Re: [Qemu-devel] [Qemu-ppc] [PATCH 0/4] spapr: disable hotplugging without OS
On 23/05/2017 20:22, Daniel Henrique Barboza wrote: > > > This is the Libvirt use case that fails with this patch set applied in > QEMU master, Libvirt 3.4.0 compiled from > source: > > # ./virsh start dhb_ub1704_nfs 2 > # > # ./virsh setvcpus dhb_ub1704_nfs 2 --live > # > # ./virsh -c 'qemu:///system' migrate --live --domain dhb_ub1704_nfs > --desturi qemu+ssh://target_ip/system --timeout 60 --verbose > error: internal error: unable to execute QEMU command 'device_add': CPU > hotplug not supported without OS Good point. I think I should refine my series to allow hotplug if the machine is not started. Thanks, Laurent
Re: [Qemu-devel] [Qemu-ppc] [PATCH 0/4] spapr: disable hotplugging without OS
On 05/23/2017 03:07 PM, Daniel Henrique Barboza wrote: On 05/23/2017 02:52 PM, Daniel Henrique Barboza wrote: Hi Laurent, This is an interesting patch series. I've been working in the last weeks in the DRC migration, mainly to solve the problem in which a hot CPU unplug will not succeed after a migration if the CPU was hotplugged in the source. The problem happened when migrating with virsh because Libvirt hotplugs the CPU in both source and target, and the DRC state of the hotplugged after the migration is inconsistent. This series solves the issue by preventing it from happening in the first place. Of course that migrating DRC states has other uses (pending unplug operations during a migration, for example) so both patch series can coexist. One possible issue I see with this series is that it breaks Libvirt migration entirely if a CPU/mem hotplug happens in the target. With your series applied the migration fails before start with: Sorry: if a migration happens in the *source*, before the migration. Hehe nothing like fixing a typo with another one ... This is the Libvirt use case that fails with this patch set applied in QEMU master, Libvirt 3.4.0 compiled from source: # ./virsh start dhb_ub1704_nfs 2 # # ./virsh setvcpus dhb_ub1704_nfs 2 --live # # ./virsh -c 'qemu:///system' migrate --live --domain dhb_ub1704_nfs --desturi qemu+ssh://target_ip/system --timeout 60 --verbose error: internal error: unable to execute QEMU command 'device_add': CPU hotplug not supported without OS This is the error msg that appears in Libvirt daemon: 2017-05-23 18:17:17.844+: 159678: error : qemuMonitorJSONCheckError:389 : internal error: unable to execute QEMU command 'device_add': CPU hotplug not supported without OS Daniel # ./virsh -c 'qemu:///system' migrate --live --domain dhb_ub1704_nfs --desturi qemu+ssh://target_ip/system --timeout 60 --verbose error: internal error: unable to execute QEMU command 'device_add': CPU hotplug not supported without OS Note that I say "possible issue" because, although I believe we do not want to break Libvirt if possible, I also believe that we need to think about what makes sense in QEMU first. Thanks, Daniel On 05/23/2017 08:18 AM, Laurent Vivier wrote: If the OS is not started, QEMU sends an event to the OS that is lost and cannot be recovered. An unplug is not able to restore QEMU in a coherent state. So, while the OS is not started, disable CPU and memory hotplug. We use option vector 6 to know if the OS is started This series moves error checking for memory hotplug in a pre_plug function, and introduces the option vector 6 management. It also revert previous fix which was not really fixing the hotplug problem when the OS is not running. Laurent Vivier (4): spapr: add pre_plug function for memory spapr: add option vector 6 spapr: disable hotplugging without OS Revert "spapr: fix memory hot-unplugging" hw/ppc/spapr.c | 103 hw/ppc/spapr_drc.c | 20 ++--- hw/ppc/spapr_hcall.c| 5 ++- hw/ppc/spapr_ovec.c | 8 include/hw/ppc/spapr.h | 2 + include/hw/ppc/spapr_drc.h | 1 - include/hw/ppc/spapr_ovec.h | 7 +++ 7 files changed, 109 insertions(+), 37 deletions(-)
Re: [Qemu-devel] [Qemu-ppc] [PATCH 0/4] spapr: disable hotplugging without OS
On 05/23/2017 02:52 PM, Daniel Henrique Barboza wrote: Hi Laurent, This is an interesting patch series. I've been working in the last weeks in the DRC migration, mainly to solve the problem in which a hot CPU unplug will not succeed after a migration if the CPU was hotplugged in the source. The problem happened when migrating with virsh because Libvirt hotplugs the CPU in both source and target, and the DRC state of the hotplugged after the migration is inconsistent. This series solves the issue by preventing it from happening in the first place. Of course that migrating DRC states has other uses (pending unplug operations during a migration, for example) so both patch series can coexist. One possible issue I see with this series is that it breaks Libvirt migration entirely if a CPU/mem hotplug happens in the target. With your series applied the migration fails before start with: Sorry: if a migration happens in the *source*, before the migration. # ./virsh -c 'qemu:///system' migrate --live --domain dhb_ub1704_nfs --desturi qemu+ssh://target_ip/system --timeout 60 --verbose error: internal error: unable to execute QEMU command 'device_add': CPU hotplug not supported without OS Note that I say "possible issue" because, although I believe we do not want to break Libvirt if possible, I also believe that we need to think about what makes sense in QEMU first. Thanks, Daniel On 05/23/2017 08:18 AM, Laurent Vivier wrote: If the OS is not started, QEMU sends an event to the OS that is lost and cannot be recovered. An unplug is not able to restore QEMU in a coherent state. So, while the OS is not started, disable CPU and memory hotplug. We use option vector 6 to know if the OS is started This series moves error checking for memory hotplug in a pre_plug function, and introduces the option vector 6 management. It also revert previous fix which was not really fixing the hotplug problem when the OS is not running. Laurent Vivier (4): spapr: add pre_plug function for memory spapr: add option vector 6 spapr: disable hotplugging without OS Revert "spapr: fix memory hot-unplugging" hw/ppc/spapr.c | 103 hw/ppc/spapr_drc.c | 20 ++--- hw/ppc/spapr_hcall.c| 5 ++- hw/ppc/spapr_ovec.c | 8 include/hw/ppc/spapr.h | 2 + include/hw/ppc/spapr_drc.h | 1 - include/hw/ppc/spapr_ovec.h | 7 +++ 7 files changed, 109 insertions(+), 37 deletions(-)
Re: [Qemu-devel] [Qemu-ppc] [PATCH 0/4] spapr: disable hotplugging without OS
Hi Laurent, This is an interesting patch series. I've been working in the last weeks in the DRC migration, mainly to solve the problem in which a hot CPU unplug will not succeed after a migration if the CPU was hotplugged in the source. The problem happened when migrating with virsh because Libvirt hotplugs the CPU in both source and target, and the DRC state of the hotplugged after the migration is inconsistent. This series solves the issue by preventing it from happening in the first place. Of course that migrating DRC states has other uses (pending unplug operations during a migration, for example) so both patch series can coexist. One possible issue I see with this series is that it breaks Libvirt migration entirely if a CPU/mem hotplug happens in the target. With your series applied the migration fails before start with: # ./virsh -c 'qemu:///system' migrate --live --domain dhb_ub1704_nfs --desturi qemu+ssh://target_ip/system --timeout 60 --verbose error: internal error: unable to execute QEMU command 'device_add': CPU hotplug not supported without OS Note that I say "possible issue" because, although I believe we do not want to break Libvirt if possible, I also believe that we need to think about what makes sense in QEMU first. Thanks, Daniel On 05/23/2017 08:18 AM, Laurent Vivier wrote: If the OS is not started, QEMU sends an event to the OS that is lost and cannot be recovered. An unplug is not able to restore QEMU in a coherent state. So, while the OS is not started, disable CPU and memory hotplug. We use option vector 6 to know if the OS is started This series moves error checking for memory hotplug in a pre_plug function, and introduces the option vector 6 management. It also revert previous fix which was not really fixing the hotplug problem when the OS is not running. Laurent Vivier (4): spapr: add pre_plug function for memory spapr: add option vector 6 spapr: disable hotplugging without OS Revert "spapr: fix memory hot-unplugging" hw/ppc/spapr.c | 103 hw/ppc/spapr_drc.c | 20 ++--- hw/ppc/spapr_hcall.c| 5 ++- hw/ppc/spapr_ovec.c | 8 include/hw/ppc/spapr.h | 2 + include/hw/ppc/spapr_drc.h | 1 - include/hw/ppc/spapr_ovec.h | 7 +++ 7 files changed, 109 insertions(+), 37 deletions(-)
