diff options
Diffstat (limited to 'drivers/virtio/virtio_ring.c')
| -rw-r--r-- | drivers/virtio/virtio_ring.c | 421 |
1 files changed, 287 insertions, 134 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index e639584b2db..4d08f45a9c2 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -23,27 +23,7 @@ #include <linux/slab.h> #include <linux/module.h> #include <linux/hrtimer.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-pci does not use). */ -#define virtio_mb(vq) \ - do { if ((vq)->weak_barriers) smp_mb(); else mb(); } while(0) -#define virtio_rmb(vq) \ - do { if ((vq)->weak_barriers) smp_rmb(); else rmb(); } while(0) -#define virtio_wmb(vq) \ - do { if ((vq)->weak_barriers) smp_wmb(); else wmb(); } while(0) -#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(vq) mb() -#define virtio_rmb(vq) rmb() -#define virtio_wmb(vq) wmb() -#endif +#include <linux/kmemleak.h> #ifdef DEBUG /* For development, we want to crash whenever the ring is screwed. */ @@ -93,8 +73,6 @@ struct vring_virtqueue /* Host publishes avail event idx */ bool event; - /* Number of free buffers */ - unsigned int num_free; /* Head of free buffer list. */ unsigned int free_head; /* Number we've added since last sync. */ @@ -104,10 +82,7 @@ struct vring_virtqueue u16 last_used_idx; /* How to notify other side. FIXME: commonalize hcalls! */ - void (*notify)(struct virtqueue *vq); - - /* Index of the queue */ - int queue_index; + bool (*notify)(struct virtqueue *vq); #ifdef DEBUG /* They're supposed to lock for us. */ @@ -124,48 +99,83 @@ struct vring_virtqueue #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 int vring_add_indirect(struct vring_virtqueue *vq, - struct scatterlist sg[], - unsigned int out, - unsigned int in, - gfp_t gfp) +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; - int i; + struct scatterlist *sg; + int i, n; - desc = kmalloc((out + in) * sizeof(struct vring_desc), gfp); + /* + * 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 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++; + /* 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 (; 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++; + 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->num_free--; + 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); + /* kmemleak gives a false positive, as it's hidden by virt_to_phys */ + kmemleak_ignore(desc); vq->vring.desc[head].len = i * sizeof(struct vring_desc); /* Update free pointer */ @@ -174,45 +184,31 @@ static int vring_add_indirect(struct vring_virtqueue *vq, return head; } -int virtqueue_get_queue_index(struct virtqueue *_vq) -{ - struct vring_virtqueue *vq = to_vvq(_vq); - return vq->queue_index; -} -EXPORT_SYMBOL_GPL(virtqueue_get_queue_index); - -/** - * 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 remaining capacity of queue or a negative error - * (ie. ENOSPC). Note that it only really makes sense to treat all - * positive return values as "available": indirect buffers mean that - * we can put an entire sg[] array inside a single queue entry. - */ -int virtqueue_add_buf(struct virtqueue *_vq, - struct scatterlist sg[], - unsigned int out, - unsigned int in, - void *data, - gfp_t gfp) +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); - unsigned int i, avail, uninitialized_var(prev); + struct scatterlist *sg; + unsigned int i, n, avail, uninitialized_var(prev), total_sg; int head; START_USE(vq); BUG_ON(data == NULL); + if (unlikely(vq->broken)) { + END_USE(vq); + return -EIO; + } + #ifdef DEBUG { ktime_t now = ktime_get(); @@ -226,46 +222,54 @@ int virtqueue_add_buf(struct virtqueue *_vq, } #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 && (out + in) > 1 && vq->num_free) { - head = vring_add_indirect(vq, sg, out, in, gfp); + 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(out + in > vq->vring.num); - BUG_ON(out + in == 0); + BUG_ON(total_sg > vq->vring.num); + BUG_ON(total_sg == 0); - if (vq->num_free < out + in) { + if (vq->vq.num_free < total_sg) { pr_debug("Can't add buf len %i - avail = %i\n", - out + in, vq->num_free); + 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) + if (out_sgs) 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++; + 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 (; 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++; + 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; @@ -284,7 +288,7 @@ add_head: /* Descriptors and available array need to be set before we expose the * new available array entries. */ - virtio_wmb(vq); + virtio_wmb(vq->weak_barriers); vq->vring.avail->idx++; vq->num_added++; @@ -296,9 +300,91 @@ add_head: pr_debug("Added buffer head %i to %p\n", head, vq); END_USE(vq); - return vq->num_free; + return 0; +} + +/** + * 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, 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_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, EIO). + */ +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, EIO). + */ +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_buf); +EXPORT_SYMBOL_GPL(virtqueue_add_inbuf); /** * virtqueue_kick_prepare - first half of split virtqueue_kick call. @@ -320,7 +406,7 @@ bool virtqueue_kick_prepare(struct virtqueue *_vq) START_USE(vq); /* We need to expose available array entries before checking avail * event. */ - virtio_mb(vq); + virtio_mb(vq->weak_barriers); old = vq->vring.avail->idx - vq->num_added; new = vq->vring.avail->idx; @@ -350,13 +436,22 @@ EXPORT_SYMBOL_GPL(virtqueue_kick_prepare); * @vq: the struct virtqueue * * This does not need to be serialized. + * + * Returns false if host notify failed or queue is broken, otherwise true. */ -void virtqueue_notify(struct virtqueue *_vq) +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. */ - vq->notify(_vq); + if (!vq->notify(_vq)) { + vq->broken = true; + return false; + } + return true; } EXPORT_SYMBOL_GPL(virtqueue_notify); @@ -364,16 +459,19 @@ 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 + * 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. */ -void virtqueue_kick(struct virtqueue *vq) +bool virtqueue_kick(struct virtqueue *vq) { if (virtqueue_kick_prepare(vq)) - virtqueue_notify(vq); + return virtqueue_notify(vq); + return true; } EXPORT_SYMBOL_GPL(virtqueue_kick); @@ -393,13 +491,13 @@ static void detach_buf(struct vring_virtqueue *vq, unsigned int head) while (vq->vring.desc[i].flags & VRING_DESC_F_NEXT) { i = vq->vring.desc[i].next; - vq->num_free++; + vq->vq.num_free++; } vq->vring.desc[i].next = vq->free_head; vq->free_head = head; /* Plus final descriptor */ - vq->num_free++; + vq->vq.num_free++; } static inline bool more_used(const struct vring_virtqueue *vq) @@ -421,7 +519,7 @@ static inline bool more_used(const struct vring_virtqueue *vq) * 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(). + * handed to virtqueue_add_*(). */ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len) { @@ -444,7 +542,7 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len) } /* Only get used array entries after they have been exposed by host. */ - virtio_rmb(vq); + virtio_rmb(vq->weak_barriers); last_used = (vq->last_used_idx & (vq->vring.num - 1)); i = vq->vring.used->ring[last_used].id; @@ -468,7 +566,7 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len) * 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); + virtio_mb(vq->weak_barriers); } #ifdef DEBUG @@ -498,19 +596,21 @@ void virtqueue_disable_cb(struct virtqueue *_vq) EXPORT_SYMBOL_GPL(virtqueue_disable_cb); /** - * virtqueue_enable_cb - restart callbacks after 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 "false" if there are pending - * buffers in the queue, to detect a possible race between the driver - * checking for more work, and enabling callbacks. + * 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). */ -bool virtqueue_enable_cb(struct virtqueue *_vq) +unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); + u16 last_used_idx; START_USE(vq); @@ -520,15 +620,45 @@ bool virtqueue_enable_cb(struct virtqueue *_vq) * 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) = vq->last_used_idx; - virtio_mb(vq); - if (unlikely(more_used(vq))) { - END_USE(vq); - return false; - } - + vring_used_event(&vq->vring) = last_used_idx = vq->last_used_idx; END_USE(vq); - return true; + 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); @@ -561,7 +691,7 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *_vq) /* 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); + virtio_mb(vq->weak_barriers); if (unlikely((u16)(vq->vring.used->idx - vq->last_used_idx) > bufs)) { END_USE(vq); return false; @@ -576,7 +706,7 @@ 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(). + * 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. */ @@ -599,7 +729,7 @@ void *virtqueue_detach_unused_buf(struct virtqueue *_vq) return buf; } /* That should have freed everything. */ - BUG_ON(vq->num_free != vq->vring.num); + BUG_ON(vq->vq.num_free != vq->vring.num); END_USE(vq); return NULL; @@ -632,7 +762,7 @@ struct virtqueue *vring_new_virtqueue(unsigned int index, struct virtio_device *vdev, bool weak_barriers, void *pages, - void (*notify)(struct virtqueue *), + bool (*notify)(struct virtqueue *), void (*callback)(struct virtqueue *), const char *name) { @@ -653,12 +783,13 @@ struct virtqueue *vring_new_virtqueue(unsigned int index, 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; - vq->queue_index = index; list_add_tail(&vq->vq.list, &vdev->vqs); #ifdef DEBUG vq->in_use = false; @@ -673,7 +804,6 @@ struct virtqueue *vring_new_virtqueue(unsigned int index, 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; @@ -727,4 +857,27 @@ unsigned int virtqueue_get_vring_size(struct virtqueue *_vq) } 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); + MODULE_LICENSE("GPL"); |