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 8EB78C433EF for ; Thu, 16 Jun 2022 17:51:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236657AbiFPRvN (ORCPT ); Thu, 16 Jun 2022 13:51:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233682AbiFPRvK (ORCPT ); Thu, 16 Jun 2022 13:51:10 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C5EC4C787 for ; Thu, 16 Jun 2022 10:51:09 -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 dfw.source.kernel.org (Postfix) with ESMTPS id AA0FB61B60 for ; Thu, 16 Jun 2022 17:51:08 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0684AC34114; Thu, 16 Jun 2022 17:51:05 +0000 (UTC) Date: Thu, 16 Jun 2022 18:51:02 +0100 From: Catalin Marinas To: Quentin Perret Cc: Marc Zyngier , James Morse , Alexandru Elisei , Suzuki K Poulose , Will Deacon , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, kernel-team@android.com, Mike Rapoport Subject: Re: [PATCH] KVM: arm64: Prevent kmemleak from accessing pKVM memory Message-ID: References: <20220616161135.3997786-1-qperret@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220616161135.3997786-1-qperret@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 16, 2022 at 04:11:34PM +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: > > $ echo scan > /sys/kernel/debug/kmemleak > [ 34.991354] kvm [304]: nVHE hyp BUG at: [] __kvm_nvhe_handle_host_mem_abort+0x270/0x290! > [ 34.991580] kvm [304]: Hyp Offset: 0xfffe8be807e00000 > [ 34.991813] Kernel panic - not syncing: HYP panic: > [ 34.991813] PS:600003c9 PC:0000f418011a3750 ESR:00000000f2000800 > [ 34.991813] FAR:ffff000439200000 HPFAR:0000000004792000 PAR:0000000000000000 > [ 34.991813] VCPU:0000000000000000 > [ 34.993660] CPU: 0 PID: 304 Comm: bash Not tainted 5.19.0-rc2 #102 > [ 34.994059] Hardware name: linux,dummy-virt (DT) > [ 34.994452] Call trace: > [ 34.994641] dump_backtrace.part.0+0xcc/0xe0 > [ 34.994932] show_stack+0x18/0x6c > [ 34.995094] dump_stack_lvl+0x68/0x84 > [ 34.995276] dump_stack+0x18/0x34 > [ 34.995484] panic+0x16c/0x354 > [ 34.995673] __hyp_pgtable_total_pages+0x0/0x60 > [ 34.995933] scan_block+0x74/0x12c > [ 34.996129] scan_gray_list+0xd8/0x19c > [ 34.996332] kmemleak_scan+0x2c8/0x580 > [ 34.996535] kmemleak_write+0x340/0x4a0 > [ 34.996744] full_proxy_write+0x60/0xbc > [ 34.996967] vfs_write+0xc4/0x2b0 > [ 34.997136] ksys_write+0x68/0xf4 > [ 34.997311] __arm64_sys_write+0x20/0x2c > [ 34.997532] invoke_syscall+0x48/0x114 > [ 34.997779] el0_svc_common.constprop.0+0x44/0xec > [ 34.998029] do_el0_svc+0x2c/0xc0 > [ 34.998205] el0_svc+0x2c/0x84 > [ 34.998421] el0t_64_sync_handler+0xf4/0x100 > [ 34.998653] el0t_64_sync+0x18c/0x190 > [ 34.999252] SMP: stopping secondary CPUs > [ 35.000034] Kernel Offset: disabled > [ 35.000261] CPU features: 0x800,00007831,00001086 > [ 35.000642] Memory Limit: none > [ 35.001329] ---[ end Kernel panic - not syncing: HYP panic: > [ 35.001329] PS:600003c9 PC:0000f418011a3750 ESR:00000000f2000800 > [ 35.001329] FAR:ffff000439200000 HPFAR:0000000004792000 PAR:0000000000000000 > [ 35.001329] VCPU:0000000000000000 ]--- > > Fix this by explicitly excluding the hypervisor's memory pool from > kmemleak like we already do for the hyp BSS. > > Cc: Mike Rapoport > Fixes: a7259df76702 ("memblock: make memblock_find_in_range method private") > Signed-off-by: Quentin Perret > --- > An alternative could be to actually exclude memory allocated using > memblock_phys_alloc_range() from kmemleak scans to revert back to the > old behaviour. But nobody else has complained about this AFAIK, so I'd > be inclined to keep this local to pKVM. No strong opinion. This works for me, I haven't heard anyone else complaining. Acked-by: Catalin Marinas