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Re: [Qemu-ppc] [PATCHv4 0/5] Clean up compatibility mode handling
From: |
David Gibson |
Subject: |
Re: [Qemu-ppc] [PATCHv4 0/5] Clean up compatibility mode handling |
Date: |
Wed, 31 May 2017 12:57:48 +1000 |
User-agent: |
Mutt/1.8.0 (2017-02-23) |
On Tue, May 30, 2017 at 10:01:36AM +0200, Greg Kurz wrote:
> On Tue, 30 May 2017 16:18:52 +1000
> David Gibson <address@hidden> wrote:
>
> > On Tue, May 30, 2017 at 01:14:16AM +0200, Greg Kurz wrote:
> > > On Fri, 26 May 2017 15:23:14 +1000
> > > David Gibson <address@hidden> wrote:
> > >
> > > [...]
> > > >
> > > >
> > > > Changes since v3:
> > > > * Backwards compatible -cpu handling now removes compat= option from
> > > > options passed on to the cpu, so it doesn't trigger further
> > > > warnings
> > >
> > > This seems to also have another interesting effect.
> > >
> > > getset_compat_deprecated() could be called either during CPU realization
> > > from:
> > >
> > > object_property_parse()
> > > {
> > > Visitor *v = string_input_visitor_new(string);
> > > object_property_set(obj, v, name, errp);
> > > ...
> > > }
> > >
> > > or during a QOM set operation from:
> > >
> > > void object_property_set_qobject(Object *obj, QObject *value,
> > > const char *name, Error **errp)
> > > {
> > > Visitor *v;
> > >
> > > v = qobject_input_visitor_new(value);
> > > object_property_set(obj, v, name, errp);
> > > ...
> > > }
> > >
> > > or similarly during a QOM get operation with a QObject output visitor.
> > >
> > > The realization path no longer exists with patch 2, so you don't need
> > > to implement a null string input visitor anymore.
> >
> > s/patch 2/patch 3/?
> >
>
> Yes indeed, sorry :)
>
> > Is that true though? It shouldn't get called through that path in
> > practice, because we strip the compat property from the cpu object
> > properties. But it could get called if either a) the user explicitly
> > creates a cpu object with -device CPU,compat=whatever or b) if the
>
> Unless I'm missing something, properties of the CPU objects aren't
> exposed by CPU devices:
>
> qemu-system-ppc64 -machine pseries \
> -device POWER8_v2.0-spapr-cpu-core,help
> POWER8_v2.0-spapr-cpu-core.core-id=int
> POWER8_v2.0-spapr-cpu-core.node-id=int32
> POWER8_v2.0-spapr-cpu-core.nr-threads=int
>
> and creation of CPU objects with -object isn't possible either since
> they don't inherit from the TYPE_USER_CREATABLE class.
Ah, true, I hadn't considered that.
> > user uses the compat= property with a machine type other than pseries.
> >
>
> But yes, it is still possible to go through the object_property_parse()
> path with another machine type indeed.
> > Of course the user *shouldn't* do either of those things, but
> > providing a meaningful error if they do is pretty much the whole
> > purpose of this getter/setter method.
> >
>
> All old non-pseries machine types already complain when started with
> a POWER7 or newer CPU. Providing the extra error message looks weird:
>
> qemu-system-ppc64 -machine ppce500 \
> -cpu POWER7,compat=power6
> qemu-system-ppc64: CPU 'compat' property is deprecated and has no effect;
> use max-cpu-compat machine property instead
> MMU model 983043 not supported by this machine.
>
> but I guess it's better than crashing. :)
Well, sure POWER7 doesn't make sense for an e500 machine for other
reasons. But POWER7 or POWER8 _would_ make sense for powernv, where
compat= doesn't.
>
> > >
> > > This means that patch 1 is no longer needed if I get things right but
> > > you probably want Markus to second that.
> > >
> > > > * Add a migration fix make cpu_synchronize_state() safe in post_load
> > > > handlers, which in turn fixes a bug in 5/5.
> > > > * A number of bugfixes and other tweaks suggested by feedback on v2.
> > > >
> > > > Changes since RFCv2:
> > > > * Many patches dropped, since they're already merged
> > > > * Rebased, fixed conflicts
> > > > * Restored support for backwards migration (wasn't as complicated as
> > > > I thought)
> > > > * Updated final patch's description to more accurately reflect the
> > > > logic
> > > >
> > > > Changes since RFCv1:
> > > > * Change CAS logic to prefer compatibility modes over raw mode
> > > > * Simplified by giving up on half-hearted attempts to maintain
> > > > backwards migration
> > > > * Folded migration stream changes into a single patch
> > > > * Removed some preliminary patches which are already merged
> > > >
> > > > David Gibson (4):
> > > > migration: Mark CPU states dirty before incoming migration/loadvm
> > > > pseries: Move CPU compatibility property to machine
> > > > pseries: Reset CPU compatibility mode
> > > > ppc: Rework CPU compatibility testing across migration
> > > >
> > > > Greg Kurz (1):
> > > > qapi: add explicit null to string input and output visitors
> > > >
> > > > cpus.c | 9 ++++
> > > > hw/ppc/spapr.c | 8 +++-
> > > > hw/ppc/spapr_cpu_core.c | 62 +++++++++++++++++++++-----
> > > > hw/ppc/spapr_hcall.c | 8 ++--
> > > > include/hw/ppc/spapr.h | 12 +++--
> > > > include/sysemu/cpus.h | 1 +
> > > > include/sysemu/hax.h | 1 +
> > > > include/sysemu/hw_accel.h | 10 +++++
> > > > include/sysemu/kvm.h | 1 +
> > > > kvm-all.c | 10 +++++
> > > > migration/savevm.c | 2 +
> > > > qapi/string-input-visitor.c | 11 +++++
> > > > qapi/string-output-visitor.c | 14 ++++++
> > > > target/i386/hax-all.c | 10 +++++
> > > > target/ppc/compat.c | 102
> > > > +++++++++++++++++++++++++++++++++++++++++++
> > > > target/ppc/cpu.h | 5 ++-
> > > > target/ppc/machine.c | 72 ++++++++++++++++++++++++++++--
> > > > target/ppc/translate_init.c | 86 +++++++++++-------------------------
> > > > 18 files changed, 340 insertions(+), 84 deletions(-)
> > > >
> > >
> >
> >
> >
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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[Qemu-ppc] [PATCHv4 1/5] qapi: add explicit null to string input and output visitors, David Gibson, 2017/05/26
[Qemu-ppc] [PATCHv4 5/5] ppc: Rework CPU compatibility testing across migration, David Gibson, 2017/05/26
[Qemu-ppc] [PATCHv4 3/5] pseries: Move CPU compatibility property to machine, David Gibson, 2017/05/26
Re: [Qemu-ppc] [PATCHv4 0/5] Clean up compatibility mode handling, Greg Kurz, 2017/05/29