From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH V5] Guest stop notification Date: Wed, 11 Jan 2012 19:36:39 +0100 Message-ID: <4F0DD6B7.9070800@siemens.com> References: <1326305847-25303-1-git-send-email-emunson@mgebm.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "ryanh@linux.vnet.ibm.com" , "aliguori@us.ibm.com" , "kvm@vger.kernel.org" , Marcelo Tosatti , "qemu-devel@nongnu.org" , Avi Kivity To: Eric B Munson Return-path: In-Reply-To: <1326305847-25303-1-git-send-email-emunson@mgebm.net> 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 2012-01-11 19:17, Eric B Munson wrote: > Often when a guest is stopped from the qemu console, it will report spurious > soft lockup warnings on resume. There are kernel patches being discussed that > will give the host the ability to tell the guest that it is being stopped and > should ignore the soft lockup warning that generates. This patch uses the qemu > Notifier system to tell the guest it is about to be stopped. > > Signed-off-by: Eric B Munson > > Cc: Avi Kivity > Cc: Marcelo Tosatti > Cc: Jan Kiszka > Cc: ryanh@linux.vnet.ibm.com > Cc: aliguori@us.ibm.com > Cc: kvm@vger.kernel.org > --- > Changes from V4: > Test if the guest paused capability is available before use > > Changes from V3: > Collapse new state change notification function into existsing function. > Correct whitespace issues > Change ioctl name to KVMCLOCK_GUEST_PAUSED > Use for loop to iterate vpcu's > > Changes from V2: > Move ioctl into hw/kvmclock.c so as other arches can use it as it is > implemented > > Changes from V1: > Remove unnecessary encapsulating function > > hw/kvmclock.c | 20 ++++++++++++++++++++ > 1 files changed, 20 insertions(+), 0 deletions(-) > > diff --git a/hw/kvmclock.c b/hw/kvmclock.c > index 5388bc4..d071d61 100644 > --- a/hw/kvmclock.c > +++ b/hw/kvmclock.c > @@ -16,6 +16,7 @@ > #include "sysbus.h" > #include "kvm.h" > #include "kvmclock.h" > +#include "cpu-all.h" > > #include > #include > @@ -62,10 +63,29 @@ static int kvmclock_post_load(void *opaque, int version_id) > static void kvmclock_vm_state_change(void *opaque, int running, > RunState state) > { > + int ret; > + CPUState *penv = first_cpu; > KVMClockState *s = opaque; > + int cap_guest_paused = kvm_check_extension(kvm_state, KVM_CAP_GUEST_PAUSED); > > if (running) { > s->clock_valid = false; > + > + if (!cap_guest_paused) { > + return; > + } Why? You already ignore -EINVAL. > + > + for (penv = first_cpu; penv != NULL; penv = penv->next_cpu) { > + ret = kvm_vcpu_ioctl(penv, KVMCLOCK_GUEST_PAUSED, 0); This indicates that the interface could still be improved: "GUEST_PAUSED" implies to me a VM state, but the IOCTL has to be applied per VCPU. This is inconsistent. Why not define a per-VM IOCTL? Would make user space's life a little bit easier as well. Or is there a valid use case of selectively paused VCPUs? Then call it KVMCLOCK_VCPU_PAUSED. > + if (ret) { > + if (ret != -EINVAL) { What is special about -EINVAL (as long as the cap is checked)? > + fprintf(stderr, > + "kvmclock_vm_state_change: %s\n", > + strerror(-ret)); > + } > + return; > + } > + } > } > } > 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 ([140.186.70.92]:53601) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Rl32f-00034u-Cg for qemu-devel@nongnu.org; Wed, 11 Jan 2012 13:36:58 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Rl32a-0002k8-SE for qemu-devel@nongnu.org; Wed, 11 Jan 2012 13:36:57 -0500 Received: from david.siemens.de ([192.35.17.14]:24176) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Rl32a-0002jX-I9 for qemu-devel@nongnu.org; Wed, 11 Jan 2012 13:36:52 -0500 Message-ID: <4F0DD6B7.9070800@siemens.com> Date: Wed, 11 Jan 2012 19:36:39 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <1326305847-25303-1-git-send-email-emunson@mgebm.net> In-Reply-To: <1326305847-25303-1-git-send-email-emunson@mgebm.net> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH V5] Guest stop notification List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Eric B Munson Cc: "ryanh@linux.vnet.ibm.com" , "aliguori@us.ibm.com" , "kvm@vger.kernel.org" , Marcelo Tosatti , "qemu-devel@nongnu.org" , Avi Kivity On 2012-01-11 19:17, Eric B Munson wrote: > Often when a guest is stopped from the qemu console, it will report spurious > soft lockup warnings on resume. There are kernel patches being discussed that > will give the host the ability to tell the guest that it is being stopped and > should ignore the soft lockup warning that generates. This patch uses the qemu > Notifier system to tell the guest it is about to be stopped. > > Signed-off-by: Eric B Munson > > Cc: Avi Kivity > Cc: Marcelo Tosatti > Cc: Jan Kiszka > Cc: ryanh@linux.vnet.ibm.com > Cc: aliguori@us.ibm.com > Cc: kvm@vger.kernel.org > --- > Changes from V4: > Test if the guest paused capability is available before use > > Changes from V3: > Collapse new state change notification function into existsing function. > Correct whitespace issues > Change ioctl name to KVMCLOCK_GUEST_PAUSED > Use for loop to iterate vpcu's > > Changes from V2: > Move ioctl into hw/kvmclock.c so as other arches can use it as it is > implemented > > Changes from V1: > Remove unnecessary encapsulating function > > hw/kvmclock.c | 20 ++++++++++++++++++++ > 1 files changed, 20 insertions(+), 0 deletions(-) > > diff --git a/hw/kvmclock.c b/hw/kvmclock.c > index 5388bc4..d071d61 100644 > --- a/hw/kvmclock.c > +++ b/hw/kvmclock.c > @@ -16,6 +16,7 @@ > #include "sysbus.h" > #include "kvm.h" > #include "kvmclock.h" > +#include "cpu-all.h" > > #include > #include > @@ -62,10 +63,29 @@ static int kvmclock_post_load(void *opaque, int version_id) > static void kvmclock_vm_state_change(void *opaque, int running, > RunState state) > { > + int ret; > + CPUState *penv = first_cpu; > KVMClockState *s = opaque; > + int cap_guest_paused = kvm_check_extension(kvm_state, KVM_CAP_GUEST_PAUSED); > > if (running) { > s->clock_valid = false; > + > + if (!cap_guest_paused) { > + return; > + } Why? You already ignore -EINVAL. > + > + for (penv = first_cpu; penv != NULL; penv = penv->next_cpu) { > + ret = kvm_vcpu_ioctl(penv, KVMCLOCK_GUEST_PAUSED, 0); This indicates that the interface could still be improved: "GUEST_PAUSED" implies to me a VM state, but the IOCTL has to be applied per VCPU. This is inconsistent. Why not define a per-VM IOCTL? Would make user space's life a little bit easier as well. Or is there a valid use case of selectively paused VCPUs? Then call it KVMCLOCK_VCPU_PAUSED. > + if (ret) { > + if (ret != -EINVAL) { What is special about -EINVAL (as long as the cap is checked)? > + fprintf(stderr, > + "kvmclock_vm_state_change: %s\n", > + strerror(-ret)); > + } > + return; > + } > + } > } > } > Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux