Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752013AbdF2HOH (ORCPT ); Thu, 29 Jun 2017 03:14:07 -0400 Received: from mail-oi0-f67.google.com ([209.85.218.67]:33691 "EHLO mail-oi0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751637AbdF2HN6 (ORCPT ); Thu, 29 Jun 2017 03:13:58 -0400 MIME-Version: 1.0 In-Reply-To: <1498705321-3927-1-git-send-email-wanpeng.li@hotmail.com> References: <1498705321-3927-1-git-send-email-wanpeng.li@hotmail.com> From: Wanpeng Li Date: Thu, 29 Jun 2017 15:13:56 +0800 Message-ID: Subject: Re: [PATCH v7 0/4] KVM: async_pf: Fix async pf exception injection To: "linux-kernel@vger.kernel.org" , kvm Cc: Paolo Bonzini , =?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-Length: 3456 Lines: 86 2017-06-29 11:01 GMT+08:00 Wanpeng Li : > INFO: task gnome-terminal-:1734 blocked for more than 120 seconds. > Not tainted 4.12.0-rc4+ #8 > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > gnome-terminal- D 0 1734 1015 0x00000000 > Call Trace: > __schedule+0x3cd/0xb30 > schedule+0x40/0x90 > kvm_async_pf_task_wait+0x1cc/0x270 > ? __vfs_read+0x37/0x150 > ? prepare_to_swait+0x22/0x70 > do_async_page_fault+0x77/0xb0 > ? do_async_page_fault+0x77/0xb0 > async_page_fault+0x28/0x30 > > This is triggered by running both win7 and win2016 on L1 KVM simultaneously, > and then gives stress to memory on L1, I can observed this hang on L1 when > at least ~70% swap area is occupied on L0. > > This is due to async pf was injected to L2 which should be injected to L1, > L2 guest starts receiving pagefault w/ bogus %cr2(apf token from the host > actually), and L1 guest starts accumulating tasks stuck in D state in > kvm_async_pf_task_wait() since missing PAGE_READY async_pfs. > > This patchset fixes it according to Radim's proposal "force a nested VM exit > from nested_vmx_check_exception if the injected #PF is async_pf and handle > the #PF VM exit in L1". https://www.spinics.net/lists/kvm/msg142498.html Note: The patchset depends on commit d4912215d10 ("KVM: nVMX: Fix exception injection") and commit 9bc1f09f6fa76fd (KVM: async_pf: avoid async pf injection when in guest mode) on the master branch. Regards, Wanpeng Li > > v6 -> v7: > * drop KVM_GET/PUT_VCPU_EVENTS stuff for nested_apf > > v5 -> v6: > * move vcpu_svm's apf_reason to vcpu->arch.apf.host_apf_reason > * introduce function kvm_handle_page_fault() to be used by both VMX/SVM > * introduce svm's codes posted by Paolo > * introduce nested_apf > * better set MSR_KVM_ASYNC_PF_EN > > v4 -> v5: > * utilize wrmsr_safe for MSR_KVM_ASYNC_PF_EN > > v3 -> v4: > * reuse pad field in kvm_vcpu_events for async_page_fault > * update kvm_vcpu_events API documentations > * change async_page_fault type in vcpu->arch.exception from bool to u8 > > v2 -> v3: > * add the flag to the userspace interface(KVM_GET/PUT_VCPU_EVENTS) > > v1 -> v2: > * remove nested_vmx_check_exception nr parameter > * construct a simple special vm-exit information field for async pf > * introduce nested_apf_token to vcpu->arch.apf to avoid change the CR2 > visible in L2 guest > * avoid pass the apf directed towards it (L1) into L2 if there is L3 > at the moment > > Wanpeng Li (4): > KVM: x86: Simple kvm_x86_ops->queue_exception parameter > KVM: async_pf: Add L1 guest async_pf #PF vmexit handler > KVM: async_pf: Force a nested vmexit if the injected #PF is async_pf > KVM: async_pf: Let host know whether the guest support delivery async_pf as #PF vmexit > > Documentation/virtual/kvm/msr.txt | 5 ++-- > arch/x86/include/asm/kvm_emulate.h | 1 + > arch/x86/include/asm/kvm_host.h | 8 +++-- > arch/x86/include/uapi/asm/kvm_para.h | 1 + > arch/x86/kernel/kvm.c | 7 ++++- > arch/x86/kvm/mmu.c | 35 +++++++++++++++++++++- > arch/x86/kvm/mmu.h | 2 ++ > arch/x86/kvm/svm.c | 58 ++++++++++++------------------------ > arch/x86/kvm/vmx.c | 39 +++++++++++++++--------- > arch/x86/kvm/x86.c | 19 +++++++----- > 10 files changed, 108 insertions(+), 67 deletions(-) > > -- > 2.7.4 >