From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751444AbdIMXPA (ORCPT ); Wed, 13 Sep 2017 19:15:00 -0400 Received: from mail-io0-f194.google.com ([209.85.223.194]:34265 "EHLO mail-io0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751125AbdIMXO6 (ORCPT ); Wed, 13 Sep 2017 19:14:58 -0400 X-Google-Smtp-Source: AOwi7QCxYV5tGUVNR8bf6H8U6uDXsdUEfnM74cIZxU9TV4BJh9dI2DO2DbAXI/6uwaMWxxFS70KSWs5Skvl+NRwb3m0= MIME-Version: 1.0 In-Reply-To: References: <1505300602-7236-1-git-send-email-wanpeng.li@hotmail.com> From: Wanpeng Li Date: Thu, 14 Sep 2017 07:14:57 +0800 Message-ID: Subject: Re: [PATCH 1/2] KVM: nVMX: Fix nested #PF intends to break L1's vmlauch/vmresume To: Paolo Bonzini Cc: "linux-kernel@vger.kernel.org" , kvm , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Wanpeng Li Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v8DNF6QH008485 2017-09-14 5:45 GMT+08:00 Paolo Bonzini : > On 13/09/2017 13:03, Wanpeng Li wrote: >> From: Wanpeng Li >> >> ------------[ cut here ]------------ >> WARNING: CPU: 4 PID: 5280 at /home/kernel/linux/arch/x86/kvm//vmx.c:11394 nested_vmx_vmexit+0xc2b/0xd70 [kvm_intel] >> CPU: 4 PID: 5280 Comm: qemu-system-x86 Tainted: G W OE 4.13.0+ #17 >> RIP: 0010:nested_vmx_vmexit+0xc2b/0xd70 [kvm_intel] >> Call Trace: >> ? emulator_read_emulated+0x15/0x20 [kvm] >> ? segmented_read+0xae/0xf0 [kvm] >> vmx_inject_page_fault_nested+0x60/0x70 [kvm_intel] >> ? vmx_inject_page_fault_nested+0x60/0x70 [kvm_intel] >> x86_emulate_instruction+0x733/0x810 [kvm] >> vmx_handle_exit+0x2f4/0xda0 [kvm_intel] >> ? kvm_arch_vcpu_ioctl_run+0xd2f/0x1c60 [kvm] >> kvm_arch_vcpu_ioctl_run+0xdab/0x1c60 [kvm] >> ? kvm_arch_vcpu_load+0x62/0x230 [kvm] >> kvm_vcpu_ioctl+0x340/0x700 [kvm] >> ? kvm_vcpu_ioctl+0x340/0x700 [kvm] >> ? __fget+0xfc/0x210 >> do_vfs_ioctl+0xa4/0x6a0 >> ? __fget+0x11d/0x210 >> SyS_ioctl+0x79/0x90 >> entry_SYSCALL_64_fastpath+0x23/0xc2 >> >> A nested #PF is triggered during L0 emulating instruction for L2. However, it >> doesn't consider we should not break L1's vmlauch/vmresme. This patch fixes >> it by queuing the #PF exception instead ,requesting an immediate VM exit from >> L2 and keeping the exception for L1 pending for a subsequent nested VM exit. >> >> Cc: Paolo Bonzini >> Cc: Radim Krčmář >> Signed-off-by: Wanpeng Li >> --- >> arch/x86/kvm/vmx.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >> index 4253ade..fda9dd6 100644 >> --- a/arch/x86/kvm/vmx.c >> +++ b/arch/x86/kvm/vmx.c >> @@ -9829,7 +9829,8 @@ static void vmx_inject_page_fault_nested(struct kvm_vcpu *vcpu, >> >> WARN_ON(!is_guest_mode(vcpu)); >> >> - if (nested_vmx_is_page_fault_vmexit(vmcs12, fault->error_code)) { >> + if (nested_vmx_is_page_fault_vmexit(vmcs12, fault->error_code) && >> + !to_vmx(vcpu)->nested.nested_run_pending) { >> vmcs12->vm_exit_intr_error_code = fault->error_code; >> nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI, >> PF_VECTOR | INTR_TYPE_HARD_EXCEPTION | >> > > Is vmx_inject_page_fault_nested even needed at all these days? > > kvm_inject_page_fault's call to kvm_queue_exception_e should transform > into an L2->L1 vmexit when vmx_check_nested_events is called. I saw L0 reboot/hang after do something like below: diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 4253ade..96b4f6f 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -9822,24 +9822,6 @@ static bool nested_vmx_is_page_fault_vmexit(struct vmcs12 *vmcs12, return inequality ^ bit; } -static void vmx_inject_page_fault_nested(struct kvm_vcpu *vcpu, - struct x86_exception *fault) -{ - struct vmcs12 *vmcs12 = get_vmcs12(vcpu); - - WARN_ON(!is_guest_mode(vcpu)); - - if (nested_vmx_is_page_fault_vmexit(vmcs12, fault->error_code)) { - vmcs12->vm_exit_intr_error_code = fault->error_code; - nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI, - PF_VECTOR | INTR_TYPE_HARD_EXCEPTION | - INTR_INFO_DELIVER_CODE_MASK | INTR_INFO_VALID_MASK, - fault->address); - } else { - kvm_inject_page_fault(vcpu, fault); - } -} - static inline bool nested_vmx_merge_msr_bitmap(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12); @@ -10654,7 +10636,7 @@ static int prepare_vmcs02(struct kvm_vcpu *vcpu, struct vmcs12 *vmcs12, return 1; if (!enable_ept) - vcpu->arch.walk_mmu->inject_page_fault = vmx_inject_page_fault_nested; + vcpu->arch.walk_mmu->inject_page_fault = kvm_inject_page_fault; /* Regards, Wanpeng Li