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virtio-sound: handle control messages and streams 

Receive guest requests in the control (CTRL) queue of the virtio sound
device and reply with a NOT SUPPORTED error to all control commands.

The receiving handler is virtio_snd_handle_ctrl(). It stores all control
messages in the queue in the device's command queue. Then it calls
virtio_snd_process_cmdq() to handle each message.

The handler is process_cmd() which replies with VIRTIO_SND_S_NOT_SUPP.

Based-on: 5a2f350eec
Signed-off-by: Igor Skalkin <Igor.Skalkin@opensynergy.com>
Signed-off-by: Anton Yakovlev <Anton.Yakovlev@opensynergy.com>
Signed-off-by: Manos Pitsidianakis <manos.pitsidianakis@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <3224aff87e7c4f2777bfe1bbbbca93b72525992c.1698062525.git.manos.pitsidianakis@linaro.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
pull/257/head
Manos Pitsidianakis 2 years ago
committed by Michael S. Tsirkin
parent
2426908590
commit
eb9ad377bb
3 changed files with 595 additions and 9 deletions
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  1. 4
      hw/audio/trace-events
  2. 487
      hw/audio/virtio-snd.c
  3. 113
      include/hw/audio/virtio-snd.h

4
hw/audio/trace-events
View File

@ -47,3 +47,7 @@ virtio_snd_vm_state_running(void) "vm state running"
virtio_snd_vm_state_stopped(void) "vm state stopped"
virtio_snd_realize(void *snd) "snd %p: realize"
virtio_snd_unrealize(void *snd) "snd %p: unrealize"
virtio_snd_handle_ctrl(void *vdev, void *vq) "snd %p: handle ctrl event for queue %p"
virtio_snd_handle_code(uint32_t val, const char *code) "ctrl code msg val = %"PRIu32" == %s"
virtio_snd_handle_chmap_info(void) "VIRTIO_SND_CHMAP_INFO called"
virtio_snd_handle_event(void) "event queue callback called"

487
hw/audio/virtio-snd.c
View File

@ -32,6 +32,29 @@
#define VIRTIO_SOUND_CHMAP_DEFAULT 0
#define VIRTIO_SOUND_HDA_FN_NID 0
static uint32_t supported_formats = BIT(VIRTIO_SND_PCM_FMT_S8)
| BIT(VIRTIO_SND_PCM_FMT_U8)
| BIT(VIRTIO_SND_PCM_FMT_S16)
| BIT(VIRTIO_SND_PCM_FMT_U16)
| BIT(VIRTIO_SND_PCM_FMT_S32)
| BIT(VIRTIO_SND_PCM_FMT_U32)
| BIT(VIRTIO_SND_PCM_FMT_FLOAT);
static uint32_t supported_rates = BIT(VIRTIO_SND_PCM_RATE_5512)
| BIT(VIRTIO_SND_PCM_RATE_8000)
| BIT(VIRTIO_SND_PCM_RATE_11025)
| BIT(VIRTIO_SND_PCM_RATE_16000)
| BIT(VIRTIO_SND_PCM_RATE_22050)
| BIT(VIRTIO_SND_PCM_RATE_32000)
| BIT(VIRTIO_SND_PCM_RATE_44100)
| BIT(VIRTIO_SND_PCM_RATE_48000)
| BIT(VIRTIO_SND_PCM_RATE_64000)
| BIT(VIRTIO_SND_PCM_RATE_88200)
| BIT(VIRTIO_SND_PCM_RATE_96000)
| BIT(VIRTIO_SND_PCM_RATE_176400)
| BIT(VIRTIO_SND_PCM_RATE_192000)
| BIT(VIRTIO_SND_PCM_RATE_384000);
static const VMStateDescription vmstate_virtio_snd_device = {
.name = TYPE_VIRTIO_SND,
.version_id = VIRTIO_SOUND_VM_VERSION,
@ -100,13 +123,397 @@ virtio_snd_set_config(VirtIODevice *vdev, const uint8_t *config)
}
static void
virtio_snd_ctrl_cmd_free(virtio_snd_ctrl_command *cmd)
{
g_free(cmd->elem);
g_free(cmd);
}
/*
* Get a specific stream from the virtio sound card device.
* Returns NULL if @stream_id is invalid or not allocated.
*
* @s: VirtIOSound device
* @stream_id: stream id
*/
static VirtIOSoundPCMStream *virtio_snd_pcm_get_stream(VirtIOSound *s,
uint32_t stream_id)
{
return stream_id >= s->snd_conf.streams ? NULL :
s->pcm->streams[stream_id];
}
/*
* Get params for a specific stream.
*
* @s: VirtIOSound device
* @stream_id: stream id
*/
static virtio_snd_pcm_set_params *virtio_snd_pcm_get_params(VirtIOSound *s,
uint32_t stream_id)
{
return stream_id >= s->snd_conf.streams ? NULL
: &s->pcm->pcm_params[stream_id];
}
/*
* Set the given stream params.
* Called by both virtio_snd_handle_pcm_set_params and during device
* initialization.
* Returns the response status code. (VIRTIO_SND_S_*).
*
* @s: VirtIOSound device
* @params: The PCM params as defined in the virtio specification
*/
static
uint32_t virtio_snd_set_pcm_params(VirtIOSound *s,
uint32_t stream_id,
virtio_snd_pcm_set_params *params)
{
virtio_snd_pcm_set_params *st_params;
if (stream_id >= s->snd_conf.streams || s->pcm->pcm_params == NULL) {
/*
* TODO: do we need to set DEVICE_NEEDS_RESET?
*/
virtio_error(VIRTIO_DEVICE(s), "Streams have not been initialized.\n");
return cpu_to_le32(VIRTIO_SND_S_BAD_MSG);
}
st_params = virtio_snd_pcm_get_params(s, stream_id);
if (params->channels < 1 || params->channels > AUDIO_MAX_CHANNELS) {
error_report("Number of channels is not supported.");
return cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
}
if (!(supported_formats & BIT(params->format))) {
error_report("Stream format is not supported.");
return cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
}
if (!(supported_rates & BIT(params->rate))) {
error_report("Stream rate is not supported.");
return cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
}
st_params->buffer_bytes = le32_to_cpu(params->buffer_bytes);
st_params->period_bytes = le32_to_cpu(params->period_bytes);
st_params->features = le32_to_cpu(params->features);
/* the following are uint8_t, so there's no need to bswap the values. */
st_params->channels = params->channels;
st_params->format = params->format;
st_params->rate = params->rate;
return cpu_to_le32(VIRTIO_SND_S_OK);
}
/*
* Get a QEMU Audiosystem compatible format value from a VIRTIO_SND_PCM_FMT_*
*/
static AudioFormat virtio_snd_get_qemu_format(uint32_t format)
{
#define CASE(FMT) \
case VIRTIO_SND_PCM_FMT_##FMT: \
return AUDIO_FORMAT_##FMT;
switch (format) {
CASE(U8)
CASE(S8)
CASE(U16)
CASE(S16)
CASE(U32)
CASE(S32)
case VIRTIO_SND_PCM_FMT_FLOAT:
return AUDIO_FORMAT_F32;
default:
g_assert_not_reached();
}
#undef CASE
}
/*
* Get a QEMU Audiosystem compatible frequency value from a
* VIRTIO_SND_PCM_RATE_*
*/
static uint32_t virtio_snd_get_qemu_freq(uint32_t rate)
{
#define CASE(RATE) \
case VIRTIO_SND_PCM_RATE_##RATE: \
return RATE;
switch (rate) {
CASE(5512)
CASE(8000)
CASE(11025)
CASE(16000)
CASE(22050)
CASE(32000)
CASE(44100)
CASE(48000)
CASE(64000)
CASE(88200)
CASE(96000)
CASE(176400)
CASE(192000)
CASE(384000)
default:
g_assert_not_reached();
}
#undef CASE
}
/*
* Get QEMU Audiosystem compatible audsettings from virtio based pcm stream
* params.
*/
static void virtio_snd_get_qemu_audsettings(audsettings *as,
virtio_snd_pcm_set_params *params)
{
as->nchannels = MIN(AUDIO_MAX_CHANNELS, params->channels);
as->fmt = virtio_snd_get_qemu_format(params->format);
as->freq = virtio_snd_get_qemu_freq(params->rate);
as->endianness = target_words_bigendian() ? 1 : 0;
}
/*
* Close a stream and free all its resources.
*
* @stream: VirtIOSoundPCMStream *stream
*/
static void virtio_snd_pcm_close(VirtIOSoundPCMStream *stream)
{
}
/*
* Queue handler stub.
* Prepares a VirtIOSound card stream.
* Returns the response status code. (VIRTIO_SND_S_*).
*
* @s: VirtIOSound device
* @stream_id: stream id
*/
static uint32_t virtio_snd_pcm_prepare(VirtIOSound *s, uint32_t stream_id)
{
audsettings as;
virtio_snd_pcm_set_params *params;
VirtIOSoundPCMStream *stream;
if (s->pcm->streams == NULL ||
s->pcm->pcm_params == NULL ||
stream_id >= s->snd_conf.streams) {
return cpu_to_le32(VIRTIO_SND_S_BAD_MSG);
}
params = virtio_snd_pcm_get_params(s, stream_id);
if (params == NULL) {
return cpu_to_le32(VIRTIO_SND_S_BAD_MSG);
}
stream = virtio_snd_pcm_get_stream(s, stream_id);
if (stream == NULL) {
stream = g_new0(VirtIOSoundPCMStream, 1);
stream->active = false;
stream->id = stream_id;
stream->pcm = s->pcm;
stream->s = s;
/*
* stream_id >= s->snd_conf.streams was checked before so this is
* in-bounds
*/
s->pcm->streams[stream_id] = stream;
}
virtio_snd_get_qemu_audsettings(&as, params);
stream->info.direction = stream_id < s->snd_conf.streams / 2 +
(s->snd_conf.streams & 1) ? VIRTIO_SND_D_OUTPUT : VIRTIO_SND_D_INPUT;
stream->info.hdr.hda_fn_nid = VIRTIO_SOUND_HDA_FN_NID;
stream->info.features = 0;
stream->info.channels_min = 1;
stream->info.channels_max = as.nchannels;
stream->info.formats = supported_formats;
stream->info.rates = supported_rates;
stream->params = *params;
stream->positions[0] = VIRTIO_SND_CHMAP_FL;
stream->positions[1] = VIRTIO_SND_CHMAP_FR;
stream->as = as;
return cpu_to_le32(VIRTIO_SND_S_OK);
}
static const char *print_code(uint32_t code)
{
#define CASE(CODE) \
case VIRTIO_SND_R_##CODE: \
return "VIRTIO_SND_R_"#CODE
switch (code) {
CASE(JACK_INFO);
CASE(JACK_REMAP);
CASE(PCM_INFO);
CASE(PCM_SET_PARAMS);
CASE(PCM_PREPARE);
CASE(PCM_RELEASE);
CASE(PCM_START);
CASE(PCM_STOP);
CASE(CHMAP_INFO);
default:
return "invalid code";
}
#undef CASE
};
/*
* The actual processing done in virtio_snd_process_cmdq().
*
* @s: VirtIOSound device
* @cmd: control command request
*/
static inline void
process_cmd(VirtIOSound *s, virtio_snd_ctrl_command *cmd)
{
uint32_t code;
size_t msg_sz = iov_to_buf(cmd->elem->out_sg,
cmd->elem->out_num,
0,
&cmd->ctrl,
sizeof(virtio_snd_hdr));
if (msg_sz != sizeof(virtio_snd_hdr)) {
/*
* TODO: do we need to set DEVICE_NEEDS_RESET?
*/
qemu_log_mask(LOG_GUEST_ERROR,
"%s: virtio-snd command size incorrect %zu vs \
%zu\n", __func__, msg_sz, sizeof(virtio_snd_hdr));
return;
}
code = le32_to_cpu(cmd->ctrl.code);
trace_virtio_snd_handle_code(code, print_code(code));
switch (code) {
case VIRTIO_SND_R_JACK_INFO:
case VIRTIO_SND_R_JACK_REMAP:
qemu_log_mask(LOG_UNIMP,
"virtio_snd: jack functionality is unimplemented.\n");
cmd->resp.code = cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
break;
case VIRTIO_SND_R_PCM_INFO:
case VIRTIO_SND_R_PCM_SET_PARAMS:
case VIRTIO_SND_R_PCM_PREPARE:
case VIRTIO_SND_R_PCM_START:
case VIRTIO_SND_R_PCM_STOP:
case VIRTIO_SND_R_PCM_RELEASE:
cmd->resp.code = cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
break;
case VIRTIO_SND_R_CHMAP_INFO:
qemu_log_mask(LOG_UNIMP,
"virtio_snd: chmap info functionality is unimplemented.\n");
trace_virtio_snd_handle_chmap_info();
cmd->resp.code = cpu_to_le32(VIRTIO_SND_S_NOT_SUPP);
break;
default:
/* error */
error_report("virtio snd header not recognized: %"PRIu32, code);
cmd->resp.code = cpu_to_le32(VIRTIO_SND_S_BAD_MSG);
}
iov_from_buf(cmd->elem->in_sg,
cmd->elem->in_num,
0,
&cmd->resp,
sizeof(virtio_snd_hdr));
virtqueue_push(cmd->vq, cmd->elem, sizeof(virtio_snd_hdr));
virtio_notify(VIRTIO_DEVICE(s), cmd->vq);
}
/*
* Consume all elements in command queue.
*
* @s: VirtIOSound device
*/
static void virtio_snd_process_cmdq(VirtIOSound *s)
{
virtio_snd_ctrl_command *cmd;
if (unlikely(qatomic_read(&s->processing_cmdq))) {
return;
}
WITH_QEMU_LOCK_GUARD(&s->cmdq_mutex) {
qatomic_set(&s->processing_cmdq, true);
while (!QTAILQ_EMPTY(&s->cmdq)) {
cmd = QTAILQ_FIRST(&s->cmdq);
/* process command */
process_cmd(s, cmd);
QTAILQ_REMOVE(&s->cmdq, cmd, next);
virtio_snd_ctrl_cmd_free(cmd);
}
qatomic_set(&s->processing_cmdq, false);
}
}
/*
* The control message handler. Pops an element from the control virtqueue,
* and stores them to VirtIOSound's cmdq queue and finally calls
* virtio_snd_process_cmdq() for processing.
*
* @vdev: VirtIOSound device
* @vq: Control virtqueue
*/
static void virtio_snd_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIOSound *s = VIRTIO_SND(vdev);
VirtQueueElement *elem;
virtio_snd_ctrl_command *cmd;
trace_virtio_snd_handle_ctrl(vdev, vq);
if (!virtio_queue_ready(vq)) {
return;
}
elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
while (elem) {
cmd = g_new0(virtio_snd_ctrl_command, 1);
cmd->elem = elem;
cmd->vq = vq;
cmd->resp.code = cpu_to_le32(VIRTIO_SND_S_OK);
QTAILQ_INSERT_TAIL(&s->cmdq, cmd, next);
elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
}
virtio_snd_process_cmdq(s);
}
/*
* The event virtqueue handler.
* Not implemented yet.
*
* @vdev: VirtIOSound device
* @vq: event vq
*/
static void virtio_snd_handle_event(VirtIODevice *vdev, VirtQueue *vq)
{
qemu_log_mask(LOG_UNIMP, "virtio_snd: event queue is unimplemented.\n");
trace_virtio_snd_handle_event();
}
/*
* Stub buffer virtqueue handler.
*
* @vdev: VirtIOSound device
* @vq: virtqueue
*/
static void virtio_snd_handle_queue(VirtIODevice *vdev, VirtQueue *vq) {}
static void virtio_snd_handle_xfer(VirtIODevice *vdev, VirtQueue *vq) {}
static uint64_t get_features(VirtIODevice *vdev, uint64_t features,
Error **errp)
@ -140,12 +547,22 @@ static void virtio_snd_realize(DeviceState *dev, Error **errp)
ERRP_GUARD();
VirtIOSound *vsnd = VIRTIO_SND(dev);
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
virtio_snd_pcm_set_params default_params = { 0 };
uint32_t status;
vsnd->pcm = NULL;
vsnd->vmstate =
qemu_add_vm_change_state_handler(virtio_snd_vm_state_change, vsnd);
trace_virtio_snd_realize(vsnd);
vsnd->pcm = g_new0(VirtIOSoundPCM, 1);
vsnd->pcm->snd = vsnd;
vsnd->pcm->streams =
g_new0(VirtIOSoundPCMStream *, vsnd->snd_conf.streams);
vsnd->pcm->pcm_params =
g_new0(virtio_snd_pcm_set_params, vsnd->snd_conf.streams);
virtio_init(vdev, VIRTIO_ID_SOUND, sizeof(virtio_snd_config));
virtio_add_feature(&vsnd->features, VIRTIO_F_VERSION_1);
@ -172,25 +589,69 @@ static void virtio_snd_realize(DeviceState *dev, Error **errp)
AUD_register_card("virtio-sound", &vsnd->card, errp);
/* set default params for all streams */
default_params.features = 0;
default_params.buffer_bytes = cpu_to_le32(8192);
default_params.period_bytes = cpu_to_le32(2048);
default_params.channels = 2;
default_params.format = VIRTIO_SND_PCM_FMT_S16;
default_params.rate = VIRTIO_SND_PCM_RATE_48000;
vsnd->queues[VIRTIO_SND_VQ_CONTROL] =
virtio_add_queue(vdev, 64, virtio_snd_handle_queue);
virtio_add_queue(vdev, 64, virtio_snd_handle_ctrl);
vsnd->queues[VIRTIO_SND_VQ_EVENT] =
virtio_add_queue(vdev, 64, virtio_snd_handle_queue);
virtio_add_queue(vdev, 64, virtio_snd_handle_event);
vsnd->queues[VIRTIO_SND_VQ_TX] =
virtio_add_queue(vdev, 64, virtio_snd_handle_queue);
virtio_add_queue(vdev, 64, virtio_snd_handle_xfer);
vsnd->queues[VIRTIO_SND_VQ_RX] =
virtio_add_queue(vdev, 64, virtio_snd_handle_queue);
virtio_add_queue(vdev, 64, virtio_snd_handle_xfer);
qemu_mutex_init(&vsnd->cmdq_mutex);
QTAILQ_INIT(&vsnd->cmdq);
for (uint32_t i = 0; i < vsnd->snd_conf.streams; i++) {
status = virtio_snd_set_pcm_params(vsnd, i, &default_params);
if (status != cpu_to_le32(VIRTIO_SND_S_OK)) {
error_setg(errp,
"Can't initalize stream params, device responded with %s.",
print_code(status));
return;
}
status = virtio_snd_pcm_prepare(vsnd, i);
if (status != cpu_to_le32(VIRTIO_SND_S_OK)) {
error_setg(errp,
"Can't prepare streams, device responded with %s.",
print_code(status));
return;
}
}
}
static void virtio_snd_unrealize(DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIOSound *vsnd = VIRTIO_SND(dev);
VirtIOSoundPCMStream *stream;
qemu_del_vm_change_state_handler(vsnd->vmstate);
trace_virtio_snd_unrealize(vsnd);
if (vsnd->pcm) {
if (vsnd->pcm->streams) {
for (uint32_t i = 0; i < vsnd->snd_conf.streams; i++) {
stream = vsnd->pcm->streams[i];
if (stream) {
virtio_snd_process_cmdq(stream->s);
virtio_snd_pcm_close(stream);
g_free(stream);
}
}
g_free(vsnd->pcm->streams);
}
g_free(vsnd->pcm->pcm_params);
g_free(vsnd->pcm);
vsnd->pcm = NULL;
}
AUD_remove_card(&vsnd->card);
qemu_mutex_destroy(&vsnd->cmdq_mutex);
virtio_delete_queue(vsnd->queues[VIRTIO_SND_VQ_CONTROL]);
virtio_delete_queue(vsnd->queues[VIRTIO_SND_VQ_EVENT]);
virtio_delete_queue(vsnd->queues[VIRTIO_SND_VQ_TX]);
@ -199,7 +660,19 @@ static void virtio_snd_unrealize(DeviceState *dev)
}
static void virtio_snd_reset(VirtIODevice *vdev) {}
static void virtio_snd_reset(VirtIODevice *vdev)
{
VirtIOSound *s = VIRTIO_SND(vdev);
virtio_snd_ctrl_command *cmd;
WITH_QEMU_LOCK_GUARD(&s->cmdq_mutex) {
while (!QTAILQ_EMPTY(&s->cmdq)) {
cmd = QTAILQ_FIRST(&s->cmdq);
QTAILQ_REMOVE(&s->cmdq, cmd, next);
virtio_snd_ctrl_cmd_free(cmd);
}
}
}
static void virtio_snd_class_init(ObjectClass *klass, void *data)
{

113
include/hw/audio/virtio-snd.h
View File

@ -67,13 +67,122 @@ typedef struct virtio_snd_pcm_xfer virtio_snd_pcm_xfer;
/* I/O request status */
typedef struct virtio_snd_pcm_status virtio_snd_pcm_status;
typedef struct VirtIOSound {
/* device structs */
typedef struct VirtIOSound VirtIOSound;
typedef struct VirtIOSoundPCMStream VirtIOSoundPCMStream;
typedef struct virtio_snd_ctrl_command virtio_snd_ctrl_command;
typedef struct VirtIOSoundPCM VirtIOSoundPCM;
struct VirtIOSoundPCM {
VirtIOSound *snd;
/*
* PCM parameters are a separate field instead of a VirtIOSoundPCMStream
* field, because the operation of PCM control requests is first
* VIRTIO_SND_R_PCM_SET_PARAMS and then VIRTIO_SND_R_PCM_PREPARE; this
* means that some times we get parameters without having an allocated
* stream yet.
*/
virtio_snd_pcm_set_params *pcm_params;
VirtIOSoundPCMStream **streams;
};
struct VirtIOSoundPCMStream {
VirtIOSoundPCM *pcm;
virtio_snd_pcm_info info;
virtio_snd_pcm_set_params params;
uint32_t id;
/* channel position values (VIRTIO_SND_CHMAP_XXX) */
uint8_t positions[VIRTIO_SND_CHMAP_MAX_SIZE];
VirtIOSound *s;
bool flushing;
audsettings as;
union {
SWVoiceIn *in;
SWVoiceOut *out;
} voice;
bool active;
};
/*
* PCM stream state machine.
* -------------------------
*
* 5.14.6.6.1 PCM Command Lifecycle
* ================================
*
* A PCM stream has the following command lifecycle:
* - `SET PARAMETERS`
* The driver negotiates the stream parameters (format, transport, etc) with
* the device.
* Possible valid transitions: `SET PARAMETERS`, `PREPARE`.
* - `PREPARE`
* The device prepares the stream (allocates resources, etc).
* Possible valid transitions: `SET PARAMETERS`, `PREPARE`, `START`,
* `RELEASE`. Output only: the driver transfers data for pre-buffing.
* - `START`
* The device starts the stream (unmute, putting into running state, etc).
* Possible valid transitions: `STOP`.
* The driver transfers data to/from the stream.
* - `STOP`
* The device stops the stream (mute, putting into non-running state, etc).
* Possible valid transitions: `START`, `RELEASE`.
* - `RELEASE`
* The device releases the stream (frees resources, etc).
* Possible valid transitions: `SET PARAMETERS`, `PREPARE`.
*
* +---------------+ +---------+ +---------+ +-------+ +-------+
* | SetParameters | | Prepare | | Release | | Start | | Stop |
* +---------------+ +---------+ +---------+ +-------+ +-------+
* |- | | | |
* || | | | |
* |< | | | |
* |------------->| | | |
* |<-------------| | | |
* | |- | | |
* | || | | |
* | |< | | |
* | |--------------------->| |
* | |---------->| | |
* | | | |-------->|
* | | | |<--------|
* | | |<-------------------|
* |<-------------------------| | |
* | |<----------| | |
*
* CTRL in the VirtIOSound device
* ==============================
*
* The control messages that affect the state of a stream arrive in the
* `virtio_snd_handle_ctrl()` queue callback and are of type `struct
* virtio_snd_ctrl_command`. They are stored in a queue field in the device
* type, `VirtIOSound`. This allows deferring the CTRL request completion if
* it's not immediately possible due to locking/state reasons.
*
* The CTRL message is finally handled in `process_cmd()`.
*/
struct VirtIOSound {
VirtIODevice parent_obj;
VirtQueue *queues[VIRTIO_SND_VQ_MAX];
uint64_t features;
VirtIOSoundPCM *pcm;
QEMUSoundCard card;
VMChangeStateEntry *vmstate;
virtio_snd_config snd_conf;
} VirtIOSound;
QemuMutex cmdq_mutex;
QTAILQ_HEAD(, virtio_snd_ctrl_command) cmdq;
bool processing_cmdq;
};
struct virtio_snd_ctrl_command {
VirtQueueElement *elem;
VirtQueue *vq;
virtio_snd_hdr ctrl;
virtio_snd_hdr resp;
QTAILQ_ENTRY(virtio_snd_ctrl_command) next;
};
#endif

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