[Qemu-devel] [PATCH qom-cpu v3 9/9] memory_mapping: Change qemu_get_guest_memory_mapping() semantics

[Andreas Färber]

Previously it would search for the first CPU with paging enabled and
retrieve memory mappings from this and any following CPUs or return an
error if that fails.

Instead walk all CPUs and if paging is enabled retrieve the memory
mappings. Fail only if retrieving memory mappings on a CPU with paging
enabled fails.

This not only allows to more easily use one qemu_for_each_cpu() instead
of open-coding two CPU loops and drops find_first_paging_enabled_cpu()
but removes the implicit assumption of heterogeneity between CPUs n..N
in having paging enabled.

Cc: Wen Congyang <address@hidden>
Signed-off-by: Andreas Färber <address@hidden>
---
 memory_mapping.c | 42 +++++++++++++++++++++++-------------------
 1 file changed, 23 insertions(+), 19 deletions(-)

diff --git a/memory_mapping.c b/memory_mapping.c
index 481530a..55ac2b8 100644
--- a/memory_mapping.c
+++ b/memory_mapping.c
@@ -165,35 +165,39 @@ void memory_mapping_list_init(MemoryMappingList *list)
     QTAILQ_INIT(&list->head);
 }
 
-static CPUArchState *find_paging_enabled_cpu(CPUArchState *start_cpu)
+typedef struct GetGuestMemoryMappingData {
+    MemoryMappingList *list;
+    int ret;
+} GetGuestMemoryMappingData;
+
+static void qemu_get_one_guest_memory_mapping(CPUState *cpu, void *data)
 {
-    CPUArchState *env;
+    GetGuestMemoryMappingData *s = data;
+    int ret;
 
-    for (env = start_cpu; env != NULL; env = env->next_cpu) {
-        if (cpu_paging_enabled(ENV_GET_CPU(env))) {
-            return env;
-        }
+    if (!cpu_paging_enabled(cpu) || s->ret == -1) {
+        return;
+    }
+    ret = cpu_get_memory_mapping(cpu, s->list);
+    if (ret < 0) {
+        s->ret = -1;
+    } else {
+        s->ret = 0;
     }
-
-    return NULL;
 }
 
 int qemu_get_guest_memory_mapping(MemoryMappingList *list)
 {
-    CPUArchState *env, *first_paging_enabled_cpu;
+    GetGuestMemoryMappingData s = {
+        .list = list,
+        .ret = -2,
+    };
     RAMBlock *block;
     ram_addr_t offset, length;
-    int ret;
 
-    first_paging_enabled_cpu = find_paging_enabled_cpu(first_cpu);
-    if (first_paging_enabled_cpu) {
-        for (env = first_paging_enabled_cpu; env != NULL; env = env->next_cpu) 
{
-            ret = cpu_get_memory_mapping(ENV_GET_CPU(env), list);
-            if (ret < 0) {
-                return -1;
-            }
-        }
-        return 0;
+    qemu_for_each_cpu(qemu_get_one_guest_memory_mapping, &s);
+    if (s.ret != -2) {
+        return s.ret;
     }
 
     /*
-- 
1.8.1.4