[Qemu-devel] [PATCH v2 1/1] spapr: Set compat type for CPUs of a core

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

Compat CPU type is typically specified on -cpu cmdline option like:
-cpu host,compat=power7 or -cpu POWER8E,compat=power7 etc. When
compat is specified on -cpu cmdline, apply the same to all the
CPUs that get created as part of CPU core devices.

This patch takes care of compat property that is specified with
-cpu cmdline option only. The other way to specify this property
is via -global cmdline option and that usage isn't addressed by
this patch because -global is already broken for some CPU class
in PowerPC. There are two issues with using -global on CPU class.

- We specify alias names for CPUs commonly and use of alias names
  won't work with -global seamlessly. For eg, When "-cpu host" is
  specified, the actual CPU type that gets created
  is host-powerpc64-cpu. Hence specifying -global host.compat=power7
  will not work, so it has to be -global host-powerpc64-cpu.compat=power7.

- PowerPC class names have . (dot) and opts parsing doesn't like it.
  Specifying -global POWER8E_v2.1-powerpc64-cpu.compat=power7 will not
  work as the driver name gets extracted as POWER8E_v2 and hence setting
  of global property fails.

The above two aspects could be considered/fixed separately from this
patch as this patch allows existing uses of -cpu cpuname,compat= to
work correctly after the introducton of sPAPR CPU cores.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
---
Changes in v2:
- No need for a separate property named compat for cores.
- Simplified spapr_get_cpu_compat_type() based on David's review.

v1: https://lists.gnu.org/archive/html/qemu-devel/2016-06/msg06279.html

 hw/ppc/spapr_cpu_core.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
index 3a5da09..e8873fd 100644
--- a/hw/ppc/spapr_cpu_core.c
+++ b/hw/ppc/spapr_cpu_core.c
@@ -96,6 +96,28 @@ char *spapr_get_cpu_core_type(const char *model)
     return core_type;
 }
 
+/*
+ * Returns the CPU compat type specified in -cpu @model.
+ */
+static char *spapr_get_cpu_compat_type(const char *model)
+{
+    char *model_str = g_strdup(model);
+    char *featurestr, *compat = NULL;
+
+    featurestr = model_str ? strtok(model_str, ",") : NULL;
+    while (featurestr) {
+        if (!strncmp(featurestr, "compat=", 7)) {
+            compat = g_strdup(featurestr + 7);
+            goto out;
+        }
+        featurestr = strtok(NULL, ",");
+    }
+
+out:
+    g_free(model_str);
+    return compat;
+}
+
 static void spapr_core_release(DeviceState *dev, void *opaque)
 {
     sPAPRCPUCore *sc = SPAPR_CPU_CORE(OBJECT(dev));
@@ -285,6 +307,8 @@ static void spapr_cpu_core_realize(DeviceState *dev, Error **errp)
     CPUCore *cc = CPU_CORE(OBJECT(dev));
     const char *typename = object_class_get_name(sc->cpu_class);
     size_t size = object_type_get_instance_size(typename);
+    MachineState *machine = MACHINE(qdev_get_machine());
+    char *compat = spapr_get_cpu_compat_type(machine->cpu_model);
     Error *local_err = NULL;
     Object *obj;
     int i;
@@ -300,11 +324,18 @@ static void spapr_cpu_core_realize(DeviceState *dev, Error **errp)
         if (local_err) {
             goto err;
         }
+        if (compat) {
+            object_property_set_str(obj, compat, "compat", &local_err);
+            if (local_err) {
+                goto err;
+            }
+        }
     }
     object_child_foreach(OBJECT(dev), spapr_cpu_core_realize_child, &local_err);
     if (local_err) {
         goto err;
     } else {
+        g_free(compat);
         return;
     }
 
@@ -315,6 +346,7 @@ err:
         i--;
     }
     g_free(sc->threads);
+    g_free(compat);
     error_propagate(errp, local_err);
 }
 
-- 
2.1.0