diff options
Diffstat (limited to 'drivers/vhost/vhost.c')
| -rw-r--r-- | drivers/vhost/vhost.c | 1098 |
1 files changed, 1098 insertions, 0 deletions
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c new file mode 100644 index 00000000000..c8c25dbc585 --- /dev/null +++ b/drivers/vhost/vhost.c @@ -0,0 +1,1098 @@ +/* Copyright (C) 2009 Red Hat, Inc. + * Copyright (C) 2006 Rusty Russell IBM Corporation + * + * Author: Michael S. Tsirkin <mst@redhat.com> + * + * Inspiration, some code, and most witty comments come from + * Documentation/lguest/lguest.c, by Rusty Russell + * + * This work is licensed under the terms of the GNU GPL, version 2. + * + * Generic code for virtio server in host kernel. + */ + +#include <linux/eventfd.h> +#include <linux/vhost.h> +#include <linux/virtio_net.h> +#include <linux/mm.h> +#include <linux/miscdevice.h> +#include <linux/mutex.h> +#include <linux/workqueue.h> +#include <linux/rcupdate.h> +#include <linux/poll.h> +#include <linux/file.h> +#include <linux/highmem.h> + +#include <linux/net.h> +#include <linux/if_packet.h> +#include <linux/if_arp.h> + +#include <net/sock.h> + +#include "vhost.h" + +enum { + VHOST_MEMORY_MAX_NREGIONS = 64, + VHOST_MEMORY_F_LOG = 0x1, +}; + +static struct workqueue_struct *vhost_workqueue; + +static void vhost_poll_func(struct file *file, wait_queue_head_t *wqh, + poll_table *pt) +{ + struct vhost_poll *poll; + poll = container_of(pt, struct vhost_poll, table); + + poll->wqh = wqh; + add_wait_queue(wqh, &poll->wait); +} + +static int vhost_poll_wakeup(wait_queue_t *wait, unsigned mode, int sync, + void *key) +{ + struct vhost_poll *poll; + poll = container_of(wait, struct vhost_poll, wait); + if (!((unsigned long)key & poll->mask)) + return 0; + + queue_work(vhost_workqueue, &poll->work); + return 0; +} + +/* Init poll structure */ +void vhost_poll_init(struct vhost_poll *poll, work_func_t func, + unsigned long mask) +{ + INIT_WORK(&poll->work, func); + init_waitqueue_func_entry(&poll->wait, vhost_poll_wakeup); + init_poll_funcptr(&poll->table, vhost_poll_func); + poll->mask = mask; +} + +/* Start polling a file. We add ourselves to file's wait queue. The caller must + * keep a reference to a file until after vhost_poll_stop is called. */ +void vhost_poll_start(struct vhost_poll *poll, struct file *file) +{ + unsigned long mask; + mask = file->f_op->poll(file, &poll->table); + if (mask) + vhost_poll_wakeup(&poll->wait, 0, 0, (void *)mask); +} + +/* Stop polling a file. After this function returns, it becomes safe to drop the + * file reference. You must also flush afterwards. */ +void vhost_poll_stop(struct vhost_poll *poll) +{ + remove_wait_queue(poll->wqh, &poll->wait); +} + +/* Flush any work that has been scheduled. When calling this, don't hold any + * locks that are also used by the callback. */ +void vhost_poll_flush(struct vhost_poll *poll) +{ + flush_work(&poll->work); +} + +void vhost_poll_queue(struct vhost_poll *poll) +{ + queue_work(vhost_workqueue, &poll->work); +} + +static void vhost_vq_reset(struct vhost_dev *dev, + struct vhost_virtqueue *vq) +{ + vq->num = 1; + vq->desc = NULL; + vq->avail = NULL; + vq->used = NULL; + vq->last_avail_idx = 0; + vq->avail_idx = 0; + vq->last_used_idx = 0; + vq->used_flags = 0; + vq->used_flags = 0; + vq->log_used = false; + vq->log_addr = -1ull; + vq->hdr_size = 0; + vq->private_data = NULL; + vq->log_base = NULL; + vq->error_ctx = NULL; + vq->error = NULL; + vq->kick = NULL; + vq->call_ctx = NULL; + vq->call = NULL; +} + +long vhost_dev_init(struct vhost_dev *dev, + struct vhost_virtqueue *vqs, int nvqs) +{ + int i; + dev->vqs = vqs; + dev->nvqs = nvqs; + mutex_init(&dev->mutex); + dev->log_ctx = NULL; + dev->log_file = NULL; + dev->memory = NULL; + dev->mm = NULL; + + for (i = 0; i < dev->nvqs; ++i) { + dev->vqs[i].dev = dev; + mutex_init(&dev->vqs[i].mutex); + vhost_vq_reset(dev, dev->vqs + i); + if (dev->vqs[i].handle_kick) + vhost_poll_init(&dev->vqs[i].poll, + dev->vqs[i].handle_kick, + POLLIN); + } + return 0; +} + +/* Caller should have device mutex */ +long vhost_dev_check_owner(struct vhost_dev *dev) +{ + /* Are you the owner? If not, I don't think you mean to do that */ + return dev->mm == current->mm ? 0 : -EPERM; +} + +/* Caller should have device mutex */ +static long vhost_dev_set_owner(struct vhost_dev *dev) +{ + /* Is there an owner already? */ + if (dev->mm) + return -EBUSY; + /* No owner, become one */ + dev->mm = get_task_mm(current); + return 0; +} + +/* Caller should have device mutex */ +long vhost_dev_reset_owner(struct vhost_dev *dev) +{ + struct vhost_memory *memory; + + /* Restore memory to default empty mapping. */ + memory = kmalloc(offsetof(struct vhost_memory, regions), GFP_KERNEL); + if (!memory) + return -ENOMEM; + + vhost_dev_cleanup(dev); + + memory->nregions = 0; + dev->memory = memory; + return 0; +} + +/* Caller should have device mutex */ +void vhost_dev_cleanup(struct vhost_dev *dev) +{ + int i; + for (i = 0; i < dev->nvqs; ++i) { + if (dev->vqs[i].kick && dev->vqs[i].handle_kick) { + vhost_poll_stop(&dev->vqs[i].poll); + vhost_poll_flush(&dev->vqs[i].poll); + } + if (dev->vqs[i].error_ctx) + eventfd_ctx_put(dev->vqs[i].error_ctx); + if (dev->vqs[i].error) + fput(dev->vqs[i].error); + if (dev->vqs[i].kick) + fput(dev->vqs[i].kick); + if (dev->vqs[i].call_ctx) + eventfd_ctx_put(dev->vqs[i].call_ctx); + if (dev->vqs[i].call) + fput(dev->vqs[i].call); + vhost_vq_reset(dev, dev->vqs + i); + } + if (dev->log_ctx) + eventfd_ctx_put(dev->log_ctx); + dev->log_ctx = NULL; + if (dev->log_file) + fput(dev->log_file); + dev->log_file = NULL; + /* No one will access memory at this point */ + kfree(dev->memory); + dev->memory = NULL; + if (dev->mm) + mmput(dev->mm); + dev->mm = NULL; +} + +static int log_access_ok(void __user *log_base, u64 addr, unsigned long sz) +{ + u64 a = addr / VHOST_PAGE_SIZE / 8; + /* Make sure 64 bit math will not overflow. */ + if (a > ULONG_MAX - (unsigned long)log_base || + a + (unsigned long)log_base > ULONG_MAX) + return -EFAULT; + + return access_ok(VERIFY_WRITE, log_base + a, + (sz + VHOST_PAGE_SIZE * 8 - 1) / VHOST_PAGE_SIZE / 8); +} + +/* Caller should have vq mutex and device mutex. */ +static int vq_memory_access_ok(void __user *log_base, struct vhost_memory *mem, + int log_all) +{ + int i; + for (i = 0; i < mem->nregions; ++i) { + struct vhost_memory_region *m = mem->regions + i; + unsigned long a = m->userspace_addr; + if (m->memory_size > ULONG_MAX) + return 0; + else if (!access_ok(VERIFY_WRITE, (void __user *)a, + m->memory_size)) + return 0; + else if (log_all && !log_access_ok(log_base, + m->guest_phys_addr, + m->memory_size)) + return 0; + } + return 1; +} + +/* Can we switch to this memory table? */ +/* Caller should have device mutex but not vq mutex */ +static int memory_access_ok(struct vhost_dev *d, struct vhost_memory *mem, + int log_all) +{ + int i; + for (i = 0; i < d->nvqs; ++i) { + int ok; + mutex_lock(&d->vqs[i].mutex); + /* If ring is inactive, will check when it's enabled. */ + if (d->vqs[i].private_data) + ok = vq_memory_access_ok(d->vqs[i].log_base, mem, + log_all); + else + ok = 1; + mutex_unlock(&d->vqs[i].mutex); + if (!ok) + return 0; + } + return 1; +} + +static int vq_access_ok(unsigned int num, + struct vring_desc __user *desc, + struct vring_avail __user *avail, + struct vring_used __user *used) +{ + return access_ok(VERIFY_READ, desc, num * sizeof *desc) && + access_ok(VERIFY_READ, avail, + sizeof *avail + num * sizeof *avail->ring) && + access_ok(VERIFY_WRITE, used, + sizeof *used + num * sizeof *used->ring); +} + +/* Can we log writes? */ +/* Caller should have device mutex but not vq mutex */ +int vhost_log_access_ok(struct vhost_dev *dev) +{ + return memory_access_ok(dev, dev->memory, 1); +} + +/* Verify access for write logging. */ +/* Caller should have vq mutex and device mutex */ +static int vq_log_access_ok(struct vhost_virtqueue *vq, void __user *log_base) +{ + return vq_memory_access_ok(log_base, vq->dev->memory, + vhost_has_feature(vq->dev, VHOST_F_LOG_ALL)) && + (!vq->log_used || log_access_ok(log_base, vq->log_addr, + sizeof *vq->used + + vq->num * sizeof *vq->used->ring)); +} + +/* Can we start vq? */ +/* Caller should have vq mutex and device mutex */ +int vhost_vq_access_ok(struct vhost_virtqueue *vq) +{ + return vq_access_ok(vq->num, vq->desc, vq->avail, vq->used) && + vq_log_access_ok(vq, vq->log_base); +} + +static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m) +{ + struct vhost_memory mem, *newmem, *oldmem; + unsigned long size = offsetof(struct vhost_memory, regions); + long r; + r = copy_from_user(&mem, m, size); + if (r) + return r; + if (mem.padding) + return -EOPNOTSUPP; + if (mem.nregions > VHOST_MEMORY_MAX_NREGIONS) + return -E2BIG; + newmem = kmalloc(size + mem.nregions * sizeof *m->regions, GFP_KERNEL); + if (!newmem) + return -ENOMEM; + + memcpy(newmem, &mem, size); + r = copy_from_user(newmem->regions, m->regions, + mem.nregions * sizeof *m->regions); + if (r) { + kfree(newmem); + return r; + } + + if (!memory_access_ok(d, newmem, vhost_has_feature(d, VHOST_F_LOG_ALL))) + return -EFAULT; + oldmem = d->memory; + rcu_assign_pointer(d->memory, newmem); + synchronize_rcu(); + kfree(oldmem); + return 0; +} + +static int init_used(struct vhost_virtqueue *vq, + struct vring_used __user *used) +{ + int r = put_user(vq->used_flags, &used->flags); + if (r) + return r; + return get_user(vq->last_used_idx, &used->idx); +} + +static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp) +{ + struct file *eventfp, *filep = NULL, + *pollstart = NULL, *pollstop = NULL; + struct eventfd_ctx *ctx = NULL; + u32 __user *idxp = argp; + struct vhost_virtqueue *vq; + struct vhost_vring_state s; + struct vhost_vring_file f; + struct vhost_vring_addr a; + u32 idx; + long r; + + r = get_user(idx, idxp); + if (r < 0) + return r; + if (idx > d->nvqs) + return -ENOBUFS; + + vq = d->vqs + idx; + + mutex_lock(&vq->mutex); + + switch (ioctl) { + case VHOST_SET_VRING_NUM: + /* Resizing ring with an active backend? + * You don't want to do that. */ + if (vq->private_data) { + r = -EBUSY; + break; + } + r = copy_from_user(&s, argp, sizeof s); + if (r < 0) + break; + if (!s.num || s.num > 0xffff || (s.num & (s.num - 1))) { + r = -EINVAL; + break; + } + vq->num = s.num; + break; + case VHOST_SET_VRING_BASE: + /* Moving base with an active backend? + * You don't want to do that. */ + if (vq->private_data) { + r = -EBUSY; + break; + } + r = copy_from_user(&s, argp, sizeof s); + if (r < 0) + break; + if (s.num > 0xffff) { + r = -EINVAL; + break; + } + vq->last_avail_idx = s.num; + /* Forget the cached index value. */ + vq->avail_idx = vq->last_avail_idx; + break; + case VHOST_GET_VRING_BASE: + s.index = idx; + s.num = vq->last_avail_idx; + r = copy_to_user(argp, &s, sizeof s); + break; + case VHOST_SET_VRING_ADDR: + r = copy_from_user(&a, argp, sizeof a); + if (r < 0) + break; + if (a.flags & ~(0x1 << VHOST_VRING_F_LOG)) { + r = -EOPNOTSUPP; + break; + } + /* For 32bit, verify that the top 32bits of the user + data are set to zero. */ + if ((u64)(unsigned long)a.desc_user_addr != a.desc_user_addr || + (u64)(unsigned long)a.used_user_addr != a.used_user_addr || + (u64)(unsigned long)a.avail_user_addr != a.avail_user_addr) { + r = -EFAULT; + break; + } + if ((a.avail_user_addr & (sizeof *vq->avail->ring - 1)) || + (a.used_user_addr & (sizeof *vq->used->ring - 1)) || + (a.log_guest_addr & (sizeof *vq->used->ring - 1))) { + r = -EINVAL; + break; + } + + /* We only verify access here if backend is configured. + * If it is not, we don't as size might not have been setup. + * We will verify when backend is configured. */ + if (vq->private_data) { + if (!vq_access_ok(vq->num, + (void __user *)(unsigned long)a.desc_user_addr, + (void __user *)(unsigned long)a.avail_user_addr, + (void __user *)(unsigned long)a.used_user_addr)) { + r = -EINVAL; + break; + } + + /* Also validate log access for used ring if enabled. */ + if ((a.flags & (0x1 << VHOST_VRING_F_LOG)) && + !log_access_ok(vq->log_base, a.log_guest_addr, + sizeof *vq->used + + vq->num * sizeof *vq->used->ring)) { + r = -EINVAL; + break; + } + } + + r = init_used(vq, (struct vring_used __user *)(unsigned long) + a.used_user_addr); + if (r) + break; + vq->log_used = !!(a.flags & (0x1 << VHOST_VRING_F_LOG)); + vq->desc = (void __user *)(unsigned long)a.desc_user_addr; + vq->avail = (void __user *)(unsigned long)a.avail_user_addr; + vq->log_addr = a.log_guest_addr; + vq->used = (void __user *)(unsigned long)a.used_user_addr; + break; + case VHOST_SET_VRING_KICK: + r = copy_from_user(&f, argp, sizeof f); + if (r < 0) + break; + eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); + if (IS_ERR(eventfp)) + return PTR_ERR(eventfp); + if (eventfp != vq->kick) { + pollstop = filep = vq->kick; + pollstart = vq->kick = eventfp; + } else + filep = eventfp; + break; + case VHOST_SET_VRING_CALL: + r = copy_from_user(&f, argp, sizeof f); + if (r < 0) + break; + eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); + if (IS_ERR(eventfp)) + return PTR_ERR(eventfp); + if (eventfp != vq->call) { + filep = vq->call; + ctx = vq->call_ctx; + vq->call = eventfp; + vq->call_ctx = eventfp ? + eventfd_ctx_fileget(eventfp) : NULL; + } else + filep = eventfp; + break; + case VHOST_SET_VRING_ERR: + r = copy_from_user(&f, argp, sizeof f); + if (r < 0) + break; + eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd); + if (IS_ERR(eventfp)) + return PTR_ERR(eventfp); + if (eventfp != vq->error) { + filep = vq->error; + vq->error = eventfp; + ctx = vq->error_ctx; + vq->error_ctx = eventfp ? + eventfd_ctx_fileget(eventfp) : NULL; + } else + filep = eventfp; + break; + default: + r = -ENOIOCTLCMD; + } + + if (pollstop && vq->handle_kick) + vhost_poll_stop(&vq->poll); + + if (ctx) + eventfd_ctx_put(ctx); + if (filep) + fput(filep); + + if (pollstart && vq->handle_kick) + vhost_poll_start(&vq->poll, vq->kick); + + mutex_unlock(&vq->mutex); + + if (pollstop && vq->handle_kick) + vhost_poll_flush(&vq->poll); + return r; +} + +/* Caller must have device mutex */ +long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, unsigned long arg) +{ + void __user *argp = (void __user *)arg; + struct file *eventfp, *filep = NULL; + struct eventfd_ctx *ctx = NULL; + u64 p; + long r; + int i, fd; + + /* If you are not the owner, you can become one */ + if (ioctl == VHOST_SET_OWNER) { + r = vhost_dev_set_owner(d); + goto done; + } + + /* You must be the owner to do anything else */ + r = vhost_dev_check_owner(d); + if (r) + goto done; + + switch (ioctl) { + case VHOST_SET_MEM_TABLE: + r = vhost_set_memory(d, argp); + break; + case VHOST_SET_LOG_BASE: + r = copy_from_user(&p, argp, sizeof p); + if (r < 0) + break; + if ((u64)(unsigned long)p != p) { + r = -EFAULT; + break; + } + for (i = 0; i < d->nvqs; ++i) { + struct vhost_virtqueue *vq; + void __user *base = (void __user *)(unsigned long)p; + vq = d->vqs + i; + mutex_lock(&vq->mutex); + /* If ring is inactive, will check when it's enabled. */ + if (vq->private_data && !vq_log_access_ok(vq, base)) + r = -EFAULT; + else + vq->log_base = base; + mutex_unlock(&vq->mutex); + } + break; + case VHOST_SET_LOG_FD: + r = get_user(fd, (int __user *)argp); + if (r < 0) + break; + eventfp = fd == -1 ? NULL : eventfd_fget(fd); + if (IS_ERR(eventfp)) { + r = PTR_ERR(eventfp); + break; + } + if (eventfp != d->log_file) { + filep = d->log_file; + ctx = d->log_ctx; + d->log_ctx = eventfp ? + eventfd_ctx_fileget(eventfp) : NULL; + } else + filep = eventfp; + for (i = 0; i < d->nvqs; ++i) { + mutex_lock(&d->vqs[i].mutex); + d->vqs[i].log_ctx = d->log_ctx; + mutex_unlock(&d->vqs[i].mutex); + } + if (ctx) + eventfd_ctx_put(ctx); + if (filep) + fput(filep); + break; + default: + r = vhost_set_vring(d, ioctl, argp); + break; + } +done: + return r; +} + +static const struct vhost_memory_region *find_region(struct vhost_memory *mem, + __u64 addr, __u32 len) +{ + struct vhost_memory_region *reg; + int i; + /* linear search is not brilliant, but we really have on the order of 6 + * regions in practice */ + for (i = 0; i < mem->nregions; ++i) { + reg = mem->regions + i; + if (reg->guest_phys_addr <= addr && + reg->guest_phys_addr + reg->memory_size - 1 >= addr) + return reg; + } + return NULL; +} + +/* TODO: This is really inefficient. We need something like get_user() + * (instruction directly accesses the data, with an exception table entry + * returning -EFAULT). See Documentation/x86/exception-tables.txt. + */ +static int set_bit_to_user(int nr, void __user *addr) +{ + unsigned long log = (unsigned long)addr; + struct page *page; + void *base; + int bit = nr + (log % PAGE_SIZE) * 8; + int r; + r = get_user_pages_fast(log, 1, 1, &page); + if (r) + return r; + base = kmap_atomic(page, KM_USER0); + set_bit(bit, base); + kunmap_atomic(base, KM_USER0); + set_page_dirty_lock(page); + put_page(page); + return 0; +} + +static int log_write(void __user *log_base, + u64 write_address, u64 write_length) +{ + int r; + if (!write_length) + return 0; + write_address /= VHOST_PAGE_SIZE; + for (;;) { + u64 base = (u64)(unsigned long)log_base; + u64 log = base + write_address / 8; + int bit = write_address % 8; + if ((u64)(unsigned long)log != log) + return -EFAULT; + r = set_bit_to_user(bit, (void __user *)(unsigned long)log); + if (r < 0) + return r; + if (write_length <= VHOST_PAGE_SIZE) + break; + write_length -= VHOST_PAGE_SIZE; + write_address += VHOST_PAGE_SIZE; + } + return r; +} + +int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log, + unsigned int log_num, u64 len) +{ + int i, r; + + /* Make sure data written is seen before log. */ + wmb(); + for (i = 0; i < log_num; ++i) { + u64 l = min(log[i].len, len); + r = log_write(vq->log_base, log[i].addr, l); + if (r < 0) + return r; + len -= l; + if (!len) + return 0; + } + if (vq->log_ctx) + eventfd_signal(vq->log_ctx, 1); + /* Length written exceeds what we have stored. This is a bug. */ + BUG(); + return 0; +} + +int translate_desc(struct vhost_dev *dev, u64 addr, u32 len, + struct iovec iov[], int iov_size) +{ + const struct vhost_memory_region *reg; + struct vhost_memory *mem; + struct iovec *_iov; + u64 s = 0; + int ret = 0; + + rcu_read_lock(); + + mem = rcu_dereference(dev->memory); + while ((u64)len > s) { + u64 size; + if (ret >= iov_size) { + ret = -ENOBUFS; + break; + } + reg = find_region(mem, addr, len); + if (!reg) { + ret = -EFAULT; + break; + } + _iov = iov + ret; + size = reg->memory_size - addr + reg->guest_phys_addr; + _iov->iov_len = min((u64)len, size); + _iov->iov_base = (void *)(unsigned long) + (reg->userspace_addr + addr - reg->guest_phys_addr); + s += size; + addr += size; + ++ret; + } + + rcu_read_unlock(); + return ret; +} + +/* Each buffer in the virtqueues is actually a chain of descriptors. This + * function returns the next descriptor in the chain, + * or -1U if we're at the end. */ +static unsigned next_desc(struct vring_desc *desc) +{ + unsigned int next; + + /* If this descriptor says it doesn't chain, we're done. */ + if (!(desc->flags & VRING_DESC_F_NEXT)) + return -1U; + + /* Check they're not leading us off end of descriptors. */ + next = desc->next; + /* Make sure compiler knows to grab that: we don't want it changing! */ + /* We will use the result as an index in an array, so most + * architectures only need a compiler barrier here. */ + read_barrier_depends(); + + return next; +} + +static unsigned get_indirect(struct vhost_dev *dev, struct vhost_virtqueue *vq, + struct iovec iov[], unsigned int iov_size, + unsigned int *out_num, unsigned int *in_num, + struct vhost_log *log, unsigned int *log_num, + struct vring_desc *indirect) +{ + struct vring_desc desc; + unsigned int i = 0, count, found = 0; + int ret; + + /* Sanity check */ + if (indirect->len % sizeof desc) { + vq_err(vq, "Invalid length in indirect descriptor: " + "len 0x%llx not multiple of 0x%zx\n", + (unsigned long long)indirect->len, + sizeof desc); + return -EINVAL; + } + + ret = translate_desc(dev, indirect->addr, indirect->len, vq->indirect, + ARRAY_SIZE(vq->indirect)); + if (ret < 0) { + vq_err(vq, "Translation failure %d in indirect.\n", ret); + return ret; + } + + /* We will use the result as an address to read from, so most + * architectures only need a compiler barrier here. */ + read_barrier_depends(); + + count = indirect->len / sizeof desc; + /* Buffers are chained via a 16 bit next field, so + * we can have at most 2^16 of these. */ + if (count > USHORT_MAX + 1) { + vq_err(vq, "Indirect buffer length too big: %d\n", + indirect->len); + return -E2BIG; + } + + do { + unsigned iov_count = *in_num + *out_num; + if (++found > count) { + vq_err(vq, "Loop detected: last one at %u " + "indirect size %u\n", + i, count); + return -EINVAL; + } + if (memcpy_fromiovec((unsigned char *)&desc, vq->indirect, + sizeof desc)) { + vq_err(vq, "Failed indirect descriptor: idx %d, %zx\n", + i, (size_t)indirect->addr + i * sizeof desc); + return -EINVAL; + } + if (desc.flags & VRING_DESC_F_INDIRECT) { + vq_err(vq, "Nested indirect descriptor: idx %d, %zx\n", + i, (size_t)indirect->addr + i * sizeof desc); + return -EINVAL; + } + + ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, + iov_size - iov_count); + if (ret < 0) { + vq_err(vq, "Translation failure %d indirect idx %d\n", + ret, i); + return ret; + } + /* If this is an input descriptor, increment that count. */ + if (desc.flags & VRING_DESC_F_WRITE) { + *in_num += ret; + if (unlikely(log)) { + log[*log_num].addr = desc.addr; + log[*log_num].len = desc.len; + ++*log_num; + } + } else { + /* If it's an output descriptor, they're all supposed + * to come before any input descriptors. */ + if (*in_num) { + vq_err(vq, "Indirect descriptor " + "has out after in: idx %d\n", i); + return -EINVAL; + } + *out_num += ret; + } + } while ((i = next_desc(&desc)) != -1); + return 0; +} + +/* This looks in the virtqueue and for the first available buffer, and converts + * it to an iovec for convenient access. Since descriptors consist of some + * number of output then some number of input descriptors, it's actually two + * iovecs, but we pack them into one and note how many of each there were. + * + * This function returns the descriptor number found, or vq->num (which + * is never a valid descriptor number) if none was found. */ +unsigned vhost_get_vq_desc(struct vhost_dev *dev, struct vhost_virtqueue *vq, + struct iovec iov[], unsigned int iov_size, + unsigned int *out_num, unsigned int *in_num, + struct vhost_log *log, unsigned int *log_num) +{ + struct vring_desc desc; + unsigned int i, head, found = 0; + u16 last_avail_idx; + int ret; + + /* Check it isn't doing very strange things with descriptor numbers. */ + last_avail_idx = vq->last_avail_idx; + if (get_user(vq->avail_idx, &vq->avail->idx)) { + vq_err(vq, "Failed to access avail idx at %p\n", + &vq->avail->idx); + return vq->num; + } + + if ((u16)(vq->avail_idx - last_avail_idx) > vq->num) { + vq_err(vq, "Guest moved used index from %u to %u", + last_avail_idx, vq->avail_idx); + return vq->num; + } + + /* If there's nothing new since last we looked, return invalid. */ + if (vq->avail_idx == last_avail_idx) + return vq->num; + + /* Only get avail ring entries after they have been exposed by guest. */ + rmb(); + + /* Grab the next descriptor number they're advertising, and increment + * the index we've seen. */ + if (get_user(head, &vq->avail->ring[last_avail_idx % vq->num])) { + vq_err(vq, "Failed to read head: idx %d address %p\n", + last_avail_idx, + &vq->avail->ring[last_avail_idx % vq->num]); + return vq->num; + } + + /* If their number is silly, that's an error. */ + if (head >= vq->num) { + vq_err(vq, "Guest says index %u > %u is available", + head, vq->num); + return vq->num; + } + + /* When we start there are none of either input nor output. */ + *out_num = *in_num = 0; + if (unlikely(log)) + *log_num = 0; + + i = head; + do { + unsigned iov_count = *in_num + *out_num; + if (i >= vq->num) { + vq_err(vq, "Desc index is %u > %u, head = %u", + i, vq->num, head); + return vq->num; + } + if (++found > vq->num) { + vq_err(vq, "Loop detected: last one at %u " + "vq size %u head %u\n", + i, vq->num, head); + return vq->num; + } + ret = copy_from_user(&desc, vq->desc + i, sizeof desc); + if (ret) { + vq_err(vq, "Failed to get descriptor: idx %d addr %p\n", + i, vq->desc + i); + return vq->num; + } + if (desc.flags & VRING_DESC_F_INDIRECT) { + ret = get_indirect(dev, vq, iov, iov_size, + out_num, in_num, + log, log_num, &desc); + if (ret < 0) { + vq_err(vq, "Failure detected " + "in indirect descriptor at idx %d\n", i); + return vq->num; + } + continue; + } + + ret = translate_desc(dev, desc.addr, desc.len, iov + iov_count, + iov_size - iov_count); + if (ret < 0) { + vq_err(vq, "Translation failure %d descriptor idx %d\n", + ret, i); + return vq->num; + } + if (desc.flags & VRING_DESC_F_WRITE) { + /* If this is an input descriptor, + * increment that count. */ + *in_num += ret; + if (unlikely(log)) { + log[*log_num].addr = desc.addr; + log[*log_num].len = desc.len; + ++*log_num; + } + } else { + /* If it's an output descriptor, they're all supposed + * to come before any input descriptors. */ + if (*in_num) { + vq_err(vq, "Descriptor has out after in: " + "idx %d\n", i); + return vq->num; + } + *out_num += ret; + } + } while ((i = next_desc(&desc)) != -1); + + /* On success, increment avail index. */ + vq->last_avail_idx++; + return head; +} + +/* Reverse the effect of vhost_get_vq_desc. Useful for error handling. */ +void vhost_discard_vq_desc(struct vhost_virtqueue *vq) +{ + vq->last_avail_idx--; +} + +/* After we've used one of their buffers, we tell them about it. We'll then + * want to notify the guest, using eventfd. */ +int vhost_add_used(struct vhost_virtqueue *vq, unsigned int head, int len) +{ + struct vring_used_elem *used; + + /* The virtqueue contains a ring of used buffers. Get a pointer to the + * next entry in that used ring. */ + used = &vq->used->ring[vq->last_used_idx % vq->num]; + if (put_user(head, &used->id)) { + vq_err(vq, "Failed to write used id"); + return -EFAULT; + } + if (put_user(len, &used->len)) { + vq_err(vq, "Failed to write used len"); + return -EFAULT; + } + /* Make sure buffer is written before we update index. */ + wmb(); + if (put_user(vq->last_used_idx + 1, &vq->used->idx)) { + vq_err(vq, "Failed to increment used idx"); + return -EFAULT; + } + if (unlikely(vq->log_used)) { + /* Make sure data is seen before log. */ + wmb(); + log_write(vq->log_base, vq->log_addr + sizeof *vq->used->ring * + (vq->last_used_idx % vq->num), + sizeof *vq->used->ring); + log_write(vq->log_base, vq->log_addr, sizeof *vq->used->ring); + if (vq->log_ctx) + eventfd_signal(vq->log_ctx, 1); + } + vq->last_used_idx++; + return 0; +} + +/* This actually signals the guest, using eventfd. */ +void vhost_signal(struct vhost_dev *dev, struct vhost_virtqueue *vq) +{ + __u16 flags = 0; + if (get_user(flags, &vq->avail->flags)) { + vq_err(vq, "Failed to get flags"); + return; + } + + /* If they don't want an interrupt, don't signal, unless empty. */ + if ((flags & VRING_AVAIL_F_NO_INTERRUPT) && + (vq->avail_idx != vq->last_avail_idx || + !vhost_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY))) + return; + + /* Signal the Guest tell them we used something up. */ + if (vq->call_ctx) + eventfd_signal(vq->call_ctx, 1); +} + +/* And here's the combo meal deal. Supersize me! */ +void vhost_add_used_and_signal(struct vhost_dev *dev, + struct vhost_virtqueue *vq, + unsigned int head, int len) +{ + vhost_add_used(vq, head, len); + vhost_signal(dev, vq); +} + +/* OK, now we need to know about added descriptors. */ +bool vhost_enable_notify(struct vhost_virtqueue *vq) +{ + u16 avail_idx; + int r; + if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY)) + return false; + vq->used_flags &= ~VRING_USED_F_NO_NOTIFY; + r = put_user(vq->used_flags, &vq->used->flags); + if (r) { + vq_err(vq, "Failed to enable notification at %p: %d\n", + &vq->used->flags, r); + return false; + } + /* They could have slipped one in as we were doing that: make + * sure it's written, then check again. */ + mb(); + r = get_user(avail_idx, &vq->avail->idx); + if (r) { + vq_err(vq, "Failed to check avail idx at %p: %d\n", + &vq->avail->idx, r); + return false; + } + + return avail_idx != vq->last_avail_idx; +} + +/* We don't need to be notified again. */ +void vhost_disable_notify(struct vhost_virtqueue *vq) +{ + int r; + if (vq->used_flags & VRING_USED_F_NO_NOTIFY) + return; + vq->used_flags |= VRING_USED_F_NO_NOTIFY; + r = put_user(vq->used_flags, &vq->used->flags); + if (r) + vq_err(vq, "Failed to enable notification at %p: %d\n", + &vq->used->flags, r); +} + +int vhost_init(void) +{ + vhost_workqueue = create_singlethread_workqueue("vhost"); + if (!vhost_workqueue) + return -ENOMEM; + return 0; +} + +void vhost_cleanup(void) +{ + destroy_workqueue(vhost_workqueue); +} |