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

Jiri Denemark posted 3 patches 4 years, 9 months ago
[libvirt PATCH 3/3] qemu_capabilities: Disable CPU models on old s390 machine types
Posted by Jiri Denemark 4 years, 9 months ago 
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@gmail.com>
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
---
 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>
-- 
2.25.0
Re: [libvirt PATCH 3/3] qemu_capabilities: Disable CPU models on old s390 machine types
Posted by Boris Fiuczynski 4 years, 9 months ago 
It does what it is supposed to do even so version checking is not really 
nice but not spending the effort to design a new qom interface is OK.

@Christian Ehrhardt: I guess you need to add the ubuntu effected machine 
type(s) to s390HostPassthroughOnlyMachines as well as add an adjusted 
test like in patch 2 of this series for ubuntu.

Reviewed-by: Boris Fiuczynski <fiuczy@linux.ibm.com>

On 2/6/20 11:24 AM, Jiri Denemark wrote:
> 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@gmail.com>
> Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
> ---
>   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>
> 


-- 
Mit freundlichen Grüßen/Kind regards
    Boris Fiuczynski

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