From patchwork Wed Jul 19 16:19:52 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= X-Patchwork-Id: 9852825 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 57383602C8 for ; Wed, 19 Jul 2017 16:20:24 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 39B4F2872F for ; Wed, 19 Jul 2017 16:20:24 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 19024286C3; Wed, 19 Jul 2017 16:20:24 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,HK_RANDOM_FROM, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 1A455286C3 for ; Wed, 19 Jul 2017 16:20:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754779AbdGSQT5 (ORCPT ); Wed, 19 Jul 2017 12:19:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56416 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753253AbdGSQT4 (ORCPT ); Wed, 19 Jul 2017 12:19:56 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E6A0461D19; Wed, 19 Jul 2017 16:19:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com E6A0461D19 Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx10.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=rkrcmar@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com E6A0461D19 Received: from potion (ovpn-204-73.brq.redhat.com [10.40.204.73]) by smtp.corp.redhat.com (Postfix) with SMTP id 8E16561F23; Wed, 19 Jul 2017 16:19:53 +0000 (UTC) Received: by potion (sSMTP sendmail emulation); Wed, 19 Jul 2017 18:19:52 +0200 Date: Wed, 19 Jul 2017 18:19:52 +0200 From: Radim =?utf-8?B?S3LEjW3DocWZ?= To: Nadav Amit Cc: Wanpeng Li , "linux-kernel@vger.kernel.org" , kvm , Paolo Bonzini , Wanpeng Li Subject: [PATCH v2] KVM: VMX: Fix invalid guest state detection after task-switch emulation Message-ID: <20170719161952.GC17303@potion> References: <1499757180-20439-1-git-send-email-wanpeng.li@hotmail.com> <20170719112926.GA13502@potion> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Wed, 19 Jul 2017 16:19:56 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 2017-07-19 08:14-0700, Nadav Amit: > Radim Krčmář wrote: > > @@ -2363,6 +2368,8 @@ static unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu) > > > > static void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags) > > { > > + unsigned long old_rflags = to_vmx(vcpu)->rflags; > > It assumes rflags was decached from the VMCS before. Probably it is true, but… Right, it's better to use accessors everywhere, thanks. The line should read: + unsigned long old_rflags = vmx_get_rflags(vcpu); ---8<--- This can be reproduced by EPT=1, unrestricted_guest=N, emulate_invalid_state=Y or EPT=0, the trace of kvm-unit-tests/taskswitch2.flat is like below, it tries to emulate invalid guest state task-switch: kvm_exit: reason TASK_SWITCH rip 0x0 info 40000058 0 kvm_emulate_insn: 42000:0:0f 0b (0x2) kvm_emulate_insn: 42000:0:0f 0b (0x2) failed kvm_inj_exception: #UD (0x0) kvm_entry: vcpu 0 kvm_exit: reason TASK_SWITCH rip 0x0 info 40000058 0 kvm_emulate_insn: 42000:0:0f 0b (0x2) kvm_emulate_insn: 42000:0:0f 0b (0x2) failed kvm_inj_exception: #UD (0x0) It appears that the task-switch emulation updates rflags (and vm86 flag) only after the segments are loaded, causing vmx->emulation_required to be set, when in fact invalid guest state emulation is not needed. This patch fixes it by updating vmx->emulation_required after the rflags (and vm86 flag) is updated. Suggested-by: Nadav Amit Signed-off-by: Wanpeng Li [Wanpeng wrote the commit message with initial patch and Radim moved the update to vmx_set_rflags and added Paolo's suggestion for the check.] Signed-off-by: Radim Krčmář --- arch/x86/kvm/vmx.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 84e62acf2dd8..a776aea0043a 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2326,6 +2326,11 @@ static void vmx_vcpu_put(struct kvm_vcpu *vcpu) __vmx_load_host_state(to_vmx(vcpu)); } +static bool emulation_required(struct kvm_vcpu *vcpu) +{ + return emulate_invalid_guest_state && !guest_state_valid(vcpu); +} + static void vmx_decache_cr0_guest_bits(struct kvm_vcpu *vcpu); /* @@ -2363,6 +2368,8 @@ static unsigned long vmx_get_rflags(struct kvm_vcpu *vcpu) static void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags) { + unsigned long old_rflags = vmx_get_rflags(vcpu); + __set_bit(VCPU_EXREG_RFLAGS, (ulong *)&vcpu->arch.regs_avail); to_vmx(vcpu)->rflags = rflags; if (to_vmx(vcpu)->rmode.vm86_active) { @@ -2370,6 +2377,9 @@ static void vmx_set_rflags(struct kvm_vcpu *vcpu, unsigned long rflags) rflags |= X86_EFLAGS_IOPL | X86_EFLAGS_VM; } vmcs_writel(GUEST_RFLAGS, rflags); + + if ((old_rflags ^ rflags) & X86_EFLAGS_VM) + to_vmx(vcpu)->emulation_required = emulation_required(vcpu); } static u32 vmx_get_pkru(struct kvm_vcpu *vcpu) @@ -3857,11 +3867,6 @@ static __init int alloc_kvm_area(void) return 0; } -static bool emulation_required(struct kvm_vcpu *vcpu) -{ - return emulate_invalid_guest_state && !guest_state_valid(vcpu); -} - static void fix_pmode_seg(struct kvm_vcpu *vcpu, int seg, struct kvm_segment *save) {