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 98802C4360C for ; Fri, 27 Sep 2019 21:45:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7127D21655 for ; Fri, 27 Sep 2019 21:45:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728483AbfI0VpZ (ORCPT ); Fri, 27 Sep 2019 17:45:25 -0400 Received: from mga12.intel.com ([192.55.52.136]:45951 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726029AbfI0VpZ (ORCPT ); Fri, 27 Sep 2019 17:45:25 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 Sep 2019 14:45:24 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,557,1559545200"; d="scan'208";a="196852054" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.41]) by FMSMGA003.fm.intel.com with ESMTP; 27 Sep 2019 14:45:24 -0700 From: Sean Christopherson To: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Reto Buerki , Liran Alon Subject: [PATCH v2 0/8] KVM: x86: nVMX GUEST_CR3 bug fix, and then some... Date: Fri, 27 Sep 2019 14:45:15 -0700 Message-Id: <20190927214523.3376-1-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.22.0 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 *sigh* v2 was shaping up to be a trivial update, until I started working on Vitaly's suggestion to add a helper to test for register availability. The primary purpose of this series is to fix a CR3 corruption in L2 reported by Reto Buerki when running with HLT interception disabled in L1. On a nested VM-Enter that puts L2 into HLT, KVM never actually enters L2 and instead mimics HLT interception by canceling the nested run and pretending that VM-Enter to L2 completed and then exited on HLT (which KVM intercepted). Because KVM never actually runs L2, KVM skips the pending MMU update for L2 and so leaves a stale value in vmcs02.GUEST_CR3. If the next wake event for L2 triggers a nested VM-Exit, KVM will refresh vmcs12->guest_cr3 from vmcs02.GUEST_CR3 and consume the stale value. Fix the issue by unconditionally writing vmcs02.GUEST_CR3 during nested VM-Enter instead of deferring the update to vmx_set_cr3(), and skip the update of GUEST_CR3 in vmx_set_cr3() when running L2. I.e. make the nested code fully responsible for vmcs02.GUEST_CR3. Patch 02/08 is a minor optimization to skip the GUEST_CR3 update if vmcs01 is already up-to-date. Patches 03 and beyond are Vitaly's fault ;-). Patches 03 and 04 are tangentially related cleanup to vmx_set_rflags() that was discovered when working through the avail/dirty testing code. Ideally they'd be sent as a separate series, but they conflict with the avail/dirty helper changes and are themselves minor and straightforward. Patches 05 and 06 clean up the register caching code so that there is a single enum for all registers which use avail/dirty tracking. While not a true prerequisite for the avail/dirty helpers, the cleanup allows the new helpers to take an 'enum kvm_reg' instead of a less helpful 'int reg'. Patch 07 is the helpers themselves, as suggested by Vitaly. Patch 08 is a truly optional change to ditch decache_cr3() in favor of handling CR3 via cache_reg() like any other avail/dirty register. Note, I collected the Reviewed-by and Tested-by tags for patches 01 and 02 even though I inverted the boolean from 'skip_cr3' to 'update_guest_cr3'. Please drop the tags if that constitutes a non-trivial functional change. v2: - Invert skip_cr3 to update_guest_cr3. [Liran] - Reword the changelog and comment to be more explicit in detailing how/when KVM will process a nested VM-Enter without runnin L2. [Liran] - Added Reviewed-by and Tested-by tags. - Add a comment in vmx_set_cr3() to explicitly state that nested VM-Enter is responsible for loading vmcs02.GUEST_CR3. [Jim] - All of the loveliness in patches 03-08. [Vitaly] Sean Christopherson (8): KVM: nVMX: Always write vmcs02.GUEST_CR3 during nested VM-Enter KVM: VMX: Skip GUEST_CR3 VMREAD+VMWRITE if the VMCS is up-to-date KVM: VMX: Consolidate to_vmx() usage in RFLAGS accessors KVM: VMX: Optimize vmx_set_rflags() for unrestricted guest KVM: x86: Add WARNs to detect out-of-bounds register indices KVM: x86: Fold 'enum kvm_ex_reg' definitions into 'enum kvm_reg' KVM: x86: Add helpers to test/mark reg availability and dirtiness KVM: x86: Fold decache_cr3() into cache_reg() arch/x86/include/asm/kvm_host.h | 5 +- arch/x86/kvm/kvm_cache_regs.h | 67 +++++++++++++++++------ arch/x86/kvm/svm.c | 5 -- arch/x86/kvm/vmx/nested.c | 14 ++++- arch/x86/kvm/vmx/vmx.c | 94 ++++++++++++++++++--------------- arch/x86/kvm/x86.c | 13 ++--- arch/x86/kvm/x86.h | 6 +-- 7 files changed, 123 insertions(+), 81 deletions(-) -- 2.22.0