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vhost: factor out setting vring addr and num
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Factoring vring address and num setting which needs special care for
accelerating vq metadata accessing.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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Jason Wang authored and Michael S. Tsirkin committed Jun 5, 2019
1 parent 4942e82 commit feebcae
Showing 1 changed file with 103 additions and 74 deletions.
177 changes: 103 additions & 74 deletions drivers/vhost/vhost.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1486,6 +1486,104 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
return -EFAULT;
}

static long vhost_vring_set_num(struct vhost_dev *d,
struct vhost_virtqueue *vq,
void __user *argp)
{
struct vhost_vring_state s;

/* Resizing ring with an active backend?
* You don't want to do that. */
if (vq->private_data)
return -EBUSY;

if (copy_from_user(&s, argp, sizeof s))
return -EFAULT;

if (!s.num || s.num > 0xffff || (s.num & (s.num - 1)))
return -EINVAL;
vq->num = s.num;

return 0;
}

static long vhost_vring_set_addr(struct vhost_dev *d,
struct vhost_virtqueue *vq,
void __user *argp)
{
struct vhost_vring_addr a;

if (copy_from_user(&a, argp, sizeof a))
return -EFAULT;
if (a.flags & ~(0x1 << VHOST_VRING_F_LOG))
return -EOPNOTSUPP;

/* 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)
return -EFAULT;

/* Make sure it's safe to cast pointers to vring types. */
BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
(a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
(a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 1)))
return -EINVAL;

/* 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, 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))
return -EINVAL;

/* 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))
return -EINVAL;
}

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;

return 0;
}

static long vhost_vring_set_num_addr(struct vhost_dev *d,
struct vhost_virtqueue *vq,
unsigned int ioctl,
void __user *argp)
{
long r;

mutex_lock(&vq->mutex);

switch (ioctl) {
case VHOST_SET_VRING_NUM:
r = vhost_vring_set_num(d, vq, argp);
break;
case VHOST_SET_VRING_ADDR:
r = vhost_vring_set_addr(d, vq, argp);
break;
default:
BUG();
}

mutex_unlock(&vq->mutex);

return r;
}
long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
{
struct file *eventfp, *filep = NULL;
Expand All @@ -1495,7 +1593,6 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
struct vhost_virtqueue *vq;
struct vhost_vring_state s;
struct vhost_vring_file f;
struct vhost_vring_addr a;
u32 idx;
long r;

Expand All @@ -1508,26 +1605,14 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
idx = array_index_nospec(idx, d->nvqs);
vq = d->vqs[idx];

if (ioctl == VHOST_SET_VRING_NUM ||
ioctl == VHOST_SET_VRING_ADDR) {
return vhost_vring_set_num_addr(d, vq, ioctl, argp);
}

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;
}
if (copy_from_user(&s, argp, sizeof s)) {
r = -EFAULT;
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. */
Expand All @@ -1553,62 +1638,6 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
if (copy_to_user(argp, &s, sizeof s))
r = -EFAULT;
break;
case VHOST_SET_VRING_ADDR:
if (copy_from_user(&a, argp, sizeof a)) {
r = -EFAULT;
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;
}

/* Make sure it's safe to cast pointers to vring types. */
BUILD_BUG_ON(__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE);
BUILD_BUG_ON(__alignof__ *vq->used > VRING_USED_ALIGN_SIZE);
if ((a.avail_user_addr & (VRING_AVAIL_ALIGN_SIZE - 1)) ||
(a.used_user_addr & (VRING_USED_ALIGN_SIZE - 1)) ||
(a.log_guest_addr & (VRING_USED_ALIGN_SIZE - 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, 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;
}
}

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:
if (copy_from_user(&f, argp, sizeof f)) {
r = -EFAULT;
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