Hi,
> -----Original Message-----
> From: Ferry Meng <[email protected]>
> Sent: Wednesday, December 18, 2024 5:25 PM
> To: Michael S . Tsirkin <[email protected]>; Jason Wang
> <[email protected]>; [email protected]; Jens Axboe
> <[email protected]>; [email protected]
> Cc: [email protected]; [email protected]; Stefan Hajnoczi
> <[email protected]>; Christoph Hellwig <[email protected]>; Joseph Qi
> <[email protected]>; Jeffle Xu <[email protected]>; Ferry
> Meng <[email protected]>
> Subject: [PATCH v1 2/3] virtio-blk: add uring_cmd support for I/O passthru on
> chardev.
>
> Add ->uring_cmd() support for virtio-blk chardev (/dev/vdXc0).
> According to virtio spec, in addition to passing 'hdr' info into kernel, we
> also
> need to pass vaddr & data length of the 'iov' requeired for the writev/readv
> op.
>
> Signed-off-by: Ferry Meng <[email protected]>
> ---
> drivers/block/virtio_blk.c | 223 +++++++++++++++++++++++++++++++-
> include/uapi/linux/virtio_blk.h | 16 +++
> 2 files changed, 235 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c index
> 3487aaa67514..cd88cf939144 100644
> --- a/drivers/block/virtio_blk.c
> +++ b/drivers/block/virtio_blk.c
> @@ -18,6 +18,9 @@
> #include <linux/vmalloc.h>
> #include <uapi/linux/virtio_ring.h>
> #include <linux/cdev.h>
> +#include <linux/io_uring/cmd.h>
> +#include <linux/types.h>
> +#include <linux/uio.h>
>
> #define PART_BITS 4
> #define VQ_NAME_LEN 16
> @@ -54,6 +57,20 @@ static struct class *vd_chr_class;
>
> static struct workqueue_struct *virtblk_wq;
>
> +struct virtblk_uring_cmd_pdu {
> + struct request *req;
> + struct bio *bio;
> + int status;
> +};
> +
> +struct virtblk_command {
> + struct virtio_blk_outhdr out_hdr;
> +
> + __u64 data;
> + __u32 data_len;
> + __u32 flag;
> +};
> +
> struct virtio_blk_vq {
> struct virtqueue *vq;
> spinlock_t lock;
> @@ -122,6 +139,11 @@ struct virtblk_req {
> struct scatterlist sg[];
> };
>
> +static void __user *virtblk_to_user_ptr(uintptr_t ptrval) {
> + return (void __user *)ptrval;
> +}
> +
> static inline blk_status_t virtblk_result(u8 status) {
> switch (status) {
> @@ -259,9 +281,6 @@ static blk_status_t virtblk_setup_cmd(struct
> virtio_device *vdev,
> if (!IS_ENABLED(CONFIG_BLK_DEV_ZONED) &&
> op_is_zone_mgmt(req_op(req)))
> return BLK_STS_NOTSUPP;
>
> - /* Set fields for all request types */
> - vbr->out_hdr.ioprio = cpu_to_virtio32(vdev, req_get_ioprio(req));
> -
> switch (req_op(req)) {
> case REQ_OP_READ:
> type = VIRTIO_BLK_T_IN;
> @@ -309,9 +328,11 @@ static blk_status_t virtblk_setup_cmd(struct
> virtio_device *vdev,
> type = VIRTIO_BLK_T_ZONE_RESET_ALL;
> break;
> case REQ_OP_DRV_IN:
> + case REQ_OP_DRV_OUT:
> /*
> * Out header has already been prepared by the caller
> (virtblk_get_id()
> - * or virtblk_submit_zone_report()), nothing to do here.
> + * virtblk_submit_zone_report() or io_uring passthrough cmd),
> nothing
> + * to do here.
> */
> return 0;
> default:
> @@ -323,6 +344,7 @@ static blk_status_t virtblk_setup_cmd(struct
> virtio_device *vdev,
> vbr->in_hdr_len = in_hdr_len;
> vbr->out_hdr.type = cpu_to_virtio32(vdev, type);
> vbr->out_hdr.sector = cpu_to_virtio64(vdev, sector);
> + vbr->out_hdr.ioprio = cpu_to_virtio32(vdev, req_get_ioprio(req));
>
> if (type == VIRTIO_BLK_T_DISCARD || type ==
> VIRTIO_BLK_T_WRITE_ZEROES ||
> type == VIRTIO_BLK_T_SECURE_ERASE) { @@ -832,6 +854,7 @@
> static int virtblk_get_id(struct gendisk *disk, char *id_str)
> vbr = blk_mq_rq_to_pdu(req);
> vbr->in_hdr_len = sizeof(vbr->in_hdr.status);
> vbr->out_hdr.type = cpu_to_virtio32(vblk->vdev,
> VIRTIO_BLK_T_GET_ID);
> + vbr->out_hdr.ioprio = cpu_to_virtio32(vblk->vdev,
> +req_get_ioprio(req));
> vbr->out_hdr.sector = 0;
>
> err = blk_rq_map_kern(q, req, id_str, VIRTIO_BLK_ID_BYTES,
> GFP_KERNEL); @@ -1250,6 +1273,197 @@ static const struct blk_mq_ops
> virtio_mq_ops = {
> .poll = virtblk_poll,
> };
>
> +static inline struct virtblk_uring_cmd_pdu *virtblk_get_uring_cmd_pdu(
> + struct io_uring_cmd *ioucmd)
> +{
> + return (struct virtblk_uring_cmd_pdu *)&ioucmd->pdu; }
> +
> +static void virtblk_uring_task_cb(struct io_uring_cmd *ioucmd,
> + unsigned int issue_flags)
> +{
> + struct virtblk_uring_cmd_pdu *pdu =
> virtblk_get_uring_cmd_pdu(ioucmd);
> + struct virtblk_req *vbr = blk_mq_rq_to_pdu(pdu->req);
> + u64 result = 0;
> +
> + if (pdu->bio)
> + blk_rq_unmap_user(pdu->bio);
> +
> + /* currently result has no use, it should be zero as cqe->res */
> + io_uring_cmd_done(ioucmd, vbr->in_hdr.status, result, issue_flags); }
> +
> +static enum rq_end_io_ret virtblk_uring_cmd_end_io(struct request *req,
> + blk_status_t err)
> +{
> + struct io_uring_cmd *ioucmd = req->end_io_data;
> + struct virtblk_uring_cmd_pdu *pdu =
> virtblk_get_uring_cmd_pdu(ioucmd);
> +
> + /*
> + * For iopoll, complete it directly. Note that using the uring_cmd
> + * helper for this is safe only because we check blk_rq_is_poll().
> + * As that returns false if we're NOT on a polled queue, then it's
> + * safe to use the polled completion helper.
> + *
> + * Otherwise, move the completion to task work.
> + */
> + if (blk_rq_is_poll(req)) {
> + if (pdu->bio)
> + blk_rq_unmap_user(pdu->bio);
> + io_uring_cmd_iopoll_done(ioucmd, 0, pdu->status);
> + } else {
> + io_uring_cmd_do_in_task_lazy(ioucmd, virtblk_uring_task_cb);
> + }
> +
> + return RQ_END_IO_FREE;
> +}
> +
> +static struct virtblk_req *virtblk_req(struct request *req) {
> + return blk_mq_rq_to_pdu(req);
> +}
> +
> +static inline enum req_op virtblk_req_op(const struct virtblk_uring_cmd
> +*cmd) {
> + return (cmd->type & VIRTIO_BLK_T_OUT) ? REQ_OP_DRV_OUT :
> +REQ_OP_DRV_IN; }
> +
> +static struct request *virtblk_alloc_user_request(
> + struct request_queue *q, struct virtblk_command *cmd,
> + blk_opf_t rq_flags, blk_mq_req_flags_t blk_flags) {
> + struct request *req;
> +
> + req = blk_mq_alloc_request(q, rq_flags, blk_flags);
> + if (IS_ERR(req))
> + return req;
> +
> + req->rq_flags |= RQF_DONTPREP;
> + memcpy(&virtblk_req(req)->out_hdr, &cmd->out_hdr, sizeof(struct
> virtio_blk_outhdr));
> + return req;
> +}
> +
> +static int virtblk_map_user_request(struct request *req, u64 ubuffer,
> + unsigned int bufflen, struct io_uring_cmd *ioucmd,
> + bool vec)
> +{
> + struct request_queue *q = req->q;
> + struct virtio_blk *vblk = q->queuedata;
> + struct block_device *bdev = vblk ? vblk->disk->part0 : NULL;
> + struct bio *bio = NULL;
> + int ret;
> +
> + if (ioucmd && (ioucmd->flags & IORING_URING_CMD_FIXED)) {
> + struct iov_iter iter;
> +
> + /* fixedbufs is only for non-vectored io */
> + if (WARN_ON_ONCE(vec))
> + return -EINVAL;
Shoule be goto out here? Or req will not be free. And I suggest to
free request in virtblk_uring_cmd_io().
> + ret = io_uring_cmd_import_fixed(ubuffer, bufflen,
> + rq_data_dir(req), &iter, ioucmd);
> + if (ret < 0)
> + goto out;
> + ret = blk_rq_map_user_iov(q, req, NULL,
> + &iter, GFP_KERNEL);
> + } else {
> + ret = blk_rq_map_user_io(req, NULL,
> + virtblk_to_user_ptr(ubuffer),
> + bufflen, GFP_KERNEL, vec, 0,
> + 0, rq_data_dir(req));
> + }
> + if (ret)
> + goto out;
> +
> + bio = req->bio;
> + if (bdev)
> + bio_set_dev(bio, bdev);
> + return 0;
> +
> +out:
> + blk_mq_free_request(req);
> + return ret;
> +}
> +
> +static int virtblk_uring_cmd_io(struct virtio_blk *vblk,
> + struct io_uring_cmd *ioucmd, unsigned int issue_flags, bool
> vec) {
> + struct virtblk_uring_cmd_pdu *pdu =
> virtblk_get_uring_cmd_pdu(ioucmd);
> + const struct virtblk_uring_cmd *cmd = io_uring_sqe_cmd(ioucmd-
> >sqe);
> + struct request_queue *q = vblk->disk->queue;
> + struct virtblk_req *vbr;
> + struct virtblk_command d;
> + struct request *req;
> + blk_opf_t rq_flags = REQ_ALLOC_CACHE | virtblk_req_op(cmd);
> + blk_mq_req_flags_t blk_flags = 0;
> + int ret;
> +
> + if (!capable(CAP_SYS_ADMIN))
> + return -EACCES;
> +
> + d.out_hdr.ioprio = cpu_to_virtio32(vblk->vdev, READ_ONCE(cmd-
> >ioprio));
> + d.out_hdr.type = cpu_to_virtio32(vblk->vdev, READ_ONCE(cmd->type));
> + d.out_hdr.sector = cpu_to_virtio64(vblk->vdev, READ_ONCE(cmd-
> >sector));
> + d.data = READ_ONCE(cmd->data);
> + d.data_len = READ_ONCE(cmd->data_len);
> +
> + if (issue_flags & IO_URING_F_NONBLOCK) {
> + rq_flags |= REQ_NOWAIT;
> + blk_flags = BLK_MQ_REQ_NOWAIT;
> + }
> + if (issue_flags & IO_URING_F_IOPOLL)
> + rq_flags |= REQ_POLLED;
> +
> + req = virtblk_alloc_user_request(q, &d, rq_flags, blk_flags);
> + if (IS_ERR(req))
> + return PTR_ERR(req);
> +
> + vbr = virtblk_req(req);
> + vbr->in_hdr_len = sizeof(vbr->in_hdr.status);
> + if (d.data && d.data_len) {
> + ret = virtblk_map_user_request(req, d.data, d.data_len,
> ioucmd, vec);
> + if (ret)
> + return ret;
> + }
> +
> + /* to free bio on completion, as req->bio will be null at that time */
> + pdu->bio = req->bio;
> + pdu->req = req;
> + req->end_io_data = ioucmd;
> + req->end_io = virtblk_uring_cmd_end_io;
> + blk_execute_rq_nowait(req, false);
> + return -EIOCBQUEUED;
> +}
> +
> +
> +static int virtblk_uring_cmd(struct virtio_blk *vblk, struct io_uring_cmd
> *ioucmd,
> + unsigned int issue_flags)
> +{
> + int ret;
> +
> + BUILD_BUG_ON(sizeof(struct virtblk_uring_cmd_pdu) >
> +sizeof(ioucmd->pdu));
> +
> + switch (ioucmd->cmd_op) {
> + case VIRTBLK_URING_CMD_IO:
> + ret = virtblk_uring_cmd_io(vblk, ioucmd, issue_flags, false);
> + break;
> + case VIRTBLK_URING_CMD_IO_VEC:
> + ret = virtblk_uring_cmd_io(vblk, ioucmd, issue_flags, true);
> + break;
> + default:
> + ret = -ENOTTY;
> + }
> +
> + return ret;
> +}
> +
> +static int virtblk_chr_uring_cmd(struct io_uring_cmd *ioucmd, unsigned
> +int issue_flags) {
> + struct virtio_blk *vblk = container_of(file_inode(ioucmd->file)->i_cdev,
> + struct virtio_blk, cdev);
> +
> + return virtblk_uring_cmd(vblk, ioucmd, issue_flags); }
> +
> static void virtblk_cdev_rel(struct device *dev) {
> ida_free(&vd_chr_minor_ida, MINOR(dev->devt)); @@ -1297,6
> +1511,7 @@ static int virtblk_cdev_add(struct virtio_blk *vblk,
>
> static const struct file_operations virtblk_chr_fops = {
> .owner = THIS_MODULE,
> + .uring_cmd = virtblk_chr_uring_cmd,
> };
>
> static unsigned int virtblk_queue_depth; diff --git
> a/include/uapi/linux/virtio_blk.h b/include/uapi/linux/virtio_blk.h index
> 3744e4da1b2a..93b6e1b5b9a4 100644
> --- a/include/uapi/linux/virtio_blk.h
> +++ b/include/uapi/linux/virtio_blk.h
> @@ -313,6 +313,22 @@ struct virtio_scsi_inhdr { }; #endif
> /* !VIRTIO_BLK_NO_LEGACY */
>
> +struct virtblk_uring_cmd {
> + /* VIRTIO_BLK_T* */
> + __u32 type;
> + /* io priority. */
> + __u32 ioprio;
> + /* Sector (ie. 512 byte offset) */
> + __u64 sector;
> +
> + __u64 data;
> + __u32 data_len;
> + __u32 flag;
> +};
> +
> +#define VIRTBLK_URING_CMD_IO 1
> +#define VIRTBLK_URING_CMD_IO_VEC 2
> +
> /* And this is the final byte of the write scatter-gather list. */
> #define VIRTIO_BLK_S_OK 0
> #define VIRTIO_BLK_S_IOERR 1
> --
> 2.43.5
>
>
