| /* Virtio ring implementation. |
| * |
| * Copyright 2007 Rusty Russell IBM Corporation |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| #include <linux/virtio.h> |
| #include <linux/virtio_ring.h> |
| #include <linux/virtio_config.h> |
| #include <linux/device.h> |
| #include <linux/slab.h> |
| #include <linux/module.h> |
| #include <linux/hrtimer.h> |
| |
| #ifdef DEBUG |
| /* For development, we want to crash whenever the ring is screwed. */ |
| #define BAD_RING(_vq, fmt, args...) \ |
| do { \ |
| dev_err(&(_vq)->vq.vdev->dev, \ |
| "%s:"fmt, (_vq)->vq.name, ##args); \ |
| BUG(); \ |
| } while (0) |
| /* Caller is supposed to guarantee no reentry. */ |
| #define START_USE(_vq) \ |
| do { \ |
| if ((_vq)->in_use) \ |
| panic("%s:in_use = %i\n", \ |
| (_vq)->vq.name, (_vq)->in_use); \ |
| (_vq)->in_use = __LINE__; \ |
| } while (0) |
| #define END_USE(_vq) \ |
| do { BUG_ON(!(_vq)->in_use); (_vq)->in_use = 0; } while(0) |
| #else |
| #define BAD_RING(_vq, fmt, args...) \ |
| do { \ |
| dev_err(&_vq->vq.vdev->dev, \ |
| "%s:"fmt, (_vq)->vq.name, ##args); \ |
| (_vq)->broken = true; \ |
| } while (0) |
| #define START_USE(vq) |
| #define END_USE(vq) |
| #endif |
| |
| struct vring_virtqueue |
| { |
| struct virtqueue vq; |
| |
| /* Actual memory layout for this queue */ |
| struct vring vring; |
| |
| /* Can we use weak barriers? */ |
| bool weak_barriers; |
| |
| /* Other side has made a mess, don't try any more. */ |
| bool broken; |
| |
| /* Host supports indirect buffers */ |
| bool indirect; |
| |
| /* Host publishes avail event idx */ |
| bool event; |
| |
| /* Head of free buffer list. */ |
| unsigned int free_head; |
| /* Number we've added since last sync. */ |
| unsigned int num_added; |
| |
| /* Last used index we've seen. */ |
| u16 last_used_idx; |
| |
| /* How to notify other side. FIXME: commonalize hcalls! */ |
| void (*notify)(struct virtqueue *vq); |
| |
| #ifdef DEBUG |
| /* They're supposed to lock for us. */ |
| unsigned int in_use; |
| |
| /* Figure out if their kicks are too delayed. */ |
| bool last_add_time_valid; |
| ktime_t last_add_time; |
| #endif |
| |
| /* Tokens for callbacks. */ |
| void *data[]; |
| }; |
| |
| #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq) |
| |
| static inline struct scatterlist *sg_next_chained(struct scatterlist *sg, |
| unsigned int *count) |
| { |
| return sg_next(sg); |
| } |
| |
| static inline struct scatterlist *sg_next_arr(struct scatterlist *sg, |
| unsigned int *count) |
| { |
| if (--(*count) == 0) |
| return NULL; |
| return sg + 1; |
| } |
| |
| /* Set up an indirect table of descriptors and add it to the queue. */ |
| static inline int vring_add_indirect(struct vring_virtqueue *vq, |
| struct scatterlist *sgs[], |
| struct scatterlist *(*next) |
| (struct scatterlist *, unsigned int *), |
| unsigned int total_sg, |
| unsigned int total_out, |
| unsigned int total_in, |
| unsigned int out_sgs, |
| unsigned int in_sgs, |
| gfp_t gfp) |
| { |
| struct vring_desc *desc; |
| unsigned head; |
| struct scatterlist *sg; |
| int i, n; |
| |
| /* |
| * We require lowmem mappings for the descriptors because |
| * otherwise virt_to_phys will give us bogus addresses in the |
| * virtqueue. |
| */ |
| gfp &= ~(__GFP_HIGHMEM | __GFP_HIGH); |
| |
| desc = kmalloc(total_sg * sizeof(struct vring_desc), gfp); |
| if (!desc) |
| return -ENOMEM; |
| |
| /* Transfer entries from the sg lists into the indirect page */ |
| i = 0; |
| for (n = 0; n < out_sgs; n++) { |
| for (sg = sgs[n]; sg; sg = next(sg, &total_out)) { |
| desc[i].flags = VRING_DESC_F_NEXT; |
| desc[i].addr = sg_phys(sg); |
| desc[i].len = sg->length; |
| desc[i].next = i+1; |
| i++; |
| } |
| } |
| for (; n < (out_sgs + in_sgs); n++) { |
| for (sg = sgs[n]; sg; sg = next(sg, &total_in)) { |
| desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; |
| desc[i].addr = sg_phys(sg); |
| desc[i].len = sg->length; |
| desc[i].next = i+1; |
| i++; |
| } |
| } |
| BUG_ON(i != total_sg); |
| |
| /* Last one doesn't continue. */ |
| desc[i-1].flags &= ~VRING_DESC_F_NEXT; |
| desc[i-1].next = 0; |
| |
| /* We're about to use a buffer */ |
| vq->vq.num_free--; |
| |
| /* Use a single buffer which doesn't continue */ |
| head = vq->free_head; |
| vq->vring.desc[head].flags = VRING_DESC_F_INDIRECT; |
| vq->vring.desc[head].addr = virt_to_phys(desc); |
| vq->vring.desc[head].len = i * sizeof(struct vring_desc); |
| |
| /* Update free pointer */ |
| vq->free_head = vq->vring.desc[head].next; |
| |
| return head; |
| } |
| |
| static inline int virtqueue_add(struct virtqueue *_vq, |
| struct scatterlist *sgs[], |
| struct scatterlist *(*next) |
| (struct scatterlist *, unsigned int *), |
| unsigned int total_out, |
| unsigned int total_in, |
| unsigned int out_sgs, |
| unsigned int in_sgs, |
| void *data, |
| gfp_t gfp) |
| { |
| struct vring_virtqueue *vq = to_vvq(_vq); |
| struct scatterlist *sg; |
| unsigned int i, n, avail, uninitialized_var(prev), total_sg; |
| int head; |
| |
| START_USE(vq); |
| |
| BUG_ON(data == NULL); |
| |
| #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 |
| |
| total_sg = total_in + total_out; |
| |
| /* 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) { |
| head = vring_add_indirect(vq, sgs, next, total_sg, total_out, |
| total_in, |
| out_sgs, in_sgs, gfp); |
| if (likely(head >= 0)) |
| goto add_head; |
| } |
| |
| BUG_ON(total_sg > vq->vring.num); |
| BUG_ON(total_sg == 0); |
| |
| if (vq->vq.num_free < total_sg) { |
| pr_debug("Can't add buf len %i - avail = %i\n", |
| total_sg, 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); |
| END_USE(vq); |
| return -ENOSPC; |
| } |
| |
| /* We're about to use some buffers from the free list. */ |
| vq->vq.num_free -= total_sg; |
| |
| head = i = vq->free_head; |
| for (n = 0; n < out_sgs; n++) { |
| for (sg = sgs[n]; sg; sg = next(sg, &total_out)) { |
| vq->vring.desc[i].flags = VRING_DESC_F_NEXT; |
| vq->vring.desc[i].addr = sg_phys(sg); |
| vq->vring.desc[i].len = sg->length; |
| prev = i; |
| i = vq->vring.desc[i].next; |
| } |
| } |
| for (; n < (out_sgs + in_sgs); n++) { |
| for (sg = sgs[n]; sg; sg = next(sg, &total_in)) { |
| vq->vring.desc[i].flags = VRING_DESC_F_NEXT|VRING_DESC_F_WRITE; |
| vq->vring.desc[i].addr = sg_phys(sg); |
| vq->vring.desc[i].len = sg->length; |
| prev = i; |
| i = vq->vring.desc[i].next; |
| } |
| } |
| /* Last one doesn't continue. */ |
| vq->vring.desc[prev].flags &= ~VRING_DESC_F_NEXT; |
| |
| /* Update free pointer */ |
| vq->free_head = i; |
| |
| add_head: |
| /* Set token. */ |
| vq->data[head] = data; |
| |
| /* Put entry in available array (but don't update avail->idx until they |
| * do sync). */ |
| avail = (vq->vring.avail->idx & (vq->vring.num-1)); |
| vq->vring.avail->ring[avail] = head; |
| |
| /* Descriptors and available array need to be set before we expose the |
| * new available array entries. */ |
| virtio_wmb(vq->weak_barriers); |
| vq->vring.avail->idx++; |
| vq->num_added++; |
| |
| /* This is very unlikely, but theoretically possible. Kick |
| * just in case. */ |
| if (unlikely(vq->num_added == (1 << 16) - 1)) |
| virtqueue_kick(_vq); |
| |
| pr_debug("Added buffer head %i to %p\n", head, vq); |
| END_USE(vq); |
| |
| return 0; |
| } |
| |
| /** |
| * virtqueue_add_buf - expose buffer to other end |
| * @vq: the struct virtqueue we're talking about. |
| * @sg: the description of the buffer(s). |
| * @out_num: the number of sg readable by other side |
| * @in_num: the number of sg which are writable (after readable ones) |
| * @data: the token identifying the buffer. |
| * @gfp: how to do memory allocations (if necessary). |
| * |
| * Caller must ensure we don't call this with other virtqueue operations |
| * at the same time (except where noted). |
| * |
| * Returns zero or a negative error (ie. ENOSPC, ENOMEM). |
| */ |
| int virtqueue_add_buf(struct virtqueue *_vq, |
| struct scatterlist sg[], |
| unsigned int out, |
| unsigned int in, |
| void *data, |
| gfp_t gfp) |
| { |
| struct scatterlist *sgs[2]; |
| |
| sgs[0] = sg; |
| sgs[1] = sg + out; |
| |
| return virtqueue_add(_vq, sgs, sg_next_arr, |
| out, in, out ? 1 : 0, in ? 1 : 0, data, gfp); |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_add_buf); |
| |
| /** |
| * virtqueue_add_sgs - expose buffers to other end |
| * @vq: the struct virtqueue we're talking about. |
| * @sgs: array of terminated scatterlists. |
| * @out_num: the number of scatterlists readable by other side |
| * @in_num: the number of scatterlists which are writable (after readable ones) |
| * @data: the token identifying the buffer. |
| * @gfp: how to do memory allocations (if necessary). |
| * |
| * Caller must ensure we don't call this with other virtqueue operations |
| * at the same time (except where noted). |
| * |
| * Returns zero or a negative error (ie. ENOSPC, ENOMEM). |
| */ |
| int virtqueue_add_sgs(struct virtqueue *_vq, |
| struct scatterlist *sgs[], |
| unsigned int out_sgs, |
| unsigned int in_sgs, |
| void *data, |
| gfp_t gfp) |
| { |
| unsigned int i, total_out, total_in; |
| |
| /* Count them first. */ |
| for (i = total_out = total_in = 0; i < out_sgs; i++) { |
| struct scatterlist *sg; |
| for (sg = sgs[i]; sg; sg = sg_next(sg)) |
| total_out++; |
| } |
| for (; i < out_sgs + in_sgs; i++) { |
| struct scatterlist *sg; |
| for (sg = sgs[i]; sg; sg = sg_next(sg)) |
| total_in++; |
| } |
| return virtqueue_add(_vq, sgs, sg_next_chained, |
| total_out, total_in, out_sgs, in_sgs, data, gfp); |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_add_sgs); |
| |
| /** |
| * virtqueue_add_outbuf - expose output buffers to other end |
| * @vq: the struct virtqueue we're talking about. |
| * @sgs: array of scatterlists (need not be terminated!) |
| * @num: the number of scatterlists readable by other side |
| * @data: the token identifying the buffer. |
| * @gfp: how to do memory allocations (if necessary). |
| * |
| * Caller must ensure we don't call this with other virtqueue operations |
| * at the same time (except where noted). |
| * |
| * Returns zero or a negative error (ie. ENOSPC, ENOMEM). |
| */ |
| int virtqueue_add_outbuf(struct virtqueue *vq, |
| struct scatterlist sg[], unsigned int num, |
| void *data, |
| gfp_t gfp) |
| { |
| return virtqueue_add(vq, &sg, sg_next_arr, num, 0, 1, 0, data, gfp); |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_add_outbuf); |
| |
| /** |
| * virtqueue_add_inbuf - expose input buffers to other end |
| * @vq: the struct virtqueue we're talking about. |
| * @sgs: array of scatterlists (need not be terminated!) |
| * @num: the number of scatterlists writable by other side |
| * @data: the token identifying the buffer. |
| * @gfp: how to do memory allocations (if necessary). |
| * |
| * Caller must ensure we don't call this with other virtqueue operations |
| * at the same time (except where noted). |
| * |
| * Returns zero or a negative error (ie. ENOSPC, ENOMEM). |
| */ |
| int virtqueue_add_inbuf(struct virtqueue *vq, |
| struct scatterlist sg[], unsigned int num, |
| void *data, |
| gfp_t gfp) |
| { |
| return virtqueue_add(vq, &sg, sg_next_arr, 0, num, 0, 1, data, gfp); |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_add_inbuf); |
| |
| /** |
| * virtqueue_kick_prepare - first half of split virtqueue_kick call. |
| * @vq: the struct virtqueue |
| * |
| * Instead of virtqueue_kick(), you can do: |
| * if (virtqueue_kick_prepare(vq)) |
| * virtqueue_notify(vq); |
| * |
| * This is sometimes useful because the virtqueue_kick_prepare() needs |
| * to be serialized, but the actual virtqueue_notify() call does not. |
| */ |
| bool virtqueue_kick_prepare(struct virtqueue *_vq) |
| { |
| struct vring_virtqueue *vq = to_vvq(_vq); |
| u16 new, old; |
| bool needs_kick; |
| |
| START_USE(vq); |
| /* We need to expose available array entries before checking avail |
| * event. */ |
| virtio_mb(vq->weak_barriers); |
| |
| old = vq->vring.avail->idx - vq->num_added; |
| new = vq->vring.avail->idx; |
| vq->num_added = 0; |
| |
| #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 |
| |
| if (vq->event) { |
| needs_kick = vring_need_event(vring_avail_event(&vq->vring), |
| new, old); |
| } else { |
| needs_kick = !(vq->vring.used->flags & VRING_USED_F_NO_NOTIFY); |
| } |
| END_USE(vq); |
| return needs_kick; |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_kick_prepare); |
| |
| /** |
| * virtqueue_notify - second half of split virtqueue_kick call. |
| * @vq: the struct virtqueue |
| * |
| * This does not need to be serialized. |
| */ |
| void virtqueue_notify(struct virtqueue *_vq) |
| { |
| struct vring_virtqueue *vq = to_vvq(_vq); |
| |
| /* Prod other side to tell it about changes. */ |
| vq->notify(_vq); |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_notify); |
| |
| /** |
| * virtqueue_kick - update after add_buf |
| * @vq: the struct virtqueue |
| * |
| * After one or more virtqueue_add_buf calls, invoke this to kick |
| * the other side. |
| * |
| * Caller must ensure we don't call this with other virtqueue |
| * operations at the same time (except where noted). |
| */ |
| void virtqueue_kick(struct virtqueue *vq) |
| { |
| if (virtqueue_kick_prepare(vq)) |
| virtqueue_notify(vq); |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_kick); |
| |
| static void detach_buf(struct vring_virtqueue *vq, unsigned int head) |
| { |
| unsigned int i; |
| |
| /* Clear data ptr. */ |
| vq->data[head] = NULL; |
| |
| /* Put back on free list: find end */ |
| i = head; |
| |
| /* Free the indirect table */ |
| if (vq->vring.desc[i].flags & VRING_DESC_F_INDIRECT) |
| kfree(phys_to_virt(vq->vring.desc[i].addr)); |
| |
| while (vq->vring.desc[i].flags & VRING_DESC_F_NEXT) { |
| i = vq->vring.desc[i].next; |
| vq->vq.num_free++; |
| } |
| |
| vq->vring.desc[i].next = vq->free_head; |
| vq->free_head = head; |
| /* Plus final descriptor */ |
| vq->vq.num_free++; |
| } |
| |
| static inline bool more_used(const struct vring_virtqueue *vq) |
| { |
| return vq->last_used_idx != vq->vring.used->idx; |
| } |
| |
| /** |
| * virtqueue_get_buf - get the next used buffer |
| * @vq: the struct virtqueue we're talking about. |
| * @len: the length written into the buffer |
| * |
| * If the driver wrote data into the buffer, @len will be set to the |
| * amount written. This means you don't need to clear the buffer |
| * beforehand to ensure there's no data leakage in the case of short |
| * writes. |
| * |
| * Caller must ensure we don't call this with other virtqueue |
| * operations at the same time (except where noted). |
| * |
| * Returns NULL if there are no used buffers, or the "data" token |
| * handed to virtqueue_add_buf(). |
| */ |
| void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len) |
| { |
| struct vring_virtqueue *vq = to_vvq(_vq); |
| void *ret; |
| unsigned int i; |
| u16 last_used; |
| |
| START_USE(vq); |
| |
| if (unlikely(vq->broken)) { |
| END_USE(vq); |
| return NULL; |
| } |
| |
| if (!more_used(vq)) { |
| pr_debug("No more buffers in queue\n"); |
| END_USE(vq); |
| return NULL; |
| } |
| |
| /* 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 = vq->vring.used->ring[last_used].id; |
| *len = vq->vring.used->ring[last_used].len; |
| |
| if (unlikely(i >= vq->vring.num)) { |
| BAD_RING(vq, "id %u out of range\n", i); |
| return NULL; |
| } |
| if (unlikely(!vq->data[i])) { |
| BAD_RING(vq, "id %u is not a head!\n", i); |
| return NULL; |
| } |
| |
| /* detach_buf clears data, so grab it now. */ |
| ret = vq->data[i]; |
| detach_buf(vq, i); |
| vq->last_used_idx++; |
| /* 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->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT)) { |
| vring_used_event(&vq->vring) = vq->last_used_idx; |
| virtio_mb(vq->weak_barriers); |
| } |
| |
| #ifdef DEBUG |
| vq->last_add_time_valid = false; |
| #endif |
| |
| END_USE(vq); |
| return ret; |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_get_buf); |
| |
| /** |
| * virtqueue_disable_cb - disable callbacks |
| * @vq: the struct virtqueue we're talking about. |
| * |
| * Note that this is not necessarily synchronous, hence unreliable and only |
| * useful as an optimization. |
| * |
| * Unlike other operations, this need not be serialized. |
| */ |
| void virtqueue_disable_cb(struct virtqueue *_vq) |
| { |
| struct vring_virtqueue *vq = to_vvq(_vq); |
| |
| vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT; |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_disable_cb); |
| |
| /** |
| * virtqueue_enable_cb_prepare - restart callbacks after disable_cb |
| * @vq: the struct virtqueue we're talking about. |
| * |
| * This re-enables callbacks; it returns current queue state |
| * in an opaque unsigned value. This value should be later tested by |
| * virtqueue_poll, to detect a possible race between the driver checking for |
| * more work, and enabling callbacks. |
| * |
| * Caller must ensure we don't call this with other virtqueue |
| * operations at the same time (except where noted). |
| */ |
| unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq) |
| { |
| struct vring_virtqueue *vq = to_vvq(_vq); |
| u16 last_used_idx; |
| |
| START_USE(vq); |
| |
| /* We optimistically turn back on interrupts, then check if there was |
| * more to do. */ |
| /* 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. */ |
| vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; |
| vring_used_event(&vq->vring) = last_used_idx = vq->last_used_idx; |
| END_USE(vq); |
| return last_used_idx; |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare); |
| |
| /** |
| * virtqueue_poll - query pending used buffers |
| * @vq: the struct virtqueue we're talking about. |
| * @last_used_idx: virtqueue state (from call to virtqueue_enable_cb_prepare). |
| * |
| * Returns "true" if there are pending used buffers in the queue. |
| * |
| * This does not need to be serialized. |
| */ |
| bool virtqueue_poll(struct virtqueue *_vq, unsigned last_used_idx) |
| { |
| struct vring_virtqueue *vq = to_vvq(_vq); |
| |
| virtio_mb(vq->weak_barriers); |
| return (u16)last_used_idx != vq->vring.used->idx; |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_poll); |
| |
| /** |
| * virtqueue_enable_cb - restart callbacks after disable_cb. |
| * @vq: the struct virtqueue we're talking about. |
| * |
| * This re-enables callbacks; it returns "false" if there are pending |
| * buffers in the queue, to detect a possible race between the driver |
| * checking for more work, and enabling callbacks. |
| * |
| * Caller must ensure we don't call this with other virtqueue |
| * operations at the same time (except where noted). |
| */ |
| bool virtqueue_enable_cb(struct virtqueue *_vq) |
| { |
| unsigned last_used_idx = virtqueue_enable_cb_prepare(_vq); |
| return !virtqueue_poll(_vq, last_used_idx); |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_enable_cb); |
| |
| /** |
| * virtqueue_enable_cb_delayed - restart callbacks after disable_cb. |
| * @vq: the struct virtqueue we're talking about. |
| * |
| * This re-enables callbacks but hints to the other side to delay |
| * interrupts until most of the available buffers have been processed; |
| * it returns "false" if there are many pending buffers in the queue, |
| * to detect a possible race between the driver checking for more work, |
| * and enabling callbacks. |
| * |
| * Caller must ensure we don't call this with other virtqueue |
| * operations at the same time (except where noted). |
| */ |
| bool virtqueue_enable_cb_delayed(struct virtqueue *_vq) |
| { |
| struct vring_virtqueue *vq = to_vvq(_vq); |
| u16 bufs; |
| |
| START_USE(vq); |
| |
| /* We optimistically turn back on interrupts, then check if there was |
| * more to do. */ |
| /* 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 do both to keep code simple. */ |
| vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT; |
| /* TODO: tune this threshold */ |
| bufs = (u16)(vq->vring.avail->idx - vq->last_used_idx) * 3 / 4; |
| vring_used_event(&vq->vring) = vq->last_used_idx + bufs; |
| virtio_mb(vq->weak_barriers); |
| if (unlikely((u16)(vq->vring.used->idx - vq->last_used_idx) > bufs)) { |
| END_USE(vq); |
| return false; |
| } |
| |
| END_USE(vq); |
| return true; |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed); |
| |
| /** |
| * virtqueue_detach_unused_buf - detach first unused buffer |
| * @vq: the struct virtqueue we're talking about. |
| * |
| * Returns NULL or the "data" token handed to virtqueue_add_buf(). |
| * This is not valid on an active queue; it is useful only for device |
| * shutdown. |
| */ |
| void *virtqueue_detach_unused_buf(struct virtqueue *_vq) |
| { |
| struct vring_virtqueue *vq = to_vvq(_vq); |
| unsigned int i; |
| void *buf; |
| |
| START_USE(vq); |
| |
| for (i = 0; i < vq->vring.num; i++) { |
| if (!vq->data[i]) |
| continue; |
| /* detach_buf clears data, so grab it now. */ |
| buf = vq->data[i]; |
| detach_buf(vq, i); |
| vq->vring.avail->idx--; |
| END_USE(vq); |
| return buf; |
| } |
| /* That should have freed everything. */ |
| BUG_ON(vq->vq.num_free != vq->vring.num); |
| |
| END_USE(vq); |
| return NULL; |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf); |
| |
| irqreturn_t vring_interrupt(int irq, void *_vq) |
| { |
| struct vring_virtqueue *vq = to_vvq(_vq); |
| |
| if (!more_used(vq)) { |
| pr_debug("virtqueue interrupt with no work for %p\n", vq); |
| return IRQ_NONE; |
| } |
| |
| if (unlikely(vq->broken)) |
| return IRQ_HANDLED; |
| |
| pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback); |
| if (vq->vq.callback) |
| vq->vq.callback(&vq->vq); |
| |
| return IRQ_HANDLED; |
| } |
| EXPORT_SYMBOL_GPL(vring_interrupt); |
| |
| struct virtqueue *vring_new_virtqueue(unsigned int index, |
| unsigned int num, |
| unsigned int vring_align, |
| struct virtio_device *vdev, |
| bool weak_barriers, |
| void *pages, |
| void (*notify)(struct virtqueue *), |
| void (*callback)(struct virtqueue *), |
| const char *name) |
| { |
| struct vring_virtqueue *vq; |
| unsigned int i; |
| |
| /* We assume num is a power of 2. */ |
| if (num & (num - 1)) { |
| dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num); |
| return NULL; |
| } |
| |
| vq = kmalloc(sizeof(*vq) + sizeof(void *)*num, GFP_KERNEL); |
| if (!vq) |
| return NULL; |
| |
| vring_init(&vq->vring, num, pages, vring_align); |
| vq->vq.callback = callback; |
| vq->vq.vdev = vdev; |
| vq->vq.name = name; |
| vq->vq.num_free = num; |
| vq->vq.index = index; |
| vq->notify = notify; |
| vq->weak_barriers = weak_barriers; |
| vq->broken = false; |
| vq->last_used_idx = 0; |
| vq->num_added = 0; |
| list_add_tail(&vq->vq.list, &vdev->vqs); |
| #ifdef DEBUG |
| vq->in_use = false; |
| vq->last_add_time_valid = false; |
| #endif |
| |
| vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC); |
| vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX); |
| |
| /* No callback? Tell other side not to bother us. */ |
| if (!callback) |
| vq->vring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT; |
| |
| /* Put everything in free lists. */ |
| vq->free_head = 0; |
| for (i = 0; i < num-1; i++) { |
| vq->vring.desc[i].next = i+1; |
| vq->data[i] = NULL; |
| } |
| vq->data[i] = NULL; |
| |
| return &vq->vq; |
| } |
| EXPORT_SYMBOL_GPL(vring_new_virtqueue); |
| |
| void vring_del_virtqueue(struct virtqueue *vq) |
| { |
| list_del(&vq->list); |
| kfree(to_vvq(vq)); |
| } |
| EXPORT_SYMBOL_GPL(vring_del_virtqueue); |
| |
| /* Manipulates transport-specific feature bits. */ |
| void vring_transport_features(struct virtio_device *vdev) |
| { |
| unsigned int i; |
| |
| for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) { |
| switch (i) { |
| case VIRTIO_RING_F_INDIRECT_DESC: |
| break; |
| case VIRTIO_RING_F_EVENT_IDX: |
| break; |
| default: |
| /* We don't understand this bit. */ |
| clear_bit(i, vdev->features); |
| } |
| } |
| } |
| EXPORT_SYMBOL_GPL(vring_transport_features); |
| |
| /** |
| * virtqueue_get_vring_size - return the size of the virtqueue's vring |
| * @vq: the struct virtqueue containing the vring of interest. |
| * |
| * Returns the size of the vring. This is mainly used for boasting to |
| * userspace. Unlike other operations, this need not be serialized. |
| */ |
| unsigned int virtqueue_get_vring_size(struct virtqueue *_vq) |
| { |
| |
| struct vring_virtqueue *vq = to_vvq(_vq); |
| |
| return vq->vring.num; |
| } |
| EXPORT_SYMBOL_GPL(virtqueue_get_vring_size); |
| |
| MODULE_LICENSE("GPL"); |