[RFC PATCH V2 2/3] vhost: fine grain userspace memory accessors

Jason Wang
2018-12-28T07:55:36Z

This is used to hide the metadata address from virtqueue helpers. This
will allow to implement a vmap based fast accessing to metadata.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/vhost/vhost.c | 94 +++++++++++++++++++++++++++++++++++--------
1 file changed, 77 insertions(+), 17 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index f179b5ee14c4..337ce6f5a098 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -868,6 +868,34 @@ static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
ret; \
})

+static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
+{
+ return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
+ vhost_avail_event(vq));
+}
+
+static inline int vhost_put_used(struct vhost_virtqueue *vq,
+ struct vring_used_elem *head, int idx,
+ int count)
+{
+ return vhost_copy_to_user(vq, vq->used->ring + idx, head,
+ count * sizeof(*head));
+}
+
+static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
+
+{
+ return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
+ &vq->used->flags);
+}
+
+static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
+
+{
+ return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
+ &vq->used->idx);
+}
+
#define vhost_get_user(vq, x, ptr, type) \
({ \
int ret; \
@@ -906,6 +934,43 @@ static void vhost_dev_unlock_vqs(struct vhost_dev *d)
mutex_unlock(&d->vqs[i]->mutex);
}

+static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
+ __virtio16 *idx)
+{
+ return vhost_get_avail(vq, *idx, &vq->avail->idx);
+}
+
+static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
+ __virtio16 *head, int idx)
+{
+ return vhost_get_avail(vq, *head,
+ &vq->avail->ring[idx & (vq->num - 1)]);
+}
+
+static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
+ __virtio16 *flags)
+{
+ return vhost_get_avail(vq, *flags, &vq->avail->flags);
+}
+
+static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
+ __virtio16 *event)
+{
+ return vhost_get_avail(vq, *event, vhost_used_event(vq));
+}
+
+static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
+ __virtio16 *idx)
+{
+ return vhost_get_used(vq, *idx, &vq->used->idx);
+}
+
+static inline int vhost_get_desc(struct vhost_virtqueue *vq,
+ struct vring_desc *desc, int idx)
+{
+ return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
+}
+
static int vhost_new_umem_range(struct vhost_umem *umem,
u64 start, u64 size, u64 end,
u64 userspace_addr, int perm)
@@ -1761,8 +1826,7 @@ EXPORT_SYMBOL_GPL(vhost_log_write);
static int vhost_update_used_flags(struct vhost_virtqueue *vq)
{
void __user *used;
- if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
- &vq->used->flags) < 0)
+ if (vhost_put_used_flags(vq))
return -EFAULT;
if (unlikely(vq->log_used)) {
/* Make sure the flag is seen before log. */
@@ -1780,8 +1844,7 @@ static int vhost_update_used_flags(struct vhost_virtqueue *vq)

static int vhost_update_avail_event(struct vhost_virtqueue *vq, u16 avail_event)
{
- if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
- vhost_avail_event(vq)))
+ if (vhost_put_avail_event(vq))
return -EFAULT;
if (unlikely(vq->log_used)) {
void __user *used;
@@ -1818,7 +1881,7 @@ int vhost_vq_init_access(struct vhost_virtqueue *vq)
r = -EFAULT;
goto err;
}
- r = vhost_get_used(vq, last_used_idx, &vq->used->idx);
+ r = vhost_get_used_idx(vq, &last_used_idx);
if (r) {
vq_err(vq, "Can't access used idx at %p\n",
&vq->used->idx);
@@ -2017,7 +2080,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
last_avail_idx = vq->last_avail_idx;

if (vq->avail_idx == vq->last_avail_idx) {
- if (unlikely(vhost_get_avail(vq, avail_idx, &vq->avail->idx))) {
+ if (unlikely(vhost_get_avail_idx(vq, &avail_idx))) {
vq_err(vq, "Failed to access avail idx at %p\n",
&vq->avail->idx);
return -EFAULT;
@@ -2044,8 +2107,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,

/* Grab the next descriptor number they're advertising, and increment
* the index we've seen. */
- if (unlikely(vhost_get_avail(vq, ring_head,
- &vq->avail->ring[last_avail_idx & (vq->num - 1)]))) {
+ if (unlikely(vhost_get_avail_head(vq, &ring_head, last_avail_idx))) {
vq_err(vq, "Failed to read head: idx %d address %p\n",
last_avail_idx,
&vq->avail->ring[last_avail_idx % vq->num]);
@@ -2080,8 +2142,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
i, vq->num, head);
return -EINVAL;
}
- ret = vhost_copy_from_user(vq, &desc, vq->desc + i,
- sizeof desc);
+ ret = vhost_get_desc(vq, &desc, i);
if (unlikely(ret)) {
vq_err(vq, "Failed to get descriptor: idx %d addr %p\n",
i, vq->desc + i);
@@ -2174,7 +2235,7 @@ static int __vhost_add_used_n(struct vhost_virtqueue *vq,

start = vq->last_used_idx & (vq->num - 1);
used = vq->used->ring + start;
- if (vhost_copy_to_user(vq, used, heads, count * sizeof *used)) {
+ if (vhost_put_used(vq, heads, start, count)) {
vq_err(vq, "Failed to write used");
return -EFAULT;
}
@@ -2218,8 +2279,7 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,

/* Make sure buffer is written before we update index. */
smp_wmb();
- if (vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
- &vq->used->idx)) {
+ if (vhost_put_used_idx(vq)) {
vq_err(vq, "Failed to increment used idx");
return -EFAULT;
}
@@ -2253,7 +2313,7 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)

if (!vhost_has_feature(vq, VIRTIO_RING_F_EVENT_IDX)) {
__virtio16 flags;
- if (vhost_get_avail(vq, flags, &vq->avail->flags)) {
+ if (vhost_get_avail_flags(vq, &flags)) {
vq_err(vq, "Failed to get flags");
return true;
}
@@ -2267,7 +2327,7 @@ static bool vhost_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
if (unlikely(!v))
return true;

- if (vhost_get_avail(vq, event, vhost_used_event(vq))) {
+ if (vhost_get_used_event(vq, &event)) {
vq_err(vq, "Failed to get used event idx");
return true;
}
@@ -2312,7 +2372,7 @@ bool vhost_vq_avail_empty(struct vhost_dev *dev, struct vhost_virtqueue *vq)
if (vq->avail_idx != vq->last_avail_idx)
return false;

- r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
+ r = vhost_get_avail_idx(vq, &avail_idx);
if (unlikely(r))
return false;
vq->avail_idx = vhost16_to_cpu(vq, avail_idx);
@@ -2348,7 +2408,7 @@ bool vhost_enable_notify(struct vhost_dev *dev, struct vhost_virtqueue *vq)
/* They could have slipped one in as we were doing that: make
* sure it's written, then check again. */
smp_mb();
- r = vhost_get_avail(vq, avail_idx, &vq->avail->idx);
+ r = vhost_get_avail_idx(vq, &avail_idx);
if (r) {
vq_err(vq, "Failed to check avail idx at %p: %d\n",
&vq->avail->idx, r);
--
2.17.1