaBLi+ sYgWQPd8DNDsg== Date: Fri, 11 Sep 2026 09:44:04 +0100 From: "Lorenzo Stoakes (ARM)" To: Jonathan Davies Cc: catalin.marinas@arm.com, christoffer.dall@arm.com, fuad.tabba@linux.dev, joey.gouly@arm.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, maz@kernel.org, oupton@kernel.org, seiden@linux.ibm.com, stable@vger.kernel.org, suzuki.poulose@arm.com, weilin.chang@arm.com, will@kernel.org, yaoyuan@linux.alibaba.com, yuzenghui@huawei.com Subject: Re: [PATCH v3 2/2] KVM: arm64: nv: Fix null ptr deref on nested wp/unmap, teardown race Message-ID: References: <20260901-kvm-arm-nested-virt-fix-v3-2-b154676f7e4c@kernel.org> <9829c704-9592-4235-b97c-dc1f5e4ea795@nutanix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9829c704-9592-4235-b97c-dc1f5e4ea795@nutanix.com> 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 Fri, Sep 11, 2026 at 09:12:20AM +0100, Jonathan Davies wrote: > On Tue, 01 Sep 2026, "Lorenzo Stoakes (ARM)" wrote: > > This means that stage2_apply_range() can drop the kvm->mmu_lock and > > thus concurrent progress can be made in lockstep with > > kvm_arch_flush_shadow_all(). > > > > If kvm_arch_flush_shadow_all() advances ahead of stage2_apply_range() > > and completes its operation it guarantees a NULL pointer deref. > > I've reproducibly hit exactly this problem when running nested guests > with concurrent memory compaction on the L0 host. This patch fixes it > for me perfectly (applied to a 6.18 kernel). > > So, for what it's worth: > > Tested-by: Jonathan Davies Amazing, thanks :) -- Cheers, Lorenzo