This driver "transfers" a dmabuf created on the Guest to the Host. A common use-case for such a transfer includes sharing the scanout buffer created by a display server or a compositor running in the Guest with Qemu UI -- running on the Host.
The "transfer" is accomplished by sharing the PFNs of all the pages associated with the dmabuf and having a new dmabuf created on the Host that is backed up by the pages mapped from the Guest.
Signed-off-by: Dongwon Kim dongwon.kim@intel.com Signed-off-by: Vivek Kasireddy vivek.kasireddy@intel.com --- drivers/virtio/Kconfig | 8 + drivers/virtio/Makefile | 1 + drivers/virtio/virtio_vdmabuf.c | 1105 +++++++++++++++++++++++++++ include/linux/virtio_vdmabuf.h | 287 +++++++ include/uapi/linux/virtio_ids.h | 1 + include/uapi/linux/virtio_vdmabuf.h | 87 +++ 6 files changed, 1489 insertions(+) create mode 100644 drivers/virtio/virtio_vdmabuf.c create mode 100644 include/linux/virtio_vdmabuf.h create mode 100644 include/uapi/linux/virtio_vdmabuf.h
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig index 7b41130d3f35..e563c12f711e 100644 --- a/drivers/virtio/Kconfig +++ b/drivers/virtio/Kconfig @@ -139,4 +139,12 @@ config VIRTIO_DMA_SHARED_BUFFER This option adds a flavor of dma buffers that are backed by virtio resources.
+config VIRTIO_VDMABUF + bool "Enables Vdmabuf driver in guest os" + default n + depends on VIRTIO + help + This driver provides a way to share the dmabufs created in + the Guest with the Host. + endif # VIRTIO_MENU diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile index 591e6f72aa54..b4bb0738009c 100644 --- a/drivers/virtio/Makefile +++ b/drivers/virtio/Makefile @@ -9,3 +9,4 @@ obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o obj-$(CONFIG_VIRTIO_VDPA) += virtio_vdpa.o obj-$(CONFIG_VIRTIO_MEM) += virtio_mem.o obj-$(CONFIG_VIRTIO_DMA_SHARED_BUFFER) += virtio_dma_buf.o +obj-$(CONFIG_VIRTIO_VDMABUF) += virtio_vdmabuf.o diff --git a/drivers/virtio/virtio_vdmabuf.c b/drivers/virtio/virtio_vdmabuf.c new file mode 100644 index 000000000000..803b7398d3ed --- /dev/null +++ b/drivers/virtio/virtio_vdmabuf.c @@ -0,0 +1,1105 @@ +// SPDX-License-Identifier: (MIT OR GPL-2.0) + +/* + * Copyright © 2021 Intel Corporation + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + * + * Authors: + * Dongwon Kim dongwon.kim@intel.com + * Mateusz Polrola mateusz.polrola@gmail.com + * Vivek Kasireddy vivek.kasireddy@intel.com + */ + +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/module.h> +#include <linux/device.h> +#include <linux/uaccess.h> +#include <linux/miscdevice.h> +#include <linux/delay.h> +#include <linux/random.h> +#include <linux/poll.h> +#include <linux/spinlock.h> +#include <linux/dma-buf.h> +#include <linux/virtio.h> +#include <linux/virtio_ids.h> +#include <linux/virtio_config.h> +#include <linux/virtio_vdmabuf.h> + +#define VIRTIO_VDMABUF_MAX_ID INT_MAX +#define REFS_PER_PAGE (PAGE_SIZE/sizeof(long)) +#define NEW_BUF_ID_GEN(vmid, cnt) (((vmid & 0xFFFFFFFF) << 32) | \ + ((cnt) & 0xFFFFFFFF)) + +/* one global drv object */ +static struct virtio_vdmabuf_info *drv_info; + +struct virtio_vdmabuf { + /* virtio device structure */ + struct virtio_device *vdev; + + /* virtual queue array */ + struct virtqueue *vqs[VDMABUF_VQ_MAX]; + + /* ID of guest OS */ + u64 vmid; + + /* spin lock that needs to be acquired before accessing + * virtual queue + */ + spinlock_t vq_lock; + struct mutex recv_lock; + struct mutex send_lock; + + struct list_head msg_list; + + /* workqueue */ + struct workqueue_struct *wq; + struct work_struct recv_work; + struct work_struct send_work; + struct work_struct send_msg_work; + + struct virtio_vdmabuf_event_queue *evq; +}; + +static virtio_vdmabuf_buf_id_t get_buf_id(struct virtio_vdmabuf *vdmabuf) +{ + virtio_vdmabuf_buf_id_t buf_id = {0, {0, 0} }; + static int count = 0; + + count = count < VIRTIO_VDMABUF_MAX_ID ? count + 1 : 0; + buf_id.id = NEW_BUF_ID_GEN(vdmabuf->vmid, count); + + /* random data embedded in the id for security */ + get_random_bytes(&buf_id.rng_key[0], 8); + + return buf_id; +} + +/* sharing pages for original DMABUF with Host */ +static int virtio_vdmabuf_share_buf(struct virtio_vdmabuf_buf *exp) +{ + struct virtio_vdmabuf_shared_pages *pages_info = exp->pages_info; + struct page **pages = pages_info->pages; + int nents = pages_info->nents; + int i; + int n_l2refs = nents/REFS_PER_PAGE + + ((nents % REFS_PER_PAGE) ? 1 : 0); + + pages_info->l3refs = (gpa_t *)__get_free_page(GFP_KERNEL); + + if (!pages_info->l3refs) { + kvfree(pages_info); + return -ENOMEM; + } + + pages_info->l2refs = (gpa_t **)__get_free_pages(GFP_KERNEL, + get_order(n_l2refs * PAGE_SIZE)); + + if (!pages_info->l2refs) { + free_page((gpa_t)pages_info->l3refs); + kvfree(pages_info); + return -ENOMEM; + } + + /* Share physical address of pages */ + for (i = 0; i < nents; i++) + pages_info->l2refs[i] = (gpa_t *)page_to_phys(pages[i]); + + for (i = 0; i < n_l2refs; i++) + pages_info->l3refs[i] = + virt_to_phys((void *)pages_info->l2refs + + i * PAGE_SIZE); + + pages_info->ref = (gpa_t)virt_to_phys(pages_info->l3refs); + + return 0; +} + +/* stop sharing pages */ +static void +virtio_vdmabuf_free_buf(struct virtio_vdmabuf_shared_pages *pages_info) +{ + int n_l2refs = (pages_info->nents/REFS_PER_PAGE + + ((pages_info->nents % REFS_PER_PAGE) ? 1 : 0)); + + free_pages((gpa_t)pages_info->l2refs, get_order(n_l2refs * PAGE_SIZE)); + free_page((gpa_t)pages_info->l3refs); + + kvfree(pages_info); +} + +static int send_msg_to_host(enum virtio_vdmabuf_cmd cmd, int *op) +{ + struct virtio_vdmabuf *vdmabuf = drv_info->priv; + struct virtio_vdmabuf_msg *msg; + int i; + + switch (cmd) { + case VIRTIO_VDMABUF_CMD_NEED_VMID: + msg = kvcalloc(1, sizeof(struct virtio_vdmabuf_msg), + GFP_KERNEL); + if (!msg) + return -ENOMEM; + + if (op) + for (i = 0; i < 4; i++) + msg->op[i] = op[i]; + break; + + case VIRTIO_VDMABUF_CMD_EXPORT: + msg = kvcalloc(1, sizeof(struct virtio_vdmabuf_msg), + GFP_KERNEL); + if (!msg) + return -ENOMEM; + + memcpy(&msg->op[0], &op[0], 10 * sizeof(int) + op[9]); + break; + + default: + /* no command found */ + return -EINVAL; + } + + msg->cmd = cmd; + list_add_tail(&msg->list, &vdmabuf->msg_list); + queue_work(vdmabuf->wq, &vdmabuf->send_msg_work); + + return 0; +} + +static int add_event_buf_rel(struct virtio_vdmabuf_buf *buf_info) +{ + struct virtio_vdmabuf *vdmabuf = drv_info->priv; + struct virtio_vdmabuf_event *e_oldest, *e_new; + struct virtio_vdmabuf_event_queue *eq = vdmabuf->evq; + unsigned long irqflags; + + e_new = kvzalloc(sizeof(*e_new), GFP_KERNEL); + if (!e_new) + return -ENOMEM; + + e_new->e_data.hdr.buf_id = buf_info->buf_id; + e_new->e_data.data = (void *)buf_info->priv; + e_new->e_data.hdr.size = buf_info->sz_priv; + + spin_lock_irqsave(&eq->e_lock, irqflags); + + /* check current number of events and if it hits the max num (32) + * then remove the oldest event in the list + */ + if (eq->pending > 31) { + e_oldest = list_first_entry(&eq->e_list, + struct virtio_vdmabuf_event, link); + list_del(&e_oldest->link); + eq->pending--; + kvfree(e_oldest); + } + + list_add_tail(&e_new->link, &eq->e_list); + + eq->pending++; + + wake_up_interruptible(&eq->e_wait); + spin_unlock_irqrestore(&eq->e_lock, irqflags); + + return 0; +} + +static void virtio_vdmabuf_clear_buf(struct virtio_vdmabuf_buf *exp) +{ + /* Start cleanup of buffer in reverse order to exporting */ + virtio_vdmabuf_free_buf(exp->pages_info); + + dma_buf_unmap_attachment(exp->attach, exp->sgt, + DMA_BIDIRECTIONAL); + + if (exp->dma_buf) { + dma_buf_detach(exp->dma_buf, exp->attach); + /* close connection to dma-buf completely */ + dma_buf_put(exp->dma_buf); + exp->dma_buf = NULL; + } +} + +static int remove_buf(struct virtio_vdmabuf *vdmabuf, + struct virtio_vdmabuf_buf *exp) +{ + int ret; + + virtio_vdmabuf_clear_buf(exp); + + ret = virtio_vdmabuf_del_buf(drv_info, &exp->buf_id); + if (ret) + return ret; + + if (exp->sz_priv > 0 && !exp->priv) + kvfree(exp->priv); + + kvfree(exp); + return 0; +} + +static int parse_msg_from_host(struct virtio_vdmabuf *vdmabuf, + struct virtio_vdmabuf_msg *msg) +{ + struct virtio_vdmabuf_buf *exp; + virtio_vdmabuf_buf_id_t buf_id; + int ret; + + switch (msg->cmd) { + case VIRTIO_VDMABUF_CMD_NEED_VMID: + vdmabuf->vmid = msg->op[0]; + + break; + case VIRTIO_VDMABUF_CMD_DMABUF_REL: + memcpy(&buf_id, msg->op, sizeof(buf_id)); + + exp = virtio_vdmabuf_find_buf(drv_info, &buf_id); + if (!exp) { + dev_err(drv_info->dev, "can't find buffer\n"); + return -EINVAL; + } + + ret = add_event_buf_rel(exp); + if (ret) + return ret; + + break; + case VIRTIO_VDMABUF_CMD_EXPORT: + break; + default: + dev_err(drv_info->dev, "empty cmd\n"); + return -EINVAL; + } + + return 0; +} + +static void virtio_vdmabuf_recv_work(struct work_struct *work) +{ + struct virtio_vdmabuf *vdmabuf = + container_of(work, struct virtio_vdmabuf, recv_work); + struct virtqueue *vq = vdmabuf->vqs[VDMABUF_VQ_RECV]; + struct virtio_vdmabuf_msg *msg; + int sz; + + mutex_lock(&vdmabuf->recv_lock); + + do { + virtqueue_disable_cb(vq); + for (;;) { + msg = virtqueue_get_buf(vq, &sz); + if (!msg) + break; + + /* valid size */ + if (sz == sizeof(struct virtio_vdmabuf_msg)) { + if (parse_msg_from_host(vdmabuf, msg)) + dev_err(drv_info->dev, + "msg parse error\n"); + + kvfree(msg); + } else { + dev_err(drv_info->dev, + "received malformed message\n"); + } + } + } while (!virtqueue_enable_cb(vq)); + + mutex_unlock(&vdmabuf->recv_lock); +} + +static void virtio_vdmabuf_fill_recv_msg(struct virtio_vdmabuf *vdmabuf) +{ + struct virtqueue *vq = vdmabuf->vqs[VDMABUF_VQ_RECV]; + struct scatterlist sg; + struct virtio_vdmabuf_msg *msg; + int ret; + + msg = kvzalloc(sizeof(*msg), GFP_KERNEL); + if (!msg) + return; + + sg_init_one(&sg, msg, sizeof(struct virtio_vdmabuf_msg)); + ret = virtqueue_add_inbuf(vq, &sg, 1, msg, GFP_KERNEL); + if (ret) + return; + + virtqueue_kick(vq); +} + +static void virtio_vdmabuf_send_msg_work(struct work_struct *work) +{ + struct virtio_vdmabuf *vdmabuf = + container_of(work, struct virtio_vdmabuf, send_msg_work); + struct virtqueue *vq = vdmabuf->vqs[VDMABUF_VQ_SEND]; + struct scatterlist sg; + struct virtio_vdmabuf_msg *msg; + bool added = false; + int ret; + + mutex_lock(&vdmabuf->send_lock); + + for (;;) { + if (list_empty(&vdmabuf->msg_list)) + break; + + virtio_vdmabuf_fill_recv_msg(vdmabuf); + + msg = list_first_entry(&vdmabuf->msg_list, + struct virtio_vdmabuf_msg, list); + list_del_init(&msg->list); + + sg_init_one(&sg, msg, sizeof(struct virtio_vdmabuf_msg)); + ret = virtqueue_add_outbuf(vq, &sg, 1, msg, GFP_KERNEL); + if (ret < 0) { + dev_err(drv_info->dev, + "failed to add msg to vq\n"); + break; + } + + added = true; + } + + if (added) + virtqueue_kick(vq); + + mutex_unlock(&vdmabuf->send_lock); +} + +static void virtio_vdmabuf_send_work(struct work_struct *work) +{ + struct virtio_vdmabuf *vdmabuf = + container_of(work, struct virtio_vdmabuf, send_work); + struct virtqueue *vq = vdmabuf->vqs[VDMABUF_VQ_SEND]; + struct virtio_vdmabuf_msg *msg; + unsigned int sz; + bool added = false; + + mutex_lock(&vdmabuf->send_lock); + + do { + virtqueue_disable_cb(vq); + + for (;;) { + msg = virtqueue_get_buf(vq, &sz); + if (!msg) + break; + + if (parse_msg_from_host(vdmabuf, msg)) + dev_err(drv_info->dev, + "msg parse error\n"); + + kvfree(msg); + added = true; + } + } while (!virtqueue_enable_cb(vq)); + + mutex_unlock(&vdmabuf->send_lock); + + if (added) + queue_work(vdmabuf->wq, &vdmabuf->send_msg_work); +} + +static void virtio_vdmabuf_recv_cb(struct virtqueue *vq) +{ + struct virtio_vdmabuf *vdmabuf = vq->vdev->priv; + + if (!vdmabuf) + return; + + queue_work(vdmabuf->wq, &vdmabuf->recv_work); +} + +static void virtio_vdmabuf_send_cb(struct virtqueue *vq) +{ + struct virtio_vdmabuf *vdmabuf = vq->vdev->priv; + + if (!vdmabuf) + return; + + queue_work(vdmabuf->wq, &vdmabuf->send_work); +} + +static int remove_all_bufs(struct virtio_vdmabuf *vdmabuf) +{ + struct virtio_vdmabuf_buf *found; + struct hlist_node *tmp; + int bkt; + int ret; + + hash_for_each_safe(drv_info->buf_list, bkt, tmp, found, node) { + ret = remove_buf(vdmabuf, found); + if (ret) + return ret; + } + + return 0; +} + +static struct sg_table +*virtio_vdmabuf_map_dmabuf(struct dma_buf_attachment *attachment, + enum dma_data_direction dir) +{ + struct virtio_vdmabuf_buf *exp_buf; + struct sg_table *sgt; + struct scatterlist *sgl; + int i, ret; + + if (!attachment->dmabuf || !attachment->dmabuf->priv) + return ERR_PTR(-EINVAL); + + exp_buf = attachment->dmabuf->priv; + + sgt = kvzalloc(sizeof(*sgt), GFP_KERNEL); + if (!sgt) + return ERR_PTR(-ENOMEM); + + ret = sg_alloc_table(sgt, exp_buf->pages_info->nents, GFP_KERNEL); + if (ret) { + kvfree(sgt); + return ERR_PTR(ret); + } + + sgl = sgt->sgl; + for (i = 0; i < exp_buf->pages_info->nents; i++) { + sg_set_page(sgl, exp_buf->pages_info->pages[i], PAGE_SIZE, 0); + sgl = sg_next(sgl); + } + + if (!dma_map_sg(attachment->dev, sgt->sgl, sgt->nents, dir)) { + sg_free_table(sgt); + kvfree(sgt); + return ERR_PTR(-EINVAL); + } + + return sgt; +} + +static int virtio_vdmabuf_mmap_dmabuf(struct dma_buf *dmabuf, + struct vm_area_struct *vma) +{ + struct virtio_vdmabuf_buf *exp_buf; + u64 uaddr; + int i, ret; + + if (!dmabuf->priv) + return -EINVAL; + + exp_buf = dmabuf->priv; + + if (!exp_buf->pages_info) + return -EINVAL; + + vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; + + uaddr = vma->vm_start; + for (i = 0; i < exp_buf->pages_info->nents; i++) { + ret = vm_insert_page(vma, uaddr, + exp_buf->pages_info->pages[i]); + if (ret) + return ret; + + uaddr += PAGE_SIZE; + } + + return 0; +} + +static void virtio_vdmabuf_unmap_dmabuf(struct dma_buf_attachment *attachment, + struct sg_table *sgt, + enum dma_data_direction dir) +{ + dma_unmap_sg(attachment->dev, sgt->sgl, sgt->nents, dir); + + sg_free_table(sgt); + kvfree(sgt); +} + +static void virtio_vdmabuf_release_dmabuf(struct dma_buf *dmabuf) +{ + struct virtio_vdmabuf_buf *exp_buf = dmabuf->priv; + int i; + + for (i = 0; i < exp_buf->pages_info->nents; i++) + put_page(exp_buf->pages_info->pages[i]); +} + +static const struct dma_buf_ops virtio_vdmabuf_dmabuf_ops = { + .map_dma_buf = virtio_vdmabuf_map_dmabuf, + .unmap_dma_buf = virtio_vdmabuf_unmap_dmabuf, + .release = virtio_vdmabuf_release_dmabuf, + .mmap = virtio_vdmabuf_mmap_dmabuf, +}; + +static int virtio_vdmabuf_create_dmabuf(struct virtio_vdmabuf *vdmabuf, + uint64_t bo_size) +{ + DEFINE_DMA_BUF_EXPORT_INFO(exp_info); + struct virtio_vdmabuf_buf *exp_buf; + struct dma_buf *dmabuf; + uint32_t num_pages = DIV_ROUND_UP(bo_size, PAGE_SIZE); + int i, j, ret; + + exp_buf = kvzalloc(sizeof(*exp_buf), GFP_KERNEL); + if (!exp_buf) + goto err_exp; + + exp_buf->pages_info = kvzalloc(sizeof (*(exp_buf->pages_info)), + GFP_KERNEL); + if (!exp_buf->pages_info) + goto err_pages_info; + + exp_buf->pages_info->pages = kvzalloc(num_pages * sizeof(struct page *), + GFP_KERNEL); + if (!exp_buf->pages_info->pages) + goto err_pages; + + exp_info.ops = &virtio_vdmabuf_dmabuf_ops; + exp_info.size = bo_size; + exp_info.flags = O_CLOEXEC; + exp_info.priv = exp_buf; + + for (i = 0; i < num_pages; i++) { + exp_buf->pages_info->pages[i] = alloc_page(GFP_KERNEL | + __GFP_ZERO); + if (!exp_buf->pages_info->pages[i]) + goto err_alloc; + } + + dmabuf = dma_buf_export(&exp_info); + if (IS_ERR_OR_NULL(dmabuf)) + goto err_alloc; + + ret = dma_buf_fd(dmabuf, 0); + if (ret < 0) + goto err_alloc; + + exp_buf->fd = ret; + exp_buf->buf_id = get_buf_id(vdmabuf); + exp_buf->pages_info->nents = num_pages; + + virtio_vdmabuf_add_buf(drv_info, exp_buf); + + return ret; + +err_alloc: + for (j = 0; j < i; j++) + put_page(exp_buf->pages_info->pages[i]); +err_pages: + kvfree(exp_buf->pages_info->pages); +err_pages_info: + kvfree(exp_buf->pages_info); +err_exp: + kvfree(exp_buf); + + return -ENOMEM; +} + +static int virtio_vdmabuf_open(struct inode *inode, struct file *filp) +{ + int ret; + + if (!drv_info) { + pr_err("virtio vdmabuf driver is not ready\n"); + return -EINVAL; + } + + ret = send_msg_to_host(VIRTIO_VDMABUF_CMD_NEED_VMID, 0); + if (ret < 0) + dev_err(drv_info->dev, "fail to receive vmid\n"); + + filp->private_data = drv_info->priv; + + return 0; +} + +static int virtio_vdmabuf_release(struct inode *inode, struct file *filp) +{ + return 0; +} + +/* Notify Host about the new vdmabuf */ +static int export_notify(struct virtio_vdmabuf_buf *exp) +{ + struct virtio_vdmabuf_shared_pages *pages_info = exp->pages_info; + int *op; + int ret; + + op = kvcalloc(1, sizeof(int) * 65, GFP_KERNEL); + if (!op) + return -ENOMEM; + + memcpy(op, &exp->buf_id, sizeof(exp->buf_id)); + + op[4] = pages_info->nents; + op[5] = pages_info->first_ofst; + //op[6] = pages_info->last_len; + op[6] = PAGE_SIZE; + + memcpy(&op[7], &pages_info->ref, sizeof(gpa_t)); + op[9] = exp->sz_priv; + + /* driver/application specific private info */ + memcpy(&op[10], exp->priv, op[9]); + + ret = send_msg_to_host(VIRTIO_VDMABUF_CMD_EXPORT, op); + + kvfree(op); + return ret; +} + +/* ioctl - exporting new vdmabuf + * + * int dmabuf_fd - File handle of original DMABUF + * virtio_vdmabuf_buf_id_t buf_id - returned vdmabuf ID + * int sz_priv - size of private data from userspace + * char *priv - buffer of user private data + * + */ +static int export_ioctl(struct file *filp, void *data) +{ + struct virtio_vdmabuf *vdmabuf = filp->private_data; + struct virtio_vdmabuf_export *attr = data; + struct virtio_vdmabuf_buf *exp; + int ret = 0; + + if (vdmabuf->vmid <= 0) + return -EINVAL; + + exp = virtio_vdmabuf_find_buf_fd(drv_info, attr->fd); + if (!exp) + return -EINVAL; + + mutex_lock(&drv_info->g_mutex); + + /* possible truncation */ + if (attr->sz_priv > MAX_SIZE_PRIV_DATA) + exp->sz_priv = MAX_SIZE_PRIV_DATA; + else + exp->sz_priv = attr->sz_priv; + + /* creating buffer for private data */ + if (exp->sz_priv != 0) { + exp->priv = kvcalloc(1, exp->sz_priv, GFP_KERNEL); + if (!exp->priv) + return -ENOMEM; + + ret = copy_from_user(exp->priv, attr->priv, exp->sz_priv); + if (ret) { + ret = -EINVAL; + goto fail_priv; + } + } + + ret = virtio_vdmabuf_share_buf(exp); + if (ret < 0) + goto fail_priv; + + ret = export_notify(exp); + if (ret < 0) + goto fail_priv; + + exp->valid = 1; + exp->filp = filp; + attr->buf_id = exp->buf_id; + + mutex_unlock(&drv_info->g_mutex); + + return ret; + +fail_priv: + kvfree(exp->priv); + mutex_unlock(&drv_info->g_mutex); + + return ret; +} + +static int alloc_ioctl(struct file *filp, void *data) +{ + struct virtio_vdmabuf *vdmabuf = filp->private_data; + struct virtio_vdmabuf_alloc *attr = data; + int ret; + + ret = virtio_vdmabuf_create_dmabuf(vdmabuf, attr->size); + if (ret < 0) + return ret; + + attr->fd = ret; + + return ret; +} + +static const struct virtio_vdmabuf_ioctl_desc virtio_vdmabuf_ioctls[] = { + VIRTIO_VDMABUF_IOCTL_DEF(VIRTIO_VDMABUF_IOCTL_ALLOC_FD, alloc_ioctl, 0), + VIRTIO_VDMABUF_IOCTL_DEF(VIRTIO_VDMABUF_IOCTL_EXPORT, export_ioctl, 0), +}; + +static long virtio_vdmabuf_ioctl(struct file *filp, unsigned int cmd, + unsigned long param) +{ + const struct virtio_vdmabuf_ioctl_desc *ioctl = NULL; + unsigned int nr = _IOC_NR(cmd); + int ret; + virtio_vdmabuf_ioctl_t func; + char *kdata; + + if (nr >= ARRAY_SIZE(virtio_vdmabuf_ioctls)) { + dev_err(drv_info->dev, "invalid ioctl\n"); + return -EINVAL; + } + + ioctl = &virtio_vdmabuf_ioctls[nr]; + + func = ioctl->func; + + if (unlikely(!func)) { + dev_err(drv_info->dev, "no function\n"); + return -EINVAL; + } + + kdata = kvmalloc(_IOC_SIZE(cmd), GFP_KERNEL); + if (!kdata) + return -ENOMEM; + + if (copy_from_user(kdata, (void __user *)param, + _IOC_SIZE(cmd)) != 0) { + dev_err(drv_info->dev, + "failed to copy from user arguments\n"); + ret = -EFAULT; + goto ioctl_error; + } + + ret = func(filp, kdata); + + if (copy_to_user((void __user *)param, kdata, + _IOC_SIZE(cmd)) != 0) { + dev_err(drv_info->dev, + "failed to copy to user arguments\n"); + ret = -EFAULT; + goto ioctl_error; + } + +ioctl_error: + kvfree(kdata); + return ret; +} + +static unsigned int virtio_vdmabuf_event_poll(struct file *filp, + struct poll_table_struct *wait) +{ + struct virtio_vdmabuf *vdmabuf = filp->private_data; + + poll_wait(filp, &vdmabuf->evq->e_wait, wait); + + if (!list_empty(&vdmabuf->evq->e_list)) + return POLLIN | POLLRDNORM; + + return 0; +} + +static ssize_t virtio_vdmabuf_event_read(struct file *filp, char __user *buf, + size_t cnt, loff_t *ofst) +{ + struct virtio_vdmabuf *vdmabuf = filp->private_data; + int ret; + + /* make sure user buffer can be written */ + if (!access_ok(buf, sizeof (*buf))) { + dev_err(drv_info->dev, "user buffer can't be written.\n"); + return -EINVAL; + } + + ret = mutex_lock_interruptible(&vdmabuf->evq->e_readlock); + if (ret) + return ret; + + for (;;) { + struct virtio_vdmabuf_event *e = NULL; + + spin_lock_irq(&vdmabuf->evq->e_lock); + if (!list_empty(&vdmabuf->evq->e_list)) { + e = list_first_entry(&vdmabuf->evq->e_list, + struct virtio_vdmabuf_event, link); + list_del(&e->link); + } + spin_unlock_irq(&vdmabuf->evq->e_lock); + + if (!e) { + if (ret) + break; + + if (filp->f_flags & O_NONBLOCK) { + ret = -EAGAIN; + break; + } + + mutex_unlock(&vdmabuf->evq->e_readlock); + ret = wait_event_interruptible(vdmabuf->evq->e_wait, + !list_empty(&vdmabuf->evq->e_list)); + + if (ret == 0) + ret = mutex_lock_interruptible( + &vdmabuf->evq->e_readlock); + + if (ret) + return ret; + } else { + unsigned int len = (sizeof(e->e_data.hdr) + + e->e_data.hdr.size); + + if (len > cnt - ret) { +put_back_event: + spin_lock_irq(&vdmabuf->evq->e_lock); + list_add(&e->link, &vdmabuf->evq->e_list); + spin_unlock_irq(&vdmabuf->evq->e_lock); + break; + } + + if (copy_to_user(buf + ret, &e->e_data.hdr, + sizeof(e->e_data.hdr))) { + if (ret == 0) + ret = -EFAULT; + + goto put_back_event; + } + + ret += sizeof(e->e_data.hdr); + + if (copy_to_user(buf + ret, e->e_data.data, + e->e_data.hdr.size)) { + /* error while copying void *data */ + + struct virtio_vdmabuf_e_hdr dummy_hdr = {0}; + + ret -= sizeof(e->e_data.hdr); + + /* nullifying hdr of the event in user buffer */ + if (copy_to_user(buf + ret, &dummy_hdr, + sizeof(dummy_hdr))) + dev_err(drv_info->dev, + "fail to nullify invalid hdr\n"); + + ret = -EFAULT; + + goto put_back_event; + } + + ret += e->e_data.hdr.size; + vdmabuf->evq->pending--; + kvfree(e); + } + } + + mutex_unlock(&vdmabuf->evq->e_readlock); + + return ret; +} + +static const struct file_operations virtio_vdmabuf_fops = { + .owner = THIS_MODULE, + .open = virtio_vdmabuf_open, + .release = virtio_vdmabuf_release, + .read = virtio_vdmabuf_event_read, + .poll = virtio_vdmabuf_event_poll, + .unlocked_ioctl = virtio_vdmabuf_ioctl, +}; + +static struct miscdevice virtio_vdmabuf_miscdev = { + .minor = MISC_DYNAMIC_MINOR, + .name = "virtio-vdmabuf", + .fops = &virtio_vdmabuf_fops, +}; + +static int virtio_vdmabuf_probe(struct virtio_device *vdev) +{ + vq_callback_t *cbs[] = { + virtio_vdmabuf_recv_cb, + virtio_vdmabuf_send_cb, + }; + static const char *const names[] = { + "recv", + "send", + }; + struct virtio_vdmabuf *vdmabuf; + int ret = 0; + + if (!drv_info) + return -EINVAL; + + vdmabuf = drv_info->priv; + + if (!vdmabuf) + return -EINVAL; + + vdmabuf->vdev = vdev; + vdev->priv = vdmabuf; + + /* initialize spinlock for synchronizing virtqueue accesses */ + spin_lock_init(&vdmabuf->vq_lock); + + ret = virtio_find_vqs(vdmabuf->vdev, VDMABUF_VQ_MAX, vdmabuf->vqs, + cbs, names, NULL); + if (ret) { + dev_err(drv_info->dev, "Cannot find any vqs\n"); + return ret; + } + + INIT_LIST_HEAD(&vdmabuf->msg_list); + INIT_WORK(&vdmabuf->recv_work, virtio_vdmabuf_recv_work); + INIT_WORK(&vdmabuf->send_work, virtio_vdmabuf_send_work); + INIT_WORK(&vdmabuf->send_msg_work, virtio_vdmabuf_send_msg_work); + + return ret; +} + +static void virtio_vdmabuf_remove(struct virtio_device *vdev) +{ + struct virtio_vdmabuf *vdmabuf; + + if (!drv_info) + return; + + vdmabuf = drv_info->priv; + flush_work(&vdmabuf->recv_work); + flush_work(&vdmabuf->send_work); + flush_work(&vdmabuf->send_msg_work); + + vdev->config->reset(vdev); + vdev->config->del_vqs(vdev); +} + +static struct virtio_device_id id_table[] = { + { VIRTIO_ID_VDMABUF, VIRTIO_DEV_ANY_ID }, + { 0 }, +}; + +static struct virtio_driver virtio_vdmabuf_vdev_drv = { + .driver.name = KBUILD_MODNAME, + .driver.owner = THIS_MODULE, + .id_table = id_table, + .probe = virtio_vdmabuf_probe, + .remove = virtio_vdmabuf_remove, +}; + +static int __init virtio_vdmabuf_init(void) +{ + struct virtio_vdmabuf *vdmabuf; + int ret = 0; + + drv_info = NULL; + + ret = misc_register(&virtio_vdmabuf_miscdev); + if (ret) { + pr_err("virtio-vdmabuf misc driver can't be registered\n"); + return ret; + } + + dma_coerce_mask_and_coherent(virtio_vdmabuf_miscdev.this_device, + DMA_BIT_MASK(64)); + + drv_info = kvcalloc(1, sizeof(*drv_info), GFP_KERNEL); + if (!drv_info) { + misc_deregister(&virtio_vdmabuf_miscdev); + return -ENOMEM; + } + + vdmabuf = kvcalloc(1, sizeof(*vdmabuf), GFP_KERNEL); + if (!vdmabuf) { + kvfree(drv_info); + misc_deregister(&virtio_vdmabuf_miscdev); + return -ENOMEM; + } + + vdmabuf->evq = kvcalloc(1, sizeof(*vdmabuf->evq), GFP_KERNEL); + if (!vdmabuf->evq) { + kvfree(drv_info); + kvfree(vdmabuf); + misc_deregister(&virtio_vdmabuf_miscdev); + return -ENOMEM; + } + + drv_info->priv = (void *)vdmabuf; + drv_info->dev = virtio_vdmabuf_miscdev.this_device; + + mutex_init(&drv_info->g_mutex); + + mutex_init(&vdmabuf->evq->e_readlock); + spin_lock_init(&vdmabuf->evq->e_lock); + + INIT_LIST_HEAD(&vdmabuf->evq->e_list); + init_waitqueue_head(&vdmabuf->evq->e_wait); + hash_init(drv_info->buf_list); + + vdmabuf->evq->pending = 0; + vdmabuf->wq = create_workqueue("virtio_vdmabuf_wq"); + + ret = register_virtio_driver(&virtio_vdmabuf_vdev_drv); + if (ret) { + dev_err(drv_info->dev, "vdmabuf driver can't be registered\n"); + misc_deregister(&virtio_vdmabuf_miscdev); + kvfree(vdmabuf); + kvfree(drv_info); + return -EFAULT; + } + + return 0; +} + +static void __exit virtio_vdmabuf_deinit(void) +{ + struct virtio_vdmabuf *vdmabuf = drv_info->priv; + struct virtio_vdmabuf_event *e, *et; + unsigned long irqflags; + + misc_deregister(&virtio_vdmabuf_miscdev); + unregister_virtio_driver(&virtio_vdmabuf_vdev_drv); + + if (vdmabuf->wq) + destroy_workqueue(vdmabuf->wq); + + spin_lock_irqsave(&vdmabuf->evq->e_lock, irqflags); + + list_for_each_entry_safe(e, et, &vdmabuf->evq->e_list, + link) { + list_del(&e->link); + kvfree(e); + vdmabuf->evq->pending--; + } + + spin_unlock_irqrestore(&vdmabuf->evq->e_lock, irqflags); + + /* freeing all exported buffers */ + remove_all_bufs(vdmabuf); + + kvfree(vdmabuf->evq); + kvfree(vdmabuf); + kvfree(drv_info); +} + +module_init(virtio_vdmabuf_init); +module_exit(virtio_vdmabuf_deinit); + +MODULE_DEVICE_TABLE(virtio, virtio_vdmabuf_id_table); +MODULE_DESCRIPTION("Virtio Vdmabuf frontend driver"); +MODULE_LICENSE("GPL and additional rights"); diff --git a/include/linux/virtio_vdmabuf.h b/include/linux/virtio_vdmabuf.h new file mode 100644 index 000000000000..ddd0d3c8a91c --- /dev/null +++ b/include/linux/virtio_vdmabuf.h @@ -0,0 +1,287 @@ +/* SPDX-License-Identifier: (MIT OR GPL-2.0) */ + +/* + * Copyright © 2021 Intel Corporation + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + * + */ + +#ifndef _LINUX_VIRTIO_VDMABUF_H +#define _LINUX_VIRTIO_VDMABUF_H + +#include <uapi/linux/virtio_vdmabuf.h> +#include <linux/hashtable.h> +#include <linux/kvm_types.h> + +struct virtio_vdmabuf_shared_pages { + /* cross-VM ref addr for the buffer */ + gpa_t ref; + + /* page array */ + struct page **pages; + gpa_t **l2refs; + gpa_t *l3refs; + + /* data offset in the first page + * and data length in the last page + */ + int first_ofst; + int last_len; + + /* number of shared pages */ + int nents; +}; + +struct virtio_vdmabuf_buf { + virtio_vdmabuf_buf_id_t buf_id; + + struct dma_buf_attachment *attach; + struct dma_buf *dma_buf; + struct sg_table *sgt; + struct virtio_vdmabuf_shared_pages *pages_info; + int vmid; + int fd; + uint64_t size; + + /* validity of the buffer */ + bool valid; + + /* set if the buffer is imported via import_ioctl */ + bool imported; + + /* size of private */ + size_t sz_priv; + /* private data associated with the exported buffer */ + void *priv; + + struct file *filp; + struct hlist_node node; +}; + +struct virtio_vdmabuf_event { + struct virtio_vdmabuf_e_data e_data; + struct list_head link; +}; + +struct virtio_vdmabuf_event_queue { + wait_queue_head_t e_wait; + struct list_head e_list; + + spinlock_t e_lock; + struct mutex e_readlock; + + /* # of pending events */ + int pending; +}; + +/* driver information */ +struct virtio_vdmabuf_info { + struct device *dev; + + struct list_head head_vdmabuf_list; + struct list_head kvm_instances; + + DECLARE_HASHTABLE(buf_list, 7); + + void *priv; + struct mutex g_mutex; + struct notifier_block kvm_notifier; +}; + +/* IOCTL definitions + */ +typedef int (*virtio_vdmabuf_ioctl_t)(struct file *filp, void *data); + +struct virtio_vdmabuf_ioctl_desc { + unsigned int cmd; + int flags; + virtio_vdmabuf_ioctl_t func; + const char *name; +}; + +#define VIRTIO_VDMABUF_IOCTL_DEF(ioctl, _func, _flags) \ + [_IOC_NR(ioctl)] = { \ + .cmd = ioctl, \ + .func = _func, \ + .flags = _flags, \ + .name = #ioctl \ +} + +#define VIRTIO_VDMABUF_VMID(buf_id) ((((buf_id).id) >> 32) & 0xFFFFFFFF) + +/* Messages between Host and Guest */ + +/* List of commands from Guest to Host: + * + * ------------------------------------------------------------------ + * A. NEED_VMID + * + * guest asks the host to provide its vmid + * + * req: + * + * cmd: VIRTIO_VDMABUF_NEED_VMID + * + * ack: + * + * cmd: same as req + * op[0] : vmid of guest + * + * ------------------------------------------------------------------ + * B. EXPORT + * + * export dmabuf to host + * + * req: + * + * cmd: VIRTIO_VDMABUF_CMD_EXPORT + * op0~op3 : HDMABUF ID + * op4 : number of pages to be shared + * op5 : offset of data in the first page + * op6 : length of data in the last page + * op7 : upper 32 bit of top-level ref of shared buf + * op8 : lower 32 bit of top-level ref of shared buf + * op9 : size of private data + * op10 ~ op64: User private date associated with the buffer + * (e.g. graphic buffer's meta info) + * + * ------------------------------------------------------------------ + * + * List of commands from Host to Guest + * + * ------------------------------------------------------------------ + * A. RELEASE + * + * notifying guest that the shared buffer is released by an importer + * + * req: + * + * cmd: VIRTIO_VDMABUF_CMD_DMABUF_REL + * op0~op3 : VDMABUF ID + * + * ------------------------------------------------------------------ + */ + +/* msg structures */ +struct virtio_vdmabuf_msg { + struct list_head list; + unsigned int cmd; + unsigned int op[64]; +}; + +enum { + VDMABUF_VQ_RECV = 0, + VDMABUF_VQ_SEND = 1, + VDMABUF_VQ_MAX = 2, +}; + +enum virtio_vdmabuf_cmd { + VIRTIO_VDMABUF_CMD_NEED_VMID, + VIRTIO_VDMABUF_CMD_EXPORT = 0x10, + VIRTIO_VDMABUF_CMD_DMABUF_REL +}; + +enum virtio_vdmabuf_ops { + VIRTIO_VDMABUF_HDMABUF_ID_ID = 0, + VIRTIO_VDMABUF_HDMABUF_ID_RNG_KEY0, + VIRTIO_VDMABUF_HDMABUF_ID_RNG_KEY1, + VIRTIO_VDMABUF_NUM_PAGES_SHARED = 4, + VIRTIO_VDMABUF_FIRST_PAGE_DATA_OFFSET, + VIRTIO_VDMABUF_LAST_PAGE_DATA_LENGTH, + VIRTIO_VDMABUF_REF_ADDR_UPPER_32BIT, + VIRTIO_VDMABUF_REF_ADDR_LOWER_32BIT, + VIRTIO_VDMABUF_PRIVATE_DATA_SIZE, + VIRTIO_VDMABUF_PRIVATE_DATA_START +}; + +/* adding exported/imported vdmabuf info to hash */ +static inline int +virtio_vdmabuf_add_buf(struct virtio_vdmabuf_info *info, + struct virtio_vdmabuf_buf *new) +{ + hash_add(info->buf_list, &new->node, new->buf_id.id); + return 0; +} + +/* comparing two vdmabuf IDs */ +static inline bool +is_same_buf(virtio_vdmabuf_buf_id_t a, + virtio_vdmabuf_buf_id_t b) +{ + int i; + + if (a.id != b.id) + return false; + + /* compare keys */ + for (i = 0; i < 2; i++) { + if (a.rng_key[i] != b.rng_key[i]) + return false; + } + + return true; +} + +/* find buf for given vdmabuf ID */ +static inline struct virtio_vdmabuf_buf +*virtio_vdmabuf_find_buf(struct virtio_vdmabuf_info *info, + virtio_vdmabuf_buf_id_t *buf_id) +{ + struct virtio_vdmabuf_buf *found; + + hash_for_each_possible(info->buf_list, found, node, buf_id->id) + if (is_same_buf(found->buf_id, *buf_id)) + return found; + + return NULL; +} + +/* find buf for given fd */ +static inline struct virtio_vdmabuf_buf +*virtio_vdmabuf_find_buf_fd(struct virtio_vdmabuf_info *info, int fd) +{ + struct virtio_vdmabuf_buf *found; + int i; + + hash_for_each(info->buf_list, i, found, node) + if (found->fd == fd) + return found; + + return NULL; +} + +/* delete buf from hash */ +static inline int +virtio_vdmabuf_del_buf(struct virtio_vdmabuf_info *info, + virtio_vdmabuf_buf_id_t *buf_id) +{ + struct virtio_vdmabuf_buf *found; + + found = virtio_vdmabuf_find_buf(info, buf_id); + if (!found) + return -ENOENT; + + hash_del(&found->node); + + return 0; +} + +#endif diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h index bc1c0621f5ed..0be3ef28dd0c 100644 --- a/include/uapi/linux/virtio_ids.h +++ b/include/uapi/linux/virtio_ids.h @@ -54,5 +54,6 @@ #define VIRTIO_ID_FS 26 /* virtio filesystem */ #define VIRTIO_ID_PMEM 27 /* virtio pmem */ #define VIRTIO_ID_MAC80211_HWSIM 29 /* virtio mac80211-hwsim */ +#define VIRTIO_ID_VDMABUF 37 /* virtio vdmabuf */
#endif /* _LINUX_VIRTIO_IDS_H */ diff --git a/include/uapi/linux/virtio_vdmabuf.h b/include/uapi/linux/virtio_vdmabuf.h new file mode 100644 index 000000000000..f71fc054bbff --- /dev/null +++ b/include/uapi/linux/virtio_vdmabuf.h @@ -0,0 +1,87 @@ +// SPDX-License-Identifier: (MIT OR GPL-2.0) + +/* + * Copyright © 2021 Intel Corporation + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS + * IN THE SOFTWARE. + * + */ + +#ifndef _UAPI_LINUX_VIRTIO_VDMABUF_H +#define _UAPI_LINUX_VIRTIO_VDMABUF_H + +#define MAX_SIZE_PRIV_DATA 192 + +typedef struct { + __u64 id; + /* 8B long Random number */ + int rng_key[2]; +} virtio_vdmabuf_buf_id_t; + +struct virtio_vdmabuf_e_hdr { + /* buf_id of new buf */ + virtio_vdmabuf_buf_id_t buf_id; + /* size of private data */ + int size; +}; + +struct virtio_vdmabuf_e_data { + struct virtio_vdmabuf_e_hdr hdr; + /* ptr to private data */ + void __user *data; +}; + +#define VIRTIO_VDMABUF_IOCTL_IMPORT \ +_IOC(_IOC_NONE, 'G', 2, sizeof(struct virtio_vdmabuf_import)) +#define VIRTIO_VDMABUF_IOCTL_RELEASE \ +_IOC(_IOC_NONE, 'G', 3, sizeof(struct virtio_vdmabuf_import)) +struct virtio_vdmabuf_import { + /* IN parameters */ + /* vdmabuf id to be imported */ + virtio_vdmabuf_buf_id_t buf_id; + /* flags */ + int flags; + /* OUT parameters */ + /* exported dma buf fd */ + int fd; +}; + +#define VIRTIO_VDMABUF_IOCTL_EXPORT \ +_IOC(_IOC_NONE, 'G', 4, sizeof(struct virtio_vdmabuf_export)) +struct virtio_vdmabuf_export { + /* IN parameters */ + /* DMA buf fd to be exported */ + int fd; + /* exported dma buf id */ + virtio_vdmabuf_buf_id_t buf_id; + int sz_priv; + char *priv; +}; + +#define VIRTIO_VDMABUF_IOCTL_ALLOC_FD \ +_IOC(_IOC_NONE, 'G', 5, sizeof(struct virtio_vdmabuf_alloc)) +struct virtio_vdmabuf_alloc { + /* IN parameters */ + uint32_t size; + /* OUT parameters */ + int fd; +}; + +#endif