On Tue, Apr 26, 2016 at 03:41:04PM +0200, Greg Kurz wrote: > The KVM API restricts vcpu ids to be < KVM_CAP_MAX_VCPUS. On PowerPC > targets, depending on the number of threads per core in the host and > in the guest, some topologies do generate higher vcpu ids actually. > When this happens, QEMU bails out with the following error: > > kvm_init_vcpu failed: Invalid argument > > The KVM_CREATE_VCPU ioctl has several EINVAL return paths, so it is > not possible to fully disambiguate. > > This patch adds a check in the code that computes vcpu ids, so that > we can detect the error earlier, and print a friendlier message instead > of calling KVM_CREATE_VCPU with an obviously bogus vcpu id. > > Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com>
Applied to ppc-for-2.7, thanks. I'm still kicking myself for doing the SMT / cpu ids that way way back when. Should have just had a "SET_SMT" ioctl() and allocated the cpu ids sequentially. Too clever by half :( > --- > include/sysemu/kvm.h | 2 ++ > kvm-all.c | 6 ++++++ > target-ppc/translate_init.c | 8 ++++++++ > 3 files changed, 16 insertions(+) > > diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h > index 0e18f15c9493..27bf50ef379e 100644 > --- a/include/sysemu/kvm.h > +++ b/include/sysemu/kvm.h > @@ -344,6 +344,8 @@ int kvm_arch_init(MachineState *ms, KVMState *s); > > int kvm_arch_init_vcpu(CPUState *cpu); > > +bool kvm_vcpu_id_is_valid(int vcpu_id); > + > /* Returns VCPU ID to be used on KVM_CREATE_VCPU ioctl() */ > unsigned long kvm_arch_vcpu_id(CPUState *cpu); > > diff --git a/kvm-all.c b/kvm-all.c > index e7b66df197fd..3625a3e07457 100644 > --- a/kvm-all.c > +++ b/kvm-all.c > @@ -1459,6 +1459,12 @@ static int kvm_max_vcpus(KVMState *s) > return (ret) ? ret : kvm_recommended_vcpus(s); > } > > +bool kvm_vcpu_id_is_valid(int vcpu_id) > +{ > + KVMState *s = KVM_STATE(current_machine->accelerator); > + return vcpu_id >= 0 && vcpu_id < kvm_max_vcpus(s); > +} > + > static int kvm_init(MachineState *ms) > { > MachineClass *mc = MACHINE_GET_CLASS(ms); > diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c > index f51572552bc2..6c89b18a05f9 100644 > --- a/target-ppc/translate_init.c > +++ b/target-ppc/translate_init.c > @@ -9247,6 +9247,14 @@ static void ppc_cpu_realizefn(DeviceState *dev, Error > **errp) > #if !defined(CONFIG_USER_ONLY) > cpu->cpu_dt_id = (cs->cpu_index / smp_threads) * max_smt > + (cs->cpu_index % smp_threads); > + > + if (kvm_enabled() && !kvm_vcpu_id_is_valid(cpu->cpu_dt_id)) { > + error_setg(errp, "Can't create CPU with id %d in KVM", > cpu->cpu_dt_id); > + error_append_hint(errp, "Adjust the number of cpus to %d " > + "or try to raise the number of threads per core\n", > + cpu->cpu_dt_id * smp_threads / max_smt); > + return; > + } > #endif > > if (tcg_enabled()) { > -- 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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