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Subject[RFC PATCH V3 5/6] vhost: factor out setting vring addr and num
Date
Factoring vring address and num setting which needs special care for
accelerating vq metadata accessing.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/vhost/vhost.c | 177 ++++++++++++++++++++++++------------------
1 file changed, 103 insertions(+), 74 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index f3f86c3ed659..c2362ed5839e 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1468,6 +1468,104 @@ 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;
@@ -1477,7 +1575,6 @@ 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;

@@ -1490,26 +1587,14 @@ 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. */
@@ -1535,62 +1620,6 @@ 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;
--
2.18.1
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