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linux/drivers/virtio/virtio_ring.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/* Virtio ring implementation.
*
* Copyright 2007 Rusty Russell IBM Corporation
*/
#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>
#include <linux/dma-mapping.h>
#include <xen/xen.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)
#define LAST_ADD_TIME_UPDATE(_vq) \
do { \
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; \
} while (0)
#define LAST_ADD_TIME_CHECK(_vq) \
do { \
if ((_vq)->last_add_time_valid) { \
WARN_ON(ktime_to_ms(ktime_sub(ktime_get(), \
(_vq)->last_add_time)) > 100); \
} \
} while (0)
#define LAST_ADD_TIME_INVALID(_vq) \
((_vq)->last_add_time_valid = false)
#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)
#define LAST_ADD_TIME_UPDATE(vq)
#define LAST_ADD_TIME_CHECK(vq)
#define LAST_ADD_TIME_INVALID(vq)
#endif
struct vring_desc_state_split {
void *data; /* Data for callback. */
struct vring_desc *indir_desc; /* Indirect descriptor, if any. */
};
struct vring_desc_state_packed {
void *data; /* Data for callback. */
struct vring_packed_desc *indir_desc; /* Indirect descriptor, if any. */
u16 num; /* Descriptor list length. */
u16 next; /* The next desc state in a list. */
u16 last; /* The last desc state in a list. */
};
struct vring_desc_extra_packed {
dma_addr_t addr; /* Buffer DMA addr. */
u32 len; /* Buffer length. */
u16 flags; /* Descriptor flags. */
};
struct vring_virtqueue {
struct virtqueue vq;
/* Is this a packed ring? */
bool packed_ring;
/* Is DMA API used? */
bool use_dma_api;
/* 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;
union {
/* Available for split ring */
struct {
/* Actual memory layout for this queue. */
struct vring vring;
/* Last written value to avail->flags */
u16 avail_flags_shadow;
/*
* Last written value to avail->idx in
* guest byte order.
*/
u16 avail_idx_shadow;
/* Per-descriptor state. */
struct vring_desc_state_split *desc_state;
/* DMA address and size information */
dma_addr_t queue_dma_addr;
size_t queue_size_in_bytes;
} split;
/* Available for packed ring */
struct {
/* Actual memory layout for this queue. */
struct {
unsigned int num;
struct vring_packed_desc *desc;
struct vring_packed_desc_event *driver;
struct vring_packed_desc_event *device;
} vring;
/* Driver ring wrap counter. */
bool avail_wrap_counter;
/* Device ring wrap counter. */
bool used_wrap_counter;
/* Avail used flags. */
u16 avail_used_flags;
/* Index of the next avail descriptor. */
u16 next_avail_idx;
/*
* Last written value to driver->flags in
* guest byte order.
*/
u16 event_flags_shadow;
/* Per-descriptor state. */
struct vring_desc_state_packed *desc_state;
struct vring_desc_extra_packed *desc_extra;
/* DMA address and size information */
dma_addr_t ring_dma_addr;
dma_addr_t driver_event_dma_addr;
dma_addr_t device_event_dma_addr;
size_t ring_size_in_bytes;
size_t event_size_in_bytes;
} packed;
};
/* How to notify other side. FIXME: commonalize hcalls! */
bool (*notify)(struct virtqueue *vq);
/* DMA, allocation, and size information */
bool we_own_ring;
#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
};
/*
* Helpers.
*/
#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.
*
* If there, the interaction between virtio and DMA API is messy.
*
* On most systems with virtio, physical addresses match bus addresses,
* and it doesn't particularly matter whether we use the DMA API.
*
* On some systems, including Xen and any system with a physical device
* that speaks virtio behind a physical IOMMU, we must use the DMA API
* for virtio DMA to work at all.
*
* On other systems, including SPARC and PPC64, virtio-pci devices are
* enumerated as though they are behind an IOMMU, but the virtio host
* ignores the IOMMU, so we must either pretend that the IOMMU isn't
* there or somehow map everything as the identity.
*
* For the time being, we preserve historic behavior and bypass the DMA
* API.
*
* TODO: install a per-device DMA ops structure that does the right thing
* taking into account all the above quirks, and use the DMA API
* unconditionally on data path.
*/
static bool vring_use_dma_api(struct virtio_device *vdev)
{
if (!virtio_has_iommu_quirk(vdev))
return true;
/* Otherwise, we are left to guess. */
/*
* In theory, it's possible to have a buggy QEMU-supposed
* emulated Q35 IOMMU and Xen enabled at the same time. On
* such a configuration, virtio has never worked and will
* not work without an even larger kludge. Instead, enable
* the DMA API if we're a Xen guest, which at least allows
* all of the sensible Xen configurations to work correctly.
*/
if (xen_domain())
return true;
return false;
}
size_t virtio_max_dma_size(struct virtio_device *vdev)
{
size_t max_segment_size = SIZE_MAX;
if (vring_use_dma_api(vdev))
max_segment_size = dma_max_mapping_size(&vdev->dev);
return max_segment_size;
}
EXPORT_SYMBOL_GPL(virtio_max_dma_size);
static void *vring_alloc_queue(struct virtio_device *vdev, size_t size,
dma_addr_t *dma_handle, gfp_t flag)
{
if (vring_use_dma_api(vdev)) {
return dma_alloc_coherent(vdev->dev.parent, size,
dma_handle, flag);
} else {
void *queue = alloc_pages_exact(PAGE_ALIGN(size), flag);
if (queue) {
phys_addr_t phys_addr = virt_to_phys(queue);
*dma_handle = (dma_addr_t)phys_addr;
/*
* Sanity check: make sure we dind't truncate
* the address. The only arches I can find that
* have 64-bit phys_addr_t but 32-bit dma_addr_t
* are certain non-highmem MIPS and x86
* configurations, but these configurations
* should never allocate physical pages above 32
* bits, so this is fine. Just in case, throw a
* warning and abort if we end up with an
* unrepresentable address.
*/
if (WARN_ON_ONCE(*dma_handle != phys_addr)) {
free_pages_exact(queue, PAGE_ALIGN(size));
return NULL;
}
}
return queue;
}
}
static void vring_free_queue(struct virtio_device *vdev, size_t size,
void *queue, dma_addr_t dma_handle)
{
if (vring_use_dma_api(vdev))
dma_free_coherent(vdev->dev.parent, size, queue, dma_handle);
else
free_pages_exact(queue, PAGE_ALIGN(size));
}
/*
* The DMA ops on various arches are rather gnarly right now, and
* making all of the arch DMA ops work on the vring device itself
* is a mess. For now, we use the parent device for DMA ops.
*/
static inline struct device *vring_dma_dev(const struct vring_virtqueue *vq)
{
return vq->vq.vdev->dev.parent;
}
/* Map one sg entry. */
static dma_addr_t vring_map_one_sg(const struct vring_virtqueue *vq,
struct scatterlist *sg,
enum dma_data_direction direction)
{
if (!vq->use_dma_api)
return (dma_addr_t)sg_phys(sg);
/*
* We can't use dma_map_sg, because we don't use scatterlists in
* the way it expects (we don't guarantee that the scatterlist
* will exist for the lifetime of the mapping).
*/
return dma_map_page(vring_dma_dev(vq),
sg_page(sg), sg->offset, sg->length,
direction);
}
static dma_addr_t vring_map_single(const struct vring_virtqueue *vq,
void *cpu_addr, size_t size,
enum dma_data_direction direction)
{
if (!vq->use_dma_api)
return (dma_addr_t)virt_to_phys(cpu_addr);
return dma_map_single(vring_dma_dev(vq),
cpu_addr, size, direction);
}
static int vring_mapping_error(const struct vring_virtqueue *vq,
dma_addr_t addr)
{
if (!vq->use_dma_api)
return 0;
return dma_mapping_error(vring_dma_dev(vq), addr);
}
/*
* Split ring specific functions - *_split().
*/
static void vring_unmap_one_split(const struct vring_virtqueue *vq,
struct vring_desc *desc)
{
u16 flags;
if (!vq->use_dma_api)
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_desc *alloc_indirect_split(struct virtqueue *_vq,
unsigned int total_sg,
gfp_t gfp)
{
struct vring_desc *desc;
unsigned int i;
/*
* 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_array(total_sg, sizeof(struct vring_desc), gfp);
if (!desc)
return NULL;
for (i = 0; i < total_sg; i++)
desc[i].next = cpu_to_virtio16(_vq->vdev, i + 1);
return desc;
}
static inline int virtqueue_add_split(struct virtqueue *_vq,
struct scatterlist *sgs[],
unsigned int total_sg,
unsigned int out_sgs,
unsigned int in_sgs,
void *data,
void *ctx,
gfp_t gfp)
{
struct vring_virtqueue *vq = to_vvq(_vq);
struct scatterlist *sg;
struct vring_desc *desc;
unsigned int i, n, avail, descs_used, uninitialized_var(prev), err_idx;
int head;
bool indirect;
START_USE(vq);
BUG_ON(data == NULL);
BUG_ON(ctx && vq->indirect);
if (unlikely(vq->broken)) {
END_USE(vq);
return -EIO;
}
LAST_ADD_TIME_UPDATE(vq);
BUG_ON(total_sg == 0);
head = vq->free_head;
if (virtqueue_use_indirect(_vq, total_sg))
desc = alloc_indirect_split(_vq, total_sg, gfp);
else {
desc = NULL;
WARN_ON_ONCE(total_sg > vq->split.vring.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->split.vring.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;
}
for (n = 0; n < out_sgs; n++) {
for (sg = sgs[n]; sg; sg = sg_next(sg)) {
dma_addr_t addr = vring_map_one_sg(vq, sg, DMA_TO_DEVICE);
if (vring_mapping_error(vq, addr))
goto unmap_release;
desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT);
desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
prev = i;
i = virtio16_to_cpu(_vq->vdev, desc[i].next);
}
}
for (; 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, DMA_FROM_DEVICE);
if (vring_mapping_error(vq, addr))
goto unmap_release;
desc[i].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_NEXT | VRING_DESC_F_WRITE);
desc[i].addr = cpu_to_virtio64(_vq->vdev, addr);
desc[i].len = cpu_to_virtio32(_vq->vdev, sg->length);
prev = i;
i = virtio16_to_cpu(_vq->vdev, desc[i].next);
}
}
/* Last one doesn't continue. */
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_desc),
DMA_TO_DEVICE);
if (vring_mapping_error(vq, addr))
goto unmap_release;
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->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. */
vq->vq.num_free -= descs_used;
/* Update free pointer */
if (indirect)
vq->free_head = virtio16_to_cpu(_vq->vdev,
vq->split.vring.desc[head].next);
else
vq->free_head = i;
/* Store token and indirect buffer state. */
vq->split.desc_state[head].data = data;
if (indirect)
vq->split.desc_state[head].indir_desc = desc;
else
vq->split.desc_state[head].indir_desc = ctx;
/* Put entry in available array (but don't update avail->idx until they
* do sync). */
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->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);
END_USE(vq);
/* This is very unlikely, but theoretically possible. Kick
* just in case. */
if (unlikely(vq->num_added == (1 << 16) - 1))
virtqueue_kick(_vq);
return 0;
unmap_release:
err_idx = i;
if (indirect)
i = 0;
else
i = head;
for (n = 0; n < total_sg; n++) {
if (i == err_idx)
break;
vring_unmap_one_split(vq, &desc[i]);
i = virtio16_to_cpu(_vq->vdev, desc[i].next);
}
if (indirect)
kfree(desc);
END_USE(vq);
return -ENOMEM;
}
static bool virtqueue_kick_prepare_split(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->split.avail_idx_shadow - vq->num_added;
new = vq->split.avail_idx_shadow;
vq->num_added = 0;
LAST_ADD_TIME_CHECK(vq);
LAST_ADD_TIME_INVALID(vq);
if (vq->event) {
needs_kick = vring_need_event(virtio16_to_cpu(_vq->vdev,
vring_avail_event(&vq->split.vring)),
new, old);
} else {
needs_kick = !(vq->split.vring.used->flags &
cpu_to_virtio16(_vq->vdev,
VRING_USED_F_NO_NOTIFY));
}
END_USE(vq);
return needs_kick;
}
static void detach_buf_split(struct vring_virtqueue *vq, unsigned int head,
void **ctx)
{
unsigned int i, j;
__virtio16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT);
/* Clear data ptr. */
vq->split.desc_state[head].data = NULL;
/* Put back on free list: unmap first-level descriptors and find end */
i = head;
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->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 */
vq->vq.num_free++;
if (vq->indirect) {
struct vring_desc *indir_desc =
vq->split.desc_state[head].indir_desc;
u32 len;
/* Free the indirect table, if any, now that it's unmapped. */
if (!indir_desc)
return;
len = virtio32_to_cpu(vq->vq.vdev,
vq->split.vring.desc[head].len);
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));
for (j = 0; j < len / sizeof(struct vring_desc); j++)
vring_unmap_one_split(vq, &indir_desc[j]);
kfree(indir_desc);
vq->split.desc_state[head].indir_desc = NULL;
} else if (ctx) {
*ctx = vq->split.desc_state[head].indir_desc;
}
}
static inline bool more_used_split(const struct vring_virtqueue *vq)
{
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,
unsigned int *len,
void **ctx)
{
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_split(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->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->split.vring.num)) {
BAD_RING(vq, "id %u out of range\n", i);
return NULL;
}
if (unlikely(!vq->split.desc_state[i].data)) {
BAD_RING(vq, "id %u is not a head!\n", i);
return NULL;
}
/* detach_buf_split clears data, so grab it now. */
ret = vq->split.desc_state[i].data;
detach_buf_split(vq, i, ctx);
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->split.avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT))
virtio_store_mb(vq->weak_barriers,
&vring_used_event(&vq->split.vring),
cpu_to_virtio16(_vq->vdev, vq->last_used_idx));
LAST_ADD_TIME_INVALID(vq);
END_USE(vq);
return ret;
}
static void virtqueue_disable_cb_split(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
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->split.vring.avail->flags =
cpu_to_virtio16(_vq->vdev,
vq->split.avail_flags_shadow);
}
}
static unsigned virtqueue_enable_cb_prepare_split(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. */
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->split.vring.avail->flags =
cpu_to_virtio16(_vq->vdev,
vq->split.avail_flags_shadow);
}
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;
}
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->split.vring.used->idx);
}
static bool virtqueue_enable_cb_delayed_split(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 update the event index to keep code simple. */
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->split.vring.avail->flags =
cpu_to_virtio16(_vq->vdev,
vq->split.avail_flags_shadow);
}
/* TODO: tune this threshold */
bufs = (u16)(vq->split.avail_idx_shadow - vq->last_used_idx) * 3 / 4;
virtio_store_mb(vq->weak_barriers,
&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->split.vring.used->idx)
- vq->last_used_idx) > bufs)) {
END_USE(vq);
return false;
}
END_USE(vq);
return true;
}
static void *virtqueue_detach_unused_buf_split(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
unsigned int i;
void *buf;
START_USE(vq);
for (i = 0; i < vq->split.vring.num; i++) {
if (!vq->split.desc_state[i].data)
continue;
/* detach_buf_split clears data, so grab it now. */
buf = vq->split.desc_state[i].data;
detach_buf_split(vq, i, NULL);
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->split.vring.num);
END_USE(vq);
return NULL;
}
static struct virtqueue *vring_create_virtqueue_split(
unsigned int index,
unsigned int num,
unsigned int vring_align,
struct virtio_device *vdev,
bool weak_barriers,
bool may_reduce_num,
bool context,
bool (*notify)(struct virtqueue *),
void (*callback)(struct virtqueue *),
const char *name)
{
struct virtqueue *vq;
void *queue = NULL;
dma_addr_t dma_addr;
size_t queue_size_in_bytes;
struct vring vring;
/* We assume num is a power of 2. */
if (num & (num - 1)) {
dev_warn(&vdev->dev, "Bad virtqueue length %u\n", num);
return NULL;
}
/* TODO: allocate each queue chunk individually */
for (; num && vring_size(num, vring_align) > PAGE_SIZE; num /= 2) {
queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
&dma_addr,
GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
if (queue)
break;
if (!may_reduce_num)
return NULL;
}
if (!num)
return NULL;
if (!queue) {
/* Try to get a single page. You are my only hope! */
queue = vring_alloc_queue(vdev, vring_size(num, vring_align),
&dma_addr, GFP_KERNEL|__GFP_ZERO);
}
if (!queue)
return NULL;
queue_size_in_bytes = vring_size(num, vring_align);
vring_init(&vring, num, queue, vring_align);
vq = __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
notify, callback, name);
if (!vq) {
vring_free_queue(vdev, queue_size_in_bytes, queue,
dma_addr);
return NULL;
}
to_vvq(vq)->split.queue_dma_addr = dma_addr;
to_vvq(vq)->split.queue_size_in_bytes = queue_size_in_bytes;
to_vvq(vq)->we_own_ring = true;
return vq;
}
/*
* Packed ring specific functions - *_packed().
*/
static void vring_unmap_state_packed(const struct vring_virtqueue *vq,
struct vring_desc_extra_packed *state)
{
u16 flags;
if (!vq->use_dma_api)
return;
flags = state->flags;
if (flags & VRING_DESC_F_INDIRECT) {
dma_unmap_single(vring_dma_dev(vq),
state->addr, state->len,
(flags & VRING_DESC_F_WRITE) ?
DMA_FROM_DEVICE : DMA_TO_DEVICE);
} else {
dma_unmap_page(vring_dma_dev(vq),
state->addr, state->len,
(flags & VRING_DESC_F_WRITE) ?
DMA_FROM_DEVICE : DMA_TO_DEVICE);
}
}
static void vring_unmap_desc_packed(const struct vring_virtqueue *vq,
struct vring_packed_desc *desc)
{
u16 flags;
if (!vq->use_dma_api)
return;
flags = le16_to_cpu(desc->flags);
if (flags & VRING_DESC_F_INDIRECT) {
dma_unmap_single(vring_dma_dev(vq),
le64_to_cpu(desc->addr),
le32_to_cpu(desc->len),
(flags & VRING_DESC_F_WRITE) ?
DMA_FROM_DEVICE : DMA_TO_DEVICE);
} else {
dma_unmap_page(vring_dma_dev(vq),
le64_to_cpu(desc->addr),
le32_to_cpu(desc->len),
(flags & VRING_DESC_F_WRITE) ?
DMA_FROM_DEVICE : DMA_TO_DEVICE);
}
}
static struct vring_packed_desc *alloc_indirect_packed(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_array(total_sg, sizeof(struct vring_packed_desc), gfp);
return desc;
}
static int virtqueue_add_indirect_packed(struct vring_virtqueue *vq,
struct scatterlist *sgs[],
unsigned int total_sg,
unsigned int out_sgs,
unsigned int in_sgs,
void *data,
gfp_t gfp)
{
struct vring_packed_desc *desc;
struct scatterlist *sg;
unsigned int i, n, err_idx;
u16 head, id;
dma_addr_t addr;
head = vq->packed.next_avail_idx;
desc = alloc_indirect_packed(total_sg, gfp);
if (unlikely(vq->vq.num_free < 1)) {
pr_debug("Can't add buf len 1 - avail = 0\n");
kfree(desc);
END_USE(vq);
return -ENOSPC;
}
i = 0;
id = vq->free_head;
BUG_ON(id == vq->packed.vring.num);
for (n = 0; n < out_sgs + in_sgs; n++) {
for (sg = sgs[n]; sg; sg = sg_next(sg)) {
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;
desc[i].flags = cpu_to_le16(n < out_sgs ?
0 : VRING_DESC_F_WRITE);
desc[i].addr = cpu_to_le64(addr);
desc[i].len = cpu_to_le32(sg->length);
i++;
}
}
/* Now that the indirect table is filled in, map it. */
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;
vq->packed.vring.desc[head].addr = cpu_to_le64(addr);
vq->packed.vring.desc[head].len = cpu_to_le32(total_sg *
sizeof(struct vring_packed_desc));
vq->packed.vring.desc[head].id = cpu_to_le16(id);
if (vq->use_dma_api) {
vq->packed.desc_extra[id].addr = addr;
vq->packed.desc_extra[id].len = total_sg *
sizeof(struct vring_packed_desc);
vq->packed.desc_extra[id].flags = VRING_DESC_F_INDIRECT |
vq->packed.avail_used_flags;
}
/*
* 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->packed.vring.desc[head].flags = cpu_to_le16(VRING_DESC_F_INDIRECT |
vq->packed.avail_used_flags);
/* We're using some buffers from the free list. */
vq->vq.num_free -= 1;
/* Update free pointer */
n = head + 1;
if (n >= vq->packed.vring.num) {
n = 0;
vq->packed.avail_wrap_counter ^= 1;
vq->packed.avail_used_flags ^=
1 << VRING_PACKED_DESC_F_AVAIL |
1 << VRING_PACKED_DESC_F_USED;
}
vq->packed.next_avail_idx = n;
vq->free_head = vq->packed.desc_state[id].next;
/* Store token and indirect buffer state. */
vq->packed.desc_state[id].num = 1;
vq->packed.desc_state[id].data = data;
vq->packed.desc_state[id].indir_desc = desc;
vq->packed.desc_state[id].last = id;
vq->num_added += 1;
pr_debug("Added buffer head %i to %p\n", head, vq);
END_USE(vq);
return 0;
unmap_release:
err_idx = i;
for (i = 0; i < err_idx; i++)
vring_unmap_desc_packed(vq, &desc[i]);
kfree(desc);
END_USE(vq);
return -ENOMEM;
}
static inline int virtqueue_add_packed(struct virtqueue *_vq,
struct scatterlist *sgs[],
unsigned int total_sg,
unsigned int out_sgs,
unsigned int in_sgs,
void *data,
void *ctx,
gfp_t gfp)
{
struct vring_virtqueue *vq = to_vvq(_vq);
struct vring_packed_desc *desc;
struct scatterlist *sg;
unsigned int i, n, c, descs_used, err_idx;
__le16 uninitialized_var(head_flags), flags;
u16 head, id, uninitialized_var(prev), curr, avail_used_flags;
START_USE(vq);
BUG_ON(data == NULL);
BUG_ON(ctx && vq->indirect);
if (unlikely(vq->broken)) {
END_USE(vq);
return -EIO;
}
LAST_ADD_TIME_UPDATE(vq);
BUG_ON(total_sg == 0);
if (virtqueue_use_indirect(_vq, total_sg))
return virtqueue_add_indirect_packed(vq, sgs, total_sg,
out_sgs, in_sgs, data, gfp);
head = vq->packed.next_avail_idx;
avail_used_flags = vq->packed.avail_used_flags;
WARN_ON_ONCE(total_sg > vq->packed.vring.num && !vq->indirect);
desc = vq->packed.vring.desc;
i = head;
descs_used = total_sg;
if (unlikely(vq->vq.num_free < descs_used)) {
pr_debug("Can't add buf len %i - avail = %i\n",
descs_used, vq->vq.num_free);
END_USE(vq);
return -ENOSPC;
}
id = vq->free_head;
BUG_ON(id == vq->packed.vring.num);
curr = id;
c = 0;
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_le16(vq->packed.avail_used_flags |
(++c == total_sg ? 0 : VRING_DESC_F_NEXT) |
(n < out_sgs ? 0 : VRING_DESC_F_WRITE));
if (i == head)
head_flags = flags;
else
desc[i].flags = flags;
desc[i].addr = cpu_to_le64(addr);
desc[i].len = cpu_to_le32(sg->length);
desc[i].id = cpu_to_le16(id);
if (unlikely(vq->use_dma_api)) {
vq->packed.desc_extra[curr].addr = addr;
vq->packed.desc_extra[curr].len = sg->length;
vq->packed.desc_extra[curr].flags =
le16_to_cpu(flags);
}
prev = curr;
curr = vq->packed.desc_state[curr].next;
if ((unlikely(++i >= vq->packed.vring.num))) {
i = 0;
vq->packed.avail_used_flags ^=
1 << VRING_PACKED_DESC_F_AVAIL |
1 << VRING_PACKED_DESC_F_USED;
}
}
}
if (i < head)
vq->packed.avail_wrap_counter ^= 1;
/* We're using some buffers from the free list. */
vq->vq.num_free -= descs_used;
/* Update free pointer */
vq->packed.next_avail_idx = i;
vq->free_head = curr;
/* Store token. */
vq->packed.desc_state[id].num = descs_used;
vq->packed.desc_state[id].data = data;
vq->packed.desc_state[id].indir_desc = ctx;
vq->packed.desc_state[id].last = prev;
/*
* 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->packed.vring.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;
vq->packed.avail_used_flags = avail_used_flags;
for (n = 0; n < total_sg; n++) {
if (i == err_idx)
break;
vring_unmap_desc_packed(vq, &desc[i]);
i++;
if (i >= vq->packed.vring.num)
i = 0;
}
END_USE(vq);
return -EIO;
}
static bool virtqueue_kick_prepare_packed(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
u16 new, old, off_wrap, flags, wrap_counter, event_idx;
bool needs_kick;
union {
struct {
__le16 off_wrap;
__le16 flags;
};
u32 u32;
} snapshot;
START_USE(vq);
/*
* We need to expose the new flags value before checking notification
* suppressions.
*/
virtio_mb(vq->weak_barriers);
old = vq->packed.next_avail_idx - vq->num_added;
new = vq->packed.next_avail_idx;
vq->num_added = 0;
snapshot.u32 = *(u32 *)vq->packed.vring.device;
flags = le16_to_cpu(snapshot.flags);
LAST_ADD_TIME_CHECK(vq);
LAST_ADD_TIME_INVALID(vq);
if (flags != VRING_PACKED_EVENT_FLAG_DESC) {
needs_kick = (flags != VRING_PACKED_EVENT_FLAG_DISABLE);
goto out;
}
off_wrap = le16_to_cpu(snapshot.off_wrap);
wrap_counter = off_wrap >> VRING_PACKED_EVENT_F_WRAP_CTR;
event_idx = off_wrap & ~(1 << VRING_PACKED_EVENT_F_WRAP_CTR);
if (wrap_counter != vq->packed.avail_wrap_counter)
event_idx -= vq->packed.vring.num;
needs_kick = vring_need_event(event_idx, new, old);
out:
END_USE(vq);
return needs_kick;
}
static void detach_buf_packed(struct vring_virtqueue *vq,
unsigned int id, void **ctx)
{
struct vring_desc_state_packed *state = NULL;
struct vring_packed_desc *desc;
unsigned int i, curr;
state = &vq->packed.desc_state[id];
/* Clear data ptr. */
state->data = NULL;
vq->packed.desc_state[state->last].next = vq->free_head;
vq->free_head = id;
vq->vq.num_free += state->num;
if (unlikely(vq->use_dma_api)) {
curr = id;
for (i = 0; i < state->num; i++) {
vring_unmap_state_packed(vq,
&vq->packed.desc_extra[curr]);
curr = vq->packed.desc_state[curr].next;
}
}
if (vq->indirect) {
u32 len;
/* Free the indirect table, if any, now that it's unmapped. */
desc = state->indir_desc;
if (!desc)
return;
if (vq->use_dma_api) {
len = vq->packed.desc_extra[id].len;
for (i = 0; i < len / sizeof(struct vring_packed_desc);
i++)
vring_unmap_desc_packed(vq, &desc[i]);
}
kfree(desc);
state->indir_desc = NULL;
} else if (ctx) {
*ctx = state->indir_desc;
}
}
static inline bool is_used_desc_packed(const struct vring_virtqueue *vq,
u16 idx, bool used_wrap_counter)
{
bool avail, used;
u16 flags;
flags = le16_to_cpu(vq->packed.vring.desc[idx].flags);
avail = !!(flags & (1 << VRING_PACKED_DESC_F_AVAIL));
used = !!(flags & (1 << VRING_PACKED_DESC_F_USED));
return avail == used && used == used_wrap_counter;
}
static inline bool more_used_packed(const struct vring_virtqueue *vq)
{
return is_used_desc_packed(vq, vq->last_used_idx,
vq->packed.used_wrap_counter);
}
static void *virtqueue_get_buf_ctx_packed(struct virtqueue *_vq,
unsigned int *len,
void **ctx)
{
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 = le16_to_cpu(vq->packed.vring.desc[last_used].id);
*len = le32_to_cpu(vq->packed.vring.desc[last_used].len);
if (unlikely(id >= vq->packed.vring.num)) {
BAD_RING(vq, "id %u out of range\n", id);
return NULL;
}
if (unlikely(!vq->packed.desc_state[id].data)) {
BAD_RING(vq, "id %u is not a head!\n", id);
return NULL;
}
/* detach_buf_packed clears data, so grab it now. */
ret = vq->packed.desc_state[id].data;
detach_buf_packed(vq, id, ctx);
vq->last_used_idx += vq->packed.desc_state[id].num;
if (unlikely(vq->last_used_idx >= vq->packed.vring.num)) {
vq->last_used_idx -= vq->packed.vring.num;
vq->packed.used_wrap_counter ^= 1;
}
/*
* 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->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DESC)
virtio_store_mb(vq->weak_barriers,
&vq->packed.vring.driver->off_wrap,
cpu_to_le16(vq->last_used_idx |
(vq->packed.used_wrap_counter <<
VRING_PACKED_EVENT_F_WRAP_CTR)));
LAST_ADD_TIME_INVALID(vq);
END_USE(vq);
return ret;
}
static void virtqueue_disable_cb_packed(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
if (vq->packed.event_flags_shadow != VRING_PACKED_EVENT_FLAG_DISABLE) {
vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
vq->packed.vring.driver->flags =
cpu_to_le16(vq->packed.event_flags_shadow);
}
}
static unsigned virtqueue_enable_cb_prepare_packed(struct virtqueue *_vq)
{
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) {
vq->packed.vring.driver->off_wrap =
cpu_to_le16(vq->last_used_idx |
(vq->packed.used_wrap_counter <<
VRING_PACKED_EVENT_F_WRAP_CTR));
/*
* We need to update event offset and event wrap
* counter first before updating event flags.
*/
virtio_wmb(vq->weak_barriers);
}
if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DISABLE) {
vq->packed.event_flags_shadow = vq->event ?
VRING_PACKED_EVENT_FLAG_DESC :
VRING_PACKED_EVENT_FLAG_ENABLE;
vq->packed.vring.driver->flags =
cpu_to_le16(vq->packed.event_flags_shadow);
}
END_USE(vq);
return vq->last_used_idx | ((u16)vq->packed.used_wrap_counter <<
VRING_PACKED_EVENT_F_WRAP_CTR);
}
static bool virtqueue_poll_packed(struct virtqueue *_vq, u16 off_wrap)
{
struct vring_virtqueue *vq = to_vvq(_vq);
bool wrap_counter;
u16 used_idx;
wrap_counter = off_wrap >> VRING_PACKED_EVENT_F_WRAP_CTR;
used_idx = off_wrap & ~(1 << VRING_PACKED_EVENT_F_WRAP_CTR);
return is_used_desc_packed(vq, used_idx, wrap_counter);
}
static bool virtqueue_enable_cb_delayed_packed(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
u16 used_idx, wrap_counter;
u16 bufs;
START_USE(vq);
/*
* We optimistically turn back on interrupts, then check if there was
* more to do.
*/
if (vq->event) {
/* TODO: tune this threshold */
bufs = (vq->packed.vring.num - vq->vq.num_free) * 3 / 4;
wrap_counter = vq->packed.used_wrap_counter;
used_idx = vq->last_used_idx + bufs;
if (used_idx >= vq->packed.vring.num) {
used_idx -= vq->packed.vring.num;
wrap_counter ^= 1;
}
vq->packed.vring.driver->off_wrap = cpu_to_le16(used_idx |
(wrap_counter << VRING_PACKED_EVENT_F_WRAP_CTR));
/*
* We need to update event offset and event wrap
* counter first before updating event flags.
*/
virtio_wmb(vq->weak_barriers);
}
if (vq->packed.event_flags_shadow == VRING_PACKED_EVENT_FLAG_DISABLE) {
vq->packed.event_flags_shadow = vq->event ?
VRING_PACKED_EVENT_FLAG_DESC :
VRING_PACKED_EVENT_FLAG_ENABLE;
vq->packed.vring.driver->flags =
cpu_to_le16(vq->packed.event_flags_shadow);
}
/*
* We need to update event suppression structure first
* before re-checking for more used buffers.
*/
virtio_mb(vq->weak_barriers);
if (is_used_desc_packed(vq,
vq->last_used_idx,
vq->packed.used_wrap_counter)) {
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);
unsigned int i;
void *buf;
START_USE(vq);
for (i = 0; i < vq->packed.vring.num; i++) {
if (!vq->packed.desc_state[i].data)
continue;
/* detach_buf clears data, so grab it now. */
buf = vq->packed.desc_state[i].data;
detach_buf_packed(vq, i, NULL);
END_USE(vq);
return buf;
}
/* That should have freed everything. */
BUG_ON(vq->vq.num_free != vq->packed.vring.num);
END_USE(vq);
return NULL;
}
static struct virtqueue *vring_create_virtqueue_packed(
unsigned int index,
unsigned int num,
unsigned int vring_align,
struct virtio_device *vdev,
bool weak_barriers,
bool may_reduce_num,
bool context,
bool (*notify)(struct virtqueue *),
void (*callback)(struct virtqueue *),
const char *name)
{
struct vring_virtqueue *vq;
struct vring_packed_desc *ring;
struct vring_packed_desc_event *driver, *device;
dma_addr_t ring_dma_addr, driver_event_dma_addr, device_event_dma_addr;
size_t ring_size_in_bytes, event_size_in_bytes;
unsigned int i;
ring_size_in_bytes = num * sizeof(struct vring_packed_desc);
ring = vring_alloc_queue(vdev, ring_size_in_bytes,
&ring_dma_addr,
GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
if (!ring)
goto err_ring;
event_size_in_bytes = sizeof(struct vring_packed_desc_event);
driver = vring_alloc_queue(vdev, event_size_in_bytes,
&driver_event_dma_addr,
GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
if (!driver)
goto err_driver;
device = vring_alloc_queue(vdev, event_size_in_bytes,
&device_event_dma_addr,
GFP_KERNEL|__GFP_NOWARN|__GFP_ZERO);
if (!device)
goto err_device;
vq = kmalloc(sizeof(*vq), GFP_KERNEL);
if (!vq)
goto err_vq;
vq->vq.callback = callback;
vq->vq.vdev = vdev;
vq->vq.name = name;
vq->vq.num_free = num;
vq->vq.index = index;
vq->we_own_ring = true;
vq->notify = notify;
vq->weak_barriers = weak_barriers;
vq->broken = false;
vq->last_used_idx = 0;
vq->num_added = 0;
vq->packed_ring = true;
vq->use_dma_api = vring_use_dma_api(vdev);
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) &&
!context;
vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
vq->weak_barriers = false;
vq->packed.ring_dma_addr = ring_dma_addr;
vq->packed.driver_event_dma_addr = driver_event_dma_addr;
vq->packed.device_event_dma_addr = device_event_dma_addr;
vq->packed.ring_size_in_bytes = ring_size_in_bytes;
vq->packed.event_size_in_bytes = event_size_in_bytes;
vq->packed.vring.num = num;
vq->packed.vring.desc = ring;
vq->packed.vring.driver = driver;
vq->packed.vring.device = device;
vq->packed.next_avail_idx = 0;
vq->packed.avail_wrap_counter = 1;
vq->packed.used_wrap_counter = 1;
vq->packed.event_flags_shadow = 0;
vq->packed.avail_used_flags = 1 << VRING_PACKED_DESC_F_AVAIL;
vq->packed.desc_state = kmalloc_array(num,
sizeof(struct vring_desc_state_packed),
GFP_KERNEL);
if (!vq->packed.desc_state)
goto err_desc_state;
memset(vq->packed.desc_state, 0,
num * sizeof(struct vring_desc_state_packed));
/* Put everything in free lists. */
vq->free_head = 0;
for (i = 0; i < num-1; i++)
vq->packed.desc_state[i].next = i + 1;
vq->packed.desc_extra = kmalloc_array(num,
sizeof(struct vring_desc_extra_packed),
GFP_KERNEL);
if (!vq->packed.desc_extra)
goto err_desc_extra;
memset(vq->packed.desc_extra, 0,
num * sizeof(struct vring_desc_extra_packed));
/* No callback? Tell other side not to bother us. */
if (!callback) {
vq->packed.event_flags_shadow = VRING_PACKED_EVENT_FLAG_DISABLE;
vq->packed.vring.driver->flags =
cpu_to_le16(vq->packed.event_flags_shadow);
}
return &vq->vq;
err_desc_extra:
kfree(vq->packed.desc_state);
err_desc_state:
kfree(vq);
err_vq:
vring_free_queue(vdev, event_size_in_bytes, device, ring_dma_addr);
err_device:
vring_free_queue(vdev, event_size_in_bytes, driver, ring_dma_addr);
err_driver:
vring_free_queue(vdev, ring_size_in_bytes, ring, ring_dma_addr);
err_ring:
return NULL;
}
/*
* Generic functions and exported symbols.
*/
static inline int virtqueue_add(struct virtqueue *_vq,
struct scatterlist *sgs[],
unsigned int total_sg,
unsigned int out_sgs,
unsigned int in_sgs,
void *data,
void *ctx,
gfp_t gfp)
{
struct vring_virtqueue *vq = to_vvq(_vq);
return vq->packed_ring ? virtqueue_add_packed(_vq, sgs, total_sg,
out_sgs, in_sgs, data, ctx, gfp) :
virtqueue_add_split(_vq, sgs, total_sg,
out_sgs, in_sgs, data, ctx, gfp);
}
/**
* virtqueue_add_sgs - expose buffers to other end
* @_vq: the struct virtqueue we're talking about.
* @sgs: array of terminated scatterlists.
* @out_sgs: the number of scatterlists readable by other side
* @in_sgs: 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, EIO).
*/
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_sg = 0;
/* Count them first. */
for (i = 0; i < out_sgs + in_sgs; i++) {
struct scatterlist *sg;
for (sg = sgs[i]; sg; sg = sg_next(sg))
total_sg++;
}
return virtqueue_add(_vq, sgs, total_sg, out_sgs, in_sgs,
data, NULL, gfp);
}
EXPORT_SYMBOL_GPL(virtqueue_add_sgs);
/**
* virtqueue_add_outbuf - expose output buffers to other end
* @vq: the struct virtqueue we're talking about.
* @sg: scatterlist (must be well-formed and terminated!)
* @num: the number of entries in @sg 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, EIO).
*/
int virtqueue_add_outbuf(struct virtqueue *vq,
struct scatterlist *sg, unsigned int num,
void *data,
gfp_t gfp)
{
return virtqueue_add(vq, &sg, num, 1, 0, data, NULL, gfp);
}
EXPORT_SYMBOL_GPL(virtqueue_add_outbuf);
/**
* virtqueue_add_inbuf - expose input buffers to other end
* @vq: the struct virtqueue we're talking about.
* @sg: scatterlist (must be well-formed and terminated!)
* @num: the number of entries in @sg 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, EIO).
*/
int virtqueue_add_inbuf(struct virtqueue *vq,
struct scatterlist *sg, unsigned int num,
void *data,
gfp_t gfp)
{
return virtqueue_add(vq, &sg, num, 0, 1, data, NULL, gfp);
}
EXPORT_SYMBOL_GPL(virtqueue_add_inbuf);
/**
* virtqueue_add_inbuf_ctx - expose input buffers to other end
* @vq: the struct virtqueue we're talking about.
* @sg: scatterlist (must be well-formed and terminated!)
* @num: the number of entries in @sg writable by other side
* @data: the token identifying the buffer.
* @ctx: extra context for the token
* @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, EIO).
*/
int virtqueue_add_inbuf_ctx(struct virtqueue *vq,
struct scatterlist *sg, unsigned int num,
void *data,
void *ctx,
gfp_t gfp)
{
return virtqueue_add(vq, &sg, num, 0, 1, data, ctx, gfp);
}
EXPORT_SYMBOL_GPL(virtqueue_add_inbuf_ctx);
/**
* 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);
return vq->packed_ring ? virtqueue_kick_prepare_packed(_vq) :
virtqueue_kick_prepare_split(_vq);
}
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.
*
* Returns false if host notify failed or queue is broken, otherwise true.
*/
bool virtqueue_notify(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
if (unlikely(vq->broken))
return false;
/* Prod other side to tell it about changes. */
if (!vq->notify(_vq)) {
vq->broken = true;
return false;
}
return true;
}
EXPORT_SYMBOL_GPL(virtqueue_notify);
/**
* virtqueue_kick - update after add_buf
* @vq: the struct virtqueue
*
* After one or more virtqueue_add_* 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).
*
* Returns false if kick failed, otherwise true.
*/
bool virtqueue_kick(struct virtqueue *vq)
{
if (virtqueue_kick_prepare(vq))
return virtqueue_notify(vq);
return true;
}
EXPORT_SYMBOL_GPL(virtqueue_kick);
/**
* virtqueue_get_buf - get the next used buffer
* @_vq: the struct virtqueue we're talking about.
* @len: the length written into the buffer
* @ctx: extra context for the token
*
* If the device 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_*().
*/
void *virtqueue_get_buf_ctx(struct virtqueue *_vq, unsigned int *len,
void **ctx)
{
struct vring_virtqueue *vq = to_vvq(_vq);
return vq->packed_ring ? virtqueue_get_buf_ctx_packed(_vq, len, ctx) :
virtqueue_get_buf_ctx_split(_vq, len, ctx);
}
EXPORT_SYMBOL_GPL(virtqueue_get_buf_ctx);
void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
{
return virtqueue_get_buf_ctx(_vq, len, NULL);
}
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);
if (vq->packed_ring)
virtqueue_disable_cb_packed(_vq);
else
virtqueue_disable_cb_split(_vq);
}
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);
return vq->packed_ring ? virtqueue_enable_cb_prepare_packed(_vq) :
virtqueue_enable_cb_prepare_split(_vq);
}
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 vq->packed_ring ? virtqueue_poll_packed(_vq, last_used_idx) :
virtqueue_poll_split(_vq, last_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);
return vq->packed_ring ? virtqueue_enable_cb_delayed_packed(_vq) :
virtqueue_enable_cb_delayed_split(_vq);
}
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_*().
* 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);
return vq->packed_ring ? virtqueue_detach_unused_buf_packed(_vq) :
virtqueue_detach_unused_buf_split(_vq);
}
EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf);
static inline bool more_used(const struct vring_virtqueue *vq)
{
return vq->packed_ring ? more_used_packed(vq) : more_used_split(vq);
}
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);
/* Only available for split ring */
struct virtqueue *__vring_new_virtqueue(unsigned int index,
struct vring vring,
struct virtio_device *vdev,
bool weak_barriers,
bool context,
bool (*notify)(struct virtqueue *),
void (*callback)(struct virtqueue *),
const char *name)
{
unsigned int i;
struct vring_virtqueue *vq;
if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
return NULL;
vq = kmalloc(sizeof(*vq), GFP_KERNEL);
if (!vq)
return NULL;
vq->packed_ring = false;
vq->vq.callback = callback;
vq->vq.vdev = vdev;
vq->vq.name = name;
vq->vq.num_free = vring.num;
vq->vq.index = index;
vq->we_own_ring = false;
vq->notify = notify;
vq->weak_barriers = weak_barriers;
vq->broken = false;
vq->last_used_idx = 0;
vq->num_added = 0;
vq->use_dma_api = vring_use_dma_api(vdev);
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) &&
!context;
vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX);
if (virtio_has_feature(vdev, VIRTIO_F_ORDER_PLATFORM))
vq->weak_barriers = false;
vq->split.queue_dma_addr = 0;
vq->split.queue_size_in_bytes = 0;
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->split.avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT;
if (!vq->event)
vq->split.vring.avail->flags = cpu_to_virtio16(vdev,
vq->split.avail_flags_shadow);
}
vq->split.desc_state = kmalloc_array(vring.num,
sizeof(struct vring_desc_state_split), GFP_KERNEL);
if (!vq->split.desc_state) {
kfree(vq);
return NULL;
}
/* Put everything in free lists. */
vq->free_head = 0;
for (i = 0; i < vring.num-1; i++)
vq->split.vring.desc[i].next = cpu_to_virtio16(vdev, i + 1);
memset(vq->split.desc_state, 0, vring.num *
sizeof(struct vring_desc_state_split));
return &vq->vq;
}
EXPORT_SYMBOL_GPL(__vring_new_virtqueue);
struct virtqueue *vring_create_virtqueue(
unsigned int index,
unsigned int num,
unsigned int vring_align,
struct virtio_device *vdev,
bool weak_barriers,
bool may_reduce_num,
bool context,
bool (*notify)(struct virtqueue *),
void (*callback)(struct virtqueue *),
const char *name)
{
if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
return vring_create_virtqueue_packed(index, num, vring_align,
vdev, weak_barriers, may_reduce_num,
context, notify, callback, name);
return vring_create_virtqueue_split(index, num, vring_align,
vdev, weak_barriers, may_reduce_num,
context, notify, callback, name);
}
EXPORT_SYMBOL_GPL(vring_create_virtqueue);
/* Only available for split ring */
struct virtqueue *vring_new_virtqueue(unsigned int index,
unsigned int num,
unsigned int vring_align,
struct virtio_device *vdev,
bool weak_barriers,
bool context,
void *pages,
bool (*notify)(struct virtqueue *vq),
void (*callback)(struct virtqueue *vq),
const char *name)
{
struct vring vring;
if (virtio_has_feature(vdev, VIRTIO_F_RING_PACKED))
return NULL;
vring_init(&vring, num, pages, vring_align);
return __vring_new_virtqueue(index, vring, vdev, weak_barriers, context,
notify, callback, name);
}
EXPORT_SYMBOL_GPL(vring_new_virtqueue);
void vring_del_virtqueue(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
if (vq->we_own_ring) {
if (vq->packed_ring) {
vring_free_queue(vq->vq.vdev,
vq->packed.ring_size_in_bytes,
vq->packed.vring.desc,
vq->packed.ring_dma_addr);
vring_free_queue(vq->vq.vdev,
vq->packed.event_size_in_bytes,
vq->packed.vring.driver,
vq->packed.driver_event_dma_addr);
vring_free_queue(vq->vq.vdev,
vq->packed.event_size_in_bytes,
vq->packed.vring.device,
vq->packed.device_event_dma_addr);
kfree(vq->packed.desc_state);
kfree(vq->packed.desc_extra);
} else {
vring_free_queue(vq->vq.vdev,
vq->split.queue_size_in_bytes,
vq->split.vring.desc,
vq->split.queue_dma_addr);
kfree(vq->split.desc_state);
}
}
list_del(&_vq->list);
kfree(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;
case VIRTIO_F_VERSION_1:
break;
case VIRTIO_F_IOMMU_PLATFORM:
break;
case VIRTIO_F_RING_PACKED:
break;
case VIRTIO_F_ORDER_PLATFORM:
break;
default:
/* We don't understand this bit. */
__virtio_clear_bit(vdev, i);
}
}
}
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->packed_ring ? vq->packed.vring.num : vq->split.vring.num;
}
EXPORT_SYMBOL_GPL(virtqueue_get_vring_size);
bool virtqueue_is_broken(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
return vq->broken;
}
EXPORT_SYMBOL_GPL(virtqueue_is_broken);
/*
* This should prevent the device from being used, allowing drivers to
* recover. You may need to grab appropriate locks to flush.
*/
void virtio_break_device(struct virtio_device *dev)
{
struct virtqueue *_vq;
list_for_each_entry(_vq, &dev->vqs, list) {
struct vring_virtqueue *vq = to_vvq(_vq);
vq->broken = true;
}
}
EXPORT_SYMBOL_GPL(virtio_break_device);
dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
BUG_ON(!vq->we_own_ring);
if (vq->packed_ring)
return vq->packed.ring_dma_addr;
return vq->split.queue_dma_addr;
}
EXPORT_SYMBOL_GPL(virtqueue_get_desc_addr);
dma_addr_t virtqueue_get_avail_addr(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
BUG_ON(!vq->we_own_ring);
if (vq->packed_ring)
return vq->packed.driver_event_dma_addr;
return vq->split.queue_dma_addr +
((char *)vq->split.vring.avail - (char *)vq->split.vring.desc);
}
EXPORT_SYMBOL_GPL(virtqueue_get_avail_addr);
dma_addr_t virtqueue_get_used_addr(struct virtqueue *_vq)
{
struct vring_virtqueue *vq = to_vvq(_vq);
BUG_ON(!vq->we_own_ring);
if (vq->packed_ring)
return vq->packed.device_event_dma_addr;
return vq->split.queue_dma_addr +
((char *)vq->split.vring.used - (char *)vq->split.vring.desc);
}
EXPORT_SYMBOL_GPL(virtqueue_get_used_addr);
/* Only available for split ring */
const struct vring *virtqueue_get_vring(struct virtqueue *vq)
{
return &to_vvq(vq)->split.vring;
}
EXPORT_SYMBOL_GPL(virtqueue_get_vring);
MODULE_LICENSE("GPL");
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