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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 9D321C3F2C2 for ; Thu, 27 Feb 2020 22:30:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 79F9D246A2 for ; Thu, 27 Feb 2020 22:30:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730184AbgB0Wav (ORCPT ); Thu, 27 Feb 2020 17:30:51 -0500 Received: from mga04.intel.com ([192.55.52.120]:35152 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729808AbgB0Wau (ORCPT ); Thu, 27 Feb 2020 17:30:50 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Feb 2020 14:30:50 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,493,1574150400"; d="scan'208";a="385312249" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.202]) by orsmga004.jf.intel.com with ESMTP; 27 Feb 2020 14:30:49 -0800 From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 0/3] KVM: VMX: Fix for kexec VMCLEAR and VMXON cleanup Date: Thu, 27 Feb 2020 14:30:44 -0800 Message-Id: <20200227223047.13125-1-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.24.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Patch 1 fixes a a theoretical bug where a crashdump NMI that arrives while KVM is messing with the percpu VMCS list would result in one or more VMCSes not being cleared, potentially causing memory corruption in the new kexec'd kernel. Patch 2 isn't directly related, but it conflicts with the crash cleanup changes, both from a code and a semantics perspective. Without the crash cleanup, IMO hardware_enable() should do crash_disable_local_vmclear() if VMXON fails, i.e. clean up after itself. But hardware_disable() doesn't even do crash_disable_local_vmclear() (which is what got me looking at that code in the first place). Basing the VMXON change on top of the crash cleanup avoids the debate entirely. Patch 3 is a simple clean up (no functional change intended ;-) ). I verified my analysis of the NMI bug by simulating what would happen if an NMI arrived in the middle of list_add() and list_del(). The below output matches expectations, e.g. nothing hangs, the entry being added doesn't show up, and the entry being deleted _does_ show up. [ 8.205898] KVM: testing NMI in list_add() [ 8.205898] KVM: testing NMI in list_del() [ 8.205899] KVM: found e3 [ 8.205899] KVM: found e2 [ 8.205899] KVM: found e1 [ 8.205900] KVM: found e3 [ 8.205900] KVM: found e1 static void vmx_test_list(struct list_head *list, struct list_head *e1, struct list_head *e2, struct list_head *e3) { struct list_head *tmp; list_for_each(tmp, list) { if (tmp == e1) pr_warn("KVM: found e1\n"); else if (tmp == e2) pr_warn("KVM: found e2\n"); else if (tmp == e3) pr_warn("KVM: found e3\n"); else pr_warn("KVM: kaboom\n"); } } static int __init vmx_init(void) { LIST_HEAD(list); LIST_HEAD(e1); LIST_HEAD(e2); LIST_HEAD(e3); pr_warn("KVM: testing NMI in list_add()\n"); list.next->prev = &e1; vmx_test_list(&list, &e1, &e2, &e3); e1.next = list.next; vmx_test_list(&list, &e1, &e2, &e3); e1.prev = &list; vmx_test_list(&list, &e1, &e2, &e3); INIT_LIST_HEAD(&list); INIT_LIST_HEAD(&e1); list_add(&e1, &list); list_add(&e2, &list); list_add(&e3, &list); pr_warn("KVM: testing NMI in list_del()\n"); e3.prev = &e1; vmx_test_list(&list, &e1, &e2, &e3); list_del(&e2); list.prev = &e1; vmx_test_list(&list, &e1, &e2, &e3); } Sean Christopherson (3): KVM: VMX: Always VMCLEAR in-use VMCSes during crash with kexec support KVM: VMX: Gracefully handle faults on VMXON KVM: VMX: Make loaded_vmcs_init() a static function arch/x86/kvm/vmx/vmx.c | 101 +++++++++++++++++------------------------ arch/x86/kvm/vmx/vmx.h | 1 - 2 files changed, 41 insertions(+), 61 deletions(-) -- 2.24.1