From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH] kvm: notify host when guest paniced Date: Tue, 28 Feb 2012 11:19:47 +0100 Message-ID: <4F4CAA43.3020805@siemens.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> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: kvm list , Avi Kivity , KAMEZAWA Hiroyuki , "Daniel P. Berrange" , "linux-kernel@vger.kernel.org" , qemu-devel To: Wen Congyang Return-path: In-Reply-To: <4F4CA17F.4020504@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:33995) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2KAI-0005ME-Kz for qemu-devel@nongnu.org; Tue, 28 Feb 2012 05:20:20 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S2KAC-0003sy-25 for qemu-devel@nongnu.org; Tue, 28 Feb 2012 05:20:14 -0500 Received: from goliath.siemens.de ([192.35.17.28]:28809) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2KAB-0003qJ-P3 for qemu-devel@nongnu.org; Tue, 28 Feb 2012 05:20:08 -0500 Message-ID: <4F4CAA43.3020805@siemens.com> Date: Tue, 28 Feb 2012 11:19:47 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <4F4AF1FB.6000903@cn.fujitsu.com> <4F4B9C57.3010407@siemens.com> <4F4C8EEB.8040709@cn.fujitsu.com> <4F4C9F8C.1060901@siemens.com> <4F4CA17F.4020504@cn.fujitsu.com> In-Reply-To: <4F4CA17F.4020504@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] kvm: notify host when guest paniced List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wen Congyang Cc: kvm list , qemu-devel , "linux-kernel@vger.kernel.org" , Avi Kivity , KAMEZAWA Hiroyuki 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. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux