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Diffstat (limited to '')
| -rw-r--r-- | drivers/virtio/virtio_ring.c | 2352 |
1 files changed, 2352 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c new file mode 100644 index 000000000..cf0e8e189 --- /dev/null +++ b/drivers/virtio/virtio_ring.c @@ -0,0 +1,2352 @@ +// 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_dma_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.parent); + + 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, 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 (!desc) + return -ENOMEM; + + 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 head_flags, flags; + u16 head, id, prev, curr, avail_used_flags; + int err; + + 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)) { + err = virtqueue_add_indirect_packed(vq, sgs, total_sg, out_sgs, + in_sgs, data, gfp); + if (err != -ENOMEM) { + END_USE(vq); + return err; + } + + /* fall back on direct */ + } + + 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); +#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); + } + + spin_lock(&vdev->vqs_list_lock); + list_add_tail(&vq->vq.list, &vdev->vqs); + spin_unlock(&vdev->vqs_list_lock); + 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, device_event_dma_addr); +err_device: + vring_free_queue(vdev, event_size_in_bytes, driver, driver_event_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); + + if (unlikely(vq->broken)) + return false; + + 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); +#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)); + + spin_lock(&vdev->vqs_list_lock); + list_add_tail(&vq->vq.list, &vdev->vqs); + spin_unlock(&vdev->vqs_list_lock); + 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); + } + } + if (!vq->packed_ring) + kfree(vq->split.desc_state); + spin_lock(&vq->vq.vdev->vqs_list_lock); + list_del(&_vq->list); + spin_unlock(&vq->vq.vdev->vqs_list_lock); + 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_ACCESS_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 READ_ONCE(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; + + spin_lock(&dev->vqs_list_lock); + list_for_each_entry(_vq, &dev->vqs, list) { + struct vring_virtqueue *vq = to_vvq(_vq); + + /* Pairs with READ_ONCE() in virtqueue_is_broken(). */ + WRITE_ONCE(vq->broken, true); + } + spin_unlock(&dev->vqs_list_lock); +} +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"); |