From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
This patch adds initial ANY_LAYOUT support with a new vhost_virtqueue
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, assuming the
layout of outgoing request header + T10_PI + Data payload comes first.
It also uses memcpy_fromiovec_out() 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.
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
---
drivers/vhost/scsi.c | 267 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 267 insertions(+)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index d2208a41..206f4ef 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -1087,6 +1087,273 @@ static void vhost_scsi_queue_desc(struct tcm_vhost_cmd *cmd, int desc)
}
static void
+vhost_scsi_handle_vqal(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
+{
+ struct tcm_vhost_tpg **vs_tpg;
+ struct virtio_scsi_cmd_req v_req;
+ struct virtio_scsi_cmd_req_pi v_req_pi;
+ struct tcm_vhost_tpg *tpg;
+ struct tcm_vhost_cmd *cmd;
+ struct iovec *iov, *iov_out, *prot_iov, *data_iov;
+ u64 tag;
+ u32 exp_data_len, data_direction;
+ unsigned out, in, i;
+ int head, ret, prot_bytes, iov_off, data_off, prot_off;
+ 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;
+ }
+ /*
+ * 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 + incoming
+ * WRITE payloads.
+ *
+ * memcpy_fromiovec_out() is modifying the iovecs as it
+ * copies over req_size bytes into req, so the returned
+ * iov_out will contain the correct start + offset of the
+ * incoming WRITE payload, if DMA_TO_DEVICE is set.
+ */
+ ret = memcpy_fromiovec_out(req, &vq->iov[0], &iov_out, req_size);
+ if (unlikely(ret)) {
+ vq_err(vq, "Faulted on virtio_scsi_cmd_req\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)) {
+ 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 memcpy_fromiovec_out()
+ * 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.
+ */
+ iov = data_iov = prot_iov = NULL;
+ iov_off = data_off = prot_off = 0;
+
+ if (data_direction == DMA_TO_DEVICE) {
+ iov = iov_out;
+ } else if (data_direction == DMA_FROM_DEVICE) {
+ int tmp_rsp_size = rsp_size;
+
+ for (i = out; i < out + in; i++) {
+ if (vq->iov[i].iov_len > tmp_rsp_size) {
+ iov = &vq->iov[i];
+ iov_off = tmp_rsp_size;
+ break;
+ } else if (vq->iov[i].iov_len == tmp_rsp_size) {
+ iov = &vq->iov[i+1];
+ break;
+ } else {
+ tmp_rsp_size -= vq->iov[i].iov_len;
+ }
+ }
+ }
+ /*
+ * If T10_PI header is present, setup prot_iov + prot_off values
+ * then recalculate data_iov + data_off for vhost_scsi_mapal()
+ * mapping from host scatterlists via get_user_pages_fast().
+ */
+ prot_bytes = 0;
+
+ if (t10_pi) {
+ int i = 0, tmp_prot_bytes;
+
+ if (v_req_pi.pi_bytesout) {
+ if (data_direction != DMA_TO_DEVICE) {
+ vq_err(vq, "Received non zero do_pi_niov"
+ ", 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 di_pi_niov"
+ ", 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_iov + prot_off values used by the iovec ->
+ * SGL mapping logic, then calculate the start of data
+ * payload after T10_PI and save to data_iov + data_off.
+ */
+ data_iov = prot_iov = iov;
+ data_off = prot_off = iov_off;
+ tmp_prot_bytes = prot_bytes;
+
+ while (tmp_prot_bytes) {
+ int iov_len = prot_iov[i].iov_len - iov_off;
+ int len = min(iov_len, tmp_prot_bytes);
+
+ if (tmp_prot_bytes -= len) {
+ i++;
+ iov_off = 0;
+ continue;
+ }
+ if (iov_len > len) {
+ data_iov = &prot_iov[i];
+ data_off = len;
+ } else if (iov_len == len) {
+ data_iov = &prot_iov[i+1];
+ data_off = 0;
+ }
+ }
+
+ exp_data_len -= 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 {
+ data_iov = iov;
+ data_off = iov_off;
+
+ 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 incoming 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];
+
+ 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_iov, prot_off,
+ exp_data_len, data_iov, data_off);
+ 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;
+ }
+ }
+ vhost_scsi_queue_desc(cmd, head);
+ }
+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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