[RFC v9 09/11] vhost/scsi: switch to buf APIs

Eugenio Pérez
2020-06-19T18:23:59Z

Switch to buf APIs. Doing this exposes a spec violation in vhost scsi:
all used bufs are marked with length 0.
Fix that is left for another day.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
drivers/vhost/scsi.c | 73 ++++++++++++++++++++++++++------------------
1 file changed, 44 insertions(+), 29 deletions(-)

diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 6fb4d7ecfa19..f09ca5244ab9 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -71,8 +71,8 @@ struct vhost_scsi_inflight {
};

struct vhost_scsi_cmd {
- /* Descriptor from vhost_get_vq_desc() for virt_queue segment */
- int tvc_vq_desc;
+ /* Descriptor from vhost_get_avail_buf() for virt_queue segment */
+ struct vhost_buf tvc_vq_desc;
/* virtio-scsi initiator task attribute */
int tvc_task_attr;
/* virtio-scsi response incoming iovecs */
@@ -213,7 +213,7 @@ struct vhost_scsi {
* Context for processing request and control queue operations.
*/
struct vhost_scsi_ctx {
- int head;
+ struct vhost_buf buf;
unsigned int out, in;
size_t req_size, rsp_size;
size_t out_size, in_size;
@@ -443,6 +443,20 @@ static int vhost_scsi_check_stop_free(struct se_cmd *se_cmd)
return target_put_sess_cmd(se_cmd);
}

+/* Signal to guest that request finished with no input buffer. */
+/* TODO calling this when writing into buffer and most likely a bug */
+static void vhost_scsi_signal_noinput(struct vhost_dev *vdev,
+ struct vhost_virtqueue *vq,
+ struct vhost_buf *bufp)
+{
+ struct vhost_buf buf = *bufp;
+
+ buf.in_len = 0;
+ vhost_put_used_buf(vq, &buf);
+ vhost_signal(vdev, vq);
+}
+
+
static void
vhost_scsi_do_evt_work(struct vhost_scsi *vs, struct vhost_scsi_evt *evt)
{
@@ -450,7 +464,8 @@ vhost_scsi_do_evt_work(struct vhost_scsi *vs, struct vhost_scsi_evt *evt)
struct virtio_scsi_event *event = &evt->event;
struct virtio_scsi_event __user *eventp;
unsigned out, in;
- int head, ret;
+ struct vhost_buf buf;
+ int ret;

if (!vhost_vq_get_backend(vq)) {
vs->vs_events_missed = true;
@@ -459,14 +474,14 @@ vhost_scsi_do_evt_work(struct vhost_scsi *vs, struct vhost_scsi_evt *evt)

again:
vhost_disable_notify(&vs->dev, vq);
- head = vhost_get_vq_desc(vq, vq->iov,
- ARRAY_SIZE(vq->iov), &out, &in,
- NULL, NULL);
- if (head < 0) {
+ ret = vhost_get_avail_buf(vq, &buf,
+ vq->iov, ARRAY_SIZE(vq->iov), &out, &in,
+ NULL, NULL);
+ if (ret < 0) {
vs->vs_events_missed = true;
return;
}
- if (head == vq->num) {
+ if (!ret) {
if (vhost_enable_notify(&vs->dev, vq))
goto again;
vs->vs_events_missed = true;
@@ -488,7 +503,7 @@ vhost_scsi_do_evt_work(struct vhost_scsi *vs, struct vhost_scsi_evt *evt)
eventp = vq->iov[out].iov_base;
ret = __copy_to_user(eventp, event, sizeof(*event));
if (!ret)
- vhost_add_used_and_signal(&vs->dev, vq, head, 0);
+ vhost_scsi_signal_noinput(&vs->dev, vq, &buf);
else
vq_err(vq, "Faulted on vhost_scsi_send_event\n");
}
@@ -549,7 +564,7 @@ static void vhost_scsi_complete_cmd_work(struct vhost_work *work)
ret = copy_to_iter(&v_rsp, sizeof(v_rsp), &iov_iter);
if (likely(ret == sizeof(v_rsp))) {
struct vhost_scsi_virtqueue *q;
- vhost_add_used(cmd->tvc_vq, cmd->tvc_vq_desc, 0);
+ vhost_put_used_buf(cmd->tvc_vq, &cmd->tvc_vq_desc);
q = container_of(cmd->tvc_vq, struct vhost_scsi_virtqueue, vq);
vq = q - vs->vqs;
__set_bit(vq, signal);
@@ -793,7 +808,7 @@ static void vhost_scsi_submission_work(struct work_struct *work)
static void
vhost_scsi_send_bad_target(struct vhost_scsi *vs,
struct vhost_virtqueue *vq,
- int head, unsigned out)
+ struct vhost_buf *buf, unsigned out)
{
struct virtio_scsi_cmd_resp __user *resp;
struct virtio_scsi_cmd_resp rsp;
@@ -804,7 +819,7 @@ vhost_scsi_send_bad_target(struct vhost_scsi *vs,
resp = vq->iov[out].iov_base;
ret = __copy_to_user(resp, &rsp, sizeof(rsp));
if (!ret)
- vhost_add_used_and_signal(&vs->dev, vq, head, 0);
+ vhost_scsi_signal_noinput(&vs->dev, vq, buf);
else
pr_err("Faulted on virtio_scsi_cmd_resp\n");
}
@@ -813,21 +828,21 @@ static int
vhost_scsi_get_desc(struct vhost_scsi *vs, struct vhost_virtqueue *vq,
struct vhost_scsi_ctx *vc)
{
- int ret = -ENXIO;
+ int r, ret = -ENXIO;

- vc->head = vhost_get_vq_desc(vq, vq->iov,
- ARRAY_SIZE(vq->iov), &vc->out, &vc->in,
- NULL, NULL);
+ r = vhost_get_avail_buf(vq, &vc->buf,
+ vq->iov, ARRAY_SIZE(vq->iov), &vc->out, &vc->in,
+ NULL, NULL);

- pr_debug("vhost_get_vq_desc: head: %d, out: %u in: %u\n",
- vc->head, vc->out, vc->in);
+ pr_debug("vhost_get_avail_buf: buf: %d, out: %u in: %u\n",
+ vc->buf.id, vc->out, vc->in);

/* On error, stop handling until the next kick. */
- if (unlikely(vc->head < 0))
+ if (unlikely(r < 0))
goto done;

/* Nothing new? Wait for eventfd to tell us they refilled. */
- if (vc->head == vq->num) {
+ if (!r) {
if (unlikely(vhost_enable_notify(&vs->dev, vq))) {
vhost_disable_notify(&vs->dev, vq);
ret = -EAGAIN;
@@ -1093,11 +1108,11 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
}
}
/*
- * Save the descriptor from vhost_get_vq_desc() to be used to
+ * Save the descriptor from vhost_get_avail_buf() to be used to
* complete the virtio-scsi request in TCM callback context via
* vhost_scsi_queue_data_in() and vhost_scsi_queue_status()
*/
- cmd->tvc_vq_desc = vc.head;
+ cmd->tvc_vq_desc = vc.buf;
/*
* Dispatch cmd descriptor for cmwq execution in process
* context provided by vhost_scsi_workqueue. This also ensures
@@ -1117,7 +1132,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
if (ret == -ENXIO)
break;
else if (ret == -EIO)
- vhost_scsi_send_bad_target(vs, vq, vc.head, vc.out);
+ vhost_scsi_send_bad_target(vs, vq, &vc.buf, vc.out);
} while (likely(!vhost_exceeds_weight(vq, ++c, 0)));
out:
mutex_unlock(&vq->mutex);
@@ -1139,9 +1154,9 @@ vhost_scsi_send_tmf_reject(struct vhost_scsi *vs,
iov_iter_init(&iov_iter, READ, &vq->iov[vc->out], vc->in, sizeof(rsp));

ret = copy_to_iter(&rsp, sizeof(rsp), &iov_iter);
- if (likely(ret == sizeof(rsp)))
- vhost_add_used_and_signal(&vs->dev, vq, vc->head, 0);
- else
+ if (likely(ret == sizeof(rsp))) {
+ vhost_scsi_signal_noinput(&vs->dev, vq, &vc->buf);
+ } else
pr_err("Faulted on virtio_scsi_ctrl_tmf_resp\n");
}

@@ -1162,7 +1177,7 @@ vhost_scsi_send_an_resp(struct vhost_scsi *vs,

ret = copy_to_iter(&rsp, sizeof(rsp), &iov_iter);
if (likely(ret == sizeof(rsp)))
- vhost_add_used_and_signal(&vs->dev, vq, vc->head, 0);
+ vhost_scsi_signal_noinput(&vs->dev, vq, &vc->buf);
else
pr_err("Faulted on virtio_scsi_ctrl_an_resp\n");
}
@@ -1269,7 +1284,7 @@ vhost_scsi_ctl_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
if (ret == -ENXIO)
break;
else if (ret == -EIO)
- vhost_scsi_send_bad_target(vs, vq, vc.head, vc.out);
+ vhost_scsi_send_bad_target(vs, vq, &vc.buf, vc.out);
} while (likely(!vhost_exceeds_weight(vq, ++c, 0)));
out:
mutex_unlock(&vq->mutex);
--
2.18.1