[Qemu-devel] [PATCH v6 1/2] target-ppc: add PowerPCCPU::cpu_dt_id

[Alexey Kardashevskiy <aik@ozlabs.ru>]

Normally CPUState::cpu_index is used to pick the right CPU for various
operations. However default consecutive numbering does not always work
for POWERPC.

These indexes are reflected in /proc/device-tree/cpus/PowerPC,POWER7@XX
and used to call KVM VCPU's ioctls. In order to achieve this,
kvmppc_fixup_cpu() was introduced. Roughly speaking, it multiplies
cpu_index by the number of threads per core.

This approach has disadvantages such as:
1. NUMA configuration stays broken after the fixup;
2. CPU-targeted commands from the QEMU Monitor do not work properly as
CPU indexes have been fixed and there is no clear way for the user to
know what the new CPU indexes are.

This introduces a @cpu_dt_id field in the CPUPPCState struct which
is initialized from @cpu_index by default and can be fixed later
to meet the device tree requirements.

This adds an API to handle @cpu_dt_id.

This removes kvmppc_fixup_cpu() as it is not more needed, @cpu_dt_id
is calculated in ppc_cpu_realize().

This will be used later in machine code.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v6: inlined kvmppc_fixup_cpu()
---
 hw/ppc/ppc.c                | 22 ++++++++++++++++++++++
 target-ppc/cpu-qom.h        |  2 ++
 target-ppc/cpu.h            | 18 ++++++++++++++++++
 target-ppc/kvm.c            | 13 -------------
 target-ppc/kvm_ppc.h        |  6 ------
 target-ppc/translate_init.c | 10 ++++------
 6 files changed, 46 insertions(+), 25 deletions(-)

diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
index 114be64..0e82719 100644
--- a/hw/ppc/ppc.c
+++ b/hw/ppc/ppc.c
@@ -26,6 +26,7 @@
 #include "hw/ppc/ppc_e500.h"
 #include "qemu/timer.h"
 #include "sysemu/sysemu.h"
+#include "sysemu/cpus.h"
 #include "hw/timer/m48t59.h"
 #include "qemu/log.h"
 #include "hw/loader.h"
@@ -1362,3 +1363,24 @@ int PPC_NVRAM_set_params (nvram_t *nvram, uint16_t NVRAM_size,
 
     return 0;
 }
+
+/* CPU device-tree ID helpers */
+int ppc_get_vcpu_dt_id(PowerPCCPU *cpu)
+{
+    return cpu->cpu_dt_id;
+}
+
+PowerPCCPU *ppc_get_vcpu_by_dt_id(int cpu_dt_id)
+{
+    CPUState *cs;
+
+    CPU_FOREACH(cs) {
+        PowerPCCPU *cpu = POWERPC_CPU(cs);
+
+        if (cpu->cpu_dt_id == cpu_dt_id) {
+            return cpu;
+        }
+    }
+
+    return NULL;
+}
diff --git a/target-ppc/cpu-qom.h b/target-ppc/cpu-qom.h
index 72b2232..b17c024 100644
--- a/target-ppc/cpu-qom.h
+++ b/target-ppc/cpu-qom.h
@@ -79,6 +79,7 @@ typedef struct PowerPCCPUClass {
 /**
  * PowerPCCPU:
  * @env: #CPUPPCState
+ * @cpu_dt_id: CPU index used in the device tree. KVM uses this index too
  *
  * A PowerPC CPU.
  */
@@ -88,6 +89,7 @@ typedef struct PowerPCCPU {
     /*< public >*/
 
     CPUPPCState env;
+    int cpu_dt_id;
 } PowerPCCPU;
 
 static inline PowerPCCPU *ppc_env_get_cpu(CPUPPCState *env)
diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
index 51bcd4a..d8577ae 100644
--- a/target-ppc/cpu.h
+++ b/target-ppc/cpu.h
@@ -2154,4 +2154,22 @@ static inline bool cpu_has_work(CPUState *cpu)
 
 void dump_mmu(FILE *f, fprintf_function cpu_fprintf, CPUPPCState *env);
 
+/**
+ * ppc_get_vcpu_dt_id:
+ * @cs: a PowerPCCPU struct.
+ *
+ * Returns a device-tree ID for a CPU.
+ */
+int ppc_get_vcpu_dt_id(PowerPCCPU *cpu);
+
+/**
+ * ppc_get_vcpu_by_dt_id:
+ * @cpu_dt_id: a device tree id
+ *
+ * Searches for a CPU by @cpu_dt_id.
+ *
+ * Returns: a PowerPCCPU struct
+ */
+PowerPCCPU *ppc_get_vcpu_by_dt_id(int cpu_dt_id);
+
 #endif /* !defined (__CPU_PPC_H__) */
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 781b72f..8bcc5fb 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -1766,19 +1766,6 @@ static void kvmppc_host_cpu_class_init(ObjectClass *oc, void *data)
     }
 }
 
-int kvmppc_fixup_cpu(PowerPCCPU *cpu)
-{
-    CPUState *cs = CPU(cpu);
-    int smt;
-
-    /* Adjust cpu index for SMT */
-    smt = kvmppc_smt_threads();
-    cs->cpu_index = (cs->cpu_index / smp_threads) * smt
-        + (cs->cpu_index % smp_threads);
-
-    return 0;
-}
-
 bool kvmppc_has_cap_epr(void)
 {
     return cap_epr;
diff --git a/target-ppc/kvm_ppc.h b/target-ppc/kvm_ppc.h
index 5f78e4b..f3afcdb 100644
--- a/target-ppc/kvm_ppc.h
+++ b/target-ppc/kvm_ppc.h
@@ -36,7 +36,6 @@ int kvmppc_remove_spapr_tce(void *table, int pfd, uint32_t window_size);
 int kvmppc_reset_htab(int shift_hint);
 uint64_t kvmppc_rma_size(uint64_t current_size, unsigned int hash_shift);
 #endif /* !CONFIG_USER_ONLY */
-int kvmppc_fixup_cpu(PowerPCCPU *cpu);
 bool kvmppc_has_cap_epr(void);
 int kvmppc_define_rtas_kernel_token(uint32_t token, const char *function);
 int kvmppc_get_htab_fd(bool write);
@@ -155,11 +154,6 @@ static inline int kvmppc_update_sdr1(CPUPPCState *env)
 
 #endif /* !CONFIG_USER_ONLY */
 
-static inline int kvmppc_fixup_cpu(PowerPCCPU *cpu)
-{
-    return -1;
-}
-
 static inline bool kvmppc_has_cap_epr(void)
 {
     return false;
diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
index 35470d4..6de7126 100644
--- a/target-ppc/translate_init.c
+++ b/target-ppc/translate_init.c
@@ -7808,14 +7808,12 @@ static void ppc_cpu_realizefn(DeviceState *dev, Error **errp)
                    max_smt, kvm_enabled() ? "KVM" : "TCG");
         return;
     }
+
+    cpu->cpu_dt_id = (cs->cpu_index / smp_threads) * max_smt
+        + (cs->cpu_index % smp_threads);
 #endif
 
-    if (kvm_enabled()) {
-        if (kvmppc_fixup_cpu(cpu) != 0) {
-            error_setg(errp, "Unable to virtualize selected CPU with KVM");
-            return;
-        }
-    } else if (tcg_enabled()) {
+    if (tcg_enabled()) {
         if (ppc_fixup_cpu(cpu) != 0) {
             error_setg(errp, "Unable to emulate selected CPU with TCG");
             return;
-- 
1.8.4.rc4