src/conf/cpu_conf.c | 25 ++++---------- src/conf/cpu_conf.h | 2 +- src/cpu/cpu_s390.c | 18 +++++----- src/qemu/qemu_domain.c | 33 ++++++++++++------- .../ppc64-host+guest-compat-none.xml | 4 +-- ...t-cpu-kvm-ccw-virtio-4.2.s390x-latest.args | 4 ++- .../cpu-check-default-partial.xml | 4 +-- .../cpu-host-model-features.xml | 1 - ...lt-cpu-kvm-ccw-virtio-4.2.s390x-latest.xml | 2 +- 9 files changed, 45 insertions(+), 48 deletions(-)
On s390 machines host-passthrough and host-model CPUs result in the same
guest ABI (with QEMU new enough to be able to tell us what "host" CPU is
expanded to, which was implemented around 2.9.0). So instead of using
host-passthrough CPU when there's no CPU specified in a domain XML we
can safely use host-model and benefit from CPU compatibility checks
during migration, snapshot restore and similar operations.
This series applies on top of "qemu: Store default CPU in domain XML"
which is already acked, but it's waiting for a QEMU patch to be applied
to 4.2.0.
You can fetch both series at once using
git fetch https://gitlab.com/jirkade/libvirt cpu-default-type
Jiri Denemark (4):
cpu_conf: Fix default value for CPU match attribute
cpu_conf: Don't format empty model for host-model CPUs
cpu_s390: Don't check match attribute for host-model CPUs
qemu: Use host-model CPU on s390 by default
src/conf/cpu_conf.c | 25 ++++----------
src/conf/cpu_conf.h | 2 +-
src/cpu/cpu_s390.c | 18 +++++-----
src/qemu/qemu_domain.c | 33 ++++++++++++-------
.../ppc64-host+guest-compat-none.xml | 4 +--
...t-cpu-kvm-ccw-virtio-4.2.s390x-latest.args | 4 ++-
.../cpu-check-default-partial.xml | 4 +--
.../cpu-host-model-features.xml | 1 -
...lt-cpu-kvm-ccw-virtio-4.2.s390x-latest.xml | 2 +-
9 files changed, 45 insertions(+), 48 deletions(-)
--
2.24.0
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On 11/14/19 10:44 AM, Jiri Denemark wrote: > On s390 machines host-passthrough and host-model CPUs result in the same > guest ABI (with QEMU new enough to be able to tell us what "host" CPU is > expanded to, which was implemented around 2.9.0). So instead of using > host-passthrough CPU when there's no CPU specified in a domain XML we > can safely use host-model and benefit from CPU compatibility checks > during migration, snapshot restore and similar operations. > > > This series applies on top of "qemu: Store default CPU in domain XML" > which is already acked, but it's waiting for a QEMU patch to be applied > to 4.2.0. > > You can fetch both series at once using > > git fetch https://gitlab.com/jirkade/libvirt cpu-default-type > > Jiri Denemark (4): > cpu_conf: Fix default value for CPU match attribute > cpu_conf: Don't format empty model for host-model CPUs > cpu_s390: Don't check match attribute for host-model CPUs > qemu: Use host-model CPU on s390 by default > > src/conf/cpu_conf.c | 25 ++++---------- > src/conf/cpu_conf.h | 2 +- > src/cpu/cpu_s390.c | 18 +++++----- > src/qemu/qemu_domain.c | 33 ++++++++++++------- > .../ppc64-host+guest-compat-none.xml | 4 +-- > ...t-cpu-kvm-ccw-virtio-4.2.s390x-latest.args | 4 ++- > .../cpu-check-default-partial.xml | 4 +-- > .../cpu-host-model-features.xml | 1 - > ...lt-cpu-kvm-ccw-virtio-4.2.s390x-latest.xml | 2 +- > 9 files changed, 45 insertions(+), 48 deletions(-) > Guest defined as expected. Once I start a guest, a dumpxml showed the model name and associated features as expected. Was able to successfully migrate the guest as well. Much preferred over the old default host-passthrough way. Built libvirt using the repo and branch you provided Built QEMU using master 4.1.92 (v4.2.0-rc2-27-g65e05c82bd) - guest used machine s390-ccw-virtio-4.2 Migrated between a weird mixed environment I'm chaotically working with :) Perhaps the testing was a bit over-extensive, but it's good to make sure. Tested-by: Collin Walling <walling@linux.ibm.com> -- Respectfully, - Collin Walling -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
Just a heads up.
After installing libvirt rpms of this branch all my existing kvm s390
domains ended up with
<cpu mode='custom' match='exact' check='none'>
<model fallback='forbid'>qemu</model>
</cpu>
Newly defined domains without specified cpu do so as well.
On 11/14/19 4:44 PM, Jiri Denemark wrote:
> On s390 machines host-passthrough and host-model CPUs result in the same
> guest ABI (with QEMU new enough to be able to tell us what "host" CPU is
> expanded to, which was implemented around 2.9.0). So instead of using
> host-passthrough CPU when there's no CPU specified in a domain XML we
> can safely use host-model and benefit from CPU compatibility checks
> during migration, snapshot restore and similar operations.
>
>
> This series applies on top of "qemu: Store default CPU in domain XML"
> which is already acked, but it's waiting for a QEMU patch to be applied
> to 4.2.0.
>
> You can fetch both series at once using
>
> git fetch https://gitlab.com/jirkade/libvirt cpu-default-type
>
> Jiri Denemark (4):
> cpu_conf: Fix default value for CPU match attribute
> cpu_conf: Don't format empty model for host-model CPUs
> cpu_s390: Don't check match attribute for host-model CPUs
> qemu: Use host-model CPU on s390 by default
>
> src/conf/cpu_conf.c | 25 ++++----------
> src/conf/cpu_conf.h | 2 +-
> src/cpu/cpu_s390.c | 18 +++++-----
> src/qemu/qemu_domain.c | 33 ++++++++++++-------
> .../ppc64-host+guest-compat-none.xml | 4 +--
> ...t-cpu-kvm-ccw-virtio-4.2.s390x-latest.args | 4 ++-
> .../cpu-check-default-partial.xml | 4 +--
> .../cpu-host-model-features.xml | 1 -
> ...lt-cpu-kvm-ccw-virtio-4.2.s390x-latest.xml | 2 +-
> 9 files changed, 45 insertions(+), 48 deletions(-)
>
--
Mit freundlichen Grüßen/Kind regards
Boris Fiuczynski
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Matthias Hartmann
Geschäftsführung: Dirk Wittkopp
Sitz der Gesellschaft: Böblingen
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On Fri, Nov 15, 2019 at 15:12:18 +0100, Boris Fiuczynski wrote: > Just a heads up. > After installing libvirt rpms of this branch all my existing kvm s390 > domains ended up with > > <cpu mode='custom' match='exact' check='none'> > <model fallback='forbid'>qemu</model> > </cpu> > > Newly defined domains without specified cpu do so as well. Unless the domains are all TCG, it seems your QEMU is too old. You need a fairly recent one which contains commit v4.1.0-1683-gde60a92ea7 (s390x/kvm: Set default cpu model for all machine classes) I the domains all use KVM and you have new enough QEMU, there might be a bug somewhere. Which should not happen :=) Jirka -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
On 15.11.19 15:47, Jiri Denemark wrote: > On Fri, Nov 15, 2019 at 15:12:18 +0100, Boris Fiuczynski wrote: >> Just a heads up. >> After installing libvirt rpms of this branch all my existing kvm s390 >> domains ended up with >> >> <cpu mode='custom' match='exact' check='none'> >> <model fallback='forbid'>qemu</model> >> </cpu> >> >> Newly defined domains without specified cpu do so as well. > > Unless the domains are all TCG, it seems your QEMU is too old. You need > a fairly recent one which contains commit v4.1.0-1683-gde60a92ea7 > (s390x/kvm: Set default cpu model for all machine classes) > > I the domains all use KVM and you have new enough QEMU, there might be a > bug somewhere. Which should not happen :=) So shouldnt libvirt fence this rework (add default model) to qemu 4.2 and newer? -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
On Fri, Nov 15, 2019 at 15:55:04 +0100, Christian Borntraeger wrote: > > > On 15.11.19 15:47, Jiri Denemark wrote: > > On Fri, Nov 15, 2019 at 15:12:18 +0100, Boris Fiuczynski wrote: > >> Just a heads up. > >> After installing libvirt rpms of this branch all my existing kvm s390 > >> domains ended up with > >> > >> <cpu mode='custom' match='exact' check='none'> > >> <model fallback='forbid'>qemu</model> > >> </cpu> > >> > >> Newly defined domains without specified cpu do so as well. > > > > Unless the domains are all TCG, it seems your QEMU is too old. You need > > a fairly recent one which contains commit v4.1.0-1683-gde60a92ea7 > > (s390x/kvm: Set default cpu model for all machine classes) > > > > I the domains all use KVM and you have new enough QEMU, there might be a > > bug somewhere. Which should not happen :=) > > So shouldnt libvirt fence this rework (add default model) to qemu 4.2 and newer? Libvirt does all this only if query-machines returns default-cpu-type, which is introduced in 4.2. But since it was introduced earlier, anyone using qemu from git between the two commits will see this behavior. Somewhat similar thing will happen on ppc64, but even with the current master. Everything should be OK once QEMU 4.2.0 final release is used, though (since it will contain all required patches). Jirka -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
On 11/15/19 4:14 PM, Jiri Denemark wrote:
> On Fri, Nov 15, 2019 at 15:55:04 +0100, Christian Borntraeger wrote:
>>
>>
>> On 15.11.19 15:47, Jiri Denemark wrote:
>>> On Fri, Nov 15, 2019 at 15:12:18 +0100, Boris Fiuczynski wrote:
>>>> Just a heads up.
>>>> After installing libvirt rpms of this branch all my existing kvm s390
>>>> domains ended up with
>>>>
>>>> <cpu mode='custom' match='exact' check='none'>
>>>> <model fallback='forbid'>qemu</model>
>>>> </cpu>
>>>>
>>>> Newly defined domains without specified cpu do so as well.
>>>
>>> Unless the domains are all TCG, it seems your QEMU is too old. You need
>>> a fairly recent one which contains commit v4.1.0-1683-gde60a92ea7
>>> (s390x/kvm: Set default cpu model for all machine classes)
>>>
>>> I the domains all use KVM and you have new enough QEMU, there might be a
>>> bug somewhere. Which should not happen :=)
>>
>> So shouldnt libvirt fence this rework (add default model) to qemu 4.2 and newer?
>
> Libvirt does all this only if query-machines returns default-cpu-type,
> which is introduced in 4.2. But since it was introduced earlier, anyone
> using qemu from git between the two commits will see this behavior.
> Somewhat similar thing will happen on ppc64, but even with the current
> master. Everything should be OK once QEMU 4.2.0 final release is used,
> though (since it will contain all required patches).
>
> Jirka
>
I tested with a newer version of qemu and it worked as you outlined.
After that I also tested with qemu v4.1.0. I was a bit surprised at
first that a default host-model cpu was generated since I though it
would only be done when the qemu has the commit your specified above.
After reading your patch 4 the generation is tied to the cpu-model
support in qemu. Since this became available on s390 with qemu v2.8.0 I
created an additional test patch just to ensure that we do not lose
backwards compatibility.
I also attached the patch if below does not work out.
=======
> From: Boris Fiuczynski <fiuczy@linux.ibm.com>
> Date: Mon, 18 Nov 2019 17:41:02 +0100
> Subject: [PATCH] qemuxml2*test: Add test cases for not setting default CPU
> models on s390
>
> Adding tests for QEMU v2.7.0 which was the last version without CPU model
> support on s390 to ensure the default CPU model is not automatically added.
>
> Signed-off-by: Boris Fiuczynski <fiuczy@linux.ibm.com>
> ---
> ...lt-cpu-kvm-ccw-virtio-2.7.s390x-2.7.0.args | 29 +++++++++++++++++++
> .../s390-default-cpu-kvm-ccw-virtio-2.7.xml | 16 ++++++++++
> tests/qemuxml2argvtest.c | 1 +
> ...ult-cpu-kvm-ccw-virtio-2.7.s390x-2.7.0.xml | 23 +++++++++++++++
> tests/qemuxml2xmltest.c | 1 +
> 5 files changed, 70 insertions(+)
> create mode 100644 tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-2.7.0.args
> create mode 100644 tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.xml
> create mode 100644 tests/qemuxml2xmloutdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-2.7.0.xml
>
> diff --git a/tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-2.7.0.args b/tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-2.7.0.args
> new file mode 100644
> index 0000000000..431de90bcc
> --- /dev/null
> +++ b/tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-2.7.0.args
> @@ -0,0 +1,29 @@
> +LC_ALL=C \
> +PATH=/bin \
> +HOME=/tmp/lib/domain--1-test \
> +USER=test \
> +LOGNAME=test \
> +XDG_DATA_HOME=/tmp/lib/domain--1-test/.local/share \
> +XDG_CACHE_HOME=/tmp/lib/domain--1-test/.cache \
> +XDG_CONFIG_HOME=/tmp/lib/domain--1-test/.config \
> +QEMU_AUDIO_DRV=none \
> +/usr/bin/qemu-system-s390x \
> +-name guest=test,debug-threads=on \
> +-S \
> +-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 \
> +-m 256 \
> +-realtime mlock=off \
> +-smp 1,sockets=1,cores=1,threads=1 \
> +-uuid 9aa4b45c-b9dd-45ef-91fe-862b27b4231f \
> +-display none \
> +-no-user-config \
> +-nodefaults \
> +-chardev socket,id=charmonitor,path=/tmp/lib/domain--1-test/monitor.sock,server,nowait \
> +-mon chardev=charmonitor,id=monitor,mode=control \
> +-rtc base=utc \
> +-no-shutdown \
> +-boot strict=on \
> +-device virtio-balloon-ccw,id=balloon0,devno=fe.0.0000 \
> +-msg timestamp=on
> diff --git a/tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.xml b/tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.xml
> new file mode 100644
> index 0000000000..5051c861ee
> --- /dev/null
> +++ b/tests/qemuxml2argvdata/s390-default-cpu-kvm-ccw-virtio-2.7.xml
> @@ -0,0 +1,16 @@
> +<domain type='kvm'>
> + <name>test</name>
> + <uuid>9aa4b45c-b9dd-45ef-91fe-862b27b4231f</uuid>
> + <memory>262144</memory>
> + <currentMemory>262144</currentMemory>
> + <os>
> + <type arch='s390x' machine='s390-ccw-virtio'>hvm</type>
> + </os>
> + <clock offset='utc'/>
> + <on_poweroff>destroy</on_poweroff>
> + <on_reboot>restart</on_reboot>
> + <on_crash>destroy</on_crash>
> + <devices>
> + <emulator>/usr/bin/qemu-system-s390x</emulator>
> + </devices>
> +</domain>
> diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
> index e3e2bc5e63..753c588f95 100644
> --- a/tests/qemuxml2argvtest.c
> +++ b/tests/qemuxml2argvtest.c
> @@ -3031,6 +3031,7 @@ mymain(void)
> DO_TEST_CAPS_ARCH_LATEST("ppc64-default-cpu-tcg-pseries-3.1", "ppc64");
> DO_TEST_CAPS_ARCH_LATEST("ppc64-default-cpu-kvm-pseries-4.2", "ppc64");
> DO_TEST_CAPS_ARCH_LATEST("ppc64-default-cpu-tcg-pseries-4.2", "ppc64");
> + DO_TEST_CAPS_ARCH_VER("s390-default-cpu-kvm-ccw-virtio-2.7", "s390x", "2.7.0");
> DO_TEST_CAPS_ARCH_LATEST("s390-default-cpu-kvm-ccw-virtio-4.2", "s390x");
> DO_TEST_CAPS_ARCH_LATEST("s390-default-cpu-tcg-ccw-virtio-4.2", "s390x");
> DO_TEST_CAPS_ARCH_LATEST("x86_64-default-cpu-kvm-pc-4.2", "x86_64");
> diff --git a/tests/qemuxml2xmloutdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-2.7.0.xml b/tests/qemuxml2xmloutdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-2.7.0.xml
> new file mode 100644
> index 0000000000..9ae5356bf3
> --- /dev/null
> +++ b/tests/qemuxml2xmloutdata/s390-default-cpu-kvm-ccw-virtio-2.7.s390x-2.7.0.xml
> @@ -0,0 +1,23 @@
> +<domain type='kvm'>
> + <name>test</name>
> + <uuid>9aa4b45c-b9dd-45ef-91fe-862b27b4231f</uuid>
> + <memory unit='KiB'>262144</memory>
> + <currentMemory unit='KiB'>262144</currentMemory>
> + <vcpu placement='static'>1</vcpu>
> + <os>
> + <type arch='s390x' machine='s390-ccw-virtio-2.7'>hvm</type>
> + <boot dev='hd'/>
> + </os>
> + <clock offset='utc'/>
> + <on_poweroff>destroy</on_poweroff>
> + <on_reboot>restart</on_reboot>
> + <on_crash>destroy</on_crash>
> + <devices>
> + <emulator>/usr/bin/qemu-system-s390x</emulator>
> + <controller type='pci' index='0' model='pci-root'/>
> + <memballoon model='virtio'>
> + <address type='ccw' cssid='0xfe' ssid='0x0' devno='0x0000'/>
> + </memballoon>
> + <panic model='s390'/>
> + </devices>
> +</domain>
> diff --git a/tests/qemuxml2xmltest.c b/tests/qemuxml2xmltest.c
> index 64a6971740..9bf1969047 100644
> --- a/tests/qemuxml2xmltest.c
> +++ b/tests/qemuxml2xmltest.c
> @@ -1349,6 +1349,7 @@ mymain(void)
> DO_TEST_CAPS_ARCH_LATEST("ppc64-default-cpu-tcg-pseries-3.1", "ppc64");
> DO_TEST_CAPS_ARCH_LATEST("ppc64-default-cpu-kvm-pseries-4.2", "ppc64");
> DO_TEST_CAPS_ARCH_LATEST("ppc64-default-cpu-tcg-pseries-4.2", "ppc64");
> + DO_TEST_CAPS_ARCH_VER("s390-default-cpu-kvm-ccw-virtio-2.7", "s390x", "2.7.0");
> DO_TEST_CAPS_ARCH_LATEST("s390-default-cpu-kvm-ccw-virtio-4.2", "s390x");
> DO_TEST_CAPS_ARCH_LATEST("s390-default-cpu-tcg-ccw-virtio-4.2", "s390x");
> DO_TEST_CAPS_ARCH_LATEST("x86_64-default-cpu-kvm-pc-4.2", "x86_64");
> --
> 2.21.0
--
Mit freundlichen Grüßen/Kind regards
Boris Fiuczynski
IBM Deutschland Research & Development GmbH
Vorsitzender des Aufsichtsrats: Matthias Hartmann
Geschäftsführung: Dirk Wittkopp
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On Mon, Nov 18, 2019 at 18:34:36 +0100, Boris Fiuczynski wrote: > > > On 11/15/19 4:14 PM, Jiri Denemark wrote: > > On Fri, Nov 15, 2019 at 15:55:04 +0100, Christian Borntraeger wrote: > >> > >> > >> On 15.11.19 15:47, Jiri Denemark wrote: > >>> On Fri, Nov 15, 2019 at 15:12:18 +0100, Boris Fiuczynski wrote: > >>>> Just a heads up. > >>>> After installing libvirt rpms of this branch all my existing kvm s390 > >>>> domains ended up with > >>>> > >>>> <cpu mode='custom' match='exact' check='none'> > >>>> <model fallback='forbid'>qemu</model> > >>>> </cpu> > >>>> > >>>> Newly defined domains without specified cpu do so as well. > >>> > >>> Unless the domains are all TCG, it seems your QEMU is too old. You need > >>> a fairly recent one which contains commit v4.1.0-1683-gde60a92ea7 > >>> (s390x/kvm: Set default cpu model for all machine classes) > >>> > >>> I the domains all use KVM and you have new enough QEMU, there might be a > >>> bug somewhere. Which should not happen :=) > >> > >> So shouldnt libvirt fence this rework (add default model) to qemu 4.2 and newer? > > > > Libvirt does all this only if query-machines returns default-cpu-type, > > which is introduced in 4.2. But since it was introduced earlier, anyone > > using qemu from git between the two commits will see this behavior. > > Somewhat similar thing will happen on ppc64, but even with the current > > master. Everything should be OK once QEMU 4.2.0 final release is used, > > though (since it will contain all required patches). > > > > Jirka > > > > I tested with a newer version of qemu and it worked as you outlined. > After that I also tested with qemu v4.1.0. I was a bit surprised at > first that a default host-model cpu was generated since I though it > would only be done when the qemu has the commit your specified above. > After reading your patch 4 the generation is tied to the cpu-model > support in qemu. Since this became available on s390 with qemu v2.8.0 I > created an additional test patch just to ensure that we do not lose > backwards compatibility. Oh, are you saying QEMU on s390 returns default-cpu-type in query-machines reply even with v4.1.0 and older? I don't see it in our test replies from anything older then v4.2.0. Anyway, libvirt should not set the default CPU with QEMU 4.1.0 and if it does, I have a bug in my patches :-) qemuDomainDefSetDefaultCPU should not be called at all on QEMU 4.1.0 or older. The check for cpu-model support in this function is an additional check and this support should not be sufficient for the default CPU to be filled in. Jirka -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
On 11/19/19 3:02 PM, Jiri Denemark wrote:
> On Mon, Nov 18, 2019 at 18:34:36 +0100, Boris Fiuczynski wrote:
>>
>>
>> On 11/15/19 4:14 PM, Jiri Denemark wrote:
>>> On Fri, Nov 15, 2019 at 15:55:04 +0100, Christian Borntraeger wrote:
>>>>
>>>>
>>>> On 15.11.19 15:47, Jiri Denemark wrote:
>>>>> On Fri, Nov 15, 2019 at 15:12:18 +0100, Boris Fiuczynski wrote:
>>>>>> Just a heads up.
>>>>>> After installing libvirt rpms of this branch all my existing kvm s390
>>>>>> domains ended up with
>>>>>>
>>>>>> <cpu mode='custom' match='exact' check='none'>
>>>>>> <model fallback='forbid'>qemu</model>
>>>>>> </cpu>
>>>>>>
>>>>>> Newly defined domains without specified cpu do so as well.
>>>>>
>>>>> Unless the domains are all TCG, it seems your QEMU is too old. You need
>>>>> a fairly recent one which contains commit v4.1.0-1683-gde60a92ea7
>>>>> (s390x/kvm: Set default cpu model for all machine classes)
>>>>>
>>>>> I the domains all use KVM and you have new enough QEMU, there might be a
>>>>> bug somewhere. Which should not happen :=)
>>>>
>>>> So shouldnt libvirt fence this rework (add default model) to qemu 4.2 and newer?
>>>
>>> Libvirt does all this only if query-machines returns default-cpu-type,
>>> which is introduced in 4.2. But since it was introduced earlier, anyone
>>> using qemu from git between the two commits will see this behavior.
>>> Somewhat similar thing will happen on ppc64, but even with the current
>>> master. Everything should be OK once QEMU 4.2.0 final release is used,
>>> though (since it will contain all required patches).
>>>
>>> Jirka
>>>
>>
>> I tested with a newer version of qemu and it worked as you outlined.
>> After that I also tested with qemu v4.1.0. I was a bit surprised at
>> first that a default host-model cpu was generated since I though it
>> would only be done when the qemu has the commit your specified above.
>> After reading your patch 4 the generation is tied to the cpu-model
>> support in qemu. Since this became available on s390 with qemu v2.8.0 I
>> created an additional test patch just to ensure that we do not lose
>> backwards compatibility.
>
> Oh, are you saying QEMU on s390 returns default-cpu-type in
> query-machines reply even with v4.1.0 and older? I don't see it in our
> test replies from anything older then v4.2.0.
>
> Anyway, libvirt should not set the default CPU with QEMU 4.1.0 and if it
> does, I have a bug in my patches :-)
No you don't have a bug in your patches. I had a bug in my tests. :-(
It works as you outlined. The cpu-model is set if QEMU 4.2.0 is used but
not for 4.1.0 and older.
>
> qemuDomainDefSetDefaultCPU should not be called at all on QEMU 4.1.0 or
> older. The check for cpu-model support in this function is an additional
> check and this support should not be sufficient for the default CPU to
> be filled in.
>
> Jirka
>
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On Thu, Nov 14, 2019 at 04:44:54PM +0100, Jiri Denemark wrote: >On s390 machines host-passthrough and host-model CPUs result in the same >guest ABI (with QEMU new enough to be able to tell us what "host" CPU is >expanded to, which was implemented around 2.9.0). So instead of using >host-passthrough CPU when there's no CPU specified in a domain XML we >can safely use host-model and benefit from CPU compatibility checks >during migration, snapshot restore and similar operations. > > >This series applies on top of "qemu: Store default CPU in domain XML" >which is already acked, but it's waiting for a QEMU patch to be applied >to 4.2.0. > >You can fetch both series at once using > > git fetch https://gitlab.com/jirkade/libvirt cpu-default-type > >Jiri Denemark (4): > cpu_conf: Fix default value for CPU match attribute > cpu_conf: Don't format empty model for host-model CPUs > cpu_s390: Don't check match attribute for host-model CPUs > qemu: Use host-model CPU on s390 by default > > src/conf/cpu_conf.c | 25 ++++---------- > src/conf/cpu_conf.h | 2 +- > src/cpu/cpu_s390.c | 18 +++++----- > src/qemu/qemu_domain.c | 33 ++++++++++++------- > .../ppc64-host+guest-compat-none.xml | 4 +-- > ...t-cpu-kvm-ccw-virtio-4.2.s390x-latest.args | 4 ++- > .../cpu-check-default-partial.xml | 4 +-- > .../cpu-host-model-features.xml | 1 - > ...lt-cpu-kvm-ccw-virtio-4.2.s390x-latest.xml | 2 +- > 9 files changed, 45 insertions(+), 48 deletions(-) > Reviewed-by: Ján Tomko <jtomko@redhat.com> Jano -- libvir-list mailing list libvir-list@redhat.com https://www.redhat.com/mailman/listinfo/libvir-list
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