target/ppc: Allow cpu compatiblity checks based on type, not instance

ppc_check_compat() is used in a number of places to check if a cpu object
supports a certain compatiblity mode, subject to various constraints.

It takes a PowerPCCPU *, however it really only depends on the cpu's class.
We have upcoming cases where it would be useful to make compatibility
checks before we fully instantiate the cpu objects.

ppc_type_check_compat() will now make an equivalent check, but based on a
CPU's QOM typename instead of an instantiated CPU object.

We make use of the new interface in several places in spapr, where we're
essentially making a global check, rather than one specific to a particular
cpu.  This avoids some ugly uses of first_cpu to grab a "representative"
instance.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>

hw/ppc/spapr.c

@@ -1616,8 +1616,8 @@ static void spapr_machine_reset(void)
 
     first_ppc_cpu = POWERPC_CPU(first_cpu);
     if (kvm_enabled() && kvmppc_has_cap_mmu_radix() &&
-        ppc_check_compat(first_ppc_cpu, CPU_POWERPC_LOGICAL_3_00, 0,
+        ppc_type_check_compat(machine->cpu_type, CPU_POWERPC_LOGICAL_3_00, 0,
-                         spapr->max_compat_pvr)) {
+                              spapr->max_compat_pvr)) {
         /* If using KVM with radix mode available, VCPUs can be started
          * without a HPT because KVM will start them in radix mode.
          * Set the GR bit in PATB so that we know there is no HPT. */
@@ -2520,7 +2520,6 @@ static void spapr_machine_init(MachineState *machine)
     long load_limit, fw_size;
     char *filename;
     Error *resize_hpt_err = NULL;
-    PowerPCCPU *first_ppc_cpu;
 
     msi_nonbroken = true;
 
@@ -2618,10 +2617,9 @@ static void spapr_machine_init(MachineState *machine)
     /* init CPUs */
     spapr_init_cpus(spapr);
 
-    first_ppc_cpu = POWERPC_CPU(first_cpu);
     if ((!kvm_enabled() || kvmppc_has_cap_mmu_radix()) &&
-        ppc_check_compat(first_ppc_cpu, CPU_POWERPC_LOGICAL_3_00, 0,
+        ppc_type_check_compat(machine->cpu_type, CPU_POWERPC_LOGICAL_3_00, 0,
-                         spapr->max_compat_pvr)) {
+                              spapr->max_compat_pvr)) {
         /* KVM and TCG always allow GTSE with radix... */
         spapr_ovec_set(spapr->ov5, OV5_MMU_RADIX_GTSE);
     }

hw/ppc/spapr_caps.c

@@ -327,27 +327,26 @@ sPAPRCapabilityInfo capability_table[SPAPR_CAP_NUM] = {
 };
 
 static sPAPRCapabilities default_caps_with_cpu(sPAPRMachineState *spapr,
-                                               CPUState *cs)
+                                               const char *cputype)
 {
     sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
-    PowerPCCPU *cpu = POWERPC_CPU(cs);
     sPAPRCapabilities caps;
 
     caps = smc->default_caps;
 
-    if (!ppc_check_compat(cpu, CPU_POWERPC_LOGICAL_2_07,
+    if (!ppc_type_check_compat(cputype, CPU_POWERPC_LOGICAL_2_07,
-                          0, spapr->max_compat_pvr)) {
+                               0, spapr->max_compat_pvr)) {
         caps.caps[SPAPR_CAP_HTM] = SPAPR_CAP_OFF;
         caps.caps[SPAPR_CAP_CFPC] = SPAPR_CAP_BROKEN;
     }
 
-    if (!ppc_check_compat(cpu, CPU_POWERPC_LOGICAL_2_06_PLUS,
+    if (!ppc_type_check_compat(cputype, CPU_POWERPC_LOGICAL_2_06_PLUS,
-                          0, spapr->max_compat_pvr)) {
+                               0, spapr->max_compat_pvr)) {
         caps.caps[SPAPR_CAP_SBBC] = SPAPR_CAP_BROKEN;
     }
 
-    if (!ppc_check_compat(cpu, CPU_POWERPC_LOGICAL_2_06,
+    if (!ppc_type_check_compat(cputype, CPU_POWERPC_LOGICAL_2_06,
-                          0, spapr->max_compat_pvr)) {
+                               0, spapr->max_compat_pvr)) {
         caps.caps[SPAPR_CAP_VSX] = SPAPR_CAP_OFF;
         caps.caps[SPAPR_CAP_DFP] = SPAPR_CAP_OFF;
         caps.caps[SPAPR_CAP_IBS] = SPAPR_CAP_BROKEN;
@@ -384,7 +383,7 @@ int spapr_caps_post_migration(sPAPRMachineState *spapr)
     sPAPRCapabilities dstcaps = spapr->eff;
     sPAPRCapabilities srccaps;
 
-    srccaps = default_caps_with_cpu(spapr, first_cpu);
+    srccaps = default_caps_with_cpu(spapr, MACHINE(spapr)->cpu_type);
     for (i = 0; i < SPAPR_CAP_NUM; i++) {
         /* If not default value then assume came in with the migration */
         if (spapr->mig.caps[i] != spapr->def.caps[i]) {
@@ -446,7 +445,7 @@ void spapr_caps_reset(sPAPRMachineState *spapr)
     int i;
 
     /* First compute the actual set of caps we're running with.. */
-    default_caps = default_caps_with_cpu(spapr, first_cpu);
+    default_caps = default_caps_with_cpu(spapr, MACHINE(spapr)->cpu_type);
 
     for (i = 0; i < SPAPR_CAP_NUM; i++) {
         /* Store the defaults */

target/ppc/compat.c

@@ -105,17 +105,13 @@ static const CompatInfo *compat_by_pvr(uint32_t pvr)
     return NULL;
 }
 
-bool ppc_check_compat(PowerPCCPU *cpu, uint32_t compat_pvr,
+static bool pcc_compat(PowerPCCPUClass *pcc, uint32_t compat_pvr,
-                      uint32_t min_compat_pvr, uint32_t max_compat_pvr)
+                       uint32_t min_compat_pvr, uint32_t max_compat_pvr)
 {
-    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
     const CompatInfo *compat = compat_by_pvr(compat_pvr);
     const CompatInfo *min = compat_by_pvr(min_compat_pvr);
     const CompatInfo *max = compat_by_pvr(max_compat_pvr);
 
-#if !defined(CONFIG_USER_ONLY)
-    g_assert(cpu->vhyp);
-#endif
     g_assert(!min_compat_pvr || min);
     g_assert(!max_compat_pvr || max);
 
@@ -134,6 +130,25 @@ bool ppc_check_compat(PowerPCCPU *cpu, uint32_t compat_pvr,
     return true;
 }
 
+bool ppc_check_compat(PowerPCCPU *cpu, uint32_t compat_pvr,
+                      uint32_t min_compat_pvr, uint32_t max_compat_pvr)
+{
+    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
+
+#if !defined(CONFIG_USER_ONLY)
+    g_assert(cpu->vhyp);
+#endif
+
+    return pcc_compat(pcc, compat_pvr, min_compat_pvr, max_compat_pvr);
+}
+
+bool ppc_type_check_compat(const char *cputype, uint32_t compat_pvr,
+                           uint32_t min_compat_pvr, uint32_t max_compat_pvr)
+{
+    PowerPCCPUClass *pcc = POWERPC_CPU_CLASS(object_class_by_name(cputype));
+    return pcc_compat(pcc, compat_pvr, min_compat_pvr, max_compat_pvr);
+}
+
 void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp)
 {
     const CompatInfo *compat = compat_by_pvr(compat_pvr);

target/ppc/cpu.h

@@ -1369,7 +1369,11 @@ static inline int cpu_mmu_index (CPUPPCState *env, bool ifetch)
 #if defined(TARGET_PPC64)
 bool ppc_check_compat(PowerPCCPU *cpu, uint32_t compat_pvr,
                       uint32_t min_compat_pvr, uint32_t max_compat_pvr);
+bool ppc_type_check_compat(const char *cputype, uint32_t compat_pvr,
+                           uint32_t min_compat_pvr, uint32_t max_compat_pvr);
+
 void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp);
+
 #if !defined(CONFIG_USER_ONLY)
 void ppc_set_compat_all(uint32_t compat_pvr, Error **errp);
 #endif