| Message ID | 146424973033.5666.486850661983708617.stgit@bahia.huguette.org |
|---|---|
| State | New |
| Headers | show |
On Thu, May 26, 2016 at 10:02:10AM +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 <gkurz@linux.vnet.ibm.com> Reviewed-by: David Gibson <david@gibson.dropbear.id.au> > --- > 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 f9f00e2e56cb..f357ccde9122 100644 > --- a/include/sysemu/kvm.h > +++ b/include/sysemu/kvm.h > @@ -345,6 +345,8 @@ 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 f9ae8f9bf809..e56f38527815 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 954195f5e494..a003c1029d31 100644 > --- a/target-ppc/translate_init.c > +++ b/target-ppc/translate_init.c > @@ -9231,6 +9231,14 @@ 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()) { >
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h index f9f00e2e56cb..f357ccde9122 100644 --- a/include/sysemu/kvm.h +++ b/include/sysemu/kvm.h @@ -345,6 +345,8 @@ 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 f9ae8f9bf809..e56f38527815 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 954195f5e494..a003c1029d31 100644 --- a/target-ppc/translate_init.c +++ b/target-ppc/translate_init.c @@ -9231,6 +9231,14 @@ 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()) {
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 <gkurz@linux.vnet.ibm.com> --- include/sysemu/kvm.h | 2 ++ kvm-all.c | 6 ++++++ target-ppc/translate_init.c | 8 ++++++++ 3 files changed, 16 insertions(+)