On Fri, Sep 13, 2019 at 11:56:39AM +0200, Eric Auger wrote: > Host kernel within [4.18, 5.3] report an erroneous KVM_MAX_VCPUS=512 > for ARM. The actual capability to instantiate more than 256 vcpus > was fixed in 5.4 with the upgrade of the KVM_IRQ_LINE ABI to support > vcpu id encoded on 12 bits instead of 8 and a redistributor consuming > a single KVM IO device instead of 2. > > So let's check this capability when attempting to use more than 256 > vcpus within any ARM kvm accelerated machine. > > Signed-off-by: Eric Auger <eric.au...@redhat.com> > > --- > > v2 -> v3: > - Implement the check in kvm_arch_init as suggested by Peter > --- > target/arm/kvm.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/target/arm/kvm.c b/target/arm/kvm.c > index b10581fa06..b473c63edb 100644 > --- a/target/arm/kvm.c > +++ b/target/arm/kvm.c > @@ -182,6 +182,7 @@ int kvm_arm_get_max_vm_ipa_size(MachineState *ms) > > int kvm_arch_init(MachineState *ms, KVMState *s) > { > + int ret = 0; > /* For ARM interrupt delivery is always asynchronous, > * whether we are using an in-kernel VGIC or not. > */ > @@ -195,7 +196,14 @@ int kvm_arch_init(MachineState *ms, KVMState *s) > > cap_has_mp_state = kvm_check_extension(s, KVM_CAP_MP_STATE); > > - return 0; > + if (ms->smp.cpus > 256 && > + !kvm_check_extension(s, KVM_CAP_ARM_IRQ_LINE_LAYOUT_2)) { > + error_report("Using more than 256 vcpus requires a host kernel " > + "with KVM_CAP_ARM_IRQ_LINE_LAYOUT_2"); > + ret = -EINVAL; > + } > + > + return ret; > } > > unsigned long kvm_arch_vcpu_id(CPUState *cpu) > -- > 2.20.1 > >
Reviewed-by: Andrew Jones <drjo...@redhat.com>