Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932539Ab2B2Jgl (ORCPT ); Wed, 29 Feb 2012 04:36:41 -0500 Received: from mx1.redhat.com ([209.132.183.28]:64159 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932213Ab2B2Jgj (ORCPT ); Wed, 29 Feb 2012 04:36:39 -0500 Date: Wed, 29 Feb 2012 11:36:27 +0200 From: Gleb Natapov To: Wen Congyang Cc: Jan Kiszka , kvm list , Avi Kivity , KAMEZAWA Hiroyuki , "Daniel P. Berrange" , "linux-kernel@vger.kernel.org" , qemu-devel Subject: Re: [PATCH] kvm: notify host when guest paniced Message-ID: <20120229093627.GC24600@redhat.com> References: <4F4AF1FB.6000903@cn.fujitsu.com> <4F4B9C57.3010407@siemens.com> <4F4C8EEB.8040709@cn.fujitsu.com> <4F4C9F8C.1060901@siemens.com> <4F4CA17F.4020504@cn.fujitsu.com> <4F4CAA43.3020805@siemens.com> <20120228104528.GB24600@redhat.com> <4F4D7AA4.3070801@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4F4D7AA4.3070801@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4680 Lines: 114 On Wed, Feb 29, 2012 at 09:08:52AM +0800, Wen Congyang wrote: > At 02/28/2012 06:45 PM, Gleb Natapov Wrote: > > On Tue, Feb 28, 2012 at 11:19:47AM +0100, Jan Kiszka wrote: > >> On 2012-02-28 10:42, Wen Congyang wrote: > >>> At 02/28/2012 05:34 PM, Jan Kiszka Wrote: > >>>> On 2012-02-28 09:23, Wen Congyang wrote: > >>>>> At 02/27/2012 11:08 PM, Jan Kiszka Wrote: > >>>>>> On 2012-02-27 04:01, Wen Congyang wrote: > >>>>>>> We can know the guest is paniced when the guest runs on xen. > >>>>>>> But we do not have such feature on kvm. This patch implemnts > >>>>>>> this feature, and the implementation is the same as xen: > >>>>>>> register panic notifier, and call hypercall when the guest > >>>>>>> is paniced. > >>>>>>> > >>>>>>> Signed-off-by: Wen Congyang > >>>>>>> --- > >>>>>>> arch/x86/kernel/kvm.c | 12 ++++++++++++ > >>>>>>> arch/x86/kvm/svm.c | 8 ++++++-- > >>>>>>> arch/x86/kvm/vmx.c | 8 ++++++-- > >>>>>>> arch/x86/kvm/x86.c | 13 +++++++++++-- > >>>>>>> include/linux/kvm.h | 1 + > >>>>>>> include/linux/kvm_para.h | 1 + > >>>>>>> 6 files changed, 37 insertions(+), 6 deletions(-) > >>>>>>> > >>>>>>> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c > >>>>>>> index f0c6fd6..b928d1d 100644 > >>>>>>> --- a/arch/x86/kernel/kvm.c > >>>>>>> +++ b/arch/x86/kernel/kvm.c > >>>>>>> @@ -331,6 +331,17 @@ static struct notifier_block kvm_pv_reboot_nb = { > >>>>>>> .notifier_call = kvm_pv_reboot_notify, > >>>>>>> }; > >>>>>>> > >>>>>>> +static int > >>>>>>> +kvm_pv_panic_notify(struct notifier_block *nb, unsigned long code, void *unused) > >>>>>>> +{ > >>>>>>> + kvm_hypercall0(KVM_HC_GUEST_PANIC); > >>>>>>> + return NOTIFY_DONE; > >>>>>>> +} > >>>>>>> + > >>>>>>> +static struct notifier_block kvm_pv_panic_nb = { > >>>>>>> + .notifier_call = kvm_pv_panic_notify, > >>>>>>> +}; > >>>>>>> + > >>>>>> > >>>>>> You should split up host and guest-side changes. > >>>>>> > >>>>>>> static u64 kvm_steal_clock(int cpu) > >>>>>>> { > >>>>>>> u64 steal; > >>>>>>> @@ -417,6 +428,7 @@ void __init kvm_guest_init(void) > >>>>>>> > >>>>>>> paravirt_ops_setup(); > >>>>>>> register_reboot_notifier(&kvm_pv_reboot_nb); > >>>>>>> + atomic_notifier_chain_register(&panic_notifier_list, &kvm_pv_panic_nb); > >>>>>>> for (i = 0; i < KVM_TASK_SLEEP_HASHSIZE; i++) > >>>>>>> spin_lock_init(&async_pf_sleepers[i].lock); > >>>>>>> if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF)) > >>>>>>> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > >>>>>>> index 0b7690e..38b4705 100644 > >>>>>>> --- a/arch/x86/kvm/svm.c > >>>>>>> +++ b/arch/x86/kvm/svm.c > >>>>>>> @@ -1900,10 +1900,14 @@ static int halt_interception(struct vcpu_svm *svm) > >>>>>>> > >>>>>>> static int vmmcall_interception(struct vcpu_svm *svm) > >>>>>>> { > >>>>>>> + int ret; > >>>>>>> + > >>>>>>> svm->next_rip = kvm_rip_read(&svm->vcpu) + 3; > >>>>>>> skip_emulated_instruction(&svm->vcpu); > >>>>>>> - kvm_emulate_hypercall(&svm->vcpu); > >>>>>>> - return 1; > >>>>>>> + ret = kvm_emulate_hypercall(&svm->vcpu); > >>>>>>> + > >>>>>>> + /* Ignore the error? */ > >>>>>>> + return ret == 0 ? 0 : 1; > >>>>>> > >>>>>> Why can't kvm_emulate_hypercall return the right value? > >>>>> > >>>>> kvm_emulate_hypercall() will call kvm_hv_hypercall(), and > >>>>> kvm_hv_hypercall() will return 0 when vcpu's CPL > 0. > >>>>> If vcpu's CPL > 0, does kvm need to exit and tell it to > >>>>> qemu? > >>>> > >>>> No, there is currently no exit to userspace due to hypercalls, neither > >>>> of HV nor KVM kind. > >>>> > >>>> The point is that the return code of kvm_emulate_hypercall is unused so > >>>> far, so you can easily redefine it to encode continue vs. exit to > >>>> userspace. Once someone has different needs, this could still be > >>>> refactored again. > >>> > >>> So, it is OK to change the return value of kvm_hv_hypercall() if vcpu's > >>> CPL > 0? > >> > >> Yes, change it to encode what vendor modules need to return to their > >> callers. > >> > > Better introduce new request flag and set it in your hypercall emulation. See > > how triple fault is handled. > > triple fault sets KVM_EXIT_SHUTDOWN and exits to userspace. Do you mean introduce > a new value(like KVM_EXIT_SHUTDOWN)? > I mean introduce new request bit (like KVM_REQ_TRIPLE_FAULT) and set it in your hypercall if exit to userspace is needed instead of changing return values. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/