From 11748ba72ea4fc03e975aa5f5d876b5b0902e356 Mon Sep 17 00:00:00 2001 From: Greg Kurz Date: Thu, 21 Sep 2017 18:01:02 +0200 Subject: kvm: check KVM_CAP_NR_VCPUS with kvm_vm_check_extension() On a modern server-class ppc host with the following CPU topology: Architecture: ppc64le Byte Order: Little Endian CPU(s): 32 On-line CPU(s) list: 0,8,16,24 Off-line CPU(s) list: 1-7,9-15,17-23,25-31 Thread(s) per core: 1 If both KVM PR and KVM HV loaded and we pass: -machine pseries,accel=kvm,kvm-type=PR -smp 8 We expect QEMU to warn that this exceeds the number of online CPUs: Warning: Number of SMP cpus requested (8) exceeds the recommended cpus supported by KVM (4) Warning: Number of hotpluggable cpus requested (8) exceeds the recommended cpus supported by KVM (4) but nothing is printed... This happens because on ppc the KVM_CAP_NR_VCPUS capability is VM specific ndreally depends on the KVM type, but we currently use it as a global capability. And KVM returns a fallback value based on KVM HV being present. Maybe KVM on POWER shouldn't presume anything as long as it doesn't have a VM, but in all cases, we should call KVM_CREATE_VM first and use KVM_CAP_NR_VCPUS as a VM capability. This patch hence changes kvm_recommended_vcpus() accordingly and moves the sanity checking of smp_cpus after the VM creation. It is okay for the other archs that also implement KVM_CAP_NR_VCPUS, ie, mips, s390, x86 and arm, because they don't depend on the VM being created or not. Signed-off-by: Greg Kurz Reviewed-by: David Gibson Reviewed-by: Thomas Huth Message-Id: <150600966286.30533.10909862523552370889.stgit@bahia.lan> Signed-off-by: Paolo Bonzini --- accel/kvm/kvm-all.c | 43 ++++++++++++++++++++++--------------------- 1 file changed, 22 insertions(+), 21 deletions(-) (limited to 'accel/kvm') diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index f54a337..90c88b5 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -1440,7 +1440,7 @@ static void kvm_irqchip_create(MachineState *machine, KVMState *s) */ static int kvm_recommended_vcpus(KVMState *s) { - int ret = kvm_check_extension(s, KVM_CAP_NR_VCPUS); + int ret = kvm_vm_check_extension(s, KVM_CAP_NR_VCPUS); return (ret) ? ret : 4; } @@ -1530,26 +1530,6 @@ static int kvm_init(MachineState *ms) s->nr_slots = 32; } - /* check the vcpu limits */ - soft_vcpus_limit = kvm_recommended_vcpus(s); - hard_vcpus_limit = kvm_max_vcpus(s); - - while (nc->name) { - if (nc->num > soft_vcpus_limit) { - warn_report("Number of %s cpus requested (%d) exceeds " - "the recommended cpus supported by KVM (%d)", - nc->name, nc->num, soft_vcpus_limit); - - if (nc->num > hard_vcpus_limit) { - fprintf(stderr, "Number of %s cpus requested (%d) exceeds " - "the maximum cpus supported by KVM (%d)\n", - nc->name, nc->num, hard_vcpus_limit); - exit(1); - } - } - nc++; - } - kvm_type = qemu_opt_get(qemu_get_machine_opts(), "kvm-type"); if (mc->kvm_type) { type = mc->kvm_type(kvm_type); @@ -1584,6 +1564,27 @@ static int kvm_init(MachineState *ms) } s->vmfd = ret; + + /* check the vcpu limits */ + soft_vcpus_limit = kvm_recommended_vcpus(s); + hard_vcpus_limit = kvm_max_vcpus(s); + + while (nc->name) { + if (nc->num > soft_vcpus_limit) { + warn_report("Number of %s cpus requested (%d) exceeds " + "the recommended cpus supported by KVM (%d)", + nc->name, nc->num, soft_vcpus_limit); + + if (nc->num > hard_vcpus_limit) { + fprintf(stderr, "Number of %s cpus requested (%d) exceeds " + "the maximum cpus supported by KVM (%d)\n", + nc->name, nc->num, hard_vcpus_limit); + exit(1); + } + } + nc++; + } + missing_cap = kvm_check_extension_list(s, kvm_required_capabilites); if (!missing_cap) { missing_cap = -- cgit v1.1