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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8429EC433EF for ; Fri, 17 Jun 2022 08:38:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1380059AbiFQIig (ORCPT ); Fri, 17 Jun 2022 04:38:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1380387AbiFQIi2 (ORCPT ); Fri, 17 Jun 2022 04:38:28 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0750F69295 for ; Fri, 17 Jun 2022 01:38:27 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 9E657B827CC for ; Fri, 17 Jun 2022 08:38:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 602D8C3411B; Fri, 17 Jun 2022 08:38:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1655455104; bh=/+PA0s6iDokI32NSUKyXUB8BkzRNE2/BPEMG8iwbzJo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lzhXz8zt15gWuroBUz4xp7oQIAyE2Zg7k0+EuLpVXGyzcayS5RLRo4utGjS2qT7Dy vZVNLx9AI4uoL3jm1N+xkt6pzKuDQ4n37PcWbOpIMDgcjt8g9IGect8wXJ2r1uk6gN ZcMijsDAlGeFKXDRQwAyc+uQj2mQk+qOKHFWpzHdERbvHu55fL2JxvFQQCcjB6ZsgN r42QoQ2bPbWgQlVapm7YHnn7gc79lQ/r1sr8/D2jAHFJXCHAdazY+kHfzMqXRxGqKb z6zabU/HjuYTH08Un3rRyqRTKm5VzO57zZpaxBeDlUbKH6UQE6z6FD2evVHpL1DdOB EHylArov6qpuA== Date: Fri, 17 Jun 2022 11:38:14 +0300 From: Mike Rapoport To: Marc Zyngier Cc: Suzuki K Poulose , Alexandru Elisei , linux-arm-kernel@lists.infradead.org, Catalin Marinas , Quentin Perret , kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, James Morse , Will Deacon , kernel-team@android.com Subject: Re: [PATCH] KVM: arm64: Prevent kmemleak from accessing pKVM memory Message-ID: References: <20220616161135.3997786-1-qperret@google.com> <165545408679.771055.5076080259874437048.b4-ty@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <165545408679.771055.5076080259874437048.b4-ty@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 17, 2022 at 09:21:31AM +0100, Marc Zyngier wrote: > On Thu, 16 Jun 2022 16:11:34 +0000, Quentin Perret wrote: > > Commit a7259df76702 ("memblock: make memblock_find_in_range method > > private") changed the API using which memory is reserved for the pKVM > > hypervisor. However, it seems that memblock_phys_alloc() differs > > from the original API in terms of kmemleak semantics -- the old one > > excluded the reserved regions from kmemleak scans when the new one > > doesn't seem to. Unfortunately, when protected KVM is enabled, all > > kernel accesses to pKVM-private memory result in a fatal exception, > > which can now happen because of kmemleak scans: > > > > [...] > > Applied to fixes, thanks! > > [1/1] KVM: arm64: Prevent kmemleak from accessing pKVM memory > commit: 9e5afa8a537f742bccc2cd91bc0bef4b6483ee98 I'd really like to update the changelog to this: Commit a7259df76702 ("memblock: make memblock_find_in_range method private") changed the API using which memory is reserved for the pKVM hypervisor. However, memblock_phys_alloc() differs from the original API in terms of kmemleak semantics -- the old one didn't report the reserved regions to kmemleak while the new one does. Unfortunately, when protected KVM is enabled, all kernel accesses to pKVM-private memory result in a fatal exception, which can now happen because of kmemleak scans: $ echo scan > /sys/kernel/debug/kmemleak [ 34.991354] kvm [304]: nVHE hyp BUG at: [] __kvm_nvhe_handle_host_mem_abort+0x270/0x290! ... Fix this by explicitly excluding the hypervisor's memory pool from kmemleak like we already do for the hyp BSS. > Cheers, > > M. > -- > Marc Zyngier > -- Sincerely yours, Mike.