From patchwork Mon Jul 25 20:27:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrey Zhadchenko X-Patchwork-Id: 12928391 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 10381C433EF for ; Mon, 25 Jul 2022 20:30:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237142AbiGYUam (ORCPT ); Mon, 25 Jul 2022 16:30:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237141AbiGYUah (ORCPT ); Mon, 25 Jul 2022 16:30:37 -0400 Received: from relay.virtuozzo.com (relay.virtuozzo.com [130.117.225.111]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F7B32250B for ; Mon, 25 Jul 2022 13:30:33 -0700 (PDT) Received: from dev006.ch-qa.sw.ru ([172.29.1.11]) by relay.virtuozzo.com with esmtp (Exim 4.95) (envelope-from ) id 1oG4hv-00BzA1-UK; Mon, 25 Jul 2022 22:30:03 +0200 From: Andrey Zhadchenko To: virtualization@lists.linux-foundation.org Cc: kvm@vger.kernel.org, mst@redhat.com, jasowang@redhat.com, asias@redhat.com, den@virtuozzo.com, andrey.zhadchenko@virtuozzo.com Subject: [RFC PATCH 1/1] drivers/vhost: vhost-blk accelerator for virtio-blk guests Date: Mon, 25 Jul 2022 23:27:53 +0300 Message-Id: <20220725202753.298725-2-andrey.zhadchenko@virtuozzo.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220725202753.298725-1-andrey.zhadchenko@virtuozzo.com> References: <20220725202753.298725-1-andrey.zhadchenko@virtuozzo.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Although QEMU virtio is quite fast, there is still some room for improvements. Disk latency can be reduced if we handle virito-blk requests in host kernel istead of passing them to QEMU. The patch adds vhost-blk kernel module to do so. Some test setups: fio --direct=1 --rw=randread --bs=4k --ioengine=libaio --iodepth=128 QEMU drive options: cache=none filesystem: xfs SSD: | randread, IOPS | randwrite, IOPS | Host | 95.8k | 85.3k | QEMU virtio | 57.5k | 79.4k | QEMU vhost-blk | 95.6k | 84.3k | RAMDISK (vq == vcpu): | randread, IOPS | randwrite, IOPS | virtio, 1vcpu | 123k | 129k | virtio, 2vcpu | 253k (??) | 250k (??) | virtio, 4vcpu | 158k | 154k | vhost-blk, 1vcpu | 110k | 113k | vhost-blk, 2vcpu | 247k | 252k | vhost-blk, 4vcpu | 576k | 567k | Signed-off-by: Andrey Zhadchenko --- drivers/vhost/Kconfig | 12 + drivers/vhost/Makefile | 3 + drivers/vhost/blk.c | 831 +++++++++++++++++++++++++++++++++++++ include/uapi/linux/vhost.h | 4 + 4 files changed, 850 insertions(+) create mode 100644 drivers/vhost/blk.c diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig index 587fbae06182..bcd21a434885 100644 --- a/drivers/vhost/Kconfig +++ b/drivers/vhost/Kconfig @@ -89,4 +89,16 @@ config VHOST_CROSS_ENDIAN_LEGACY If unsure, say "N". +config VHOST_BLK + tristate "Host kernel accelerator for virtio-blk (EXPERIMENTAL)" + depends on BLOCK && EVENTFD + select VHOST + default n + help + This kernel module can be loaded in host kernel to accelerate + guest vm with virtio-blk driver. + + To compile this driver as a module, choose M here: the module will + be called vhost_blk. + endif diff --git a/drivers/vhost/Makefile b/drivers/vhost/Makefile index f3e1897cce85..c76cc4f5fcd8 100644 --- a/drivers/vhost/Makefile +++ b/drivers/vhost/Makefile @@ -17,3 +17,6 @@ obj-$(CONFIG_VHOST) += vhost.o obj-$(CONFIG_VHOST_IOTLB) += vhost_iotlb.o vhost_iotlb-y := iotlb.o + +obj-$(CONFIG_VHOST_BLK) += vhost_blk.o +vhost_blk-y := blk.o diff --git a/drivers/vhost/blk.c b/drivers/vhost/blk.c new file mode 100644 index 000000000000..2c3cda47b54f --- /dev/null +++ b/drivers/vhost/blk.c @@ -0,0 +1,831 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2011 Taobao, Inc. + * Author: Liu Yuan + * + * Copyright (C) 2012 Red Hat, Inc. + * Author: Asias He + * + * Copyright (c) 2022 Virtuozzo International GmbH. + * Author: Andrey Zhadchenko + * + * virtio-blk host kernel accelerator. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "vhost.h" + +enum { + VHOST_BLK_FEATURES = VHOST_FEATURES | + (1ULL << VIRTIO_RING_F_INDIRECT_DESC) | + (1ULL << VIRTIO_RING_F_EVENT_IDX) | + (1ULL << VIRTIO_BLK_F_MQ) | + (1ULL << VIRTIO_BLK_F_FLUSH), +}; + +/* + * Max number of bytes transferred before requeueing the job. + * Using this limit prevents one virtqueue from starving others. + */ +#define VHOST_DEV_WEIGHT 0x80000 + +/* + * Max number of packets transferred before requeueing the job. + * Using this limit prevents one virtqueue from starving others with + * pkts. + */ +#define VHOST_DEV_PKT_WEIGHT 256 + +enum { + VHOST_BLK_VQ = 0, + VHOST_BLK_VQ_MAX = 8, +}; + +#define VHOST_MAX_METADATA_IOV 1 + +struct req_page_list { + struct page **pages; + int pages_nr; +}; + +#define NR_INLINE 16 + +struct vhost_blk_req { + struct req_page_list inline_pl[NR_INLINE]; + struct page *inline_page[NR_INLINE]; + struct bio *inline_bio[NR_INLINE]; + struct req_page_list *pl; + int during_flush; + bool use_inline; + + struct llist_node llnode; + + struct vhost_blk *blk; + + struct iovec *iov; + int iov_nr; + + struct bio **bio; + atomic_t bio_nr; + + struct iovec status[VHOST_MAX_METADATA_IOV]; + + sector_t sector; + int bi_opf; + u16 head; + long len; + int bio_err; + + struct vhost_blk_vq *blk_vq; +}; + +struct vhost_blk_vq { + struct vhost_virtqueue vq; + struct vhost_blk_req *req; + struct iovec iov[UIO_MAXIOV]; + struct llist_head llhead; + struct vhost_work work; +}; + +struct vhost_blk { + wait_queue_head_t flush_wait; + struct vhost_blk_vq vqs[VHOST_BLK_VQ_MAX]; + atomic_t req_inflight[2]; + spinlock_t flush_lock; + struct vhost_dev dev; + int during_flush; + struct file *backend; + int index; +}; + +static int gen; + +static int move_iovec(struct iovec *from, struct iovec *to, + size_t len, int iov_count_from, int iov_count_to) +{ + int moved_seg = 0, spent_seg = 0; + size_t size; + + while (len && spent_seg < iov_count_from && moved_seg < iov_count_to) { + if (from->iov_len == 0) { + ++from; + ++spent_seg; + continue; + } + size = min(from->iov_len, len); + to->iov_base = from->iov_base; + to->iov_len = size; + from->iov_len -= size; + from->iov_base += size; + len -= size; + ++from; + ++to; + ++moved_seg; + ++spent_seg; + } + + return len ? -1 : moved_seg; +} + +static inline int iov_num_pages(struct iovec *iov) +{ + return (PAGE_ALIGN((unsigned long)iov->iov_base + iov->iov_len) - + ((unsigned long)iov->iov_base & PAGE_MASK)) >> PAGE_SHIFT; +} + +static inline int vhost_blk_set_status(struct vhost_blk_req *req, u8 status) +{ + struct iov_iter iter; + int ret; + + iov_iter_init(&iter, WRITE, req->status, ARRAY_SIZE(req->status), sizeof(status)); + ret = copy_to_iter(&status, sizeof(status), &iter); + if (ret != sizeof(status)) { + vq_err(&req->blk_vq->vq, "Failed to write status\n"); + return -EFAULT; + } + + return 0; +} + +static void vhost_blk_req_done(struct bio *bio) +{ + struct vhost_blk_req *req = bio->bi_private; + struct vhost_blk *blk = req->blk; + + req->bio_err = blk_status_to_errno(bio->bi_status); + + if (atomic_dec_and_test(&req->bio_nr)) { + llist_add(&req->llnode, &req->blk_vq->llhead); + vhost_work_queue(&blk->dev, &req->blk_vq->work); + } + + bio_put(bio); +} + +static void vhost_blk_req_umap(struct vhost_blk_req *req) +{ + struct req_page_list *pl; + int i, j; + + if (req->pl) { + for (i = 0; i < req->iov_nr; i++) { + pl = &req->pl[i]; + + for (j = 0; j < pl->pages_nr; j++) { + if (!req->bi_opf) + set_page_dirty_lock(pl->pages[j]); + put_page(pl->pages[j]); + } + } + } + + if (!req->use_inline) + kfree(req->pl); +} + +static int vhost_blk_bio_make_simple(struct vhost_blk_req *req, + struct block_device *bdev) +{ + struct bio *bio; + + req->use_inline = true; + req->pl = NULL; + req->bio = req->inline_bio; + + bio = bio_alloc(GFP_KERNEL, 1); + if (!bio) + return -ENOMEM; + + bio->bi_iter.bi_sector = req->sector; + bio_set_dev(bio, bdev); + bio->bi_private = req; + bio->bi_end_io = vhost_blk_req_done; + bio->bi_opf = req->bi_opf; + req->bio[0] = bio; + + atomic_set(&req->bio_nr, 1); + + return 0; +} + +static struct page **vhost_blk_prepare_req(struct vhost_blk_req *req, + int total_pages, int iov_nr) +{ + int pl_len, page_len, bio_len; + void *buf; + + req->use_inline = false; + pl_len = iov_nr * sizeof(req->pl[0]); + page_len = total_pages * sizeof(struct page *); + bio_len = total_pages * sizeof(struct bio *); + + buf = kmalloc(pl_len + page_len + bio_len, GFP_KERNEL); + if (!buf) + return NULL; + + req->pl = buf; + req->bio = buf + pl_len + page_len; + + return buf + pl_len; +} + +static int vhost_blk_bio_make(struct vhost_blk_req *req, + struct block_device *bdev) +{ + int pages_nr_total, i, j, ret; + struct iovec *iov = req->iov; + int iov_nr = req->iov_nr; + struct page **pages, *page; + struct bio *bio = NULL; + int bio_nr = 0; + + if (unlikely(req->bi_opf == REQ_OP_FLUSH)) + return vhost_blk_bio_make_simple(req, bdev); + + pages_nr_total = 0; + for (i = 0; i < iov_nr; i++) + pages_nr_total += iov_num_pages(&iov[i]); + + if (pages_nr_total > NR_INLINE) { + pages = vhost_blk_prepare_req(req, pages_nr_total, iov_nr); + if (!pages) + return -ENOMEM; + } else { + req->use_inline = true; + req->pl = req->inline_pl; + pages = req->inline_page; + req->bio = req->inline_bio; + } + + req->iov_nr = 0; + for (i = 0; i < iov_nr; i++) { + int pages_nr = iov_num_pages(&iov[i]); + unsigned long iov_base, iov_len; + struct req_page_list *pl; + + iov_base = (unsigned long)iov[i].iov_base; + iov_len = (unsigned long)iov[i].iov_len; + + ret = get_user_pages_fast(iov_base, pages_nr, + !req->bi_opf, pages); + if (ret != pages_nr) + goto fail; + + req->iov_nr++; + pl = &req->pl[i]; + pl->pages_nr = pages_nr; + pl->pages = pages; + + for (j = 0; j < pages_nr; j++) { + unsigned int off, len; + + page = pages[j]; + off = iov_base & ~PAGE_MASK; + len = PAGE_SIZE - off; + if (len > iov_len) + len = iov_len; + + bio = bio_alloc(GFP_KERNEL, 1); + if (!bio) + goto fail; + bio->bi_iter.bi_sector = req->sector; + bio_set_dev(bio, bdev); + bio->bi_private = req; + bio->bi_end_io = vhost_blk_req_done; + bio->bi_opf = req->bi_opf; + req->bio[bio_nr++] = bio; + bio_add_page(bio, page, len, off); + req->sector += len >> 9; + iov_base += len; + iov_len -= len; + } + + pages += pages_nr; + } + atomic_set(&req->bio_nr, bio_nr); + return 0; + +fail: + for (i = 0; i < bio_nr; i++) + bio_put(req->bio[i]); + vhost_blk_req_umap(req); + return -ENOMEM; +} + +static inline void vhost_blk_bio_send(struct vhost_blk_req *req) +{ + struct blk_plug plug; + int i, bio_nr; + + bio_nr = atomic_read(&req->bio_nr); + blk_start_plug(&plug); + for (i = 0; i < bio_nr; i++) + submit_bio(req->bio[i]); + + blk_finish_plug(&plug); +} + +static int vhost_blk_req_submit(struct vhost_blk_req *req, struct file *file) +{ + + struct inode *inode = file->f_mapping->host; + struct block_device *bdev = I_BDEV(inode); + int ret; + + ret = vhost_blk_bio_make(req, bdev); + if (ret < 0) + return ret; + + vhost_blk_bio_send(req); + + spin_lock(&req->blk->flush_lock); + req->during_flush = req->blk->during_flush; + atomic_inc(&req->blk->req_inflight[req->during_flush]); + spin_unlock(&req->blk->flush_lock); + + return ret; +} + +static int vhost_blk_req_handle(struct vhost_virtqueue *vq, + struct virtio_blk_outhdr *hdr, + u16 head, u16 total_iov_nr, + struct file *file) +{ + struct vhost_blk *blk = container_of(vq->dev, struct vhost_blk, dev); + struct vhost_blk_vq *blk_vq = container_of(vq, struct vhost_blk_vq, vq); + unsigned char id[VIRTIO_BLK_ID_BYTES]; + struct vhost_blk_req *req; + struct iov_iter iter; + int ret, len; + u8 status; + + req = &blk_vq->req[head]; + req->blk_vq = blk_vq; + req->head = head; + req->blk = blk; + req->sector = hdr->sector; + req->iov = blk_vq->iov; + + req->len = iov_length(vq->iov, total_iov_nr) - sizeof(status); + req->iov_nr = move_iovec(vq->iov, req->iov, req->len, total_iov_nr, + ARRAY_SIZE(blk_vq->iov)); + + move_iovec(vq->iov, req->status, sizeof(status), total_iov_nr, ARRAY_SIZE(req->status)); + if (req->iov_nr < 0) + return -EINVAL; + + switch (hdr->type) { + case VIRTIO_BLK_T_OUT: + req->bi_opf = REQ_OP_WRITE; + ret = vhost_blk_req_submit(req, file); + break; + case VIRTIO_BLK_T_IN: + req->bi_opf = REQ_OP_READ; + ret = vhost_blk_req_submit(req, file); + break; + case VIRTIO_BLK_T_FLUSH: + req->bi_opf = REQ_OP_FLUSH; + ret = vhost_blk_req_submit(req, file); + break; + case VIRTIO_BLK_T_GET_ID: + ret = snprintf(id, VIRTIO_BLK_ID_BYTES, + "vhost-blk%d", blk->index); + if (ret < 0) + break; + len = ret; + iov_iter_init(&iter, WRITE, req->iov, req->iov_nr, req->len); + ret = copy_to_iter(id, len, &iter); + status = ret < 0 ? VIRTIO_BLK_S_IOERR : VIRTIO_BLK_S_OK; + ret = vhost_blk_set_status(req, status); + if (ret) + break; + vhost_add_used_and_signal(&blk->dev, vq, head, len); + break; + default: + vq_err(vq, "Unsupported request type %d\n", hdr->type); + status = VIRTIO_BLK_S_UNSUPP; + ret = vhost_blk_set_status(req, status); + if (ret) + break; + vhost_add_used_and_signal(&blk->dev, vq, head, 0); + } + + return ret; +} + +static void vhost_blk_handle_guest_kick(struct vhost_work *work) +{ + struct virtio_blk_outhdr hdr; + struct vhost_blk_vq *blk_vq; + struct vhost_virtqueue *vq; + struct iovec hdr_iovec[VHOST_MAX_METADATA_IOV]; + struct vhost_blk *blk; + struct iov_iter iter; + int in, out, ret; + struct file *f; + u16 head; + + vq = container_of(work, struct vhost_virtqueue, poll.work); + blk = container_of(vq->dev, struct vhost_blk, dev); + blk_vq = container_of(vq, struct vhost_blk_vq, vq); + + f = vhost_vq_get_backend(vq); + if (!f) + return; + + vhost_disable_notify(&blk->dev, vq); + for (;;) { + head = vhost_get_vq_desc(vq, vq->iov, + ARRAY_SIZE(vq->iov), + &out, &in, NULL, NULL); + if (unlikely(head < 0)) + break; + + if (unlikely(head == vq->num)) { + if (unlikely(vhost_enable_notify(&blk->dev, vq))) { + vhost_disable_notify(&blk->dev, vq); + continue; + } + break; + } + + ret = move_iovec(vq->iov, hdr_iovec, sizeof(hdr), in + out, ARRAY_SIZE(hdr_iovec)); + if (ret < 0) { + vq_err(vq, "virtio_blk_hdr is too split!"); + vhost_discard_vq_desc(vq, 1); + break; + } + + iov_iter_init(&iter, READ, hdr_iovec, ARRAY_SIZE(hdr_iovec), sizeof(hdr)); + ret = copy_from_iter(&hdr, sizeof(hdr), &iter); + if (ret != sizeof(hdr)) { + vq_err(vq, "Failed to get block header: read %d bytes instead of %ld!\n", + ret, sizeof(hdr)); + vhost_discard_vq_desc(vq, 1); + break; + } + + if (vhost_blk_req_handle(vq, &hdr, head, out + in, f) < 0) + break; + + if (!llist_empty(&blk_vq->llhead)) { + vhost_poll_queue(&vq->poll); + break; + } + } +} + +static void vhost_blk_handle_host_kick(struct vhost_work *work) +{ + struct vhost_blk_vq *blk_vq; + struct vhost_virtqueue *vq; + struct vhost_blk_req *req; + struct llist_node *llnode; + struct vhost_blk *blk = NULL; + bool added, zero; + u8 status; + int ret; + + blk_vq = container_of(work, struct vhost_blk_vq, work); + vq = &blk_vq->vq; + llnode = llist_del_all(&blk_vq->llhead); + added = false; + while (llnode) { + req = llist_entry(llnode, struct vhost_blk_req, llnode); + llnode = llist_next(llnode); + + if (!blk) + blk = req->blk; + + vhost_blk_req_umap(req); + + status = req->bio_err == 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR; + ret = vhost_blk_set_status(req, status); + if (unlikely(ret)) + continue; + + vhost_add_used(vq, req->head, req->len); + added = true; + + spin_lock(&req->blk->flush_lock); + zero = atomic_dec_and_test( + &req->blk->req_inflight[req->during_flush]); + if (zero && !req->during_flush) + wake_up(&blk->flush_wait); + spin_unlock(&req->blk->flush_lock); + + } + + if (likely(added)) + vhost_signal(&blk->dev, vq); +} + +static void vhost_blk_flush(struct vhost_blk *blk) +{ + int i; + + spin_lock(&blk->flush_lock); + blk->during_flush = 1; + spin_unlock(&blk->flush_lock); + + for (i = 0; i < VHOST_BLK_VQ_MAX; i++) + vhost_poll_flush(&blk->vqs[i].vq.poll); + vhost_work_dev_flush(&blk->dev); + /* + * Wait until requests fired before the flush to be finished + * req_inflight[0] is used to track the requests fired before the flush + * req_inflight[1] is used to track the requests fired during the flush + */ + wait_event(blk->flush_wait, !atomic_read(&blk->req_inflight[0])); + + spin_lock(&blk->flush_lock); + blk->during_flush = 0; + spin_unlock(&blk->flush_lock); +} + +static inline void vhost_blk_drop_backends(struct vhost_blk *blk) +{ + struct vhost_virtqueue *vq; + int i; + + for (i = 0; i < VHOST_BLK_VQ_MAX; i++) { + vq = &blk->vqs[i].vq; + + mutex_lock(&vq->mutex); + vhost_vq_set_backend(vq, NULL); + mutex_unlock(&vq->mutex); + } +} + +static int vhost_blk_open(struct inode *inode, struct file *file) +{ + struct vhost_blk *blk; + struct vhost_virtqueue **vqs; + int ret = 0, i = 0; + + blk = kvzalloc(sizeof(*blk), GFP_KERNEL); + if (!blk) { + ret = -ENOMEM; + goto out; + } + + vqs = kcalloc(VHOST_BLK_VQ_MAX, sizeof(*vqs), GFP_KERNEL); + if (!vqs) { + ret = -ENOMEM; + goto out_blk; + } + + for (i = 0; i < VHOST_BLK_VQ_MAX; i++) { + blk->vqs[i].vq.handle_kick = vhost_blk_handle_guest_kick; + vqs[i] = &blk->vqs[i].vq; + } + + blk->index = gen++; + + atomic_set(&blk->req_inflight[0], 0); + atomic_set(&blk->req_inflight[1], 0); + blk->during_flush = 0; + spin_lock_init(&blk->flush_lock); + init_waitqueue_head(&blk->flush_wait); + + vhost_dev_init(&blk->dev, vqs, VHOST_BLK_VQ_MAX, UIO_MAXIOV, + VHOST_DEV_WEIGHT, VHOST_DEV_PKT_WEIGHT, true, NULL); + file->private_data = blk; + + for (i = 0; i < VHOST_BLK_VQ_MAX; i++) + vhost_work_init(&blk->vqs[i].work, vhost_blk_handle_host_kick); + + return ret; +out_blk: + kvfree(blk); +out: + return ret; +} + +static int vhost_blk_release(struct inode *inode, struct file *f) +{ + struct vhost_blk *blk = f->private_data; + int i; + + vhost_blk_drop_backends(blk); + vhost_blk_flush(blk); + vhost_dev_stop(&blk->dev); + if (blk->backend) + fput(blk->backend); + vhost_dev_cleanup(&blk->dev); + for (i = 0; i < VHOST_BLK_VQ_MAX; i++) + kvfree(blk->vqs[i].req); + kfree(blk->dev.vqs); + kvfree(blk); + + return 0; +} + +static int vhost_blk_set_features(struct vhost_blk *blk, u64 features) +{ + struct vhost_virtqueue *vq; + int i; + + mutex_lock(&blk->dev.mutex); + if ((features & (1 << VHOST_F_LOG_ALL)) && + !vhost_log_access_ok(&blk->dev)) { + mutex_unlock(&blk->dev.mutex); + return -EFAULT; + } + + for (i = 0; i < VHOST_BLK_VQ_MAX; i++) { + vq = &blk->vqs[i].vq; + mutex_lock(&vq->mutex); + vq->acked_features = features & (VHOST_BLK_FEATURES); + mutex_unlock(&vq->mutex); + } + + vhost_blk_flush(blk); + mutex_unlock(&blk->dev.mutex); + + return 0; +} + +static long vhost_blk_set_backend(struct vhost_blk *blk, int fd) +{ + struct vhost_virtqueue *vq; + struct file *file, *oldfile = NULL; + struct inode *inode; + int ret, i; + + mutex_lock(&blk->dev.mutex); + ret = vhost_dev_check_owner(&blk->dev); + if (ret) + goto out_dev; + + file = fget(fd); + if (IS_ERR(file)) { + ret = PTR_ERR(file); + goto out_dev; + } + + if (file == blk->backend) { + fput(file); + goto out_dev; + } + + oldfile = blk->backend; + blk->backend = file; + + inode = file->f_mapping->host; + if (!S_ISBLK(inode->i_mode)) { + ret = -EFAULT; + goto out_file; + } + + for (i = 0; i < VHOST_BLK_VQ_MAX; i++) { + vq = &blk->vqs[i].vq; + if (!vhost_vq_access_ok(vq)) { + ret = -EFAULT; + goto out_drop; + } + + mutex_lock(&vq->mutex); + vhost_vq_set_backend(vq, file); + ret = vhost_vq_init_access(vq); + mutex_unlock(&vq->mutex); + } + + if (oldfile) { + vhost_blk_flush(blk); + fput(oldfile); + } + + mutex_unlock(&blk->dev.mutex); + return 0; + +out_drop: + vhost_blk_drop_backends(blk); +out_file: + fput(file); + blk->backend = NULL; +out_dev: + mutex_unlock(&blk->dev.mutex); + return ret; +} + +static long vhost_blk_reset_owner(struct vhost_blk *blk) +{ + struct vhost_iotlb *umem; + int err, i; + + mutex_lock(&blk->dev.mutex); + err = vhost_dev_check_owner(&blk->dev); + if (err) + goto done; + umem = vhost_dev_reset_owner_prepare(); + if (!umem) { + err = -ENOMEM; + goto done; + } + vhost_blk_drop_backends(blk); + if (blk->backend) { + fput(blk->backend); + blk->backend = NULL; + } + vhost_blk_flush(blk); + vhost_dev_stop(&blk->dev); + vhost_dev_reset_owner(&blk->dev, umem); + + for (i = 0; i < VHOST_BLK_VQ_MAX; i++) { + kvfree(blk->vqs[i].req); + blk->vqs[i].req = NULL; + } + +done: + mutex_unlock(&blk->dev.mutex); + return err; +} + +static int vhost_blk_setup(struct vhost_blk *blk, void __user *argp) +{ + struct vhost_vring_state s; + + if (copy_from_user(&s, argp, sizeof(s))) + return -EFAULT; + + if (blk->vqs[s.index].req) + return 0; + + blk->vqs[s.index].req = kvmalloc(sizeof(struct vhost_blk_req) * s.num, GFP_KERNEL); + if (!blk->vqs[s.index].req) + return -ENOMEM; + + return 0; +} + +static long vhost_blk_ioctl(struct file *f, unsigned int ioctl, + unsigned long arg) +{ + struct vhost_blk *blk = f->private_data; + void __user *argp = (void __user *)arg; + struct vhost_vring_file backend; + u64 __user *featurep = argp; + u64 features; + int ret; + + switch (ioctl) { + case VHOST_BLK_SET_BACKEND: + if (copy_from_user(&backend, argp, sizeof(backend))) + return -EFAULT; + return vhost_blk_set_backend(blk, backend.fd); + case VHOST_GET_FEATURES: + features = VHOST_BLK_FEATURES; + if (copy_to_user(featurep, &features, sizeof(features))) + return -EFAULT; + return 0; + case VHOST_SET_FEATURES: + if (copy_from_user(&features, featurep, sizeof(features))) + return -EFAULT; + if (features & ~VHOST_BLK_FEATURES) + return -EOPNOTSUPP; + return vhost_blk_set_features(blk, features); + case VHOST_RESET_OWNER: + return vhost_blk_reset_owner(blk); + default: + mutex_lock(&blk->dev.mutex); + ret = vhost_dev_ioctl(&blk->dev, ioctl, argp); + if (ret == -ENOIOCTLCMD) + ret = vhost_vring_ioctl(&blk->dev, ioctl, argp); + if (!ret && ioctl == VHOST_SET_VRING_NUM) + ret = vhost_blk_setup(blk, argp); + vhost_blk_flush(blk); + mutex_unlock(&blk->dev.mutex); + return ret; + } +} + +static const struct file_operations vhost_blk_fops = { + .owner = THIS_MODULE, + .open = vhost_blk_open, + .release = vhost_blk_release, + .llseek = noop_llseek, + .unlocked_ioctl = vhost_blk_ioctl, +}; + +static struct miscdevice vhost_blk_misc = { + MISC_DYNAMIC_MINOR, + "vhost-blk", + &vhost_blk_fops, +}; +module_misc_device(vhost_blk_misc); + +MODULE_VERSION("0.0.1"); +MODULE_LICENSE("GPL v2"); +MODULE_AUTHOR("Andrey Zhadchenko"); +MODULE_DESCRIPTION("Host kernel accelerator for virtio_blk"); diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h index cab645d4a645..a54861e9633e 100644 --- a/include/uapi/linux/vhost.h +++ b/include/uapi/linux/vhost.h @@ -171,4 +171,8 @@ #define VHOST_VDPA_SET_GROUP_ASID _IOW(VHOST_VIRTIO, 0x7C, \ struct vhost_vring_state) +/* VHOST_BLK specific defines */ +#define VHOST_BLK_SET_BACKEND _IOW(VHOST_VIRTIO, 0x90, \ + struct vhost_vring_file) + #endif