From 0d02dbd68c47b66367130b696baef7246720791c Mon Sep 17 00:00:00 2001 From: Bijan Mottahedeh Date: Mon, 17 Sep 2018 17:09:47 -0700 Subject: vhost/scsi: Respond to control queue operations The vhost-scsi driver currently does not handle any control queue operations. In particular, vhost_scsi_ctl_handle_kick, merely prints out a debug message but does nothing else. This can cause guest VMs to hang. As part of SCSI recovery from an error, e.g., an I/O timeout, the SCSI midlayer attempts to abort the failed operation. The SCSI virtio driver translates the abort to a SCSI TMF request that gets put on the control queue (virtscsi_abort -> virtscsi_tmf). The SCSI virtio driver then waits indefinitely for this request to be completed, but it never will because vhost-scsi never responds to that request. To avoid a hang, always respond to control queue operations; explicitly reject TMF requests, and return a no-op response to event requests. Signed-off-by: Bijan Mottahedeh Signed-off-by: Michael S. Tsirkin --- drivers/vhost/scsi.c | 190 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 190 insertions(+) (limited to 'drivers/vhost') diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c index e7e3ae13516d..1c33d6e39152 100644 --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -1050,9 +1050,199 @@ out: mutex_unlock(&vq->mutex); } +static void +vhost_scsi_send_tmf_resp(struct vhost_scsi *vs, + struct vhost_virtqueue *vq, + int head, unsigned int out) +{ + struct virtio_scsi_ctrl_tmf_resp __user *resp; + struct virtio_scsi_ctrl_tmf_resp rsp; + int ret; + + pr_debug("%s\n", __func__); + memset(&rsp, 0, sizeof(rsp)); + rsp.response = VIRTIO_SCSI_S_FUNCTION_REJECTED; + 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); + else + pr_err("Faulted on virtio_scsi_ctrl_tmf_resp\n"); +} + +static void +vhost_scsi_send_an_resp(struct vhost_scsi *vs, + struct vhost_virtqueue *vq, + int head, unsigned int out) +{ + struct virtio_scsi_ctrl_an_resp __user *resp; + struct virtio_scsi_ctrl_an_resp rsp; + int ret; + + pr_debug("%s\n", __func__); + memset(&rsp, 0, sizeof(rsp)); /* event_actual = 0 */ + rsp.response = VIRTIO_SCSI_S_OK; + 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); + else + pr_err("Faulted on virtio_scsi_ctrl_an_resp\n"); +} + +static void +vhost_scsi_ctl_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq) +{ + union { + __virtio32 type; + struct virtio_scsi_ctrl_an_req an; + struct virtio_scsi_ctrl_tmf_req tmf; + } v_req; + struct iov_iter out_iter; + unsigned int out = 0, in = 0; + int head; + size_t req_size, rsp_size, typ_size; + size_t out_size, in_size; + u8 *lunp; + void *req; + + mutex_lock(&vq->mutex); + /* + * We can handle the vq only after the endpoint is setup by calling the + * VHOST_SCSI_SET_ENDPOINT ioctl. + */ + if (!vq->private_data) + 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; + } + + /* + * Get the size of request and response buffers. + */ + out_size = iov_length(vq->iov, out); + in_size = iov_length(&vq->iov[out], in); + + /* + * Copy over the virtio-scsi request header, which for a + * ANY_LAYOUT enabled guest may span multiple iovecs, or a + * single iovec may contain both the header + outgoing + * WRITE payloads. + * + * copy_from_iter() will advance out_iter, so that it will + * point at the start of the outgoing WRITE payload, if + * DMA_TO_DEVICE is set. + */ + iov_iter_init(&out_iter, WRITE, vq->iov, out, out_size); + + req = &v_req.type; + typ_size = sizeof(v_req.type); + + if (unlikely(!copy_from_iter_full(req, typ_size, &out_iter))) { + vq_err(vq, "Faulted on copy_from_iter tmf type\n"); + /* + * The size of the response buffer varies based on + * the request type and must be validated against it. + * Since the request type is not known, don't send + * a response. + */ + continue; + } + + switch (v_req.type) { + case VIRTIO_SCSI_T_TMF: + req = &v_req.tmf; + lunp = &v_req.tmf.lun[0]; + req_size = sizeof(struct virtio_scsi_ctrl_tmf_req); + rsp_size = sizeof(struct virtio_scsi_ctrl_tmf_resp); + break; + case VIRTIO_SCSI_T_AN_QUERY: + case VIRTIO_SCSI_T_AN_SUBSCRIBE: + req = &v_req.an; + lunp = &v_req.an.lun[0]; + req_size = sizeof(struct virtio_scsi_ctrl_an_req); + rsp_size = sizeof(struct virtio_scsi_ctrl_an_resp); + break; + default: + vq_err(vq, "Unknown control request %d", v_req.type); + continue; + } + + /* + * Check for a sane response buffer so we can report early + * errors back to the guest. + */ + if (unlikely(in_size < rsp_size)) { + vq_err(vq, + "Resp buf too small, need min %zu bytes got %zu", + rsp_size, in_size); + /* + * Notifications are disabled at this point; + * continue so they can be eventually enabled + * when processing terminates. + */ + continue; + } + + if (unlikely(out_size < req_size)) { + vq_err(vq, + "Req buf too small, need min %zu bytes got %zu", + req_size, out_size); + vhost_scsi_send_bad_target(vs, vq, head, out); + continue; + } + + req += typ_size; + req_size -= typ_size; + + if (unlikely(!copy_from_iter_full(req, req_size, &out_iter))) { + 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; + } + + if (v_req.type == VIRTIO_SCSI_T_TMF) { + pr_debug("%s tmf %d\n", __func__, v_req.tmf.subtype); + vhost_scsi_send_tmf_resp(vs, vq, head, out); + } else + vhost_scsi_send_an_resp(vs, vq, head, out); + } +out: + mutex_unlock(&vq->mutex); +} + static void vhost_scsi_ctl_handle_kick(struct vhost_work *work) { + struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue, + poll.work); + struct vhost_scsi *vs = container_of(vq->dev, struct vhost_scsi, dev); + pr_debug("%s: The handling func for control queue.\n", __func__); + vhost_scsi_ctl_handle_vq(vs, vq); } static void -- cgit v1.2.3-59-g8ed1b