From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
This patch adds ANY_LAYOUT support with a new vqs[].vq.handle_kick()
callback in vhost_scsi_handle_vqal().
It calculates data_direction + exp_data_len for the new tcm_vhost_cmd
descriptor by walking both outgoing + incoming iovecs using iov_iter,
assuming the layout of outgoing request header + T10_PI + Data payload
comes first.
It also uses copy_from_iter() to copy leading virtio-scsi request header
that may or may not include SCSI CDB, that returns a re-calculated iovec
to start of T10_PI or Data SGL memory.
v2 changes:
- Fix up vhost_scsi_handle_vqal comments
- Minor vhost_scsi_handle_vqal simplifications
- Add missing minimum virtio-scsi response buffer size check
- Fix pi_bytes* error message typo
- Convert to use vhost_skip_iovec_bytes() common code
- Add max_niov sanity checks vs. out + in offset into vq
v3 changes:
- Convert to copy_from_iter usage
- Update vhost_scsi_handle_vqal comments for iov_iter usage
- Convert prot_bytes offset to use iov_iter_advance
- Drop max_niov usage in vhost_scsi_handle_vqal
- Drop vhost_skip_iovec_bytes in favour of iov_iter
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/vhost/scsi.c | 260 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 260 insertions(+)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 7dfff15..e1fe003 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -1062,6 +1062,266 @@ vhost_scsi_send_bad_target(struct vhost_scsi *vs,
}
static void
+vhost_scsi_handle_vqal(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
+{
+ struct tcm_vhost_tpg **vs_tpg, *tpg;
+ struct virtio_scsi_cmd_req v_req;
+ struct virtio_scsi_cmd_req_pi v_req_pi;
+ struct tcm_vhost_cmd *cmd;
+ struct iov_iter out_iter, in_iter, prot_iter, data_iter;
+ u64 tag;
+ u32 exp_data_len, data_direction;
+ unsigned out, in, i;
+ int head, ret, prot_bytes;
+ size_t req_size, rsp_size = sizeof(struct virtio_scsi_cmd_resp);
+ size_t out_size, in_size;
+ u16 lun;
+ u8 *target, *lunp, task_attr;
+ bool t10_pi = vhost_has_feature(vq, VIRTIO_SCSI_F_T10_PI);
+ void *req, *cdb;
+
+ mutex_lock(&vq->mutex);
+ /*
+ * We can handle the vq only after the endpoint is setup by calling the
+ * VHOST_SCSI_SET_ENDPOINT ioctl.
+ */
+ vs_tpg = vq->private_data;
+ if (!vs_tpg)
+ goto out;
+
+ vhost_disable_notify(&vs->dev, vq);
+
+ for (;;) {
+ head = vhost_get_vq_desc(vq, vq->iov,
+ ARRAY_SIZE(vq->iov), &out, &in,
+ NULL, NULL);
+ pr_debug("vhost_get_vq_desc: head: %d, out: %u in: %u\n",
+ head, out, in);
+ /* On error, stop handling until the next kick. */
+ if (unlikely(head < 0))
+ break;
+ /* Nothing new? Wait for eventfd to tell us they refilled. */
+ if (head == vq->num) {
+ if (unlikely(vhost_enable_notify(&vs->dev, vq))) {
+ vhost_disable_notify(&vs->dev, vq);
+ continue;
+ }
+ break;
+ }
+ /*
+ * Check for a sane response buffer so we can report early
+ * errors back to the guest.
+ */
+ if (unlikely(vq->iov[out].iov_len < rsp_size)) {
+ vq_err(vq, "Expecting at least virtio_scsi_cmd_resp"
+ " size, got %zu bytes\n", vq->iov[out].iov_len);
+ break;
+ }
+ /*
+ * Setup pointers and values based upon different virtio-scsi
+ * request header if T10_PI is enabled in KVM guest.
+ */
+ if (t10_pi) {
+ req = &v_req_pi;
+ req_size = sizeof(v_req_pi);
+ lunp = &v_req_pi.lun[0];
+ target = &v_req_pi.lun[1];
+ } else {
+ req = &v_req;
+ req_size = sizeof(v_req);
+ lunp = &v_req.lun[0];
+ target = &v_req.lun[1];
+ }
+ /*
+ * Determine data_direction for ANY_LAYOUT by calculating the
+ * total outgoing iovec sizes / incoming iovec sizes vs.
+ * virtio-scsi request / response headers respectively.
+ *
+ * FIXME: Not correct for BIDI operation
+ */
+ out_size = in_size = 0;
+ for (i = 0; i < out; i++)
+ out_size += vq->iov[i].iov_len;
+ for (i = out; i < out + in; i++)
+ in_size += vq->iov[i].iov_len;
+ /*
+ * Any associated T10_PI bytes for the outgoing / incoming
+ * payloads are included in calculation of exp_data_len here.
+ */
+ if (out_size > req_size) {
+ data_direction = DMA_TO_DEVICE;
+ exp_data_len = out_size - req_size;
+ } else if (in_size > rsp_size) {
+ data_direction = DMA_FROM_DEVICE;
+ exp_data_len = in_size - rsp_size;
+ } else {
+ data_direction = DMA_NONE;
+ exp_data_len = 0;
+ }
+ /*
+ * Copy over the virtio-scsi request header, which when
+ * ANY_LAYOUT is enabled may span multiple iovecs, or a
+ * single iovec may contain both the header + outgoing
+ * WRITE payloads.
+ *
+ * copy_from_iter() is modifying the iovecs as copies over
+ * req_size bytes into req, so the returned out_iter.iov[0]
+ * will contain the correct start + offset of the outgoing
+ * WRITE payload, if DMA_TO_DEVICE is set.
+ */
+ iov_iter_init(&out_iter, READ, &vq->iov[0], out,
+ (data_direction == DMA_TO_DEVICE) ?
+ req_size + exp_data_len : req_size);
+
+ ret = copy_from_iter(req, req_size, &out_iter);
+ if (unlikely(ret != req_size)) {
+ vq_err(vq, "Faulted on copy_from_iter\n");
+ vhost_scsi_send_bad_target(vs, vq, head, out);
+ continue;
+ }
+ /* virtio-scsi spec requires byte 0 of the lun to be 1 */
+ if (unlikely(*lunp != 1)) {
+ vq_err(vq, "Illegal virtio-scsi lun: %u\n", *lunp);
+ vhost_scsi_send_bad_target(vs, vq, head, out);
+ continue;
+ }
+
+ tpg = ACCESS_ONCE(vs_tpg[*target]);
+ if (unlikely(!tpg)) {
+ /* Target does not exist, fail the request */
+ vhost_scsi_send_bad_target(vs, vq, head, out);
+ continue;
+ }
+ /*
+ * Determine start of T10_PI or data payload iovec in ANY_LAYOUT
+ * mode based upon data_direction.
+ *
+ * For DMA_TO_DEVICE, this is iov_out from copy_from_iter()
+ * with the already recalculated iov_base + iov_len.
+ *
+ * For DMA_FROM_DEVICE, the iovec will be just past the end
+ * of the virtio-scsi response header in either the same
+ * or immediately following iovec.
+ */
+ prot_bytes = 0;
+
+ if (data_direction == DMA_TO_DEVICE) {
+ data_iter = out_iter;
+ } else if (data_direction == DMA_FROM_DEVICE) {
+ iov_iter_init(&in_iter, WRITE, &vq->iov[out], in,
+ rsp_size + exp_data_len);
+ iov_iter_advance(&in_iter, rsp_size);
+ data_iter = in_iter;
+ }
+ /*
+ * If T10_PI header + payload is present, setup prot_iter values
+ * and recalculate data_iter for vhost_scsi_mapal() mapping to
+ * host scatterlists via get_user_pages_fast().
+ */
+ if (t10_pi) {
+ if (v_req_pi.pi_bytesout) {
+ if (data_direction != DMA_TO_DEVICE) {
+ vq_err(vq, "Received non zero pi_bytesout,"
+ " but wrong data_direction\n");
+ vhost_scsi_send_bad_target(vs, vq, head, out);
+ continue;
+ }
+ prot_bytes = vhost32_to_cpu(vq, v_req_pi.pi_bytesout);
+ } else if (v_req_pi.pi_bytesin) {
+ if (data_direction != DMA_FROM_DEVICE) {
+ vq_err(vq, "Received non zero pi_bytesin,"
+ " but wrong data_direction\n");
+ vhost_scsi_send_bad_target(vs, vq, head, out);
+ continue;
+ }
+ prot_bytes = vhost32_to_cpu(vq, v_req_pi.pi_bytesin);
+ }
+ /*
+ * Set prot_iter to data_iter, and advance past any
+ * preceeding prot_bytes that may be present.
+ *
+ * Also fix up the exp_data_len to reflect only the
+ * actual data payload length.
+ */
+ if (prot_bytes) {
+ exp_data_len -= prot_bytes;
+ prot_iter = data_iter;
+ iov_iter_advance(&data_iter, prot_bytes);
+ }
+ tag = vhost64_to_cpu(vq, v_req_pi.tag);
+ task_attr = v_req_pi.task_attr;
+ cdb = &v_req_pi.cdb[0];
+ lun = ((v_req_pi.lun[2] << 8) | v_req_pi.lun[3]) & 0x3FFF;
+ } else {
+ tag = vhost64_to_cpu(vq, v_req.tag);
+ task_attr = v_req.task_attr;
+ cdb = &v_req.cdb[0];
+ lun = ((v_req.lun[2] << 8) | v_req.lun[3]) & 0x3FFF;
+ }
+ /*
+ * Check that the recieved CDB size does not exceeded our
+ * hardcoded max for vhost-scsi, then get a pre-allocated
+ * cmd descriptor for the new virtio-scsi tag.
+ *
+ * TODO what if cdb was too small for varlen cdb header?
+ */
+ if (unlikely(scsi_command_size(cdb) > TCM_VHOST_MAX_CDB_SIZE)) {
+ vq_err(vq, "Received SCSI CDB with command_size: %d that"
+ " exceeds SCSI_MAX_VARLEN_CDB_SIZE: %d\n",
+ scsi_command_size(cdb), TCM_VHOST_MAX_CDB_SIZE);
+ vhost_scsi_send_bad_target(vs, vq, head, out);
+ continue;
+ }
+ cmd = vhost_scsi_get_tag(vq, tpg, cdb, tag, lun, task_attr,
+ exp_data_len + prot_bytes,
+ data_direction);
+ if (IS_ERR(cmd)) {
+ vq_err(vq, "vhost_scsi_get_tag failed %ld\n",
+ PTR_ERR(cmd));
+ vhost_scsi_send_bad_target(vs, vq, head, out);
+ continue;
+ }
+ cmd->tvc_vhost = vs;
+ cmd->tvc_vq = vq;
+ cmd->tvc_resp_iov = &vq->iov[out];
+ cmd->tvc_in_iovs = in;
+
+ pr_debug("vhost_scsi got command opcode: %#02x, lun: %d\n",
+ cmd->tvc_cdb[0], cmd->tvc_lun);
+ pr_debug("cmd: %p exp_data_len: %d, prot_bytes: %d data_direction:"
+ " %d\n", cmd, exp_data_len, prot_bytes, data_direction);
+
+ if (data_direction != DMA_NONE) {
+ ret = vhost_scsi_mapal(cmd,
+ prot_bytes, &prot_iter,
+ exp_data_len, &data_iter);
+ if (unlikely(ret)) {
+ vq_err(vq, "Failed to map iov to sgl\n");
+ tcm_vhost_release_cmd(&cmd->tvc_se_cmd);
+ vhost_scsi_send_bad_target(vs, vq, head, out);
+ continue;
+ }
+ }
+ /*
+ * Save the descriptor from vhost_get_vq_desc() 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 = head;
+ /*
+ * Dispatch cmd descriptor for cmwq execution in process
+ * context provided by vhost_scsi_workqueue. This also ensures
+ * cmd is executed on the same kworker CPU as this vhost
+ * thread to gain positive L2 cache locality effects.
+ */
+ INIT_WORK(&cmd->work, tcm_vhost_submission_work);
+ queue_work(tcm_vhost_workqueue, &cmd->work);
+ }
+out:
+ mutex_unlock(&vq->mutex);
+}
+
+static void
vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
{
struct tcm_vhost_tpg **vs_tpg;
--
1.9.1
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