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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 9F0AAC4707F for ; Thu, 27 May 2021 05:02:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 77C8A613AB for ; Thu, 27 May 2021 05:02:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234954AbhE0FDo (ORCPT ); Thu, 27 May 2021 01:03:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60262 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232324AbhE0FDn (ORCPT ); Thu, 27 May 2021 01:03:43 -0400 Received: from mail-pf1-x434.google.com (mail-pf1-x434.google.com [IPv6:2607:f8b0:4864:20::434]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6A43BC061574; Wed, 26 May 2021 22:02:11 -0700 (PDT) Received: by mail-pf1-x434.google.com with SMTP id q67so2732282pfb.4; Wed, 26 May 2021 22:02:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id; bh=JyLaYThv3NNpHzg8SQfk89DGWSaPbCfxZj9NwLUkGkc=; b=JniPRzLBCo1/vCFwMMamhh/yUPPMCJEiF+NF9ut+dLAonrFX/PPFbMeJFE6IvbLRai uiAHhTOAgIie7aKlt1G/vobcCBeEXisOn619t0xajxw+5qddHvj8+znCaSgZnqZ7VjFr dJ8o7DZe0XR2av6Ska+8BgQr89es+5V6Sg2rELxZY4y5r0RLX75LYs13TE5QCGiZ7vyw pmrLEkwVzfPxCoY/KpCOi0TWAO33VdvbvHXSj2CH0y8skLN727htkEQt8pZMkK62viO8 p0iu7MCe7h0RlQMdzLOVQmrv4mx++G0aEz5a3UDoXpOBEkzROyJWauqv1R5/2LBh0AIw HPww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=JyLaYThv3NNpHzg8SQfk89DGWSaPbCfxZj9NwLUkGkc=; b=uAbZkMl4D8P7I9tYP5zqVgcj2sQoUwaaWtEJ9iA0I0B+czcWWbfNPvOXDCSB+EB22U 90FCUYfXJeGGk7hE92TvpsDONhgneXfrWC78QWiYUoqKiEu4sjYynHBG7WumqnFtJLW0 kMM0UmQObXxe+wkvqHDwSn5Fk9bJqmmlXDffhEoyOv6AW/eUtEawj93LbmNMeTqAmaAG qqT7cjWOe+EQYdMg+3lR62jjywmrCz/vjvVm+PqAO6GDxILkfe0uXD7fGymIfZweRqnV lRSOtFnDrQWO/8SDUJc8ddlTbzXiZLPbpqHhPtwEpPI9IhOPLGzTWeB3EN22JSmOAbq3 CpWA== X-Gm-Message-State: AOAM532+eK+4LBiNJw5EONNJpUW5lPpLe69vujM5Nb61XhQmb8tJ2DHG 9S5FUbl1eoLW1EDh5yQAp4v0b+ExlxM= X-Google-Smtp-Source: ABdhPJykSfoIMilDriJP/wgdluGR2twpNZG+C1IxxNAuGD3mkXExMbtBxK7kA2l5j9dPVbtPVyo3OA== X-Received: by 2002:a05:6a00:2126:b029:2e2:89d8:5c89 with SMTP id n6-20020a056a002126b02902e289d85c89mr1951538pfj.37.1622091730652; Wed, 26 May 2021 22:02:10 -0700 (PDT) Received: from localhost.localdomain ([203.205.141.40]) by smtp.googlemail.com with ESMTPSA id z7sm668384pgr.28.2021.05.26.22.02.07 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 May 2021 22:02:10 -0700 (PDT) From: Wanpeng Li X-Google-Original-From: Wanpeng Li To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel Subject: [PATCH v3 1/2] KVM: X86: Fix warning caused by stale emulation context Date: Wed, 26 May 2021 22:01:18 -0700 Message-Id: <1622091679-31683-1-git-send-email-wanpengli@tencent.com> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Wanpeng Li Reported by syzkaller: WARNING: CPU: 7 PID: 10526 at /home/kernel/ssd/linux/arch/x86/kvm//x86.c:7621 x86_emulate_instruction+0x41b/0x510 [kvm] RIP: 0010:x86_emulate_instruction+0x41b/0x510 [kvm] Call Trace: kvm_mmu_page_fault+0x126/0x8f0 [kvm] vmx_handle_exit+0x11e/0x680 [kvm_intel] vcpu_enter_guest+0xd95/0x1b40 [kvm] kvm_arch_vcpu_ioctl_run+0x377/0x6a0 [kvm] kvm_vcpu_ioctl+0x389/0x630 [kvm] __x64_sys_ioctl+0x8e/0xd0 do_syscall_64+0x3c/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae Commit 4a1e10d5b5d8c (KVM: x86: handle hardware breakpoints during emulation()) adds hardware breakpoints check before emulation the instruction and parts of emulation context initialization, actually we don't have the EMULTYPE_NO_DECODE flag here and the emulation context will not be reused. Commit c8848cee74ff (KVM: x86: set ctxt->have_exception in x86_decode_insn()) triggers the warning because it catches the stale emulation context has #UD, however, it is not during instruction decoding which should result in EMULATION_FAILED. This patch fixes it by moving the second part emulation context initialization into init_emulate_ctxt() and before hardware breakpoints check. syzkaller source: https://syzkaller.appspot.com/x/repro.c?x=134683fdd00000 Reported-by: syzbot+71271244f206d17f6441@syzkaller.appspotmail.com Fixes: 4a1e10d5b5d8 (KVM: x86: handle hardware breakpoints during emulation) Signed-off-by: Wanpeng Li --- v2 -> v3: * squash ctxt->ud v1 -> v2: * move the second part emulation context initialization into init_emulate_ctxt() arch/x86/kvm/x86.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index bbc4e04..ae47b19 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7226,6 +7226,13 @@ static void init_emulate_ctxt(struct kvm_vcpu *vcpu) BUILD_BUG_ON(HF_SMM_MASK != X86EMUL_SMM_MASK); BUILD_BUG_ON(HF_SMM_INSIDE_NMI_MASK != X86EMUL_SMM_INSIDE_NMI_MASK); + ctxt->interruptibility = 0; + ctxt->have_exception = false; + ctxt->exception.vector = -1; + ctxt->perm_ok = false; + + ctxt->ud = emulation_type & EMULTYPE_TRAP_UD; + init_decode_cache(ctxt); vcpu->arch.emulate_regs_need_sync_from_vcpu = false; } @@ -7561,13 +7568,6 @@ int x86_decode_emulated_instruction(struct kvm_vcpu *vcpu, int emulation_type, kvm_vcpu_check_breakpoint(vcpu, &r)) return r; - ctxt->interruptibility = 0; - ctxt->have_exception = false; - ctxt->exception.vector = -1; - ctxt->perm_ok = false; - - ctxt->ud = emulation_type & EMULTYPE_TRAP_UD; - r = x86_decode_insn(ctxt, insn, insn_len); trace_kvm_emulate_insn_start(vcpu); -- 2.7.4