forked from Minki/linux
1fe9b6fef1
virtio ring was changed to return an error code on OOM, but one caller was missed and still checks for vq->vring.num. The fix is just to check for <0 error code. Long term it might make sense to change goto add_head to just return an error on oom instead, but let's apply a minimal fix for 2.6.35. Reported-by: Chris Mason <chris.mason@oracle.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Tested-by: Chris Mason <chris.mason@oracle.com> Cc: stable@kernel.org # .34.x Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
486 lines
12 KiB
C
486 lines
12 KiB
C
/* 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>
|
|
|
|
/* virtio guest is communicating with a virtual "device" that actually runs on
|
|
* a host processor. Memory barriers are used to control SMP effects. */
|
|
#ifdef CONFIG_SMP
|
|
/* Where possible, use SMP barriers which are more lightweight than mandatory
|
|
* barriers, because mandatory barriers control MMIO effects on accesses
|
|
* through relaxed memory I/O windows (which virtio does not use). */
|
|
#define virtio_mb() smp_mb()
|
|
#define virtio_rmb() smp_rmb()
|
|
#define virtio_wmb() smp_wmb()
|
|
#else
|
|
/* We must force memory ordering even if guest is UP since host could be
|
|
* running on another CPU, but SMP barriers are defined to barrier() in that
|
|
* configuration. So fall back to mandatory barriers instead. */
|
|
#define virtio_mb() mb()
|
|
#define virtio_rmb() rmb()
|
|
#define virtio_wmb() wmb()
|
|
#endif
|
|
|
|
#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;
|
|
|
|
/* Other side has made a mess, don't try any more. */
|
|
bool broken;
|
|
|
|
/* Host supports indirect buffers */
|
|
bool indirect;
|
|
|
|
/* Number of free buffers */
|
|
unsigned int num_free;
|
|
/* 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;
|
|
#endif
|
|
|
|
/* Tokens for callbacks. */
|
|
void *data[];
|
|
};
|
|
|
|
#define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq)
|
|
|
|
/* Set up an indirect table of descriptors and add it to the queue. */
|
|
static int vring_add_indirect(struct vring_virtqueue *vq,
|
|
struct scatterlist sg[],
|
|
unsigned int out,
|
|
unsigned int in,
|
|
gfp_t gfp)
|
|
{
|
|
struct vring_desc *desc;
|
|
unsigned head;
|
|
int i;
|
|
|
|
desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp);
|
|
if (!desc)
|
|
return -ENOMEM;
|
|
|
|
/* Transfer entries from the sg list into the indirect page */
|
|
for (i = 0; i < out; i++) {
|
|
desc[i].flags = VRING_DESC_F_NEXT;
|
|
desc[i].addr = sg_phys(sg);
|
|
desc[i].len = sg->length;
|
|
desc[i].next = i+1;
|
|
sg++;
|
|
}
|
|
for (; i < (out + in); i++) {
|
|
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;
|
|
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->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;
|
|
}
|
|
|
|
int virtqueue_add_buf_gfp(struct virtqueue *_vq,
|
|
struct scatterlist sg[],
|
|
unsigned int out,
|
|
unsigned int in,
|
|
void *data,
|
|
gfp_t gfp)
|
|
{
|
|
struct vring_virtqueue *vq = to_vvq(_vq);
|
|
unsigned int i, avail, uninitialized_var(prev);
|
|
int head;
|
|
|
|
START_USE(vq);
|
|
|
|
BUG_ON(data == NULL);
|
|
|
|
/* If the host supports indirect descriptor tables, and we have multiple
|
|
* buffers, then go indirect. FIXME: tune this threshold */
|
|
if (vq->indirect && (out + in) > 1 && vq->num_free) {
|
|
head = vring_add_indirect(vq, sg, out, in, gfp);
|
|
if (likely(head >= 0))
|
|
goto add_head;
|
|
}
|
|
|
|
BUG_ON(out + in > vq->vring.num);
|
|
BUG_ON(out + in == 0);
|
|
|
|
if (vq->num_free < out + in) {
|
|
pr_debug("Can't add buf len %i - avail = %i\n",
|
|
out + in, 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)
|
|
vq->notify(&vq->vq);
|
|
END_USE(vq);
|
|
return -ENOSPC;
|
|
}
|
|
|
|
/* We're about to use some buffers from the free list. */
|
|
vq->num_free -= out + in;
|
|
|
|
head = vq->free_head;
|
|
for (i = vq->free_head; out; i = vq->vring.desc[i].next, 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;
|
|
sg++;
|
|
}
|
|
for (; in; i = vq->vring.desc[i].next, 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;
|
|
sg++;
|
|
}
|
|
/* 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). FIXME: avoid modulus here? */
|
|
avail = (vq->vring.avail->idx + vq->num_added++) % vq->vring.num;
|
|
vq->vring.avail->ring[avail] = head;
|
|
|
|
pr_debug("Added buffer head %i to %p\n", head, vq);
|
|
END_USE(vq);
|
|
|
|
/* If we're indirect, we can fit many (assuming not OOM). */
|
|
if (vq->indirect)
|
|
return vq->num_free ? vq->vring.num : 0;
|
|
return vq->num_free;
|
|
}
|
|
EXPORT_SYMBOL_GPL(virtqueue_add_buf_gfp);
|
|
|
|
void virtqueue_kick(struct virtqueue *_vq)
|
|
{
|
|
struct vring_virtqueue *vq = to_vvq(_vq);
|
|
START_USE(vq);
|
|
/* Descriptors and available array need to be set before we expose the
|
|
* new available array entries. */
|
|
virtio_wmb();
|
|
|
|
vq->vring.avail->idx += vq->num_added;
|
|
vq->num_added = 0;
|
|
|
|
/* Need to update avail index before checking if we should notify */
|
|
virtio_mb();
|
|
|
|
if (!(vq->vring.used->flags & VRING_USED_F_NO_NOTIFY))
|
|
/* Prod other side to tell it about changes. */
|
|
vq->notify(&vq->vq);
|
|
|
|
END_USE(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->num_free++;
|
|
}
|
|
|
|
vq->vring.desc[i].next = vq->free_head;
|
|
vq->free_head = head;
|
|
/* Plus final descriptor */
|
|
vq->num_free++;
|
|
}
|
|
|
|
static inline bool more_used(const struct vring_virtqueue *vq)
|
|
{
|
|
return vq->last_used_idx != vq->vring.used->idx;
|
|
}
|
|
|
|
void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len)
|
|
{
|
|
struct vring_virtqueue *vq = to_vvq(_vq);
|
|
void *ret;
|
|
unsigned int i;
|
|
|
|
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();
|
|
|
|
i = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].id;
|
|
*len = vq->vring.used->ring[vq->last_used_idx%vq->vring.num].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++;
|
|
END_USE(vq);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(virtqueue_get_buf);
|
|
|
|
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);
|
|
|
|
bool virtqueue_enable_cb(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. */
|
|
vq->vring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT;
|
|
virtio_mb();
|
|
if (unlikely(more_used(vq))) {
|
|
END_USE(vq);
|
|
return false;
|
|
}
|
|
|
|
END_USE(vq);
|
|
return true;
|
|
}
|
|
EXPORT_SYMBOL_GPL(virtqueue_enable_cb);
|
|
|
|
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);
|
|
END_USE(vq);
|
|
return buf;
|
|
}
|
|
/* That should have freed everything. */
|
|
BUG_ON(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 num,
|
|
unsigned int vring_align,
|
|
struct virtio_device *vdev,
|
|
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->notify = notify;
|
|
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;
|
|
#endif
|
|
|
|
vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC);
|
|
|
|
/* 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->num_free = num;
|
|
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;
|
|
default:
|
|
/* We don't understand this bit. */
|
|
clear_bit(i, vdev->features);
|
|
}
|
|
}
|
|
}
|
|
EXPORT_SYMBOL_GPL(vring_transport_features);
|
|
|
|
MODULE_LICENSE("GPL");
|