Re: [libvirt PATCH 3/3] qemu_capabilities: Disable CPU models on old s390 machine types

Starting a KVM domain on s390 with old machine type (such as s390-ccw-virtio-2.5) and without any guest CPU model configured fails with CPU models are not available: KVM doesn't support CPU models QEMU error. This is cause by libvirt using host-model CPU as the default CPU based on QEMU reporting "host" CPU model as being the default one (see commit v5.9.0-402-g24d8202294: qemu: Use host-model CPU on s390 by default). However, even though both QEMU and KVM support CPU models on s390 and QEMU can give us the host-model CPU, we can't use it with old machine types which only support -cpu host. https://bugzilla.redhat.com/show_bug.cgi?id=1795651 Reported-by: Christian Ehrhardt <paelzer(a)gmail.com&gt; Signed-off-by: Jiri Denemark <jdenemar(a)redhat.com&gt; --- src/qemu/qemu_capabilities.c | 19 ++++++++++++++++++- ...t-cpu-kvm-ccw-virtio-2.7.s390x-latest.args | 4 +--- ...lt-cpu-kvm-ccw-virtio-2.7.s390x-latest.xml | 2 +- 3 files changed, 20 insertions(+), 5 deletions(-) diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c index 162e49e2d4..dd2311cfa9 100644 --- a/src/qemu/qemu_capabilities.c +++ b/src/qemu/qemu_capabilities.c @@ -2274,16 +2274,33 @@ virQEMUCapsIsVirtTypeSupported(virQEMUCapsPtr qemuCaps, return false; } +const char *s390HostPassthroughOnlyMachines[] = { + "s390-ccw-virtio-2.4", + "s390-ccw-virtio-2.5", + "s390-ccw-virtio-2.6", + "s390-ccw-virtio-2.7", + NULL +}; bool virQEMUCapsIsCPUModeSupported(virQEMUCapsPtr qemuCaps, virArch hostarch, virDomainVirtType type, virCPUMode mode, - const char *machineType G_GNUC_UNUSED) + const char *machineType) { qemuMonitorCPUDefsPtr cpus; + /* CPU models (except for "host") are not supported by QEMU for on s390 + * KVM domains with old machine types regardless on QEMU version. */ + if (ARCH_IS_S390(qemuCaps->arch) && + type == VIR_DOMAIN_VIRT_KVM && + mode != VIR_CPU_MODE_HOST_PASSTHROUGH && + machineType && + g_strv_contains(s390HostPassthroughOnlyMachines, machineType)) { + return false; + } + switch (mode) { case VIR_CPU_MODE_HOST_PASSTHROUGH: return type == VIR_DOMAIN_VIRT_KVM && diff --git a/tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-latest.args b/tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-latest.args index 8c25a01e74..0c2567df6c 100644 --- a/tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-latest.args +++ b/tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-latest.args @@ -13,9 +13,7 @@ QEMU_AUDIO_DRV=none \ -object secret,id=masterKey0,format=raw,\ file=/tmp/lib/domain--1-test/master-key.aes \ -machine s390-ccw-virtio-2.7,accel=kvm,usb=off,dump-guest-core=off \ --cpu z13.2-base,aen=on,aefsi=on,msa5=on,msa4=on,msa3=on,msa2=on,msa1=on,\ -sthyi=on,edat=on,ri=on,edat2=on,vx=on,ipter=on,ap=on,esop=on,apft=on,apqci=on,\ -cte=on,bpb=on,ppa15=on,zpci=on,sea_esop2=on,te=on,cmm=on \ +-cpu host \ -m 256 \ -overcommit mem-lock=off \ -smp 1,sockets=1,cores=1,threads=1 \ diff --git a/tests/qemuxml2xmloutdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-latest.xml b/tests/qemuxml2xmloutdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-latest.xml index 56fd22b6e5..8799584c11 100644 --- a/tests/qemuxml2xmloutdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-latest.xml +++ b/tests/qemuxml2xmloutdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-latest.xml @@ -8,7 +8,7 @@ <type arch='s390x' machine='s390-ccw-virtio-2.7'>hvm</type> <boot dev='hd'/> </os> - <cpu mode='host-model' check='partial'/> + <cpu mode='host-passthrough' check='none'/> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot>