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Re: [Qemu-devel] [PATCH v4] target-i386: Register QOM properties for fea
From: |
Eduardo Habkost |
Subject: |
Re: [Qemu-devel] [PATCH v4] target-i386: Register QOM properties for feature flags |
Date: |
Tue, 14 Apr 2015 11:08:39 -0300 |
User-agent: |
Mutt/1.5.23 (2014-03-12) |
On Tue, Apr 14, 2015 at 01:49:19PM +0200, Igor Mammedov wrote:
> On Fri, 10 Apr 2015 17:02:29 -0300
> Eduardo Habkost <address@hidden> wrote:
>
> > This uses the feature name arrays to register QOM properties for feature
> > flags. This simply adds properties that can be configured using -global,
> > but doesn't change x86_cpu_parse_featurestr() to use them yet.
> >
> > Signed-off-by: Eduardo Habkost <address@hidden>
> > ---
> > Changes v1 -> v2:
> > * Use "cpuid-" prefix instead of "feat-"
> > * Register release function for property
> > * Convert '_' to '-' on feature name before registering property
> > * Add dev->realized check to property setter
> >
> > Changes v2 -> v3:
> > * Register alias properties for feature name aliases
> > * Patch is based on x86 tree, at:
> > https://github.com/ehabkost/qemu.git x86
> >
> > Changes v3 -> v4:
> > * Remove "cpuid-" prefix altogether
> > ---
> > target-i386/cpu.c | 115
> > ++++++++++++++++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 115 insertions(+)
> >
> > diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> > index e657f10..1d97656 100644
> > --- a/target-i386/cpu.c
> > +++ b/target-i386/cpu.c
> > @@ -2848,12 +2848,120 @@ out:
> > }
> > }
> >
> > +typedef struct FeatureProperty {
> > + FeatureWord word;
> > + uint32_t mask;
> > +} FeatureProperty;
> > +
> > +static void x86_cpu_get_feature_prop(Object *obj,
> > + struct Visitor *v,
> > + void *opaque,
> > + const char *name,
> > + Error **errp)
> > +{
> > + X86CPU *cpu = X86_CPU(obj);
> > + CPUX86State *env = &cpu->env;
> > + FeatureProperty *fp = opaque;
> > + bool value = (env->features[fp->word] & fp->mask) == fp->mask;
> maybe s/env->features[fp->word]/*fp->feature_word_ptr/
> it would consolidate possible out of bound error place to 1
> instead of several as it's now.
> Also it makes it easier to read for me :).
That makes sense, and would make it easier to convert this code to
generic QOM code later.
>
> > + visit_type_bool(v, &value, name, errp);
> > +}
> > +
> > +static void x86_cpu_set_feature_prop(Object *obj,
> > + struct Visitor *v,
> > + void *opaque,
> > + const char *name,
> > + Error **errp)
> > +{
> > + X86CPU *cpu = X86_CPU(obj);
> > + DeviceState *dev = DEVICE(obj);
> > + CPUX86State *env = &cpu->env;
> > + FeatureProperty *fp = opaque;
> > + bool value;
> > +
> > + if (dev->realized) {
> > + qdev_prop_set_after_realize(dev, name, errp);
> > + return;
> > + }
> > +
> > + visit_type_bool(v, &value, name, errp);
> should check error here and return in case of it's set,
> + local_err + error_propagate()
Will do it. Thanks for catching it!
>
> > + if (value) {
> > + env->features[fp->word] |= fp->mask;
> > + } else {
> > + env->features[fp->word] &= ~fp->mask;
> > + }
> > +}
> > +
> > +static void x86_cpu_release_feature_prop(Object *obj, const char *name,
> > + void *opaque)
> > +{
> > + FeatureProperty *prop = opaque;
> > + g_free(prop);
> > +}
> > +
> > +/* Register a boolean feature-bits property.
> > + * If mask has multiple bits, all must be set for the property to return
> > true.
> > + * The same property name can be registered multiple times to make it
> > affect
> > + * multiple bits in the same FeatureWord.
> > + */
> > +static void x86_cpu_register_feature_prop(X86CPU *cpu,
> > + const char *prop_name,
> > + FeatureWord w,
> > + uint32_t mask)
> isn't used as mask by caller, s/mask/bit/ ???
There will be an use case for mask containing multiple bits, later. My
plan is to remove the duplicate "kvmclock" alias from kvm_feature_name,
and call this manually:
x86_cpu_register_feature_prop(cpu, "kvmclock", FEAT_KVM,
(1 << KVM_FEATURE_CLOCKSOURCE) |
(1 << KVM_FEATURE_CLOCKSOURCE2));
I didn't do that yet because I need the existing
x86_cpu_parse_featurestr() code to keep working until it is converted to
use object_property_set().
>
> > +{
> > + FeatureProperty *fp;
> > + ObjectProperty *op;
> white line here?
Will do it.
>
> > + op = object_property_find(OBJECT(cpu), prop_name, NULL);
> > + if (op) {
> > + fp = op->opaque;
> > + assert(fp->word == w);
> > + fp->mask |= mask;
^^^ This is the block of code that will be removed once I add the manual
"kvmclock" registration call I mentioned above.
> > + } else {
> > + fp = g_new0(FeatureProperty, 1);
> > + fp->word = w;
> > + fp->mask = mask;
> > + object_property_add(OBJECT(cpu), prop_name, "bool",
> > + x86_cpu_get_feature_prop,
> > + x86_cpu_set_feature_prop,
> > + x86_cpu_release_feature_prop, fp,
> > &error_abort);
> > + }
> > +}
> > +
> > +static void x86_cpu_register_feature_bit_props(X86CPU *cpu,
> this adds 1 property and possibly aliases, _props() is confusing here.
Alias properties are still properties like any other, aren't they? The
function is still responsible for registering multiple properties. Is
the "_props()" suffix really that confusing?
> I'd rename it to x86_cpu_add_feature_bit_prop() and inline
> above x86_cpu_register_feature_prop() since it's not going to be reused
I prefer to keep the single-property function separated, as it may
become a generic bitmap property registration function inside generic
QOM code later. With your feature_word_ptr suggestion, it would be even
more generic and non-x86-specific.
(To be honest, I would prefer to keep the single-property function
registration code clearly separated even if it was never going to be
reused anywhere. 20-line functions are already too long for my taste.)
>
> > + FeatureWord w,
> > + int bit)
> > +{
> > + Object *obj = OBJECT(cpu);
> > + int i;
> > + char **names;
> > + FeatureWordInfo *fi = &feature_word_info[w];
> > +
> > + if (!fi->feat_names) {
> > + return;
> > + }
> > + if (!fi->feat_names[bit]) {
> > + return;
> > + }
> > +
> > + names = g_strsplit(fi->feat_names[bit], "|", 0);
> > +
> > + feat2prop(names[0]);
> > + x86_cpu_register_feature_prop(cpu, names[0], w, (1UL << bit));
> > +
> > + for (i = 1; names[i]; i++) {
> > + feat2prop(names[i]);
> > + object_property_add_alias(obj, names[i], obj, names[0],
> > &error_abort);
> > + }
> > +
> > + g_strfreev(names);
> > +}
> > +
> > static void x86_cpu_initfn(Object *obj)
> > {
> > CPUState *cs = CPU(obj);
> > X86CPU *cpu = X86_CPU(obj);
> > X86CPUClass *xcc = X86_CPU_GET_CLASS(obj);
> > CPUX86State *env = &cpu->env;
> > + FeatureWord w;
> > static int inited;
> >
> > cs->env_ptr = env;
> > @@ -2894,6 +3002,13 @@ static void x86_cpu_initfn(Object *obj)
> > cpu->apic_id = -1;
> > #endif
> >
> > + for (w = 0; w < FEATURE_WORDS; w++) {
> > + int bit;
> white line here?
Will change it. Thanks!
>
> > + for (bit = 0; bit < 32; bit++) {
> > + x86_cpu_register_feature_bit_props(cpu, w, bit);
> > + }
> > + }
> > +
> > x86_cpu_load_def(cpu, xcc->cpu_def, &error_abort);
> >
> > /* init various static tables used in TCG mode */
>
--
Eduardo