1:26 p.m.
I'm working on the CPU model checking support in libvirt for s390x and I've
found when generating the -cpu +feature,-feature command, Qemu does not like
the ± syntax when adding cpu features for s390x machines and expects us to
use key=value pairs (e.g. feature=on,feature=off).
Since x86 Qemu code supports both the ± and key=value methods of enabling CPU
features, could we switch to just using key=value syntax in libvirt or do we
need to maintain the ± format as well? I assume we could do something more
sophisticated than wrapping the check in an if cpu->arch == VIR_ARCH_S390X?
Another option would be to just change Qemu to support both formats, but I
suspect we would get push back as key=value seems to be the preferred interface.
Thanks for your time.
- Collin
Collin L. Walling (1):
qemu: command: rework cpu feature argument support
src/qemu/qemu_command.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--
2.7.4
1:26 p.m.
New subject: [libvirt] [PATCH v1] qemu: command: rework cpu feature argument support
cpu features are passed to the qemu command with feature=on/off
instead of +/-feature.
Signed-off-by: Collin L. Walling <walling(a)linux.vnet.ibm.com>
---
src/qemu/qemu_command.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index b68da3d..a0eba0e 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -6560,12 +6560,12 @@ qemuBuildCpuModelArgStr(virQEMUDriverPtr driver,
switch ((virCPUFeaturePolicy) cpu->features[i].policy) {
case VIR_CPU_FEATURE_FORCE:
case VIR_CPU_FEATURE_REQUIRE:
- virBufferAsprintf(buf, ",+%s", cpu->features[i].name);
+ virBufferAsprintf(buf, ",%s=on", cpu->features[i].name);
break;
case VIR_CPU_FEATURE_DISABLE:
case VIR_CPU_FEATURE_FORBID:
- virBufferAsprintf(buf, ",-%s", cpu->features[i].name);
+ virBufferAsprintf(buf, ",%s=off", cpu->features[i].name);
break;
case VIR_CPU_FEATURE_OPTIONAL:
--
2.7.4
2:02 p.m.
New subject: [libvirt] [PATCH v1] qemu: command: rework cpu feature argument support
On Mon, Nov 14, 2016 at 02:26:03PM -0500, Collin L. Walling wrote:
cpu features are passed to the qemu command with feature=on/off
instead of +/-feature.
Signed-off-by: Collin L. Walling <walling(a)linux.vnet.ibm.com>
If I'm not mistaken, the "feature=on|off" syntax was added on
QEMU 2.0.0. Does current libvirt support older QEMU versions?
---
src/qemu/qemu_command.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index b68da3d..a0eba0e 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -6560,12 +6560,12 @@ qemuBuildCpuModelArgStr(virQEMUDriverPtr driver,
switch ((virCPUFeaturePolicy) cpu->features[i].policy) {
case VIR_CPU_FEATURE_FORCE:
case VIR_CPU_FEATURE_REQUIRE:
- virBufferAsprintf(buf, ",+%s", cpu->features[i].name);
+ virBufferAsprintf(buf, ",%s=on", cpu->features[i].name);
break;
case VIR_CPU_FEATURE_DISABLE:
case VIR_CPU_FEATURE_FORBID:
- virBufferAsprintf(buf, ",-%s", cpu->features[i].name);
+ virBufferAsprintf(buf, ",%s=off", cpu->features[i].name);
break;
case VIR_CPU_FEATURE_OPTIONAL:
--
2.7.4
--
Eduardo
1:42 a.m.
New subject: [libvirt] [PATCH v1] qemu: command: rework cpu feature argument support
On Mon, Nov 14, 2016 at 18:02:29 -0200, Eduardo Habkost wrote:
On Mon, Nov 14, 2016 at 02:26:03PM -0500, Collin L. Walling wrote:
> cpu features are passed to the qemu command with feature=on/off
> instead of +/-feature.
>
> Signed-off-by: Collin L. Walling <walling(a)linux.vnet.ibm.com>
If I'm not mistaken, the "feature=on|off" syntax was added on
QEMU 2.0.0. Does current libvirt support older QEMU versions?
Of course it does. I'd love to switch to feature=on|off, but how can we
check if QEMU supports it? We can't really start using this syntax
without it.
Jirka
7:44 a.m.
New subject: [libvirt] [PATCH v1] qemu: command: rework cpu feature argument support
CCing qemu-devel.
CCing Markus, in case he has any insights about the interface
introspection.
On Tue, Nov 15, 2016 at 08:42:12AM +0100, Jiri Denemark wrote:
On Mon, Nov 14, 2016 at 18:02:29 -0200, Eduardo Habkost wrote:
> On Mon, Nov 14, 2016 at 02:26:03PM -0500, Collin L. Walling wrote:
> > cpu features are passed to the qemu command with feature=on/off
> > instead of +/-feature.
> >
> > Signed-off-by: Collin L. Walling <walling(a)linux.vnet.ibm.com>
>
> If I'm not mistaken, the "feature=on|off" syntax was added on
> QEMU 2.0.0. Does current libvirt support older QEMU versions?
Of course it does. I'd love to switch to feature=on|off, but how can we
check if QEMU supports it? We can't really start using this syntax
without it.
Actually, I was wrong, this was added in v2.4.0. "feat=on|off"
needs two things to work (in x86):
* Translation of all "foo=bar" options to QOM property setting.
This was added in v2.0.0-rc0~162^2
* The actual QOM properties for feature names to be present. They
were added in v2.4.0-rc0~101^2~1
So you can be sure "feat=on" is supported by checking if the
feature flags are present in device-list-properties output for
the CPU model. But device-list-properties is also messy[1].
Maybe we can use the availability of query-cpu-model-expansion to
check if we can safely use the new "feat=on|off" system? It's
easier than taking all the variables above into account.
---
[1] * device-list-properties support for x86 CPU QOM classes
will be in QEMU 2.8.
* device-list-properties on x86 CPU QOM classes returns
an error on QEMU 2.5-2.7.
* device-list-properties on x86 CPU classes may crash QEMU in
QEMU older than 2.5 (see commit 4c315c27).
But:
* query-cpu-definitions will probably return the CPU QOM
typename in QEMU 2.9+ only.
--
Eduardo
7:15 a.m.
New subject: [libvirt] [PATCH v1] qemu: command: rework cpu feature argument support
On Tue, Nov 15, 2016 at 11:44:00 -0200, Eduardo Habkost wrote:
CCing qemu-devel.
CCing Markus, in case he has any insights about the interface
introspection.
On Tue, Nov 15, 2016 at 08:42:12AM +0100, Jiri Denemark wrote:
> On Mon, Nov 14, 2016 at 18:02:29 -0200, Eduardo Habkost wrote:
> > On Mon, Nov 14, 2016 at 02:26:03PM -0500, Collin L. Walling wrote:
> > > cpu features are passed to the qemu command with feature=on/off
> > > instead of +/-feature.
> > >
> > > Signed-off-by: Collin L. Walling <walling(a)linux.vnet.ibm.com>
> >
> > If I'm not mistaken, the "feature=on|off" syntax was added on
> > QEMU 2.0.0. Does current libvirt support older QEMU versions?
>
> Of course it does. I'd love to switch to feature=on|off, but how can we
> check if QEMU supports it? We can't really start using this syntax
> without it.
Actually, I was wrong, this was added in v2.4.0. "feat=on|off"
needs two things to work (in x86):
* Translation of all "foo=bar" options to QOM property setting.
This was added in v2.0.0-rc0~162^2
* The actual QOM properties for feature names to be present. They
were added in v2.4.0-rc0~101^2~1
So you can be sure "feat=on" is supported by checking if the
feature flags are present in device-list-properties output for
the CPU model. But device-list-properties is also messy[1].
Maybe we can use the availability of query-cpu-model-expansion to
check if we can safely use the new "feat=on|off" system? It's
easier than taking all the variables above into account.
Yeah, this could work since s390 already supports
query-cpu-model-expansion. It would cause feature=on|off not to be used
on x86_64 with QEMU older than 2.9.0, but I guess that's not a big deal,
is it?
Jirka
8:05 a.m.
New subject: [libvirt] [PATCH v1] qemu: command: rework cpu feature argument support
On Wed, Nov 16, 2016 at 02:15:02PM +0100, Jiri Denemark wrote:
On Tue, Nov 15, 2016 at 11:44:00 -0200, Eduardo Habkost wrote:
> CCing qemu-devel.
>
> CCing Markus, in case he has any insights about the interface
> introspection.
>
> On Tue, Nov 15, 2016 at 08:42:12AM +0100, Jiri Denemark wrote:
> > On Mon, Nov 14, 2016 at 18:02:29 -0200, Eduardo Habkost wrote:
> > > On Mon, Nov 14, 2016 at 02:26:03PM -0500, Collin L. Walling wrote:
> > > > cpu features are passed to the qemu command with feature=on/off
> > > > instead of +/-feature.
> > > >
> > > > Signed-off-by: Collin L. Walling <walling(a)linux.vnet.ibm.com>
> > >
> > > If I'm not mistaken, the "feature=on|off" syntax was added
on
> > > QEMU 2.0.0. Does current libvirt support older QEMU versions?
> >
> > Of course it does. I'd love to switch to feature=on|off, but how can we
> > check if QEMU supports it? We can't really start using this syntax
> > without it.
>
> Actually, I was wrong, this was added in v2.4.0. "feat=on|off"
> needs two things to work (in x86):
>
> * Translation of all "foo=bar" options to QOM property setting.
> This was added in v2.0.0-rc0~162^2
> * The actual QOM properties for feature names to be present. They
> were added in v2.4.0-rc0~101^2~1
>
> So you can be sure "feat=on" is supported by checking if the
> feature flags are present in device-list-properties output for
> the CPU model. But device-list-properties is also messy[1].
>
> Maybe we can use the availability of query-cpu-model-expansion to
> check if we can safely use the new "feat=on|off" system? It's
> easier than taking all the variables above into account.
Yeah, this could work since s390 already supports
query-cpu-model-expansion. It would cause feature=on|off not to be used
on x86_64 with QEMU older than 2.9.0, but I guess that's not a big deal,
is it?
Not a problem, as we have no plans to remove +feat/-feat support
in x86 anymore.
--
Eduardo
9:44 a.m.
New subject: [libvirt] [PATCH v1] qemu: command: rework cpu feature argument support
On 11/16/2016 09:05 AM, Eduardo Habkost wrote:
On Wed, Nov 16, 2016 at 02:15:02PM +0100, Jiri Denemark wrote:
> On Tue, Nov 15, 2016 at 11:44:00 -0200, Eduardo Habkost wrote:
>> CCing qemu-devel.
>>
>> CCing Markus, in case he has any insights about the interface
>> introspection.
>>
>> On Tue, Nov 15, 2016 at 08:42:12AM +0100, Jiri Denemark wrote:
>>> On Mon, Nov 14, 2016 at 18:02:29 -0200, Eduardo Habkost wrote:
>>>> On Mon, Nov 14, 2016 at 02:26:03PM -0500, Collin L. Walling wrote:
>>>>> cpu features are passed to the qemu command with feature=on/off
>>>>> instead of +/-feature.
>>>>>
>>>>> Signed-off-by: Collin L. Walling <walling(a)linux.vnet.ibm.com>
>>>> If I'm not mistaken, the "feature=on|off" syntax was added
on
>>>> QEMU 2.0.0. Does current libvirt support older QEMU versions?
>>> Of course it does. I'd love to switch to feature=on|off, but how can we
>>> check if QEMU supports it? We can't really start using this syntax
>>> without it.
>> Actually, I was wrong, this was added in v2.4.0. "feat=on|off"
>> needs two things to work (in x86):
>>
>> * Translation of all "foo=bar" options to QOM property setting.
>> This was added in v2.0.0-rc0~162^2
>> * The actual QOM properties for feature names to be present. They
>> were added in v2.4.0-rc0~101^2~1
>>
>> So you can be sure "feat=on" is supported by checking if the
>> feature flags are present in device-list-properties output for
>> the CPU model. But device-list-properties is also messy[1].
>>
>> Maybe we can use the availability of query-cpu-model-expansion to
>> check if we can safely use the new "feat=on|off" system? It's
>> easier than taking all the variables above into account.
> Yeah, this could work since s390 already supports
> query-cpu-model-expansion. It would cause feature=on|off not to be used
> on x86_64 with QEMU older than 2.9.0, but I guess that's not a big deal,
> is it?
Not a problem, as we have no plans to remove +feat/-feat support
in x86 anymore.
Beautiful. Thanks for your responses everyone. :)
9:04 a.m.
New subject: [libvirt] [Qemu-devel] [PATCH v1] qemu: command: rework cpu feature argument support
Eduardo Habkost <ehabkost(a)redhat.com> writes:
CCing qemu-devel.
CCing Markus, in case he has any insights about the interface
introspection.
On Tue, Nov 15, 2016 at 08:42:12AM +0100, Jiri Denemark wrote:
> On Mon, Nov 14, 2016 at 18:02:29 -0200, Eduardo Habkost wrote:
> > On Mon, Nov 14, 2016 at 02:26:03PM -0500, Collin L. Walling wrote:
> > > cpu features are passed to the qemu command with feature=on/off
> > > instead of +/-feature.
> > >
> > > Signed-off-by: Collin L. Walling <walling(a)linux.vnet.ibm.com>
> >
> > If I'm not mistaken, the "feature=on|off" syntax was added on
> > QEMU 2.0.0. Does current libvirt support older QEMU versions?
>
> Of course it does. I'd love to switch to feature=on|off, but how can we
> check if QEMU supports it? We can't really start using this syntax
> without it.
Actually, I was wrong, this was added in v2.4.0. "feat=on|off"
needs two things to work (in x86):
* Translation of all "foo=bar" options to QOM property setting.
This was added in v2.0.0-rc0~162^2
* The actual QOM properties for feature names to be present. They
were added in v2.4.0-rc0~101^2~1
So you can be sure "feat=on" is supported by checking if the
feature flags are present in device-list-properties output for
the CPU model. But device-list-properties is also messy[1].
Maybe we can use the availability of query-cpu-model-expansion to
check if we can safely use the new "feat=on|off" system? It's
easier than taking all the variables above into account.
---
[1] * device-list-properties support for x86 CPU QOM classes
will be in QEMU 2.8.
* device-list-properties on x86 CPU QOM classes returns
an error on QEMU 2.5-2.7.
* device-list-properties on x86 CPU classes may crash QEMU in
QEMU older than 2.5 (see commit 4c315c27).
But:
* query-cpu-definitions will probably return the CPU QOM
typename in QEMU 2.9+ only.
In other words:
* feature=on|off works since 2.4, but what's the best way to probe for
it?
* device-list-properties can act as a witness, but there are two
problems: you need to map between CPU model and QOM typename to use
it, and it can fail or even crash before 2.8.
* 2.9 will take provide the information to map between CPU model and QOM
typename.
I guess the sane choice is to probe for the CPU model - QOM typename
mapping information, and if it's there, assume device-list-properties
and feature=on|off work. Eduardo, what do you think?
10:36 a.m.
New subject: [libvirt] [Qemu-devel] [PATCH v1] qemu: command: rework cpu feature argument support
On Thu, Nov 17, 2016 at 04:04:33PM +0100, Markus Armbruster wrote:
Eduardo Habkost <ehabkost(a)redhat.com> writes:
> CCing qemu-devel.
>
> CCing Markus, in case he has any insights about the interface
> introspection.
>
> On Tue, Nov 15, 2016 at 08:42:12AM +0100, Jiri Denemark wrote:
>> On Mon, Nov 14, 2016 at 18:02:29 -0200, Eduardo Habkost wrote:
>> > On Mon, Nov 14, 2016 at 02:26:03PM -0500, Collin L. Walling wrote:
>> > > cpu features are passed to the qemu command with feature=on/off
>> > > instead of +/-feature.
>> > >
>> > > Signed-off-by: Collin L. Walling <walling(a)linux.vnet.ibm.com>
>> >
>> > If I'm not mistaken, the "feature=on|off" syntax was added
on
>> > QEMU 2.0.0. Does current libvirt support older QEMU versions?
>>
>> Of course it does. I'd love to switch to feature=on|off, but how can we
>> check if QEMU supports it? We can't really start using this syntax
>> without it.
>
> Actually, I was wrong, this was added in v2.4.0. "feat=on|off"
> needs two things to work (in x86):
>
> * Translation of all "foo=bar" options to QOM property setting.
> This was added in v2.0.0-rc0~162^2
> * The actual QOM properties for feature names to be present. They
> were added in v2.4.0-rc0~101^2~1
>
> So you can be sure "feat=on" is supported by checking if the
> feature flags are present in device-list-properties output for
> the CPU model. But device-list-properties is also messy[1].
>
> Maybe we can use the availability of query-cpu-model-expansion to
> check if we can safely use the new "feat=on|off" system? It's
> easier than taking all the variables above into account.
>
> ---
>
> [1] * device-list-properties support for x86 CPU QOM classes
> will be in QEMU 2.8.
> * device-list-properties on x86 CPU QOM classes returns
> an error on QEMU 2.5-2.7.
> * device-list-properties on x86 CPU classes may crash QEMU in
> QEMU older than 2.5 (see commit 4c315c27).
> But:
> * query-cpu-definitions will probably return the CPU QOM
> typename in QEMU 2.9+ only.
In other words:
* feature=on|off works since 2.4, but what's the best way to probe for
it?
* device-list-properties can act as a witness, but there are two
problems: you need to map between CPU model and QOM typename to use
it, and it can fail or even crash before 2.8.
* 2.9 will take provide the information to map between CPU model and QOM
typename.
I guess the sane choice is to probe for the CPU model - QOM typename
mapping information, and if it's there, assume device-list-properties
and feature=on|off work. Eduardo, what do you think?
That would work for x86, but not for s390x on QEMU <= 2.8 (where
only feat=on|off is supported). Using query-cpu-model-expansion
as a witness would work for both s390x and i386, even with
QEMU <= 2.8.
--
Eduardo
2927
days inactive
2930
days old
9 comments
4 participants
participants (4)
-
Collin L. Walling -
Eduardo Habkost -
Jiri Denemark -
Markus Armbruster