lkml.org 
[lkml]   [2018]   [May]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[RFC v4 3/5] virtio_ring: add packed ring support
Date
This commit introduces the basic support (without EVENT_IDX)
for packed ring.

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
---
drivers/virtio/virtio_ring.c | 491 ++++++++++++++++++++++++++++++++++-
1 file changed, 481 insertions(+), 10 deletions(-)

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index 62d7c407841a..c6c5deb0e3ae 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -58,7 +58,8 @@

struct vring_desc_state {
void *data; /* Data for callback. */
- struct vring_desc *indir_desc; /* Indirect descriptor, if any. */
+ void *indir_desc; /* Indirect descriptor, if any. */
+ int num; /* Descriptor list length. */
};

struct vring_virtqueue {
@@ -116,6 +117,9 @@ struct vring_virtqueue {
/* Last written value to driver->flags in
* guest byte order. */
u16 event_flags_shadow;
+
+ /* ID allocation. */
+ struct idr buffer_id;
};
};

@@ -142,6 +146,16 @@ struct vring_virtqueue {

#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)

+static inline bool virtqueue_use_indirect(struct virtqueue *_vq,
+ unsigned int total_sg)
+{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ /* If the host supports indirect descriptor tables, and we have multiple
+ * buffers, then go indirect. FIXME: tune this threshold */
+ return (vq->indirect && total_sg > 1 && vq->vq.num_free);
+}
+
/*
* Modern virtio devices have feature bits to specify whether they need a
* quirk and bypass the IOMMU. If not there, just use the DMA API.
@@ -327,9 +341,7 @@ static inline int virtqueue_add_split(struct virtqueue *_vq,

head = vq->free_head;

- /* If the host supports indirect descriptor tables, and we have multiple
- * buffers, then go indirect. FIXME: tune this threshold */
- if (vq->indirect && total_sg > 1 && vq->vq.num_free)
+ if (virtqueue_use_indirect(_vq, total_sg))
desc = alloc_indirect_split(_vq, total_sg, gfp);
else {
desc = NULL;
@@ -741,6 +753,63 @@ static inline unsigned vring_size_packed(unsigned int num, unsigned long align)
& ~(align - 1)) + sizeof(struct vring_packed_desc_event) * 2;
}

+static void vring_unmap_one_packed(const struct vring_virtqueue *vq,
+ struct vring_packed_desc *desc)
+{
+ u16 flags;
+
+ if (!vring_use_dma_api(vq->vq.vdev))
+ return;
+
+ flags = virtio16_to_cpu(vq->vq.vdev, desc->flags);
+
+ if (flags & VRING_DESC_F_INDIRECT) {
+ dma_unmap_single(vring_dma_dev(vq),
+ virtio64_to_cpu(vq->vq.vdev, desc->addr),
+ virtio32_to_cpu(vq->vq.vdev, desc->len),
+ (flags & VRING_DESC_F_WRITE) ?
+ DMA_FROM_DEVICE : DMA_TO_DEVICE);
+ } else {
+ dma_unmap_page(vring_dma_dev(vq),
+ virtio64_to_cpu(vq->vq.vdev, desc->addr),
+ virtio32_to_cpu(vq->vq.vdev, desc->len),
+ (flags & VRING_DESC_F_WRITE) ?
+ DMA_FROM_DEVICE : DMA_TO_DEVICE);
+ }
+}
+
+static struct vring_packed_desc *alloc_indirect_packed(struct virtqueue *_vq,
+ unsigned int total_sg,
+ gfp_t gfp)
+{
+ struct vring_packed_desc *desc;
+
+ /*
+ * We require lowmem mappings for the descriptors because
+ * otherwise virt_to_phys will give us bogus addresses in the
+ * virtqueue.
+ */
+ gfp &= ~__GFP_HIGHMEM;
+
+ desc = kmalloc(total_sg * sizeof(struct vring_packed_desc), gfp);
+
+ return desc;
+}
+
+static u16 alloc_id_packed(struct vring_virtqueue *vq)
+{
+ u16 id;
+
+ id = idr_alloc(&vq->buffer_id, NULL, 0, vq->vring_packed.num,
+ GFP_KERNEL);
+ return id;
+}
+
+static void free_id_packed(struct vring_virtqueue *vq, u16 id)
+{
+ idr_remove(&vq->buffer_id, id);
+}
+
static inline int virtqueue_add_packed(struct virtqueue *_vq,
struct scatterlist *sgs[],
unsigned int total_sg,
@@ -750,47 +819,446 @@ static inline int virtqueue_add_packed(struct virtqueue *_vq,
void *ctx,
gfp_t gfp)
{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+ struct vring_packed_desc *desc;
+ struct scatterlist *sg;
+ unsigned int i, n, descs_used, uninitialized_var(prev), err_idx;
+ __virtio16 uninitialized_var(head_flags), flags;
+ u16 head, wrap_counter, id;
+ bool indirect;
+
+ START_USE(vq);
+
+ BUG_ON(data == NULL);
+ BUG_ON(ctx && vq->indirect);
+
+ if (unlikely(vq->broken)) {
+ END_USE(vq);
+ return -EIO;
+ }
+
+#ifdef DEBUG
+ {
+ ktime_t now = ktime_get();
+
+ /* No kick or get, with .1 second between? Warn. */
+ if (vq->last_add_time_valid)
+ WARN_ON(ktime_to_ms(ktime_sub(now, vq->last_add_time))
+ > 100);
+ vq->last_add_time = now;
+ vq->last_add_time_valid = true;
+ }
+#endif
+
+ BUG_ON(total_sg == 0);
+
+ head = vq->next_avail_idx;
+ wrap_counter = vq->wrap_counter;
+
+ if (virtqueue_use_indirect(_vq, total_sg))
+ desc = alloc_indirect_packed(_vq, total_sg, gfp);
+ else {
+ desc = NULL;
+ WARN_ON_ONCE(total_sg > vq->vring_packed.num && !vq->indirect);
+ }
+
+ if (desc) {
+ /* Use a single buffer which doesn't continue */
+ indirect = true;
+ /* Set up rest to use this indirect table. */
+ i = 0;
+ descs_used = 1;
+ } else {
+ indirect = false;
+ desc = vq->vring_packed.desc;
+ i = head;
+ descs_used = total_sg;
+ }
+
+ if (vq->vq.num_free < descs_used) {
+ pr_debug("Can't add buf len %i - avail = %i\n",
+ descs_used, vq->vq.num_free);
+ /* FIXME: for historical reasons, we force a notify here if
+ * there are outgoing parts to the buffer. Presumably the
+ * host should service the ring ASAP. */
+ if (out_sgs)
+ vq->notify(&vq->vq);
+ if (indirect)
+ kfree(desc);
+ END_USE(vq);
+ return -ENOSPC;
+ }
+
+ id = alloc_id_packed(vq);
+
+ for (n = 0; n < out_sgs + in_sgs; n++) {
+ for (sg = sgs[n]; sg; sg = sg_next(sg)) {
+ dma_addr_t addr = vring_map_one_sg(vq, sg, n < out_sgs ?
+ DMA_TO_DEVICE : DMA_FROM_DEVICE);
+ if (vring_mapping_error(vq, addr))
+ goto unmap_release;
+
+ flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT |
+ (n < out_sgs ? 0 : VRING_DESC_F_WRITE) |
+ VRING_DESC_F_AVAIL(vq->wrap_counter) |
+ VRING_DESC_F_USED(!vq->wrap_counter));
+ if (!indirect && i == head)
+ head_flags = flags;
+ else
+ desc[i].flags = flags;
+
+ desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
+ desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
+ i++;
+ if (!indirect && i >= vq->vring_packed.num) {
+ i = 0;
+ vq->wrap_counter ^= 1;
+ }
+ }
+ }
+
+ prev = (i > 0 ? i : vq->vring_packed.num) - 1;
+ desc[prev].id = cpu_to_virtio16(_vq->vdev, id);
+
+ /* Last one doesn't continue. */
+ if (total_sg == 1)
+ head_flags &= cpu_to_virtio16(_vq->vdev, ~VRING_DESC_F_NEXT);
+ else
+ desc[prev].flags &= cpu_to_virtio16(_vq->vdev,
+ ~VRING_DESC_F_NEXT);
+
+ if (indirect) {
+ /* Now that the indirect table is filled in, map it. */
+ dma_addr_t addr = vring_map_single(
+ vq, desc, total_sg * sizeof(struct vring_packed_desc),
+ DMA_TO_DEVICE);
+ if (vring_mapping_error(vq, addr))
+ goto unmap_release;
+
+ head_flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_INDIRECT |
+ VRING_DESC_F_AVAIL(wrap_counter) |
+ VRING_DESC_F_USED(!wrap_counter));
+ vq->vring_packed.desc[head].addr = cpu_to_virtio64(_vq->vdev,
+ addr);
+ vq->vring_packed.desc[head].len = cpu_to_virtio32(_vq->vdev,
+ total_sg * sizeof(struct vring_packed_desc));
+ vq->vring_packed.desc[head].id = cpu_to_virtio16(_vq->vdev, id);
+ }
+
+ /* We're using some buffers from the free list. */
+ vq->vq.num_free -= descs_used;
+
+ /* Update free pointer */
+ if (indirect) {
+ n = head + 1;
+ if (n >= vq->vring_packed.num) {
+ n = 0;
+ vq->wrap_counter ^= 1;
+ }
+ vq->next_avail_idx = n;
+ } else
+ vq->next_avail_idx = i;
+
+ /* Store token and indirect buffer state. */
+ vq->desc_state[id].num = descs_used;
+ vq->desc_state[id].data = data;
+ if (indirect)
+ vq->desc_state[id].indir_desc = desc;
+ else
+ vq->desc_state[id].indir_desc = ctx;
+
+ /* A driver MUST NOT make the first descriptor in the list
+ * available before all subsequent descriptors comprising
+ * the list are made available. */
+ virtio_wmb(vq->weak_barriers);
+ vq->vring_packed.desc[head].flags = head_flags;
+ vq->num_added += descs_used;
+
+ pr_debug("Added buffer head %i to %p\n", head, vq);
+ END_USE(vq);
+
+ return 0;
+
+unmap_release:
+ err_idx = i;
+ i = head;
+
+ for (n = 0; n < total_sg; n++) {
+ if (i == err_idx)
+ break;
+ vring_unmap_one_packed(vq, &desc[i]);
+ i++;
+ if (!indirect && i >= vq->vring_packed.num)
+ i = 0;
+ }
+
+ vq->wrap_counter = wrap_counter;
+
+ if (indirect)
+ kfree(desc);
+
+ free_id_packed(vq, id);
+
+ END_USE(vq);
return -EIO;
}

static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
{
- return false;
+ struct vring_virtqueue *vq = to_vvq(_vq);
+ u16 flags;
+ bool needs_kick;
+ u32 snapshot;
+
+ START_USE(vq);
+ /* We need to expose the new flags value before checking notification
+ * suppressions. */
+ virtio_mb(vq->weak_barriers);
+
+ snapshot = *(u32 *)vq->vring_packed.device;
+ flags = virtio16_to_cpu(_vq->vdev, (__virtio16)(snapshot >> 16)) & 0x3;
+
+#ifdef DEBUG
+ if (vq->last_add_time_valid) {
+ WARN_ON(ktime_to_ms(ktime_sub(ktime_get(),
+ vq->last_add_time)) > 100);
+ }
+ vq->last_add_time_valid = false;
+#endif
+
+ needs_kick = (flags != VRING_EVENT_F_DISABLE);
+ END_USE(vq);
+ return needs_kick;
+}
+
+static void detach_buf_packed(struct vring_virtqueue *vq, unsigned int head,
+ unsigned int id, void **ctx)
+{
+ struct vring_packed_desc *desc;
+ unsigned int i, j;
+
+ /* Clear data ptr. */
+ vq->desc_state[id].data = NULL;
+
+ i = head;
+
+ for (j = 0; j < vq->desc_state[id].num; j++) {
+ desc = &vq->vring_packed.desc[i];
+ vring_unmap_one_packed(vq, desc);
+ i++;
+ if (i >= vq->vring_packed.num)
+ i = 0;
+ }
+
+ vq->vq.num_free += vq->desc_state[id].num;
+
+ if (vq->indirect) {
+ u32 len;
+
+ /* Free the indirect table, if any, now that it's unmapped. */
+ desc = vq->desc_state[id].indir_desc;
+ if (!desc)
+ goto out;
+
+ len = virtio32_to_cpu(vq->vq.vdev,
+ vq->vring_packed.desc[head].len);
+
+ for (j = 0; j < len / sizeof(struct vring_packed_desc); j++)
+ vring_unmap_one_packed(vq, &desc[j]);
+
+ kfree(desc);
+ vq->desc_state[id].indir_desc = NULL;
+ } else if (ctx) {
+ *ctx = vq->desc_state[id].indir_desc;
+ }
+
+out:
+ free_id_packed(vq, id);
}

static inline bool more_used_packed(const struct vring_virtqueue *vq)
{
- return false;
+ u16 last_used, flags;
+ bool avail, used;
+
+ if (vq->vq.num_free == vq->vring_packed.num)
+ return false;
+
+ last_used = vq->last_used_idx;
+ flags = virtio16_to_cpu(vq->vq.vdev,
+ vq->vring_packed.desc[last_used].flags);
+ avail = flags & VRING_DESC_F_AVAIL(1);
+ used = flags & VRING_DESC_F_USED(1);
+
+ return avail == used;
}

static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
unsigned int *len,
void **ctx)
{
- return NULL;
+ struct vring_virtqueue *vq = to_vvq(_vq);
+ u16 last_used, id;
+ void *ret;
+
+ START_USE(vq);
+
+ if (unlikely(vq->broken)) {
+ END_USE(vq);
+ return NULL;
+ }
+
+ if (!more_used_packed(vq)) {
+ pr_debug("No more buffers in queue\n");
+ END_USE(vq);
+ return NULL;
+ }
+
+ /* Only get used elements after they have been exposed by host. */
+ virtio_rmb(vq->weak_barriers);
+
+ last_used = vq->last_used_idx;
+ id = virtio16_to_cpu(_vq->vdev, vq->vring_packed.desc[last_used].id);
+ *len = virtio32_to_cpu(_vq->vdev, vq->vring_packed.desc[last_used].len);
+
+ if (unlikely(id >= vq->vring_packed.num)) {
+ BAD_RING(vq, "id %u out of range\n", id);
+ return NULL;
+ }
+ if (unlikely(!vq->desc_state[id].data)) {
+ BAD_RING(vq, "id %u is not a head!\n", id);
+ return NULL;
+ }
+
+ vq->last_used_idx += vq->desc_state[id].num;
+ if (vq->last_used_idx >= vq->vring_packed.num)
+ vq->last_used_idx -= vq->vring_packed.num;
+
+ /* detach_buf_packed clears data, so grab it now. */
+ ret = vq->desc_state[id].data;
+ detach_buf_packed(vq, last_used, id, ctx);
+
+#ifdef DEBUG
+ vq->last_add_time_valid = false;
+#endif
+
+ END_USE(vq);
+ return ret;
}

static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ if (vq->event_flags_shadow != VRING_EVENT_F_DISABLE) {
+ vq->event_flags_shadow = VRING_EVENT_F_DISABLE;
+ vq->vring_packed.driver->flags = cpu_to_virtio16(_vq->vdev,
+ vq->event_flags_shadow);
+ }
}

static unsigned virtqueue_enable_cb_prepare_packed(struct virtqueue *_vq)
{
- return 0;
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ START_USE(vq);
+
+ /* We optimistically turn back on interrupts, then check if there was
+ * more to do. */
+
+ if (vq->event_flags_shadow == VRING_EVENT_F_DISABLE) {
+ virtio_wmb(vq->weak_barriers);
+ vq->event_flags_shadow = VRING_EVENT_F_ENABLE;
+ vq->vring_packed.driver->flags = cpu_to_virtio16(_vq->vdev,
+ vq->event_flags_shadow);
+ }
+
+ END_USE(vq);
+ return vq->last_used_idx;
}

static bool virtqueue_poll_packed(struct virtqueue *_vq, unsigned last_used_idx)
{
- return false;
+ struct vring_virtqueue *vq = to_vvq(_vq);
+ bool avail, used;
+ u16 flags;
+
+ virtio_mb(vq->weak_barriers);
+ flags = virtio16_to_cpu(vq->vq.vdev,
+ vq->vring_packed.desc[last_used_idx].flags);
+ avail = flags & VRING_DESC_F_AVAIL(1);
+ used = flags & VRING_DESC_F_USED(1);
+ return avail == used;
}

static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq)
{
- return false;
+ struct vring_virtqueue *vq = to_vvq(_vq);
+
+ START_USE(vq);
+
+ /* We optimistically turn back on interrupts, then check if there was
+ * more to do. */
+
+ if (vq->event_flags_shadow == VRING_EVENT_F_DISABLE) {
+ virtio_wmb(vq->weak_barriers);
+ vq->event_flags_shadow = VRING_EVENT_F_ENABLE;
+ vq->vring_packed.driver->flags = cpu_to_virtio16(_vq->vdev,
+ vq->event_flags_shadow);
+ }
+
+ if (more_used_packed(vq)) {
+ END_USE(vq);
+ return false;
+ }
+
+ END_USE(vq);
+ return true;
}

static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq)
{
+ struct vring_virtqueue *vq = to_vvq(_vq);
+ u16 flags, head, id, i;
+ unsigned int len;
+ void *buf;
+
+ START_USE(vq);
+
+ /* Detach the used descriptors. */
+ if (more_used_packed(vq)) {
+ buf = virtqueue_get_buf_ctx_packed(_vq, &len, NULL);
+ END_USE(vq);
+ return buf;
+ }
+
+ /* Detach the available descriptors. */
+ for (i = vq->last_used_idx; i != vq->next_avail_idx;
+ i = (i + 1) % vq->vring_packed.num) {
+ flags = virtio16_to_cpu(vq->vq.vdev,
+ vq->vring_packed.desc[i].flags);
+ while (flags & VRING_DESC_F_NEXT) {
+ i = (i + 1) % vq->vring_packed.num;
+ flags = virtio16_to_cpu(vq->vq.vdev,
+ vq->vring_packed.desc[i].flags);
+ }
+ id = virtio16_to_cpu(_vq->vdev, vq->vring_packed.desc[i].id);
+ if (!vq->desc_state[id].data)
+ continue;
+
+ len = vq->desc_state[id].num - 1;
+ head = (i < len ? i + vq->vring_packed.num : i) - len;
+
+ /* detach_buf clears data, so grab it now. */
+ buf = vq->desc_state[id].data;
+ detach_buf_packed(vq, head, id, NULL);
+ END_USE(vq);
+ return buf;
+ }
+ /* That should have freed everything. */
+ BUG_ON(vq->vq.num_free != vq->vring_packed.num);
+
+ END_USE(vq);
return NULL;
}

@@ -1198,6 +1666,7 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
vq->next_avail_idx = 0;
vq->wrap_counter = 1;
vq->event_flags_shadow = 0;
+ idr_init(&vq->buffer_id);
} else {
vq->vring = vring.vring_split;
vq->avail_flags_shadow = 0;
@@ -1384,6 +1853,8 @@ void vring_del_virtqueue(struct virtqueue *_vq)
(void *)vq->vring.desc,
vq->queue_dma_addr);
}
+ if (vq->packed)
+ idr_destroy(&vq->buffer_id);
list_del(&_vq->list);
kfree(vq);
}
--
2.17.0
\
 
 \ /
  Last update: 2018-05-16 10:40    [W:0.053 / U:15.664 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site