Re: [Qemu-devel] [PATCH v2 6/6] qdev: switch property accessors to fixed-width visitor interfaces

[Michael Roth]

On Fri, Feb 24, 2012 at 11:22:06AM -0600, Anthony Liguori wrote:
> According to git bisect and qemu-test, this breaks:
> 
> qemu-system-x86_64 -kernel bin/vmlinuz-3.0 -initrd
> .tmp-26227/initramfs-26227.img.gz -append console=ttyS0 seed=1498
> -nographic -enable-kvm -device virtio-balloon-pci,id=balloon0
> -pidfile .tmp-26227/pidfile-26227.pid -qmp
> unix:.tmp-26227/qmpsock-26227.sock,server,nowait
> qemu-system-x86_64: Parameter 'id' expects int8_t
> Aborted

Sorry, put way too much faith in the unit tests catching this.

The issue is we currently use set_int* for both uint* and int*
properties. In this case the default uint8_t property value was
(uint8_t)-1 = 255, which we'd stick in a qobject and feed to the
visitors. Before, we'd just read that back into an int64_t container and
let it be re-interpreted as -1 or 255 depending on the property type.

Now, we still fall back to visit_type_int() for QmpInputVisitor, but in
the case of visit_type_int8() we check that the value falls within the
signed range, which isn't the case for 255.

There's a few other places where we hit similar issues. The 2 possible
solutions are:

1) Loosen the range checks in qapi-visit-core.c so that we ignore
signedness and only check that (uintX_t)value is small enough to fit
in X bytes, or

2) Add set_uint*/get_uint* accessors for uint* qdev properties.

1 is less code, and more forgiving of cases were we might use int*/uint*
interchangeably, but 2 I think is more correct and tightens up the
bounds checking for qdev and whatever else we use QmpInputVisitor for.
> 
> Regards,
> 
> Anthony Liguori
> 
> On 02/23/2012 02:22 PM, Michael Roth wrote:
> >Signed-off-by: Michael Roth<address@hidden>
> >---
> >  hw/qdev-addr.c       |    4 ++--
> >  hw/qdev-properties.c |   42 +++++++++++++++++-------------------------
> >  2 files changed, 19 insertions(+), 27 deletions(-)
> >
> >diff --git a/hw/qdev-addr.c b/hw/qdev-addr.c
> >index 0bb16c7..b711b6b 100644
> >--- a/hw/qdev-addr.c
> >+++ b/hw/qdev-addr.c
> >@@ -27,7 +27,7 @@ static void get_taddr(Object *obj, Visitor *v, void 
> >*opaque,
> >      int64_t value;
> >
> >      value = *ptr;
> >-    visit_type_int(v,&value, name, errp);
> >+    visit_type_int64(v,&value, name, errp);
> >  }
> >
> >  static void set_taddr(Object *obj, Visitor *v, void *opaque,
> >@@ -44,7 +44,7 @@ static void set_taddr(Object *obj, Visitor *v, void 
> >*opaque,
> >          return;
> >      }
> >
> >-    visit_type_int(v,&value, name,&local_err);
> >+    visit_type_int64(v,&value, name,&local_err);
> >      if (local_err) {
> >          error_propagate(errp, local_err);
> >          return;
> >diff --git a/hw/qdev-properties.c b/hw/qdev-properties.c
> >index 0423af1..98d95fb 100644
> >--- a/hw/qdev-properties.c
> >+++ b/hw/qdev-properties.c
> >@@ -82,10 +82,8 @@ static void get_int8(Object *obj, Visitor *v, void 
> >*opaque,
> >      DeviceState *dev = DEVICE(obj);
> >      Property *prop = opaque;
> >      int8_t *ptr = qdev_get_prop_ptr(dev, prop);
> >-    int64_t value;
> >
> >-    value = *ptr;
> >-    visit_type_int(v,&value, name, errp);
> >+    visit_type_int8(v, ptr, name, errp);
> >  }
> >
> >  static void set_int8(Object *obj, Visitor *v, void *opaque,
> >@@ -93,16 +91,15 @@ static void set_int8(Object *obj, Visitor *v, void 
> >*opaque,
> >  {
> >      DeviceState *dev = DEVICE(obj);
> >      Property *prop = opaque;
> >-    int8_t *ptr = qdev_get_prop_ptr(dev, prop);
> >+    int8_t value, *ptr = qdev_get_prop_ptr(dev, prop);
> >      Error *local_err = NULL;
> >-    int64_t value;
> >
> >      if (dev->state != DEV_STATE_CREATED) {
> >          error_set(errp, QERR_PERMISSION_DENIED);
> >          return;
> >      }
> >
> >-    visit_type_int(v,&value, name,&local_err);
> >+    visit_type_int8(v,&value, name,&local_err);
> >      if (local_err) {
> >          error_propagate(errp, local_err);
> >          return;
> >@@ -111,7 +108,7 @@ static void set_int8(Object *obj, Visitor *v, void 
> >*opaque,
> >          *ptr = value;
> >      } else {
> >          error_set(errp, QERR_PROPERTY_VALUE_OUT_OF_RANGE,
> >-                  dev->id?:"", name, value, prop->info->min,
> >+                  dev->id?:"", name, (int64_t)value, prop->info->min,
> >                    prop->info->max);
> >      }
> >  }
> >@@ -168,10 +165,8 @@ static void get_int16(Object *obj, Visitor *v, void 
> >*opaque,
> >      DeviceState *dev = DEVICE(obj);
> >      Property *prop = opaque;
> >      int16_t *ptr = qdev_get_prop_ptr(dev, prop);
> >-    int64_t value;
> >
> >-    value = *ptr;
> >-    visit_type_int(v,&value, name, errp);
> >+    visit_type_int16(v, ptr, name, errp);
> >  }
> >
> >  static void set_int16(Object *obj, Visitor *v, void *opaque,
> >@@ -179,16 +174,15 @@ static void set_int16(Object *obj, Visitor *v, void 
> >*opaque,
> >  {
> >      DeviceState *dev = DEVICE(obj);
> >      Property *prop = opaque;
> >-    int16_t *ptr = qdev_get_prop_ptr(dev, prop);
> >+    int16_t value, *ptr = qdev_get_prop_ptr(dev, prop);
> >      Error *local_err = NULL;
> >-    int64_t value;
> >
> >      if (dev->state != DEV_STATE_CREATED) {
> >          error_set(errp, QERR_PERMISSION_DENIED);
> >          return;
> >      }
> >
> >-    visit_type_int(v,&value, name,&local_err);
> >+    visit_type_int16(v,&value, name,&local_err);
> >      if (local_err) {
> >          error_propagate(errp, local_err);
> >          return;
> >@@ -197,7 +191,7 @@ static void set_int16(Object *obj, Visitor *v, void 
> >*opaque,
> >          *ptr = value;
> >      } else {
> >          error_set(errp, QERR_PROPERTY_VALUE_OUT_OF_RANGE,
> >-                  dev->id?:"", name, value, prop->info->min,
> >+                  dev->id?:"", name, (int64_t)value, prop->info->min,
> >                    prop->info->max);
> >      }
> >  }
> >@@ -217,11 +211,10 @@ static void get_int32(Object *obj, Visitor *v, void 
> >*opaque,
> >  {
> >      DeviceState *dev = DEVICE(obj);
> >      Property *prop = opaque;
> >-    int32_t *ptr = qdev_get_prop_ptr(dev, prop);
> >-    int64_t value;
> >+    int32_t value, *ptr = qdev_get_prop_ptr(dev, prop);
> >
> >      value = *ptr;
> >-    visit_type_int(v,&value, name, errp);
> >+    visit_type_int32(v,&value, name, errp);
> >  }
> >
> >  static void set_int32(Object *obj, Visitor *v, void *opaque,
> >@@ -229,16 +222,15 @@ static void set_int32(Object *obj, Visitor *v, void 
> >*opaque,
> >  {
> >      DeviceState *dev = DEVICE(obj);
> >      Property *prop = opaque;
> >-    int32_t *ptr = qdev_get_prop_ptr(dev, prop);
> >+    int32_t value, *ptr = qdev_get_prop_ptr(dev, prop);
> >      Error *local_err = NULL;
> >-    int64_t value;
> >
> >      if (dev->state != DEV_STATE_CREATED) {
> >          error_set(errp, QERR_PERMISSION_DENIED);
> >          return;
> >      }
> >
> >-    visit_type_int(v,&value, name,&local_err);
> >+    visit_type_int32(v,&value, name,&local_err);
> >      if (local_err) {
> >          error_propagate(errp, local_err);
> >          return;
> >@@ -247,7 +239,7 @@ static void set_int32(Object *obj, Visitor *v, void 
> >*opaque,
> >          *ptr = value;
> >      } else {
> >          error_set(errp, QERR_PROPERTY_VALUE_OUT_OF_RANGE,
> >-                  dev->id?:"", name, value, prop->info->min,
> >+                  dev->id?:"", name, (int64_t)value, prop->info->min,
> >                    prop->info->max);
> >      }
> >  }
> >@@ -313,7 +305,7 @@ static void get_int64(Object *obj, Visitor *v, void 
> >*opaque,
> >      Property *prop = opaque;
> >      int64_t *ptr = qdev_get_prop_ptr(dev, prop);
> >
> >-    visit_type_int(v, ptr, name, errp);
> >+    visit_type_int64(v, ptr, name, errp);
> >  }
> >
> >  static void set_int64(Object *obj, Visitor *v, void *opaque,
> >@@ -328,7 +320,7 @@ static void set_int64(Object *obj, Visitor *v, void 
> >*opaque,
> >          return;
> >      }
> >
> >-    visit_type_int(v, ptr, name, errp);
> >+    visit_type_int64(v, ptr, name, errp);
> >  }
> >
> >  PropertyInfo qdev_prop_uint64 = {
> >@@ -649,7 +641,7 @@ static void get_vlan(Object *obj, Visitor *v, void 
> >*opaque,
> >      int64_t id;
> >
> >      id = *ptr ? (*ptr)->id : -1;
> >-    visit_type_int(v,&id, name, errp);
> >+    visit_type_int64(v,&id, name, errp);
> >  }
> >
> >  static void set_vlan(Object *obj, Visitor *v, void *opaque,
> >@@ -667,7 +659,7 @@ static void set_vlan(Object *obj, Visitor *v, void 
> >*opaque,
> >          return;
> >      }
> >
> >-    visit_type_int(v,&id, name,&local_err);
> >+    visit_type_int64(v,&id, name,&local_err);
> >      if (local_err) {
> >          error_propagate(errp, local_err);
> >          return;
>