From c9019469c5689d860ee6ea5c4a9ea7caa5009daa Mon Sep 17 00:00:00 2001 From: Matias Ezequiel Vara Larsen Date: Tue, 17 Oct 2023 16:34:28 +0900 Subject: [PATCH] ALSA: virtio: use copy and fill_silence callbacks This commit replaces the mmap mechanism with the copy() and fill_silence() callbacks for both capturing and playback for the virtio-sound driver. This change is required to prevent the updating of the content of a buffer that is already in the available ring. The current mechanism splits a dma buffer into descriptors that are exposed to the device. This dma buffer is shared with the user application. When the device consumes a buffer, the driver moves the request from the used ring to available ring. The driver exposes the buffer to the device without knowing if the content has been updated from the user. The section 2.8.21.1 of the virtio spec states that: "The device MAY access the descriptor chains the driver created and the memory they refer to immediately". If the device picks up buffers from the available ring just after it is notified, it happens that the content may be old. By providing the copy() callback, the driver first updates the content of the buffer, and then, exposes the buffer to the device by enqueuing it in the available ring. Thus, device always picks up a buffer that is updated. For capturing, the driver starts by exposing all the available buffers to device. After device updates the content of a buffer, it enqueues it in the used ring. It is only after the copy() for capturing is issued that the driver re-enqueues the buffer in the available ring. Note that the copy() function assumes that user is always writing a period. Testing shows that this is true but I may be wrong. This RFC aims at clarifying this. Signed-off-by: Matias Ezequiel Vara Larsen --- sound/virtio/virtio_pcm.c | 7 ++- sound/virtio/virtio_pcm.h | 9 ++-- sound/virtio/virtio_pcm_msg.c | 87 +++++++++++++++++++++++------------ sound/virtio/virtio_pcm_ops.c | 81 ++++++++++++++++++++++++++------ 4 files changed, 135 insertions(+), 49 deletions(-) diff --git a/sound/virtio/virtio_pcm.c b/sound/virtio/virtio_pcm.c index c10d91fff2fb..66d67eef1bcc 100644 --- a/sound/virtio/virtio_pcm.c +++ b/sound/virtio/virtio_pcm.c @@ -104,12 +104,11 @@ static int virtsnd_pcm_build_hw(struct virtio_pcm_substream *vss, * only message-based transport. */ vss->hw.info = - SNDRV_PCM_INFO_MMAP | - SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_BATCH | SNDRV_PCM_INFO_BLOCK_TRANSFER | SNDRV_PCM_INFO_INTERLEAVED | - SNDRV_PCM_INFO_PAUSE; + SNDRV_PCM_INFO_PAUSE | + SNDRV_PCM_INFO_NO_REWINDS; if (!info->channels_min || info->channels_min > info->channels_max) { dev_err(&vdev->dev, @@ -471,7 +470,7 @@ int virtsnd_pcm_build_devs(struct virtio_snd *snd) for (kss = ks->substream; kss; kss = kss->next) vs->substreams[kss->number]->substream = kss; - snd_pcm_set_ops(vpcm->pcm, i, &virtsnd_pcm_ops); + snd_pcm_set_ops(vpcm->pcm, i, &virtsnd_pcm_ops[i]); } snd_pcm_set_managed_buffer_all(vpcm->pcm, diff --git a/sound/virtio/virtio_pcm.h b/sound/virtio/virtio_pcm.h index 062eb8e8f2cf..8b42928a8e01 100644 --- a/sound/virtio/virtio_pcm.h +++ b/sound/virtio/virtio_pcm.h @@ -57,7 +57,6 @@ struct virtio_pcm_substream { bool suspended; struct virtio_pcm_msg **msgs; unsigned int nmsgs; - int msg_last_enqueued; unsigned int msg_count; wait_queue_head_t msg_empty; }; @@ -90,7 +89,7 @@ struct virtio_pcm { struct virtio_pcm_stream streams[SNDRV_PCM_STREAM_LAST + 1]; }; -extern const struct snd_pcm_ops virtsnd_pcm_ops; +extern const struct snd_pcm_ops virtsnd_pcm_ops[]; int virtsnd_pcm_validate(struct virtio_device *vdev); @@ -117,7 +116,11 @@ int virtsnd_pcm_msg_alloc(struct virtio_pcm_substream *vss, void virtsnd_pcm_msg_free(struct virtio_pcm_substream *vss); -int virtsnd_pcm_msg_send(struct virtio_pcm_substream *vss); +int virtsnd_pcm_msg_send(struct virtio_pcm_substream *vss, unsigned long offset, + unsigned long bytes); + +int virtsnd_pcm_msg_send_locked(struct virtio_pcm_substream *vss, + unsigned long offset, unsigned long bytes); unsigned int virtsnd_pcm_msg_pending_num(struct virtio_pcm_substream *vss); diff --git a/sound/virtio/virtio_pcm_msg.c b/sound/virtio/virtio_pcm_msg.c index aca2dc1989ba..3bc0a61a046d 100644 --- a/sound/virtio/virtio_pcm_msg.c +++ b/sound/virtio/virtio_pcm_msg.c @@ -155,7 +155,6 @@ int virtsnd_pcm_msg_alloc(struct virtio_pcm_substream *vss, sizeof(msg->xfer)); sg_init_one(&msg->sgs[PCM_MSG_SG_STATUS], &msg->status, sizeof(msg->status)); - msg->length = period_bytes; virtsnd_pcm_sg_from(&msg->sgs[PCM_MSG_SG_DATA], sg_num, data, period_bytes); @@ -198,49 +197,63 @@ void virtsnd_pcm_msg_free(struct virtio_pcm_substream *vss) * spinlocks to be held by caller. * Return: 0 on success, -errno on failure. */ -int virtsnd_pcm_msg_send(struct virtio_pcm_substream *vss) +int virtsnd_pcm_msg_send(struct virtio_pcm_substream *vss, unsigned long offset, + unsigned long bytes) { - struct snd_pcm_runtime *runtime = vss->substream->runtime; struct virtio_snd *snd = vss->snd; struct virtio_device *vdev = snd->vdev; struct virtqueue *vqueue = virtsnd_pcm_queue(vss)->vqueue; - int i; - int n; + unsigned long period_bytes = snd_pcm_lib_period_bytes(vss->substream); + unsigned long start, end, i; + unsigned int msg_count = vss->msg_count; bool notify = false; + int rc; - i = (vss->msg_last_enqueued + 1) % runtime->periods; - n = runtime->periods - vss->msg_count; + start = offset / period_bytes; + end = (offset + bytes - 1) / period_bytes; - for (; n; --n, i = (i + 1) % runtime->periods) { + for (i = start; i <= end; i++) { struct virtio_pcm_msg *msg = vss->msgs[i]; struct scatterlist *psgs[] = { &msg->sgs[PCM_MSG_SG_XFER], &msg->sgs[PCM_MSG_SG_DATA], &msg->sgs[PCM_MSG_SG_STATUS] }; - int rc; - - msg->xfer.stream_id = cpu_to_le32(vss->sid); - memset(&msg->status, 0, sizeof(msg->status)); - - if (vss->direction == SNDRV_PCM_STREAM_PLAYBACK) - rc = virtqueue_add_sgs(vqueue, psgs, 2, 1, msg, - GFP_ATOMIC); - else - rc = virtqueue_add_sgs(vqueue, psgs, 1, 2, msg, - GFP_ATOMIC); - - if (rc) { - dev_err(&vdev->dev, - "SID %u: failed to send I/O message\n", - vss->sid); - return rc; + unsigned long n; + + n = period_bytes - (offset % period_bytes); + if (n > bytes) + n = bytes; + + msg->length += n; + if (msg->length == period_bytes) { + msg->xfer.stream_id = cpu_to_le32(vss->sid); + memset(&msg->status, 0, sizeof(msg->status)); + + if (vss->direction == SNDRV_PCM_STREAM_PLAYBACK) + rc = virtqueue_add_sgs(vqueue, psgs, 2, 1, msg, + GFP_ATOMIC); + else + rc = virtqueue_add_sgs(vqueue, psgs, 1, 2, msg, + GFP_ATOMIC); + + if (rc) { + dev_err(&vdev->dev, + "SID %u: failed to send I/O message\n", + vss->sid); + return rc; + } + + vss->msg_count++; } - vss->msg_last_enqueued = i; - vss->msg_count++; + offset = 0; + bytes -= n; } + if (msg_count == vss->msg_count) + return 0; + if (!(vss->features & (1U << VIRTIO_SND_PCM_F_MSG_POLLING))) notify = virtqueue_kick_prepare(vqueue); @@ -250,6 +263,22 @@ int virtsnd_pcm_msg_send(struct virtio_pcm_substream *vss) return 0; } +int virtsnd_pcm_msg_send_locked(struct virtio_pcm_substream *vss, + unsigned long offset, unsigned long bytes) +{ + struct virtio_snd_queue *queue = virtsnd_pcm_queue(vss); + unsigned long flags; + int rc; + + spin_lock_irqsave(&queue->lock, flags); + spin_lock(&vss->lock); + rc = virtsnd_pcm_msg_send(vss, offset, bytes); + spin_unlock(&vss->lock); + spin_unlock_irqrestore(&queue->lock, flags); + + return rc; +} + /** * virtsnd_pcm_msg_pending_num() - Returns the number of pending I/O messages. * @vss: VirtIO substream. @@ -309,6 +338,8 @@ static void virtsnd_pcm_msg_complete(struct virtio_pcm_msg *msg, if (vss->hw_ptr >= vss->buffer_bytes) vss->hw_ptr -= vss->buffer_bytes; + msg->length = 0; + vss->xfer_xrun = false; vss->msg_count--; @@ -320,8 +351,6 @@ static void virtsnd_pcm_msg_complete(struct virtio_pcm_msg *msg, le32_to_cpu(msg->status.latency_bytes)); schedule_work(&vss->elapsed_period); - - virtsnd_pcm_msg_send(vss); } else if (!vss->msg_count) { wake_up_all(&vss->msg_empty); } diff --git a/sound/virtio/virtio_pcm_ops.c b/sound/virtio/virtio_pcm_ops.c index f8bfb87624be..4569b285f520 100644 --- a/sound/virtio/virtio_pcm_ops.c +++ b/sound/virtio/virtio_pcm_ops.c @@ -282,7 +282,6 @@ static int virtsnd_pcm_prepare(struct snd_pcm_substream *substream) vss->buffer_bytes = snd_pcm_lib_buffer_bytes(substream); vss->hw_ptr = 0; - vss->msg_last_enqueued = -1; } else { struct snd_pcm_runtime *runtime = substream->runtime; unsigned int buffer_bytes = snd_pcm_lib_buffer_bytes(substream); @@ -324,7 +323,7 @@ static int virtsnd_pcm_trigger(struct snd_pcm_substream *substream, int command) struct virtio_snd_queue *queue; struct virtio_snd_msg *msg; unsigned long flags; - int rc; + int rc = 0; switch (command) { case SNDRV_PCM_TRIGGER_START: @@ -333,7 +332,8 @@ static int virtsnd_pcm_trigger(struct snd_pcm_substream *substream, int command) spin_lock_irqsave(&queue->lock, flags); spin_lock(&vss->lock); - rc = virtsnd_pcm_msg_send(vss); + if (vss->direction == SNDRV_PCM_STREAM_CAPTURE) + rc = virtsnd_pcm_msg_send(vss, 0, vss->buffer_bytes); if (!rc) vss->xfer_enabled = true; spin_unlock(&vss->lock); @@ -450,15 +450,70 @@ virtsnd_pcm_pointer(struct snd_pcm_substream *substream) return hw_ptr; } +static int virtsnd_pcm_pb_silence(struct snd_pcm_substream *substream, + int channel, unsigned long pos, + unsigned long bytes) +{ + struct virtio_pcm_substream *vss = snd_pcm_substream_chip(substream); + struct snd_pcm_runtime *runtime = substream->runtime; + + snd_pcm_format_set_silence(runtime->format, runtime->dma_area + pos, + bytes_to_samples(runtime, bytes)); + + return virtsnd_pcm_msg_send_locked(vss, pos, bytes); +} + +static int virtsnd_pcm_pb_copy(struct snd_pcm_substream *substream, int channel, + unsigned long pos, struct iov_iter *iter, + unsigned long bytes) +{ + struct virtio_pcm_substream *vss = snd_pcm_substream_chip(substream); + struct snd_pcm_runtime *runtime = substream->runtime; + + if (copy_from_iter(runtime->dma_area + pos, bytes, iter) != bytes) + return -EFAULT; + + return virtsnd_pcm_msg_send_locked(vss, pos, bytes); +} + +static int virtsnd_pcm_cp_copy(struct snd_pcm_substream *substream, int channel, + unsigned long pos, struct iov_iter *iter, + unsigned long bytes) +{ + struct virtio_pcm_substream *vss = snd_pcm_substream_chip(substream); + struct snd_pcm_runtime *runtime = substream->runtime; + + if (copy_to_iter(runtime->dma_area + pos, bytes, iter) != bytes) + return -EFAULT; + + return virtsnd_pcm_msg_send_locked(vss, pos, bytes); +} + /* PCM substream operators map. */ -const struct snd_pcm_ops virtsnd_pcm_ops = { - .open = virtsnd_pcm_open, - .close = virtsnd_pcm_close, - .ioctl = snd_pcm_lib_ioctl, - .hw_params = virtsnd_pcm_hw_params, - .hw_free = virtsnd_pcm_hw_free, - .prepare = virtsnd_pcm_prepare, - .trigger = virtsnd_pcm_trigger, - .sync_stop = virtsnd_pcm_sync_stop, - .pointer = virtsnd_pcm_pointer, +const struct snd_pcm_ops virtsnd_pcm_ops[] = { + { + .open = virtsnd_pcm_open, + .close = virtsnd_pcm_close, + .ioctl = snd_pcm_lib_ioctl, + .hw_params = virtsnd_pcm_hw_params, + .hw_free = virtsnd_pcm_hw_free, + .prepare = virtsnd_pcm_prepare, + .trigger = virtsnd_pcm_trigger, + .sync_stop = virtsnd_pcm_sync_stop, + .pointer = virtsnd_pcm_pointer, + .copy = virtsnd_pcm_pb_copy, + .fill_silence = virtsnd_pcm_pb_silence, + }, + { + .open = virtsnd_pcm_open, + .close = virtsnd_pcm_close, + .ioctl = snd_pcm_lib_ioctl, + .hw_params = virtsnd_pcm_hw_params, + .hw_free = virtsnd_pcm_hw_free, + .prepare = virtsnd_pcm_prepare, + .trigger = virtsnd_pcm_trigger, + .sync_stop = virtsnd_pcm_sync_stop, + .pointer = virtsnd_pcm_pointer, + .copy = virtsnd_pcm_cp_copy, + }, }; -- 2.42.0