On Fri, Mar 04, 2016 at 11:57:18AM +0100, Igor Mammedov wrote: > On Fri, 4 Mar 2016 12:24:11 +0530 > Bharata B Rao <bhar...@linux.vnet.ibm.com> wrote: > > > Hi, > > > > This is the next version of "Core based CPU hotplug for PowerPC sPAPR" that > > was posted at > > https://lists.gnu.org/archive/html/qemu-ppc/2016-02/msg00286.html > > > > Here is a quick summary on how this approach is different from the > > previous approaches that I have been pursuing with the last one being > > v7 that posted here: > > https://lists.gnu.org/archive/html/qemu-ppc/2016-01/msg00477.html > > > > - Earlier approaches used an independent PowerPC specific core device while > > this approach uses an sPAPR specific core device that is derived from > > generic core device. > > - The earlier approach didn't have the notion of where the boot time as > > well as hot-plugged cores would sit. In this approach QOM links are > > created from machine object to all possible core objects. While the > > links are set for boot time cores during machine init, the same is done > > for hotplugged cores at hotplug time. The name of this link property > > is standardized as "core[N]" since these links link the machine object > > with core devices. The link name ("core[N]") is used with core device's > > "slot" property to identify the QOM link to set for this core. > > (qemu) device_add > > spapr-cpu-core,id=core2,nr_threads=8,cpu_model=host,slot=core[2] > > - The ealier approach created threads from instance_init of the core object > > using a modified cpu_generic_init() routine. It used smp_threads and > > MachineState->cpu_model globals. In the current approach, nr_threads and > > cpu_model are obtained as properties and threads are created from > > property setters. The thread objects are allocated as part of core > > device and object_initialize() is used to initialize them. > > > > Some open questions remain: > > > > - Does this device_add semantics look ok ? > > (qemu) device_add > > spapr-cpu-core,id=core2,nr_threads=8,cpu_model=host,slot=core[2] > looks fine to me, only I'd do following changes: > s/nr_threads/threads/ > s/slot/core/ and make it numeric property > > > - Is there need for machine to core object links ? If not, what would > > determine the slot/location of the core device ? > I'd drop links altogether for this series as they were a part of an attempt > to implement QOM based introspection interface, which is not must have > provided QMP interface would provide all necessary for hotplug information > which links aren't capable of to do.
Yeah, I tend to agree. > Back in the days Anthony suggested that we 'might' use links to implement > hotplug because there wasn't any other infrastructure hotplug > infrastructure for bus-less devices. But now we have HOTPLUG_HANDLER > interface that obsoleted, what links were supposed to handle at > link set time hooks. > > But somehow we stuck on links idea, though their initial role in hotplug > were obsoleted and we still trying to fit them in design where > they are not really necessary. > > > - How to fit this with CPUSlotProperties HMP interface that Igor is > > working on ? > I'll try to re-factor QMP interface RFC on top of this series > so it would be easier for you to review it wrt spapr. > > > > This version has the following changes: > > > > - Dropped QMP and HMP enumeration patches for now since it isn't clear > > if the approach I took would be preferrable by all archs. Will wait > > and see how Igor's patches evolve here. > > - Added the following pre-req patches to support CPU removal: > > exec: Remove cpu from cpus list during cpu_exec_exit() > > exec: Do vmstate unregistration from cpu_exec_exit() > > cpu: Reclaim vCPU objects > > cpu: Add a sync version of cpu_remove() > > - Added sPAPR CPU hot removal support > > xics,xics_kvm: Handle CPU unplug correctly > > spapr: CPU hot unplug support > > - Moved up the "slot" property into abstract cpu-core device. > > - Recover when thread creation fails (spapr_cpu_core_create_threads()) > > - cpu_model property in spapr-cpu-core deivce is now tracked using > > ObjectClass pointer instead of string. > > - Fail topologies with incomplete cores from within sPAPR's machine init. > > - Fixes in spapr-cpu-core object creation from machine init to create > > only boottime CPUs. > > - Moved board specific wiring code for CPU threads (spapr_cpu_init) > > into core's realize method to be called after each thread's realization. > > - No specific action under TYPE_CPU in ->plug() handler either for hotplug > > or hot removal. > > - Moved all core related CPU hotplug routines into spapr_cpu_core.c where > > it truly belongs. > > - Setting of NUMA node for hotplugged CPUs moved to spapr_cpu_init()). > > - Compared to previous implementation of hot removal that was part of > > different series earlier, this implementation moves all core removal > > logic into spapr_cpu_core.c. > > - Some minor cleanups like use of g_new0 instead of g_malloc0 etc. > > > > This patchset is present at: > > https://github.com/bharata/qemu/commits/spapr-cpu-core > > > > Bharata B Rao (9): > > exec: Remove cpu from cpus list during cpu_exec_exit() > > exec: Do vmstate unregistration from cpu_exec_exit() > > cpu: Add a sync version of cpu_remove() > > cpu: Abstract CPU core type > > spapr: CPU core device > > spapr: Represent boot CPUs as spapr-cpu-core devices > > spapr: CPU hotplug support > > xics,xics_kvm: Handle CPU unplug correctly > > spapr: CPU hot unplug support > > > > Gu Zheng (1): > > cpu: Reclaim vCPU objects > > > > cpus.c | 50 ++++++ > > exec.c | 44 ++++- > > hw/cpu/Makefile.objs | 1 + > > hw/cpu/core.c | 44 +++++ > > hw/intc/xics.c | 14 ++ > > hw/intc/xics_kvm.c | 8 +- > > hw/ppc/Makefile.objs | 1 + > > hw/ppc/spapr.c | 174 +++++++++++++++++-- > > hw/ppc/spapr_cpu_core.c | 361 > > ++++++++++++++++++++++++++++++++++++++++ > > hw/ppc/spapr_events.c | 3 + > > hw/ppc/spapr_rtas.c | 24 +++ > > include/hw/cpu/core.h | 30 ++++ > > include/hw/ppc/spapr.h | 9 + > > include/hw/ppc/spapr_cpu_core.h | 42 +++++ > > include/hw/ppc/xics.h | 1 + > > include/qom/cpu.h | 18 ++ > > include/sysemu/kvm.h | 1 + > > kvm-all.c | 57 ++++++- > > kvm-stub.c | 5 + > > 19 files changed, 862 insertions(+), 25 deletions(-) > > create mode 100644 hw/cpu/core.c > > create mode 100644 hw/ppc/spapr_cpu_core.c > > create mode 100644 include/hw/cpu/core.h > > create mode 100644 include/hw/ppc/spapr_cpu_core.h > > > > -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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