Add QMP callback

panda/include/panda/callbacks/cb-defs.h

@@ -57,6 +57,7 @@ typedef enum panda_cb_type {
     PANDA_CB_HD_WRITE,              // Each HDD write
     PANDA_CB_GUEST_HYPERCALL,       // Hypercall from the guest (e.g. CPUID)
     PANDA_CB_MONITOR,               // Monitor callback
+    PANDA_CB_QMP,                   // QMP callback
     PANDA_CB_CPU_RESTORE_STATE,     // In cpu_restore_state() (fault/exception)
     PANDA_CB_BEFORE_LOADVM,         // at start of replay, before loadvm
     PANDA_CB_ASID_CHANGED,          // When CPU asid (address space identifier) changes
@@ -592,6 +593,23 @@ typedef union panda_cb {
     */
     int (*monitor)(Monitor *mon, const char *cmd);
 
+    /* Callback ID: PANDA_CB_QMP
+
+       qmp:
+        Called when someone sends an unhandled QMP command
+
+       Arguments:
+         char *command: the command string as json
+         char *args:    the arguments string as json
+         char **result: pointer to a json result or NULL
+
+       Helper call location: TBA
+
+       Return value:
+         bool: true IFF the command was handled by the plugin
+    */
+    bool (*qmp)(char *command, char* args, char **result);
+
 
     /* Callback ID: PANDA_CB_CPU_RESTORE_STATE
 
@@ -1544,6 +1562,23 @@ typedef union panda_cb_with_context {
     */
     int (*monitor)(void* context, Monitor *mon, const char *cmd);
 
+    /* Callback ID: PANDA_CB_QMP
+
+       qmp:
+        Called when someone sends an unhandled QMP command
+
+       Arguments:
+         char *command: the command string as json
+         char *args:    the arguments string as json
+         char **result: pointer to a json result or NULL
+
+       Helper call location: TBA
+
+       Return value:
+         bool: true IFF the command was handled by the plugin
+    */
+    bool (*qmp)(void* context, char *command, char* args, char **result);
+
 
     /* Callback ID: PANDA_CB_CPU_RESTORE_STATE
 

panda/include/panda/callbacks/cb-support.h

@@ -75,6 +75,7 @@ bool panda_callbacks_after_find_fast(CPUState *cpu, TranslationBlock *tb, bool b
 int panda_callbacks_insn_exec(CPUState *env, target_ptr_t pc);
 int panda_callbacks_after_insn_exec(CPUState *env, target_ptr_t pc);
 int panda_callbacks_monitor(Monitor *mon, const char *cmd);
+bool panda_callbacks_qmp(char *command, char *args, char **result);
 int panda_callbacks_before_loadvm(void);
 void panda_callbacks_replay_hd_transfer(CPUState *env, uint32_t type, target_ptr_t src_addr, target_ptr_t dest_addr, size_t num_bytes);
 void panda_callbacks_after_machine_init(CPUState *env);

panda/include/panda/callbacks/cb-trampolines.h

@@ -19,6 +19,7 @@ void panda_cb_trampoline_phys_mem_after_write(void* context, CPUState *env, targ
 int panda_cb_trampoline_insn_exec(void* context, CPUState *env, target_ptr_t pc);
 int panda_cb_trampoline_after_insn_exec(void* context, CPUState *env, target_ptr_t pc);
 int panda_cb_trampoline_monitor(void* context, Monitor *mon, const char *cmd);
+bool panda_cb_trampoline_qmp(void* context, char *command, char *args, char **result);
 //int panda_cb_trampoline_before_loadvm(void* context);
 void panda_cb_trampoline_replay_hd_transfer(void* context, CPUState *env, uint32_t type, target_ptr_t src_addr, target_ptr_t dest_addr, size_t num_bytes);
 void panda_cb_trampoline_after_machine_init(void* context, CPUState *env);

panda/src/callbacks.c

@@ -474,6 +474,7 @@ panda_cb_with_context panda_get_cb_trampoline(panda_cb_type type) {
         CASE_CB_TRAMPOLINE(HD_WRITE,hd_write)
         CASE_CB_TRAMPOLINE(GUEST_HYPERCALL,guest_hypercall)
         CASE_CB_TRAMPOLINE(MONITOR,monitor)
+        CASE_CB_TRAMPOLINE(QMP,qmp)
         CASE_CB_TRAMPOLINE(CPU_RESTORE_STATE,cpu_restore_state)
 
         //CASE_CB_TRAMPOLINE(BEFORE_LOADVM,before_loadvm)

panda/src/cb-support.c

@@ -101,7 +101,9 @@ void panda_cb_trampoline_start_block_exec(void* context, CPUState *cpu, Translat
 // these aren't used
 MAKE_CALLBACK(void, HD_READ, hd_read, CPUState*, env);
 MAKE_CALLBACK(void, HD_WRITE, hd_write, CPUState*, env);
+
 MAKE_CALLBACK(int, MONITOR, monitor, Monitor*, mon, const char*, cmd);
+MAKE_CALLBACK(bool, QMP, qmp, char*, cmd, char*, args, char **, result);
 
 // Helper - get a physical address
 static inline hwaddr get_paddr(CPUState *cpu, target_ptr_t addr, void *ram_ptr) {

qapi/qmp-dispatch.c

@@ -19,6 +19,8 @@
 #include "qapi/qmp/qjson.h"
 #include "qapi-types.h"
 #include "qapi/qmp/qerror.h"
+//#include "panda/callbacks/cb-support.h"
+extern bool panda_callbacks_qmp(char *command, char* args, char **result);
 
 static QDict *qmp_dispatch_check_obj(const QObject *request, Error **errp)
 {
@@ -83,24 +85,55 @@ static QObject *do_qmp_dispatch(QmpCommandList *cmds, QObject *request,
 
     command = qdict_get_str(dict, "execute");
     cmd = qmp_find_command(cmds, command);
+
+    if (!qdict_haskey(dict, "arguments")) {
+        args = qdict_new();
+    } else {
+        args = qdict_get_qdict(dict, "arguments");
+        QINCREF(args);
+    }
+
     if (cmd == NULL) {
+        // Call any PANDA consumers of the unhandled command
+        // Provide them with arguments in json format.
+        // If any plugin returns true, we assume it handled the command
+        // and we expect a json output in result.
+        char *result = NULL;
+        const QString* cmd_args_q = qobject_to_json(QOBJECT(args));
+        const char *cmd_args = qstring_get_str(cmd_args_q);
+
+        if (panda_callbacks_qmp((char*)command, (char*)cmd_args, &result)) {
+            if (result != NULL) {
+                // We have a return value from the callback. Let's convert it to a qobject
+                ret = qobject_from_json(result, &local_err);
+                if (local_err) {
+                    printf("PANDA ERROR decoding result json in callback");
+                    error_propagate(errp, local_err);
+                    return NULL;
+                }
+            }
+
+            if (!ret) {
+                printf("PANDA WARNING: a qmp callback consumer returned TRUE without providing \
+                        a return value! Creating empty dictionary");
+
+                ret = QOBJECT(qdict_new());
+            }
+            QDECREF(args);
+            return ret;
+        }
+
         error_set(errp, ERROR_CLASS_COMMAND_NOT_FOUND,
                   "The command %s has not been found", command);
         return NULL;
     }
+
     if (!cmd->enabled) {
         error_setg(errp, "The command %s has been disabled for this instance",
                    command);
         return NULL;
     }
 
-    if (!qdict_haskey(dict, "arguments")) {
-        args = qdict_new();
-    } else {
-        args = qdict_get_qdict(dict, "arguments");
-        QINCREF(args);
-    }
-
     cmd->fn(args, &ret, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);