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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D8C9EC433EF for ; Mon, 27 Dec 2021 15:51:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240230AbhL0Puu (ORCPT ); Mon, 27 Dec 2021 10:50:50 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:43264 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240728AbhL0Pph (ORCPT ); Mon, 27 Dec 2021 10:45:37 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 1F53D60C9F; Mon, 27 Dec 2021 15:45:37 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 02075C36AEA; Mon, 27 Dec 2021 15:45:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1640619936; bh=C6Zp6+2bfvVibCrB+uC/baKd/b9bAzS/rmlskemiI7A=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=skaxKrylNmlGpBoutH7G44OrhMKYl2EBMfLHG8wEri87mD+nso/psm4f703Ors9Fe s+sKr4nsk2ZyvQVl+RdfpnDMwRCuctdhf051C8F7ZJxNZecLrPSxcZQH/mSx4qKZ3Q uQeW45oYAtOTqRFVHxF+kG/R7ZlPmof3shrjIpIA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+f1d2136db9c80d4733e8@syzkaller.appspotmail.com, Maxim Levitsky , Sean Christopherson , Paolo Bonzini Subject: [PATCH 5.15 089/128] KVM: VMX: Always clear vmx->fail on emulation_required Date: Mon, 27 Dec 2021 16:31:04 +0100 Message-Id: <20211227151334.486201564@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20211227151331.502501367@linuxfoundation.org> References: <20211227151331.502501367@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sean Christopherson commit a80dfc025924024d2c61a4c1b8ef62b2fce76a04 upstream. Revert a relatively recent change that set vmx->fail if the vCPU is in L2 and emulation_required is true, as that behavior is completely bogus. Setting vmx->fail and synthesizing a VM-Exit is contradictory and wrong: (a) it's impossible to have both a VM-Fail and VM-Exit (b) vmcs.EXIT_REASON is not modified on VM-Fail (c) emulation_required refers to guest state and guest state checks are always VM-Exits, not VM-Fails. For KVM specifically, emulation_required is handled before nested exits in __vmx_handle_exit(), thus setting vmx->fail has no immediate effect, i.e. KVM calls into handle_invalid_guest_state() and vmx->fail is ignored. Setting vmx->fail can ultimately result in a WARN in nested_vmx_vmexit() firing when tearing down the VM as KVM never expects vmx->fail to be set when L2 is active, KVM always reflects those errors into L1. ------------[ cut here ]------------ WARNING: CPU: 0 PID: 21158 at arch/x86/kvm/vmx/nested.c:4548 nested_vmx_vmexit+0x16bd/0x17e0 arch/x86/kvm/vmx/nested.c:4547 Modules linked in: CPU: 0 PID: 21158 Comm: syz-executor.1 Not tainted 5.16.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:nested_vmx_vmexit+0x16bd/0x17e0 arch/x86/kvm/vmx/nested.c:4547 Code: <0f> 0b e9 2e f8 ff ff e8 57 b3 5d 00 0f 0b e9 00 f1 ff ff 89 e9 80 Call Trace: vmx_leave_nested arch/x86/kvm/vmx/nested.c:6220 [inline] nested_vmx_free_vcpu+0x83/0xc0 arch/x86/kvm/vmx/nested.c:330 vmx_free_vcpu+0x11f/0x2a0 arch/x86/kvm/vmx/vmx.c:6799 kvm_arch_vcpu_destroy+0x6b/0x240 arch/x86/kvm/x86.c:10989 kvm_vcpu_destroy+0x29/0x90 arch/x86/kvm/../../../virt/kvm/kvm_main.c:441 kvm_free_vcpus arch/x86/kvm/x86.c:11426 [inline] kvm_arch_destroy_vm+0x3ef/0x6b0 arch/x86/kvm/x86.c:11545 kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:1189 [inline] kvm_put_kvm+0x751/0xe40 arch/x86/kvm/../../../virt/kvm/kvm_main.c:1220 kvm_vcpu_release+0x53/0x60 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3489 __fput+0x3fc/0x870 fs/file_table.c:280 task_work_run+0x146/0x1c0 kernel/task_work.c:164 exit_task_work include/linux/task_work.h:32 [inline] do_exit+0x705/0x24f0 kernel/exit.c:832 do_group_exit+0x168/0x2d0 kernel/exit.c:929 get_signal+0x1740/0x2120 kernel/signal.c:2852 arch_do_signal_or_restart+0x9c/0x730 arch/x86/kernel/signal.c:868 handle_signal_work kernel/entry/common.c:148 [inline] exit_to_user_mode_loop kernel/entry/common.c:172 [inline] exit_to_user_mode_prepare+0x191/0x220 kernel/entry/common.c:207 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline] syscall_exit_to_user_mode+0x2e/0x70 kernel/entry/common.c:300 do_syscall_64+0x53/0xd0 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x44/0xae Fixes: c8607e4a086f ("KVM: x86: nVMX: don't fail nested VM entry on invalid guest state if !from_vmentry") Reported-by: syzbot+f1d2136db9c80d4733e8@syzkaller.appspotmail.com Reviewed-by: Maxim Levitsky Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-Id: <20211207193006.120997-2-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/vmx/vmx.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6612,9 +6612,7 @@ static fastpath_t vmx_vcpu_run(struct kv * consistency check VM-Exit due to invalid guest state and bail. */ if (unlikely(vmx->emulation_required)) { - - /* We don't emulate invalid state of a nested guest */ - vmx->fail = is_guest_mode(vcpu); + vmx->fail = 0; vmx->exit_reason.full = EXIT_REASON_INVALID_STATE; vmx->exit_reason.failed_vmentry = 1;