[Qemu-devel] [PATCH v8 10/20] cpu: introduce CPUClass::virtio_is_big_endian()

[Greg Kurz <gkurz@linux.vnet.ibm.com>]

If we want to support targets that can change endianness (modern PPC and
ARM for the moment), we need to add a per-CPU class method to be called
from the virtio code. The virtio_ prefix in the name is a hint for people
to avoid misusage (aka. anywhere but from the virtio code).

The default behaviour is to return the compile-time default target
endianness.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
---
 include/qom/cpu.h |   10 ++++++++++
 qom/cpu.c         |    6 ++++++
 2 files changed, 16 insertions(+)

diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 4b352a2..30e8fe3 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -116,6 +116,7 @@ typedef struct CPUClass {
     CPUUnassignedAccess do_unassigned_access;
     void (*do_unaligned_access)(CPUState *cpu, vaddr addr,
                                 int is_write, int is_user, uintptr_t retaddr);
+    bool (*virtio_is_big_endian)(CPUState *cpu);
     int (*memory_rw_debug)(CPUState *cpu, vaddr addr,
                            uint8_t *buf, int len, bool is_write);
     void (*dump_state)(CPUState *cpu, FILE *f, fprintf_function cpu_fprintf,
@@ -548,6 +549,15 @@ void cpu_interrupt(CPUState *cpu, int mask);
 
 #endif /* USER_ONLY */
 
+#ifndef CONFIG_USER_ONLY
+static inline bool cpu_virtio_is_big_endian(CPUState *cpu)
+{
+    CPUClass *cc = CPU_GET_CLASS(cpu);
+
+    return cc->virtio_is_big_endian(cpu);
+}
+#endif
+
 #ifdef CONFIG_SOFTMMU
 static inline void cpu_unassigned_access(CPUState *cpu, hwaddr addr,
                                          bool is_write, bool is_exec,
diff --git a/qom/cpu.c b/qom/cpu.c
index fada2d4..d9bf151 100644
--- a/qom/cpu.c
+++ b/qom/cpu.c
@@ -25,6 +25,7 @@
 #include "qemu/log.h"
 #include "qemu/error-report.h"
 #include "sysemu/sysemu.h"
+#include "exec/cpu-common.h"
 
 bool cpu_exists(int64_t id)
 {
@@ -196,6 +197,10 @@ static int cpu_common_gdb_write_register(CPUState *cpu, uint8_t *buf, int reg)
     return 0;
 }
 
+static bool cpu_common_virtio_is_big_endian(CPUState *cpu)
+{
+    return target_words_bigendian();
+}
 
 void cpu_dump_state(CPUState *cpu, FILE *f, fprintf_function cpu_fprintf,
                     int flags)
@@ -334,6 +339,7 @@ static void cpu_class_init(ObjectClass *klass, void *data)
     k->write_elf64_note = cpu_common_write_elf64_note;
     k->gdb_read_register = cpu_common_gdb_read_register;
     k->gdb_write_register = cpu_common_gdb_write_register;
+    k->virtio_is_big_endian = cpu_common_virtio_is_big_endian;
     dc->realize = cpu_common_realizefn;
     /*
      * Reason: CPUs still need special care by board code: wiring up