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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Michael S. Tsirkin](/assets/img/avatar_default.png)
commit 2ae76693b8bcabf370b981cd00c36cd41d33fabc vhost: replace rcu with mutex replaced rcu sync for memory accesses with VQ mutex locl/unlock. This is correct since all accesses are under VQ mutex, but incomplete: we still do useless rcu lock/unlock operations, someone might copy this code into some other context where this won't be right. This use of RCU is also non standard and hard to understand. Let's copy the pointer to each VQ structure, this way the access rules become straight-forward, and there's no need for RCU anymore. Reported-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
179 lines
5.3 KiB
C
179 lines
5.3 KiB
C
#ifndef _VHOST_H
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#define _VHOST_H
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#include <linux/eventfd.h>
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#include <linux/vhost.h>
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#include <linux/mm.h>
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#include <linux/mutex.h>
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#include <linux/poll.h>
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#include <linux/file.h>
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#include <linux/uio.h>
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#include <linux/virtio_config.h>
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#include <linux/virtio_ring.h>
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#include <linux/atomic.h>
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struct vhost_device;
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struct vhost_work;
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typedef void (*vhost_work_fn_t)(struct vhost_work *work);
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struct vhost_work {
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struct list_head node;
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vhost_work_fn_t fn;
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wait_queue_head_t done;
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int flushing;
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unsigned queue_seq;
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unsigned done_seq;
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};
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/* Poll a file (eventfd or socket) */
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/* Note: there's nothing vhost specific about this structure. */
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struct vhost_poll {
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poll_table table;
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wait_queue_head_t *wqh;
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wait_queue_t wait;
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struct vhost_work work;
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unsigned long mask;
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struct vhost_dev *dev;
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};
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void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
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void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
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void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
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unsigned long mask, struct vhost_dev *dev);
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int vhost_poll_start(struct vhost_poll *poll, struct file *file);
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void vhost_poll_stop(struct vhost_poll *poll);
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void vhost_poll_flush(struct vhost_poll *poll);
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void vhost_poll_queue(struct vhost_poll *poll);
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void vhost_work_flush(struct vhost_dev *dev, struct vhost_work *work);
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long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp);
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struct vhost_log {
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u64 addr;
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u64 len;
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};
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struct vhost_virtqueue;
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/* The virtqueue structure describes a queue attached to a device. */
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struct vhost_virtqueue {
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struct vhost_dev *dev;
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/* The actual ring of buffers. */
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struct mutex mutex;
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unsigned int num;
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struct vring_desc __user *desc;
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struct vring_avail __user *avail;
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struct vring_used __user *used;
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struct file *kick;
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struct file *call;
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struct file *error;
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struct eventfd_ctx *call_ctx;
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struct eventfd_ctx *error_ctx;
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struct eventfd_ctx *log_ctx;
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struct vhost_poll poll;
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/* The routine to call when the Guest pings us, or timeout. */
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vhost_work_fn_t handle_kick;
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/* Last available index we saw. */
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u16 last_avail_idx;
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/* Caches available index value from user. */
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u16 avail_idx;
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/* Last index we used. */
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u16 last_used_idx;
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/* Used flags */
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u16 used_flags;
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/* Last used index value we have signalled on */
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u16 signalled_used;
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/* Last used index value we have signalled on */
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bool signalled_used_valid;
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/* Log writes to used structure. */
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bool log_used;
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u64 log_addr;
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struct iovec iov[UIO_MAXIOV];
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struct iovec *indirect;
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struct vring_used_elem *heads;
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/* Protected by virtqueue mutex. */
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struct vhost_memory *memory;
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void *private_data;
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unsigned acked_features;
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/* Log write descriptors */
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void __user *log_base;
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struct vhost_log *log;
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};
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struct vhost_dev {
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struct vhost_memory *memory;
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struct mm_struct *mm;
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struct mutex mutex;
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struct vhost_virtqueue **vqs;
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int nvqs;
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struct file *log_file;
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struct eventfd_ctx *log_ctx;
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spinlock_t work_lock;
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struct list_head work_list;
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struct task_struct *worker;
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};
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void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs, int nvqs);
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long vhost_dev_set_owner(struct vhost_dev *dev);
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bool vhost_dev_has_owner(struct vhost_dev *dev);
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long vhost_dev_check_owner(struct vhost_dev *);
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struct vhost_memory *vhost_dev_reset_owner_prepare(void);
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void vhost_dev_reset_owner(struct vhost_dev *, struct vhost_memory *);
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void vhost_dev_cleanup(struct vhost_dev *, bool locked);
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void vhost_dev_stop(struct vhost_dev *);
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long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
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long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp);
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int vhost_vq_access_ok(struct vhost_virtqueue *vq);
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int vhost_log_access_ok(struct vhost_dev *);
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int vhost_get_vq_desc(struct vhost_virtqueue *,
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struct iovec iov[], unsigned int iov_count,
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unsigned int *out_num, unsigned int *in_num,
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struct vhost_log *log, unsigned int *log_num);
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void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
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int vhost_init_used(struct vhost_virtqueue *);
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int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
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int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
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unsigned count);
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void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
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unsigned int id, int len);
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void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
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struct vring_used_elem *heads, unsigned count);
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void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
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void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
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bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
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int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
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unsigned int log_num, u64 len);
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#define vq_err(vq, fmt, ...) do { \
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pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \
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if ((vq)->error_ctx) \
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eventfd_signal((vq)->error_ctx, 1);\
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} while (0)
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enum {
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VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
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(1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
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(1ULL << VIRTIO_RING_F_EVENT_IDX) |
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(1ULL << VHOST_F_LOG_ALL),
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};
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static inline int vhost_has_feature(struct vhost_virtqueue *vq, int bit)
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{
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return vq->acked_features & (1 << bit);
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}
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#endif
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