Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965061Ab2B1Kpk (ORCPT ); Tue, 28 Feb 2012 05:45:40 -0500 Received: from mx1.redhat.com ([209.132.183.28]:11098 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753646Ab2B1Kpj (ORCPT ); Tue, 28 Feb 2012 05:45:39 -0500 Date: Tue, 28 Feb 2012 12:45:28 +0200 From: Gleb Natapov To: Jan Kiszka Cc: Wen Congyang , 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: <20120228104528.GB24600@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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4F4CAA43.3020805@siemens.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4085 Lines: 105 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. -- 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/