target/i386/cpu.h | 2 ++ target/i386/cpu.c | 33 +++++++++++++++++++++------------ 2 files changed, 23 insertions(+), 12 deletions(-)
The existing code for "host" and "max" CPU models overrides every
single feature in the CPU object at realize time, even the ones
that were explicitly enabled or disabled by the user using
"feat=on" or "feat=off", while features set using +feat/-feat are
kept.
This means "-cpu host,+invtsc" works as expected, while
"-cpu host,invtsc=on" doesn't.
This was a known bug, already documented in a comment inside
x86_cpu_expand_features(). What makes this bug worse now is that
libvirt 3.0.0 and newer now use "feat=on|off" instead of
+feat/-feat when it detects a QEMU version that supports it (see
libvirt commit d47db7b16dd5422c7e487c8c8ee5b181a2f9cd66).
Change the feature property getter/setter to set a
env->user_features field, to keep track of features that were
explicitly changed using QOM properties. Then make the
max_features code not override user features when handling "-cpu
host" and "-cpu max".
This will also allow us to remove the plus_features/minus_features
hack in the future, but I plan to do that after 2.9.0 is
released.
Reported-by: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
---
target/i386/cpu.h | 2 ++
target/i386/cpu.c | 33 +++++++++++++++++++++------------
2 files changed, 23 insertions(+), 12 deletions(-)
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 07401ad9fe..c4602ca80d 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1147,6 +1147,8 @@ typedef struct CPUX86State {
uint32_t cpuid_vendor3;
uint32_t cpuid_version;
FeatureWordArray features;
+ /* Features that were explicitly enabled/disabled */
+ FeatureWordArray user_features;
uint32_t cpuid_model[12];
/* MTRRs */
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 7aa762245a..5f2addbf75 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -3373,15 +3373,20 @@ static void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
GList *l;
Error *local_err = NULL;
- /*TODO: cpu->max_features incorrectly overwrites features
- * set using "feat=on|off". Once we fix this, we can convert
+ /*TODO: Now cpu->max_features doesn't overwrite features
+ * set using QOM properties, and we can convert
* plus_features & minus_features to global properties
* inside x86_cpu_parse_featurestr() too.
*/
if (cpu->max_features) {
for (w = 0; w < FEATURE_WORDS; w++) {
- env->features[w] =
- x86_cpu_get_supported_feature_word(w, cpu->migratable);
+ /* Override only features that weren't not set explicitly
+ * by the user.
+ */
+ env->features[w] &= env->user_features[w];
+ env->features[w] |=
+ x86_cpu_get_supported_feature_word(w, cpu->migratable) &
+ ~env->user_features[w];
}
}
@@ -3692,15 +3697,17 @@ static void x86_cpu_unrealizefn(DeviceState *dev, Error **errp)
}
typedef struct BitProperty {
- uint32_t *ptr;
+ FeatureWord w;
uint32_t mask;
} BitProperty;
static void x86_cpu_get_bit_prop(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
+ X86CPU *cpu = X86_CPU(obj);
BitProperty *fp = opaque;
- bool value = (*fp->ptr & fp->mask) == fp->mask;
+ uint32_t f = cpu->env.features[fp->w];
+ bool value = (f & fp->mask) == fp->mask;
visit_type_bool(v, name, &value, errp);
}
@@ -3708,6 +3715,7 @@ static void x86_cpu_set_bit_prop(Object *obj, Visitor *v, const char *name,
void *opaque, Error **errp)
{
DeviceState *dev = DEVICE(obj);
+ X86CPU *cpu = X86_CPU(obj);
BitProperty *fp = opaque;
Error *local_err = NULL;
bool value;
@@ -3724,10 +3732,11 @@ static void x86_cpu_set_bit_prop(Object *obj, Visitor *v, const char *name,
}
if (value) {
- *fp->ptr |= fp->mask;
+ cpu->env.features[fp->w] |= fp->mask;
} else {
- *fp->ptr &= ~fp->mask;
+ cpu->env.features[fp->w] &= ~fp->mask;
}
+ cpu->env.user_features[fp->w] |= fp->mask;
}
static void x86_cpu_release_bit_prop(Object *obj, const char *name,
@@ -3745,7 +3754,7 @@ static void x86_cpu_release_bit_prop(Object *obj, const char *name,
*/
static void x86_cpu_register_bit_prop(X86CPU *cpu,
const char *prop_name,
- uint32_t *field,
+ FeatureWord w,
int bitnr)
{
BitProperty *fp;
@@ -3755,11 +3764,11 @@ static void x86_cpu_register_bit_prop(X86CPU *cpu,
op = object_property_find(OBJECT(cpu), prop_name, NULL);
if (op) {
fp = op->opaque;
- assert(fp->ptr == field);
+ assert(fp->w == w);
fp->mask |= mask;
} else {
fp = g_new0(BitProperty, 1);
- fp->ptr = field;
+ fp->w = w;
fp->mask = mask;
object_property_add(OBJECT(cpu), prop_name, "bool",
x86_cpu_get_bit_prop,
@@ -3787,7 +3796,7 @@ static void x86_cpu_register_feature_bit_props(X86CPU *cpu,
/* aliases don't use "|" delimiters anymore, they are registered
* manually using object_property_add_alias() */
assert(!strchr(name, '|'));
- x86_cpu_register_bit_prop(cpu, name, &cpu->env.features[w], bitnr);
+ x86_cpu_register_bit_prop(cpu, name, w, bitnr);
}
static GuestPanicInformation *x86_cpu_get_crash_info(CPUState *cs)
--
2.11.0.259.g40922b1
On Fri, 24 Mar 2017 17:36:45 -0300
Eduardo Habkost <ehabkost@redhat.com> wrote:
> The existing code for "host" and "max" CPU models overrides every
> single feature in the CPU object at realize time, even the ones
> that were explicitly enabled or disabled by the user using
> "feat=on" or "feat=off", while features set using +feat/-feat are
> kept.
>
> This means "-cpu host,+invtsc" works as expected, while
> "-cpu host,invtsc=on" doesn't.
>
> This was a known bug, already documented in a comment inside
> x86_cpu_expand_features(). What makes this bug worse now is that
> libvirt 3.0.0 and newer now use "feat=on|off" instead of
> +feat/-feat when it detects a QEMU version that supports it (see
> libvirt commit d47db7b16dd5422c7e487c8c8ee5b181a2f9cd66).
>
> Change the feature property getter/setter to set a
> env->user_features field, to keep track of features that were
> explicitly changed using QOM properties. Then make the
> max_features code not override user features when handling "-cpu
> host" and "-cpu max".
>
> This will also allow us to remove the plus_features/minus_features
> hack in the future, but I plan to do that after 2.9.0 is
> released.
>
> Reported-by: Jiri Denemark <jdenemar@redhat.com>
> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> ---
> target/i386/cpu.h | 2 ++
> target/i386/cpu.c | 33 +++++++++++++++++++++------------
> 2 files changed, 23 insertions(+), 12 deletions(-)
>
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index 07401ad9fe..c4602ca80d 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -1147,6 +1147,8 @@ typedef struct CPUX86State {
> uint32_t cpuid_vendor3;
> uint32_t cpuid_version;
> FeatureWordArray features;
> + /* Features that were explicitly enabled/disabled */
> + FeatureWordArray user_features;
> uint32_t cpuid_model[12];
>
> /* MTRRs */
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 7aa762245a..5f2addbf75 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -3373,15 +3373,20 @@ static void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
> GList *l;
> Error *local_err = NULL;
>
> - /*TODO: cpu->max_features incorrectly overwrites features
> - * set using "feat=on|off". Once we fix this, we can convert
> + /*TODO: Now cpu->max_features doesn't overwrite features
> + * set using QOM properties, and we can convert
> * plus_features & minus_features to global properties
> * inside x86_cpu_parse_featurestr() too.
> */
> if (cpu->max_features) {
> for (w = 0; w < FEATURE_WORDS; w++) {
> - env->features[w] =
> - x86_cpu_get_supported_feature_word(w, cpu->migratable);
> + /* Override only features that weren't not set explicitly
> + * by the user.
s/not// or if it was intended rephrase to avoid double negation.
> + */
> + env->features[w] &= env->user_features[w];
it probably should be assert to catch features not set via property,
which shouldn't be there in the first place, I don't like silent
filtering that happens here.
> + env->features[w] |=
> + x86_cpu_get_supported_feature_word(w, cpu->migratable) &
> + ~env->user_features[w];
> }
> }
>
> @@ -3692,15 +3697,17 @@ static void x86_cpu_unrealizefn(DeviceState *dev, Error **errp)
> }
>
> typedef struct BitProperty {
> - uint32_t *ptr;
> + FeatureWord w;
it would be better if this refactoring and related changes
were in a separate patch, something along lines:
"x86/cpu: use FeatureWord instead of keeping a pointer to cpuid leaf"
> uint32_t mask;
> } BitProperty;
>
> static void x86_cpu_get_bit_prop(Object *obj, Visitor *v, const char *name,
> void *opaque, Error **errp)
> {
> + X86CPU *cpu = X86_CPU(obj);
> BitProperty *fp = opaque;
> - bool value = (*fp->ptr & fp->mask) == fp->mask;
> + uint32_t f = cpu->env.features[fp->w];
> + bool value = (f & fp->mask) == fp->mask;
> visit_type_bool(v, name, &value, errp);
> }
>
> @@ -3708,6 +3715,7 @@ static void x86_cpu_set_bit_prop(Object *obj, Visitor *v, const char *name,
> void *opaque, Error **errp)
> {
> DeviceState *dev = DEVICE(obj);
> + X86CPU *cpu = X86_CPU(obj);
> BitProperty *fp = opaque;
> Error *local_err = NULL;
> bool value;
> @@ -3724,10 +3732,11 @@ static void x86_cpu_set_bit_prop(Object *obj, Visitor *v, const char *name,
> }
>
> if (value) {
> - *fp->ptr |= fp->mask;
> + cpu->env.features[fp->w] |= fp->mask;
> } else {
> - *fp->ptr &= ~fp->mask;
> + cpu->env.features[fp->w] &= ~fp->mask;
> }
> + cpu->env.user_features[fp->w] |= fp->mask;
> }
>
> static void x86_cpu_release_bit_prop(Object *obj, const char *name,
> @@ -3745,7 +3754,7 @@ static void x86_cpu_release_bit_prop(Object *obj, const char *name,
> */
> static void x86_cpu_register_bit_prop(X86CPU *cpu,
> const char *prop_name,
> - uint32_t *field,
> + FeatureWord w,
> int bitnr)
> {
> BitProperty *fp;
> @@ -3755,11 +3764,11 @@ static void x86_cpu_register_bit_prop(X86CPU *cpu,
> op = object_property_find(OBJECT(cpu), prop_name, NULL);
> if (op) {
> fp = op->opaque;
> - assert(fp->ptr == field);
> + assert(fp->w == w);
> fp->mask |= mask;
> } else {
> fp = g_new0(BitProperty, 1);
> - fp->ptr = field;
> + fp->w = w;
> fp->mask = mask;
> object_property_add(OBJECT(cpu), prop_name, "bool",
> x86_cpu_get_bit_prop,
> @@ -3787,7 +3796,7 @@ static void x86_cpu_register_feature_bit_props(X86CPU *cpu,
> /* aliases don't use "|" delimiters anymore, they are registered
> * manually using object_property_add_alias() */
> assert(!strchr(name, '|'));
> - x86_cpu_register_bit_prop(cpu, name, &cpu->env.features[w], bitnr);
> + x86_cpu_register_bit_prop(cpu, name, w, bitnr);
> }
>
> static GuestPanicInformation *x86_cpu_get_crash_info(CPUState *cs)
On Mon, Mar 27, 2017 at 01:10:59PM +0200, Igor Mammedov wrote:
> On Fri, 24 Mar 2017 17:36:45 -0300
> Eduardo Habkost <ehabkost@redhat.com> wrote:
>
> > The existing code for "host" and "max" CPU models overrides every
> > single feature in the CPU object at realize time, even the ones
> > that were explicitly enabled or disabled by the user using
> > "feat=on" or "feat=off", while features set using +feat/-feat are
> > kept.
> >
> > This means "-cpu host,+invtsc" works as expected, while
> > "-cpu host,invtsc=on" doesn't.
> >
> > This was a known bug, already documented in a comment inside
> > x86_cpu_expand_features(). What makes this bug worse now is that
> > libvirt 3.0.0 and newer now use "feat=on|off" instead of
> > +feat/-feat when it detects a QEMU version that supports it (see
> > libvirt commit d47db7b16dd5422c7e487c8c8ee5b181a2f9cd66).
> >
> > Change the feature property getter/setter to set a
> > env->user_features field, to keep track of features that were
> > explicitly changed using QOM properties. Then make the
> > max_features code not override user features when handling "-cpu
> > host" and "-cpu max".
> >
> > This will also allow us to remove the plus_features/minus_features
> > hack in the future, but I plan to do that after 2.9.0 is
> > released.
> >
> > Reported-by: Jiri Denemark <jdenemar@redhat.com>
> > Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
> > ---
> > target/i386/cpu.h | 2 ++
> > target/i386/cpu.c | 33 +++++++++++++++++++++------------
> > 2 files changed, 23 insertions(+), 12 deletions(-)
> >
> > diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> > index 07401ad9fe..c4602ca80d 100644
> > --- a/target/i386/cpu.h
> > +++ b/target/i386/cpu.h
> > @@ -1147,6 +1147,8 @@ typedef struct CPUX86State {
> > uint32_t cpuid_vendor3;
> > uint32_t cpuid_version;
> > FeatureWordArray features;
> > + /* Features that were explicitly enabled/disabled */
> > + FeatureWordArray user_features;
> > uint32_t cpuid_model[12];
> >
> > /* MTRRs */
> > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > index 7aa762245a..5f2addbf75 100644
> > --- a/target/i386/cpu.c
> > +++ b/target/i386/cpu.c
> > @@ -3373,15 +3373,20 @@ static void x86_cpu_expand_features(X86CPU *cpu, Error **errp)
> > GList *l;
> > Error *local_err = NULL;
> >
> > - /*TODO: cpu->max_features incorrectly overwrites features
> > - * set using "feat=on|off". Once we fix this, we can convert
> > + /*TODO: Now cpu->max_features doesn't overwrite features
> > + * set using QOM properties, and we can convert
> > * plus_features & minus_features to global properties
> > * inside x86_cpu_parse_featurestr() too.
> > */
> > if (cpu->max_features) {
> > for (w = 0; w < FEATURE_WORDS; w++) {
> > - env->features[w] =
> > - x86_cpu_get_supported_feature_word(w, cpu->migratable);
> > + /* Override only features that weren't not set explicitly
> > + * by the user.
> s/not// or if it was intended rephrase to avoid double negation.
I will fix that, thanks for spotting it.
>
> > + */
> > + env->features[w] &= env->user_features[w];
> it probably should be assert to catch features not set via property,
> which shouldn't be there in the first place, I don't like silent
> filtering that happens here.
I wouldn't like to add an assert() so late in the 2.9 schedule.
But you are right that having anything present in
(env->features & ~env->user_features) would be a bug somewhere
else, and this line is not necessary.
>
> > + env->features[w] |=
> > + x86_cpu_get_supported_feature_word(w, cpu->migratable) &
> > + ~env->user_features[w];
> > }
> > }
> >
> > @@ -3692,15 +3697,17 @@ static void x86_cpu_unrealizefn(DeviceState *dev, Error **errp)
> > }
> >
> > typedef struct BitProperty {
> > - uint32_t *ptr;
> > + FeatureWord w;
> it would be better if this refactoring and related changes
> were in a separate patch, something along lines:
> "x86/cpu: use FeatureWord instead of keeping a pointer to cpuid leaf"
I will do it in v2.
>
> > uint32_t mask;
> > } BitProperty;
> >
> > static void x86_cpu_get_bit_prop(Object *obj, Visitor *v, const char *name,
> > void *opaque, Error **errp)
> > {
> > + X86CPU *cpu = X86_CPU(obj);
> > BitProperty *fp = opaque;
> > - bool value = (*fp->ptr & fp->mask) == fp->mask;
> > + uint32_t f = cpu->env.features[fp->w];
> > + bool value = (f & fp->mask) == fp->mask;
> > visit_type_bool(v, name, &value, errp);
> > }
> >
> > @@ -3708,6 +3715,7 @@ static void x86_cpu_set_bit_prop(Object *obj, Visitor *v, const char *name,
> > void *opaque, Error **errp)
> > {
> > DeviceState *dev = DEVICE(obj);
> > + X86CPU *cpu = X86_CPU(obj);
> > BitProperty *fp = opaque;
> > Error *local_err = NULL;
> > bool value;
> > @@ -3724,10 +3732,11 @@ static void x86_cpu_set_bit_prop(Object *obj, Visitor *v, const char *name,
> > }
> >
> > if (value) {
> > - *fp->ptr |= fp->mask;
> > + cpu->env.features[fp->w] |= fp->mask;
> > } else {
> > - *fp->ptr &= ~fp->mask;
> > + cpu->env.features[fp->w] &= ~fp->mask;
> > }
> > + cpu->env.user_features[fp->w] |= fp->mask;
> > }
> >
> > static void x86_cpu_release_bit_prop(Object *obj, const char *name,
> > @@ -3745,7 +3754,7 @@ static void x86_cpu_release_bit_prop(Object *obj, const char *name,
> > */
> > static void x86_cpu_register_bit_prop(X86CPU *cpu,
> > const char *prop_name,
> > - uint32_t *field,
> > + FeatureWord w,
> > int bitnr)
> > {
> > BitProperty *fp;
> > @@ -3755,11 +3764,11 @@ static void x86_cpu_register_bit_prop(X86CPU *cpu,
> > op = object_property_find(OBJECT(cpu), prop_name, NULL);
> > if (op) {
> > fp = op->opaque;
> > - assert(fp->ptr == field);
> > + assert(fp->w == w);
> > fp->mask |= mask;
> > } else {
> > fp = g_new0(BitProperty, 1);
> > - fp->ptr = field;
> > + fp->w = w;
> > fp->mask = mask;
> > object_property_add(OBJECT(cpu), prop_name, "bool",
> > x86_cpu_get_bit_prop,
> > @@ -3787,7 +3796,7 @@ static void x86_cpu_register_feature_bit_props(X86CPU *cpu,
> > /* aliases don't use "|" delimiters anymore, they are registered
> > * manually using object_property_add_alias() */
> > assert(!strchr(name, '|'));
> > - x86_cpu_register_bit_prop(cpu, name, &cpu->env.features[w], bitnr);
> > + x86_cpu_register_bit_prop(cpu, name, w, bitnr);
> > }
> >
> > static GuestPanicInformation *x86_cpu_get_crash_info(CPUState *cs)
>
--
Eduardo
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