[PATCH net-next v3 04/13] virtio_ring: put split ring fields in a sub struct

From: Tiwei Bie
Date: Wed Nov 21 2018 - 05:05:39 EST

Put the split ring specific fields in a sub-struct named
as "split" to avoid misuse after introducing packed ring.
There is no functional change.

Signed-off-by: Tiwei Bie <tiwei.bie@xxxxxxxxx>
---
drivers/virtio/virtio_ring.c | 156 +++++++++++++++++++++++++------------------
1 file changed, 91 insertions(+), 65 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 7cd40a2a0d21..0b97e5c79654 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -63,9 +63,6 @@ struct vring_desc_state {
struct vring_virtqueue {
struct virtqueue vq;

- /* Actual memory layout for this queue */
- struct vring vring;
-
/* Can we use weak barriers? */
bool weak_barriers;

@@ -86,11 +83,16 @@ struct vring_virtqueue {
/* Last used index we've seen. */
u16 last_used_idx;

- /* Last written value to avail->flags */
- u16 avail_flags_shadow;
+ struct {
+ /* Actual memory layout for this queue */
+ struct vring vring;

- /* Last written value to avail->idx in guest byte order */
- u16 avail_idx_shadow;
+ /* Last written value to avail->flags */
+ u16 avail_flags_shadow;
+
+ /* Last written value to avail->idx in guest byte order */
+ u16 avail_idx_shadow;
+ } split;

/* How to notify other side. FIXME: commonalize hcalls! */
bool (*notify)(struct virtqueue *vq);
@@ -316,7 +318,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
desc = alloc_indirect_split(_vq, total_sg, gfp);
else {
desc = NULL;
- WARN_ON_ONCE(total_sg > vq->vring.num && !vq->indirect);
+ WARN_ON_ONCE(total_sg > vq->split.vring.num && !vq->indirect);
}

if (desc) {
@@ -327,7 +329,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
descs_used = 1;
} else {
indirect = false;
- desc = vq->vring.desc;
+ desc = vq->split.vring.desc;
i = head;
descs_used = total_sg;
}
@@ -383,10 +385,13 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
if (vring_mapping_error(vq, addr))
goto unmap_release;

- vq->vring.desc[head].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_INDIRECT);
- vq->vring.desc[head].addr = cpu_to_virtio64(_vq->vdev, addr);
+ vq->split.vring.desc[head].flags = cpu_to_virtio16(_vq->vdev,
+ VRING_DESC_F_INDIRECT);
+ vq->split.vring.desc[head].addr = cpu_to_virtio64(_vq->vdev,
+ addr);

- vq->vring.desc[head].len = cpu_to_virtio32(_vq->vdev, total_sg * sizeof(struct vring_desc));
+ vq->split.vring.desc[head].len = cpu_to_virtio32(_vq->vdev,
+ total_sg * sizeof(struct vring_desc));
}

/* We're using some buffers from the free list. */
@@ -394,7 +399,8 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,

/* Update free pointer */
if (indirect)
- vq->free_head = virtio16_to_cpu(_vq->vdev, vq->vring.desc[head].next);
+ vq->free_head = virtio16_to_cpu(_vq->vdev,
+ vq->split.vring.desc[head].next);
else
vq->free_head = i;

@@ -407,14 +413,15 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,

/* Put entry in available array (but don't update avail->idx until they
* do sync). */
- avail = vq->avail_idx_shadow & (vq->vring.num - 1);
- vq->vring.avail->ring[avail] = cpu_to_virtio16(_vq->vdev, head);
+ avail = vq->split.avail_idx_shadow & (vq->split.vring.num - 1);
+ vq->split.vring.avail->ring[avail] = cpu_to_virtio16(_vq->vdev, head);

/* Descriptors and available array need to be set before we expose the
* new available array entries. */
virtio_wmb(vq->weak_barriers);
- vq->avail_idx_shadow++;
- vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, vq->avail_idx_shadow);
+ vq->split.avail_idx_shadow++;
+ vq->split.vring.avail->idx = cpu_to_virtio16(_vq->vdev,
+ vq->split.avail_idx_shadow);
vq->num_added++;

pr_debug("Added buffer head %i to %p\n", head, vq);
@@ -435,7 +442,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,
if (i == err_idx)
break;
vring_unmap_one_split(vq, &desc[i]);
- i = virtio16_to_cpu(_vq->vdev, vq->vring.desc[i].next);
+ i = virtio16_to_cpu(_vq->vdev, vq->split.vring.desc[i].next);
}

if (indirect)
@@ -456,8 +463,8 @@ static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
* event. */
virtio_mb(vq->weak_barriers);

- old = vq->avail_idx_shadow - vq->num_added;
- new = vq->avail_idx_shadow;
+ old = vq->split.avail_idx_shadow - vq->num_added;
+ new = vq->split.avail_idx_shadow;
vq->num_added = 0;

#ifdef DEBUG
@@ -469,10 +476,13 @@ static bool virtqueue_kick_prepare_split(struct virtqueue *_vq)
#endif

if (vq->event) {
- needs_kick = vring_need_event(virtio16_to_cpu(_vq->vdev, vring_avail_event(&vq->vring)),
+ needs_kick = vring_need_event(virtio16_to_cpu(_vq->vdev,
+ vring_avail_event(&vq->split.vring)),
new, old);
} else {
- needs_kick = !(vq->vring.used->flags & cpu_to_virtio16(_vq->vdev, VRING_USED_F_NO_NOTIFY));
+ needs_kick = !(vq->split.vring.used->flags &
+ cpu_to_virtio16(_vq->vdev,
+ VRING_USED_F_NO_NOTIFY));
}
END_USE(vq);
return needs_kick;
@@ -490,14 +500,15 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
/* Put back on free list: unmap first-level descriptors and find end */
i = head;

- while (vq->vring.desc[i].flags & nextflag) {
- vring_unmap_one_split(vq, &vq->vring.desc[i]);
- i = virtio16_to_cpu(vq->vq.vdev, vq->vring.desc[i].next);
+ while (vq->split.vring.desc[i].flags & nextflag) {
+ vring_unmap_one_split(vq, &vq->split.vring.desc[i]);
+ i = virtio16_to_cpu(vq->vq.vdev, vq->split.vring.desc[i].next);
vq->vq.num_free++;
}

- vring_unmap_one_split(vq, &vq->vring.desc[i]);
- vq->vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev, vq->free_head);
+ vring_unmap_one_split(vq, &vq->split.vring.desc[i]);
+ vq->split.vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev,
+ vq->free_head);
vq->free_head = head;

/* Plus final descriptor */
@@ -511,9 +522,10 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
if (!indir_desc)
return;

- len = virtio32_to_cpu(vq->vq.vdev, vq->vring.desc[head].len);
+ len = virtio32_to_cpu(vq->vq.vdev,
+ vq->split.vring.desc[head].len);

- BUG_ON(!(vq->vring.desc[head].flags &
+ BUG_ON(!(vq->split.vring.desc[head].flags &
cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_INDIRECT)));
BUG_ON(len == 0 || len % sizeof(struct vring_desc));

@@ -529,7 +541,8 @@ static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,

static inline bool more_used_split(const struct vring_virtqueue *vq)
{
- return vq->last_used_idx != virtio16_to_cpu(vq->vq.vdev, vq->vring.used->idx);
+ return vq->last_used_idx != virtio16_to_cpu(vq->vq.vdev,
+ vq->split.vring.used->idx);
}

static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
@@ -557,11 +570,13 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
/* Only get used array entries after they have been exposed by host. */
virtio_rmb(vq->weak_barriers);

- last_used = (vq->last_used_idx & (vq->vring.num - 1));
- i = virtio32_to_cpu(_vq->vdev, vq->vring.used->ring[last_used].id);
- *len = virtio32_to_cpu(_vq->vdev, vq->vring.used->ring[last_used].len);
+ last_used = (vq->last_used_idx & (vq->split.vring.num - 1));
+ i = virtio32_to_cpu(_vq->vdev,
+ vq->split.vring.used->ring[last_used].id);
+ *len = virtio32_to_cpu(_vq->vdev,
+ vq->split.vring.used->ring[last_used].len);

- if (unlikely(i >= vq->vring.num)) {
+ if (unlikely(i >= vq->split.vring.num)) {
BAD_RING(vq, "id %u out of range\n", i);
return NULL;
}
@@ -577,9 +592,9 @@ static void *virtqueue_get_buf_ctx_split(struct virtqueue *_vq,
/* If we expect an interrupt for the next entry, tell host
* by writing event index and flush out the write before
* the read in the next get_buf call. */
- if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
+ if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
virtio_store_mb(vq->weak_barriers,
- &vring_used_event(&vq->vring),
+ &vring_used_event(&vq->split.vring),
cpu_to_virtio16(_vq->vdev, vq->last_used_idx));

#ifdef DEBUG
@@ -594,10 +609,12 @@ static void virtqueue_disable_cb_split(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);

- if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
- vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
+ if (!(vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) {
+ vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
if (!vq->event)
- vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
+ vq->split.vring.avail->flags =
+ cpu_to_virtio16(_vq->vdev,
+ vq->split.avail_flags_shadow);
}
}

@@ -613,12 +630,15 @@ static unsigned virtqueue_enable_cb_prepare_split(struct virtqueue *_vq)
/* Depending on the VIRTIO_RING_F_EVENT_IDX feature, we need to
* either clear the flags bit or point the event index at the next
* entry. Always do both to keep code simple. */
- if (vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
- vq->avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
+ if (vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
+ vq->split.avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
if (!vq->event)
- vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
+ vq->split.vring.avail->flags =
+ cpu_to_virtio16(_vq->vdev,
+ vq->split.avail_flags_shadow);
}
- vring_used_event(&vq->vring) = cpu_to_virtio16(_vq->vdev, last_used_idx = vq->last_used_idx);
+ vring_used_event(&vq->split.vring) = cpu_to_virtio16(_vq->vdev,
+ last_used_idx = vq->last_used_idx);
END_USE(vq);
return last_used_idx;
}
@@ -628,7 +648,7 @@ static bool virtqueue_poll_split(struct virtqueue *_vq, unsigned last_used_idx)
struct vring_virtqueue *vq = to_vvq(_vq);

return (u16)last_used_idx != virtio16_to_cpu(_vq->vdev,
- vq->vring.used->idx);
+ vq->split.vring.used->idx);
}

static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
@@ -643,19 +663,22 @@ static bool virtqueue_enable_cb_delayed_split(struct virtqueue *_vq)
/* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to
* either clear the flags bit or point the event index at the next
* entry. Always update the event index to keep code simple. */
- if (vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
- vq->avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
+ if (vq->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) {
+ vq->split.avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT;
if (!vq->event)
- vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow);
+ vq->split.vring.avail->flags =
+ cpu_to_virtio16(_vq->vdev,
+ vq->split.avail_flags_shadow);
}
/* TODO: tune this threshold */
- bufs = (u16)(vq->avail_idx_shadow - vq->last_used_idx) * 3 / 4;
+ bufs = (u16)(vq->split.avail_idx_shadow - vq->last_used_idx) * 3 / 4;

virtio_store_mb(vq->weak_barriers,
- &vring_used_event(&vq->vring),
+ &vring_used_event(&vq->split.vring),
cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs));

- if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->vring.used->idx) - vq->last_used_idx) > bufs)) {
+ if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->split.vring.used->idx)
+ - vq->last_used_idx) > bufs)) {
END_USE(vq);
return false;
}
@@ -672,19 +695,20 @@ static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)

START_USE(vq);

- for (i = 0; i < vq->vring.num; i++) {
+ for (i = 0; i < vq->split.vring.num; i++) {
if (!vq->desc_state[i].data)
continue;
/* detach_buf_split clears data, so grab it now. */
buf = vq->desc_state[i].data;
detach_buf_split(vq, i, NULL);
- vq->avail_idx_shadow--;
- vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, vq->avail_idx_shadow);
+ vq->split.avail_idx_shadow--;
+ vq->split.vring.avail->idx = cpu_to_virtio16(_vq->vdev,
+ vq->split.avail_idx_shadow);
END_USE(vq);
return buf;
}
/* That should have freed everything. */
- BUG_ON(vq->vq.num_free != vq->vring.num);
+ BUG_ON(vq->vq.num_free != vq->split.vring.num);

END_USE(vq);
return NULL;
@@ -1046,7 +1070,6 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
if (!vq)
return NULL;

- vq->vring = vring;
vq->vq.callback = callback;
vq->vq.vdev = vdev;
vq->vq.name = name;
@@ -1059,8 +1082,6 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
vq->weak_barriers = weak_barriers;
vq->broken = false;
vq->last_used_idx = 0;
- vq->avail_flags_shadow = 0;
- vq->avail_idx_shadow = 0;
vq->num_added = 0;
list_add_tail(&vq->vq.list, &vdev->vqs);
#ifdef DEBUG
@@ -1072,17 +1093,22 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
!context;
vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);

+ vq->split.vring = vring;
+ vq->split.avail_flags_shadow = 0;
+ vq->split.avail_idx_shadow = 0;
+
/* No callback? Tell other side not to bother us. */
if (!callback) {
- vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
+ vq->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
if (!vq->event)
- vq->vring.avail->flags = cpu_to_virtio16(vdev, vq->avail_flags_shadow);
+ vq->split.vring.avail->flags = cpu_to_virtio16(vdev,
+ vq->split.avail_flags_shadow);
}

/* Put everything in free lists. */
vq->free_head = 0;
for (i = 0; i < vring.num-1; i++)
- vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
+ vq->split.vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
memset(vq->desc_state, 0, vring.num * sizeof(struct vring_desc_state));

return &vq->vq;
@@ -1218,7 +1244,7 @@ void vring_del_virtqueue(struct virtqueue *_vq)

if (vq->we_own_ring) {
vring_free_queue(vq->vq.vdev, vq->queue_size_in_bytes,
- vq->vring.desc, vq->queue_dma_addr);
+ vq->split.vring.desc, vq->queue_dma_addr);
}
list_del(&_vq->list);
kfree(vq);
@@ -1260,7 +1286,7 @@ unsigned int virtqueue_get_vring_size(struct virtqueue *_vq)

struct vring_virtqueue *vq = to_vvq(_vq);

- return vq->vring.num;
+ return vq->split.vring.num;
}
EXPORT_SYMBOL_GPL(virtqueue_get_vring_size);

@@ -1304,7 +1330,7 @@ dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
BUG_ON(!vq->we_own_ring);

return vq->queue_dma_addr +
- ((char *)vq->vring.avail - (char *)vq->vring.desc);
+ ((char *)vq->split.vring.avail - (char *)vq->split.vring.desc);
}
EXPORT_SYMBOL_GPL(virtqueue_get_avail_addr);

@@ -1315,13 +1341,13 @@ dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
BUG_ON(!vq->we_own_ring);

return vq->queue_dma_addr +
- ((char *)vq->vring.used - (char *)vq->vring.desc);
+ ((char *)vq->split.vring.used - (char *)vq->split.vring.desc);
}
EXPORT_SYMBOL_GPL(virtqueue_get_used_addr);

const struct vring *virtqueue_get_vring(struct virtqueue *vq)
{
- return &to_vvq(vq)->vring;
+ return &to_vvq(vq)->split.vring;
}
EXPORT_SYMBOL_GPL(virtqueue_get_vring);

--
2.14.5