Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753344AbdCFMDn (ORCPT ); Mon, 6 Mar 2017 07:03:43 -0500 Received: from mail-pg0-f67.google.com ([74.125.83.67]:33868 "EHLO mail-pg0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752685AbdCFMDf (ORCPT ); Mon, 6 Mar 2017 07:03:35 -0500 From: Wanpeng Li X-Google-Original-From: Wanpeng Li To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , Wanpeng Li , Dmitry Vyukov , David Hildenbrand Subject: [PATCH v3] KVM: nVMX: reset nested_run_pending if the vCPU is going to be reset Date: Mon, 6 Mar 2017 04:03:28 -0800 Message-Id: <1488801808-12027-1-git-send-email-wanpeng.li@hotmail.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3091 Lines: 92 From: Wanpeng Li Reported by syzkaller: WARNING: CPU: 1 PID: 27742 at arch/x86/kvm/vmx.c:11029 nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029 CPU: 1 PID: 27742 Comm: a.out Not tainted 4.10.0+ #229 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:15 [inline] dump_stack+0x2ee/0x3ef lib/dump_stack.c:51 panic+0x1fb/0x412 kernel/panic.c:179 __warn+0x1c4/0x1e0 kernel/panic.c:540 warn_slowpath_null+0x2c/0x40 kernel/panic.c:583 nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029 vmx_leave_nested arch/x86/kvm/vmx.c:11136 [inline] vmx_set_msr+0x1565/0x1910 arch/x86/kvm/vmx.c:3324 kvm_set_msr+0xd4/0x170 arch/x86/kvm/x86.c:1099 do_set_msr+0x11e/0x190 arch/x86/kvm/x86.c:1128 __msr_io arch/x86/kvm/x86.c:2577 [inline] msr_io+0x24b/0x450 arch/x86/kvm/x86.c:2614 kvm_arch_vcpu_ioctl+0x35b/0x46a0 arch/x86/kvm/x86.c:3497 kvm_vcpu_ioctl+0x232/0x1120 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2721 vfs_ioctl fs/ioctl.c:43 [inline] do_vfs_ioctl+0x1bf/0x1790 fs/ioctl.c:683 SYSC_ioctl fs/ioctl.c:698 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689 entry_SYSCALL_64_fastpath+0x1f/0xc2 The syzkaller folks reported a nested_run_pending warning during userspace clear VMX capability which is exposed to L1 before. The warning gets thrown while doing (*(uint32_t*)0x20aecfe8 = (uint32_t)0x1); (*(uint32_t*)0x20aecfec = (uint32_t)0x0); (*(uint32_t*)0x20aecff0 = (uint32_t)0x3a); (*(uint32_t*)0x20aecff4 = (uint32_t)0x0); (*(uint64_t*)0x20aecff8 = (uint64_t)0x0); r[29] = syscall(__NR_ioctl, r[4], 0x4008ae89ul, 0x20aecfe8ul, 0, 0, 0, 0, 0, 0); i.e. KVM_SET_MSR ioctl with struct kvm_msrs { .nmsrs = 1, .pad = 0, .entries = { {.index = MSR_IA32_FEATURE_CONTROL, .reserved = 0, .data = 0} } } The VMLANCH/VMRESUME emulation should be stopped since the CPU is going to reset here. This patch resets the nested_run_pending since the CPU is going to be reset hence there should be nothing pending. Reported-by: Dmitry Vyukov Suggested-by: Radim Krčmář Cc: Paolo Bonzini Cc: Radim Krčmář Cc: Dmitry Vyukov Cc: David Hildenbrand Signed-off-by: Wanpeng Li --- v2 -> v3: * move the reset to vmx_leave_nested() v1 -> v2: * cleanup comments format arch/x86/kvm/vmx.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 3b626d6..ab33858 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -11107,8 +11107,10 @@ static void nested_vmx_vmexit(struct kvm_vcpu *vcpu, u32 exit_reason, */ static void vmx_leave_nested(struct kvm_vcpu *vcpu) { - if (is_guest_mode(vcpu)) + if (is_guest_mode(vcpu)) { + to_vmx(vcpu)->nested.nested_run_pending = 0; nested_vmx_vmexit(vcpu, -1, 0, 0); + } free_nested(to_vmx(vcpu)); } -- 2.7.4