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 10:34:04 +0100 Message-ID: <4F4C9F8C.1060901@siemens.com> References: <4F4AF1FB.6000903@cn.fujitsu.com> <4F4B9C57.3010407@siemens.com> <4F4C8EEB.8040709@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: kvm list , qemu-devel , "linux-kernel@vger.kernel.org" , Avi Kivity , KAMEZAWA Hiroyuki To: Wen Congyang Return-path: In-Reply-To: <4F4C8EEB.8040709@cn.fujitsu.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org List-Id: kvm.vger.kernel.org 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. 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 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932163Ab2B1Jea (ORCPT ); Tue, 28 Feb 2012 04:34:30 -0500 Received: from goliath.siemens.de ([192.35.17.28]:15256 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752561Ab2B1Je0 (ORCPT ); Tue, 28 Feb 2012 04:34:26 -0500 Message-ID: <4F4C9F8C.1060901@siemens.com> Date: Tue, 28 Feb 2012 10:34:04 +0100 From: Jan Kiszka User-Agent: Mozilla/5.0 (X11; U; Linux i686 (x86_64); de; rv:1.8.1.12) Gecko/20080226 SUSE/2.0.0.12-1.1 Thunderbird/2.0.0.12 Mnenhy/0.7.5.666 MIME-Version: 1.0 To: Wen Congyang CC: 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 References: <4F4AF1FB.6000903@cn.fujitsu.com> <4F4B9C57.3010407@siemens.com> <4F4C8EEB.8040709@cn.fujitsu.com> In-Reply-To: <4F4C8EEB.8040709@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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]:36343) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2JRz-0000rw-O1 for qemu-devel@nongnu.org; Tue, 28 Feb 2012 04:34:32 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S2JRu-00048H-Hj for qemu-devel@nongnu.org; Tue, 28 Feb 2012 04:34:27 -0500 Received: from goliath.siemens.de ([192.35.17.28]:20948) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2JRu-000484-88 for qemu-devel@nongnu.org; Tue, 28 Feb 2012 04:34:22 -0500 Message-ID: <4F4C9F8C.1060901@siemens.com> Date: Tue, 28 Feb 2012 10:34:04 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <4F4AF1FB.6000903@cn.fujitsu.com> <4F4B9C57.3010407@siemens.com> <4F4C8EEB.8040709@cn.fujitsu.com> In-Reply-To: <4F4C8EEB.8040709@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 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. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux