target-ppc: Add "compat" CPU option

PowerISA defines a compatibility mode for server POWERPC CPUs which
is supported by the PCR special register which is hypervisor privileged.
To support this mode for guests, SPAPR defines a set of virtual PVRs,
one per PowerISA spec version. When a hypervisor needs a guest to work in
a compatibility mode, it puts a virtual PVR value into @cpu-version
property of a CPU node.

This introduces a "compat" CPU option which defines maximal compatibility
mode enabled. The supported modes are power6/power7/power8.

This does not change the existing behaviour, new property will be used
by next patches.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Alexander Graf <agraf@suse.de>

target-ppc/cpu-models.h

@@ -595,6 +595,16 @@ enum {
     CPU_POWERPC_PA6T               = 0x00900000,
 };
 
+/* Logical PVR definitions for sPAPR */
+enum {
+    CPU_POWERPC_LOGICAL_2_04       = 0x0F000001,
+    CPU_POWERPC_LOGICAL_2_05       = 0x0F000002,
+    CPU_POWERPC_LOGICAL_2_06       = 0x0F000003,
+    CPU_POWERPC_LOGICAL_2_06_PLUS  = 0x0F100003,
+    CPU_POWERPC_LOGICAL_2_07       = 0x0F000004,
+    CPU_POWERPC_LOGICAL_2_08       = 0x0F000005,
+};
+
 /* System version register (used on MPC 8xxx)                                */
 enum {
     POWERPC_SVR_NONE               = 0x00000000,

target-ppc/cpu-qom.h

@@ -83,6 +83,7 @@ typedef struct PowerPCCPUClass {
  * PowerPCCPU:
  * @env: #CPUPPCState
  * @cpu_dt_id: CPU index used in the device tree. KVM uses this index too
+ * @max_compat: Maximal supported logical PVR from the command line
  *
  * A PowerPC CPU.
  */
@@ -93,6 +94,7 @@ struct PowerPCCPU {
 
     CPUPPCState env;
     int cpu_dt_id;
+    uint32_t max_compat;
 };
 
 static inline PowerPCCPU *ppc_env_get_cpu(CPUPPCState *env)

target-ppc/translate_init.c

@@ -28,6 +28,8 @@
 #include "mmu-hash32.h"
 #include "mmu-hash64.h"
 #include "qemu/error-report.h"
+#include "qapi/visitor.h"
+#include "hw/qdev-properties.h"
 
 //#define PPC_DUMP_CPU
 //#define PPC_DEBUG_SPR
@@ -7680,6 +7682,76 @@ POWERPC_FAMILY(POWER5P)(ObjectClass *oc, void *data)
     pcc->l1_icache_size = 0x10000;
 }
 
+static void powerpc_get_compat(Object *obj, Visitor *v,
+                               void *opaque, const char *name, Error **errp)
+{
+    char *value = (char *)"";
+    Property *prop = opaque;
+    uint32_t *max_compat = qdev_get_prop_ptr(DEVICE(obj), prop);
+
+    switch (*max_compat) {
+    case CPU_POWERPC_LOGICAL_2_05:
+        value = (char *)"power6";
+        break;
+    case CPU_POWERPC_LOGICAL_2_06:
+        value = (char *)"power7";
+        break;
+    case CPU_POWERPC_LOGICAL_2_07:
+        value = (char *)"power8";
+        break;
+    case 0:
+        break;
+    default:
+        error_setg(errp, "Internal error: compat is set to %x",
+                   max_compat ? *max_compat : -1);
+        break;
+    }
+
+    visit_type_str(v, &value, name, errp);
+}
+
+static void powerpc_set_compat(Object *obj, Visitor *v,
+                               void *opaque, const char *name, Error **errp)
+{
+    Error *error = NULL;
+    char *value = NULL;
+    Property *prop = opaque;
+    uint32_t *max_compat = qdev_get_prop_ptr(DEVICE(obj), prop);
+
+    visit_type_str(v, &value, name, &error);
+    if (error) {
+        error_propagate(errp, error);
+        return;
+    }
+
+    if (strcmp(value, "power6") == 0) {
+        *max_compat = CPU_POWERPC_LOGICAL_2_05;
+    } else if (strcmp(value, "power7") == 0) {
+        *max_compat = CPU_POWERPC_LOGICAL_2_06;
+    } else if (strcmp(value, "power8") == 0) {
+        *max_compat = CPU_POWERPC_LOGICAL_2_07;
+    } else {
+        error_setg(errp, "Invalid compatibility mode \"%s\"", value);
+    }
+
+    g_free(value);
+}
+
+static PropertyInfo powerpc_compat_propinfo = {
+    .name = "str",
+    .legacy_name = "powerpc-server-compat",
+    .get = powerpc_get_compat,
+    .set = powerpc_set_compat,
+};
+
+#define DEFINE_PROP_POWERPC_COMPAT(_n, _s, _f) \
+    DEFINE_PROP(_n, _s, _f, powerpc_compat_propinfo, uint32_t)
+
+static Property powerpc_servercpu_properties[] = {
+    DEFINE_PROP_POWERPC_COMPAT("compat", PowerPCCPU, max_compat),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
 static void init_proc_POWER7 (CPUPPCState *env)
 {
     gen_spr_ne_601(env);
@@ -7766,6 +7838,7 @@ POWERPC_FAMILY(POWER7)(ObjectClass *oc, void *data)
 
     dc->fw_name = "PowerPC,POWER7";
     dc->desc = "POWER7";
+    dc->props = powerpc_servercpu_properties;
     pcc->pvr = CPU_POWERPC_POWER7_BASE;
     pcc->pvr_mask = CPU_POWERPC_POWER7_MASK;
     pcc->init_proc = init_proc_POWER7;
@@ -7825,6 +7898,7 @@ POWERPC_FAMILY(POWER7P)(ObjectClass *oc, void *data)
 
     dc->fw_name = "PowerPC,POWER7+";
     dc->desc = "POWER7+";
+    dc->props = powerpc_servercpu_properties;
     pcc->pvr = CPU_POWERPC_POWER7P_BASE;
     pcc->pvr_mask = CPU_POWERPC_POWER7P_MASK;
     pcc->init_proc = init_proc_POWER7;
@@ -7896,6 +7970,7 @@ POWERPC_FAMILY(POWER8)(ObjectClass *oc, void *data)
 
     dc->fw_name = "PowerPC,POWER8";
     dc->desc = "POWER8";
+    dc->props = powerpc_servercpu_properties;
     pcc->pvr = CPU_POWERPC_POWER8_BASE;
     pcc->pvr_mask = CPU_POWERPC_POWER8_MASK;
     pcc->init_proc = init_proc_POWER8;