All the functions will be implemented in later patches.
This patch includes the API that libxl can use to send QMP commands to
QEMU.
This patch also include a description of the internal states of the QMP
client in charge of connecting to QEMU, sending command and handling
responces.
Signed-off-by: Anthony PERARD <anthony.per...@citrix.com>
---
tools/libxl/libxl_internal.h | 58 ++++++++++++++++++++
tools/libxl/libxl_qmp.c | 102 +++++++++++++++++++++++++++++++++++
tools/libxl/libxl_types.idl | 4 ++
3 files changed, 164 insertions(+)
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 2a1fb784ec..7c88f4c3b5 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -357,6 +357,64 @@ struct libxl__ev_child {
};
+/*
+ * QMP asynchronous calls
+ */
+
+/*
+ * This facility allows a command to be sent to QEMU, and the response to be
+ * handed to a callback function. Each libxl__ev_qmp handles zero or one
+ * outstanding command; if multiple commands are to be sent concurrently,
+ * multiple libxl__ev_qmp's must be used.
+ *
+ * Possible states:
+ * Undefined
+ * Might contain anything.
+ * Idle
+ * Struct contents are defined enough to pass to any libxl__ev_qmp_*
+ * functions.
+ * The struct does not contain references to any allocated private resources
+ * so can be thrown away.
+ * Active
+ * Currently waiting for the callback to be called.
+ * _dispose must be called to reclaim resources (or wait for the callback to
+ * be called).
+ *
+ * libxl__ev_qmp_init: Undefined/Idle -> Idle
+ *
+ * libxl__ev_qmp_send: Idle -> Active (on error: Idle)
+ * Sends a command to QEMU.
+ *
+ * libxl__ev_qmp_dispose: Active/Idle -> Idle
+ *
+ * callback:
+ * When called, ev is Idle, so can be reused or thrown away.
+ * When an error occured, it is called with response == NULL and the error
+ * code in rc.
+ */
+typedef struct libxl__ev_qmp libxl__ev_qmp;
+typedef libxl__ev_qmp_callback(libxl__gc *gc, libxl__ev_qmp *ev,
+ const libxl__json_object *response,
+ int rc);
+
+_hidden void libxl__ev_qmp_init(libxl__ev_qmp *ev);
+_hidden int libxl__ev_qmp_send(libxl__gc *gc, libxl__ev_qmp *ev,
+ const char *cmd, libxl__json_object *args);
+_hidden void libxl__ev_qmp_dispose(libxl__gc *gc, libxl__ev_qmp *ev);
+
+struct libxl__ev_qmp {
+ /* caller should include this in their own struct */
+ /* caller must fill these in, and they must all remain valid */
+ uint32_t domid;
+ libxl__ev_qmp_callback *callback;
+ libxl__carefd *efd; /* set to send a fd with the command, NULL otherwise */
+
+ /* remaining fields are private to libxl_ev_qmp_* */
+ int id;
+ LIBXL_TAILQ_ENTRY(libxl__ev_qmp) entry;
+};
+
+
/*
* evgen structures, which are the state we use for generating
* events for the caller.
diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c
index 760f2798c7..1e6fbb64a5 100644
--- a/tools/libxl/libxl_qmp.c
+++ b/tools/libxl/libxl_qmp.c
@@ -1237,6 +1237,108 @@ int libxl__qmp_initializations(libxl__gc *gc, uint32_t
domid,
return ret;
}
+/* ------------ Implementation of asynchronous QMP calls ------------ */
+
+/*
+ * Implementation of the QMP client.
+ *
+ * This are different state possible in which the client can be in, with the
+ * list of possible transition listed after.
+ *
+ * States:
+ * Disconnected
+ * Nothing, no allocated ressources.
+ * Connecting
+ * Have allocated ressources, including a connection to a QMP socket.
+ * Waiting for server greeting.
+ * Capability Negociation
+ * QMP server is in Capabilities Negotiation mode.
+ * Waiting for a response to the "qmp_capabilities" command.
+ * Connected
+ * QMP server is in command mode, commands can be issued.
+ * There is outstanding command to be sent and/or there are in-flight
+ * libxl_ev_qmp with callback.
+ * Within A Callback
+ * The QMP client enter this state when a callback is called.
+ * The connection to QEMU is kept open until at least the callback
+ * return.
+ *
+ * Here is the transition from one state to the next:
+ * Disconnected -> Connecting
+ * Connect to the QMP socket.
+ * Connecting -> Capability Negociation
+ * Server greeting received
+ * Send "qmp_capabilities"
+ * Capability Negociation -> Connected
+ * Response to "qmp_capabilities" received"
+ *
+ * Connected -> Within A Callback
+ * When a response is received, if there's a callback associated to it,
+ * it is called.
+ * Connected -> Disconnected
+ * When both list of in-flight event and command to send are empty.
+ *
+ * Within A Callback -> Connected
+ * On return from a libxl__ev_qmp callback, there are more command to send
+ * or there are other in-flight event.
+ * Within A Callback -> Disconnected
+ * On return from a libxl__ev_qmp callback, both list of command to send
+ * and list of in-flight event are empty.
+ * QMP socket connection is closed, all ressources are deallocated.
+ *
+ * * -> Disconnected
+ * Whenever a error occure with the QMP socket, all outstanding callback
+ * will be called with an error, all ressource will be deallocated.
+ *
+ *
+ * checkout qemu.git:docs/interop/qmp-spec.txt for more information on the
+ * qmp protocol.
+ */
+
+typedef enum qmp_states {
+ qmp_state_disconnected = 1,
+ qmp_state_connecting,
+ qmp_state_capability_negociation,
+ qmp_state_connected,
+ qmp_state_within_callback,
+} qmp_states;
+
+typedef struct qmp_tx_buf qmp_tx_buf;
+struct qmp_tx_buf {
+ char *buf;
+ size_t len;
+ /* File descriptor to send along the command */
+ libxl__carefd *efd;
+ LIBXL_TAILQ_ENTRY(qmp_tx_buf) entry;
+};
+
+struct qmp_state {
+ libxl__carefd *cfd;
+ libxl__ev_fd efd;
+ uint32_t domid;
+
+ /* Current state */
+ qmp_states state;
+
+ /* id associated with the last generated command */
+ unsigned int last_id_used;
+
+ /* receive buffer, with:
+ * buf_size: current allocated size,
+ * buf_used: actual data in the buffer,
+ * buf_consumed: data already parsed. */
+ char *rx_buf;
+ size_t buf_size;
+ size_t buf_used;
+ size_t buf_consumed;
+
+ /* List of buffers to send */
+ LIBXL_TAILQ_HEAD(qmp_tx_bufs, qmp_tx_buf) tx_buf;
+
+ /* List of in-flight events */
+ LIBXL_SLIST_HEAD(libxl__ev_qmps, libxl__ev_qmp) qmp_events;
+};
+
/*
* Local variables:
* mode: C
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 01ec1d1afa..bb2ea253f6 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -69,6 +69,10 @@ libxl_error = Enumeration("error", [
(-23, "NOTFOUND"),
(-24, "DOMAIN_DESTROYED"), # Target domain ceased to exist during op
(-25, "FEATURE_REMOVED"), # For functionality that has been removed
+ (-26, "QMP_GENERIC_ERROR"), # unspecified qmp error
+ (-27, "QMP_COMMAND_NOT_FOUND"), # the requested command has not been found
+ (-28, "QMP_DEVICE_NOT_ACTIVE"), # a device has failed to be become active
+ (-29, "QMP_DEVICE_NOT_FOUND"), # the requested device has not been found
], value_namespace = "")
libxl_domain_type = Enumeration("domain_type", [
--
Anthony PERARD
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