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 X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7EAEC34056 for ; Wed, 19 Feb 2020 19:10:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 88F682465D for ; Wed, 19 Feb 2020 19:10:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="FvwBCaum" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726750AbgBSTKY (ORCPT ); Wed, 19 Feb 2020 14:10:24 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:22391 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726708AbgBSTKX (ORCPT ); Wed, 19 Feb 2020 14:10:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1582139422; 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: in-reply-to:in-reply-to:references:references; bh=Iu+zDafgQ7GdYGR/n8pxbgWtAD7a9J36y82BGwKTfA0=; b=FvwBCaumwf7eAvvx3m+aVGLR6Fwi6xADelRb+eqtDmycLOpfbsnQ9n26I/M6b1Y+1DQ+mZ 1ruoblj/A9Zndj//MteOyjdYqs1zNA98B4lXaW136IwQHbEvYF0b6CqHwMr7bEXdvdMnu+ zRVifVtVRc1w2P2+A9bHt8wJ11JN/G8= Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-301-xx9lNZf0NwqG0nfCwqSIxA-1; Wed, 19 Feb 2020 14:10:20 -0500 X-MC-Unique: xx9lNZf0NwqG0nfCwqSIxA-1 Received: by mail-qt1-f198.google.com with SMTP id n4so847609qtv.5 for ; Wed, 19 Feb 2020 11:10:20 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=Iu+zDafgQ7GdYGR/n8pxbgWtAD7a9J36y82BGwKTfA0=; b=slYdwsFCLZafHmwur6c/OynM+59Xs19Qdkq2lWJ8ahHUenh8Qrc6/4/bKdvQdxxeps 5/zhlEVqc2dCtWXLOb//m2AvUjEO140qM9RmmehZVfOAeezOtpS3eZ/9E76l9OGRhOs7 qMdUSjG/lI0DwlWvxEh2+JEmyGYXSGD/YCmvbhK8rxHOo4mWXXT9bxkTF4X6tbmTT3An 1AurYdiH7jGn1kqoaJkwHDFY/FyLTR+ez9Ql5wo+w8On7xcpEDf9hbWmtGB9FPFag8BD sGWoSFKd+rnOES+tl29dpQ0GnLgwC7lObYb1I9w5RPtNkA3pA/BQGtFYI5L0ySpaI6eG xHwA== X-Gm-Message-State: APjAAAWW/8xjZlt1grjxSOrviqgwMR72pmvk9qnFubJwyQcEsx8vBej8 8GpJBP/L6kcQim776dlRhMHfTPY9PbKXfGZP2lpwVwxXDyLmcxTo54NQloW8U5OGtsyyEpehrlA pHi7FZWD2je8NJPYYDcm5U1YN X-Received: by 2002:aed:29e2:: with SMTP id o89mr23723347qtd.353.1582139419971; Wed, 19 Feb 2020 11:10:19 -0800 (PST) X-Google-Smtp-Source: APXvYqyR4tvaG55rn+oIGW+9DmQY+Q5rgmtUB62N9SOWO2kSCX8x9uyUbBuaGecyF0GgmgJCEJ7bJQ== X-Received: by 2002:aed:29e2:: with SMTP id o89mr23723317qtd.353.1582139419685; Wed, 19 Feb 2020 11:10:19 -0800 (PST) Received: from xz-x1 ([104.156.64.75]) by smtp.gmail.com with ESMTPSA id m95sm453246qte.41.2020.02.19.11.10.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Feb 2020 11:10:19 -0800 (PST) Date: Wed, 19 Feb 2020 14:10:17 -0500 From: Peter Xu To: Sean Christopherson Cc: Paolo Bonzini , Paul Mackerras , Christian Borntraeger , Janosch Frank , David Hildenbrand , Cornelia Huck , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Marc Zyngier , James Morse , Julien Thierry , Suzuki K Poulose , linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, Christoffer Dall , Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [PATCH v6 01/22] KVM: x86: Allocate new rmap and large page tracking when moving memslot Message-ID: <20200219191017.GA37550@xz-x1> References: <20200218210736.16432-1-sean.j.christopherson@intel.com> <20200218210736.16432-2-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200218210736.16432-2-sean.j.christopherson@intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 18, 2020 at 01:07:15PM -0800, Sean Christopherson wrote: > Reallocate a rmap array and recalcuate large page compatibility when > moving an existing memslot to correctly handle the alignment properties > of the new memslot. The number of rmap entries required at each level > is dependent on the alignment of the memslot's base gfn with respect to > that level, e.g. moving a large-page aligned memslot so that it becomes > unaligned will increase the number of rmap entries needed at the now > unaligned level. > > Not updating the rmap array is the most obvious bug, as KVM accesses > garbage data beyond the end of the rmap. KVM interprets the bad data as > pointers, leading to non-canonical #GPs, unexpected #PFs, etc... > > general protection fault: 0000 [#1] SMP > CPU: 0 PID: 1909 Comm: move_memory_reg Not tainted 5.4.0-rc7+ #139 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 > RIP: 0010:rmap_get_first+0x37/0x50 [kvm] > Code: <48> 8b 3b 48 85 ff 74 ec e8 6c f4 ff ff 85 c0 74 e3 48 89 d8 5b c3 > RSP: 0018:ffffc9000021bbc8 EFLAGS: 00010246 > RAX: ffff00617461642e RBX: ffff00617461642e RCX: 0000000000000012 > RDX: ffff88827400f568 RSI: ffffc9000021bbe0 RDI: ffff88827400f570 > RBP: 0010000000000000 R08: ffffc9000021bd00 R09: ffffc9000021bda8 > R10: ffffc9000021bc48 R11: 0000000000000000 R12: 0030000000000000 > R13: 0000000000000000 R14: ffff88827427d700 R15: ffffc9000021bce8 > FS: 00007f7eda014700(0000) GS:ffff888277a00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f7ed9216ff8 CR3: 0000000274391003 CR4: 0000000000162eb0 > Call Trace: > kvm_mmu_slot_set_dirty+0xa1/0x150 [kvm] > __kvm_set_memory_region.part.64+0x559/0x960 [kvm] > kvm_set_memory_region+0x45/0x60 [kvm] > kvm_vm_ioctl+0x30f/0x920 [kvm] > do_vfs_ioctl+0xa1/0x620 > ksys_ioctl+0x66/0x70 > __x64_sys_ioctl+0x16/0x20 > do_syscall_64+0x4c/0x170 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > RIP: 0033:0x7f7ed9911f47 > Code: <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 21 6f 2c 00 f7 d8 64 89 01 48 > RSP: 002b:00007ffc00937498 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 0000000001ab0010 RCX: 00007f7ed9911f47 > RDX: 0000000001ab1350 RSI: 000000004020ae46 RDI: 0000000000000004 > RBP: 000000000000000a R08: 0000000000000000 R09: 00007f7ed9214700 > R10: 00007f7ed92149d0 R11: 0000000000000246 R12: 00000000bffff000 > R13: 0000000000000003 R14: 00007f7ed9215000 R15: 0000000000000000 > Modules linked in: kvm_intel kvm irqbypass > ---[ end trace 0c5f570b3358ca89 ]--- > > The disallow_lpage tracking is more subtle. Failure to update results > in KVM creating large pages when it shouldn't, either due to stale data > or again due to indexing beyond the end of the metadata arrays, which > can lead to memory corruption and/or leaking data to guest/userspace. > > Note, the arrays for the old memslot are freed by the unconditional call > to kvm_free_memslot() in __kvm_set_memory_region(). > > Fixes: 05da45583de9b ("KVM: MMU: large page support") > Cc: stable@vger.kernel.org > Signed-off-by: Sean Christopherson Reviewed-by: Peter Xu -- Peter Xu