/* Virtio ring implementation. * * Copyright 2007 Rusty Russell IBM Corporation * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #include <linux/virtio.h> #include <linux/virtio_ring.h> #include <linux/virtio_config.h> #include <linux/device.h> #include <linux/slab.h> #include <linux/module.h> #include <linux/hrtimer.h> #include <linux/kmemleak.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) #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_desc_state { void *data; /* Data for callback. */ struct vring_desc *indir_desc; /* Indirect descriptor, if any. */ }; struct vring_virtqueue { struct virtqueue vq; /* Actual memory layout for this queue */ struct vring vring; /* Can we use weak barriers? */ bool weak_barriers; /* Other side has made a mess, don't try any more. */ bool broken; /* Host supports indirect buffers */ bool indirect; /* Host publishes avail event idx */ bool event; /* Head of free buffer list. */ unsigned int free_head; /* Number we've added since last sync. */ unsigned int num_added; /* Last used index we've seen. */ u16 last_used_idx; /* Last written value to avail->flags */ u16 avail_flags_shadow; /* Last written value to avail->idx in guest byte order */ u16 avail_idx_shadow; /* How to notify other side. FIXME: commonalize hcalls! */ bool (*notify)(struct virtqueue *vq); /* DMA, allocation, and size information */ bool we_own_ring; size_t queue_size_in_bytes; dma_addr_t queue_dma_addr; #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 /* Per-descriptor state. */ struct vring_desc_state desc_state[]; }; #define to_vvq(_vq) container_of(_vq, struct vring_virtqueue, vq) /* * Modern virtio devices have feature bits to specify whether they need a * quirk and bypass the IOMMU. If not there, just use the DMA API. * * If there, the interaction between virtio and DMA API is messy. * * On most systems with virtio, physical addresses match bus addresses, * and it doesn't particularly matter whether we use the DMA API. * * On some systems, including Xen and any system with a physical device * that speaks virtio behind a physical IOMMU, we must use the DMA API * for virtio DMA to work at all. * * On other systems, including SPARC and PPC64, virtio-pci devices are * enumerated as though they are behind an IOMMU, but the virtio host * ignores the IOMMU, so we must either pretend that the IOMMU isn't * there or somehow map everything as the identity. * * For the time being, we preserve historic behavior and bypass the DMA * API. * * TODO: install a per-device DMA ops structure that does the right thing * taking into account all the above quirks, and use the DMA API * unconditionally on data path. */ static bool vring_use_dma_api(struct virtio_device *vdev) { if (!virtio_has_iommu_quirk(vdev)) return true; /* Otherwise, we are left to guess. */ /* * In theory, it's possible to have a buggy QEMU-supposed * emulated Q35 IOMMU and Xen enabled at the same time. On * such a configuration, virtio has never worked and will * not work without an even larger kludge. Instead, enable * the DMA API if we're a Xen guest, which at least allows * all of the sensible Xen configurations to work correctly. */ if (xen_domain()) return true; return false; } /* * 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 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 (!vring_use_dma_api(vq->vq.vdev)) 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 (!vring_use_dma_api(vq->vq.vdev)) return (dma_addr_t)virt_to_phys(cpu_addr); return dma_map_single(vring_dma_dev(vq), cpu_addr, size, direction); } static void vring_unmap_one(const struct vring_virtqueue *vq, struct vring_desc *desc) { u16 flags; if (!vring_use_dma_api(vq->vq.vdev)) 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 int vring_mapping_error(const struct vring_virtqueue *vq, dma_addr_t addr) { if (!vring_use_dma_api(vq->vq.vdev)) return 0; return dma_mapping_error(vring_dma_dev(vq), addr); } static struct vring_desc *alloc_indirect(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(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(struct virtqueue *_vq, struct scatterlist *sgs[], unsigned int total_sg, unsigned int out_sgs, unsigned int in_sgs, void *data, gfp_t gfp) { struct vring_virtqueue *vq = to_vvq(_vq); struct scatterlist *sg; struct vring_desc *desc; unsigned int i, n, avail, descs_used, uninitialized_var(prev), err_idx; int head; bool indirect; START_USE(vq); BUG_ON(data == NULL); if (unlikely(vq->broken)) { END_USE(vq); return -EIO; } #ifdef DEBUG { ktime_t now = ktime_get(); /* No kick or get, with .1 second between? Warn. */ if (vq->last_add_time_valid) WARN_ON(ktime_to_ms(ktime_sub(now, vq->last_add_time)) > 100); vq->last_add_time = now; vq->last_add_time_valid = true; } #endif BUG_ON(total_sg > vq->vring.num); BUG_ON(total_sg == 0); head = vq->free_head; /* If the host supports indirect descriptor tables, and we have multiple * buffers, then go indirect. FIXME: tune this threshold */ if (vq->indirect && total_sg > 1 && vq->vq.num_free) desc = alloc_indirect(_vq, total_sg, gfp); else desc = NULL; 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->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->vring.desc[head].flags = cpu_to_virtio16(_vq->vdev, VRING_DESC_F_INDIRECT); vq->vring.desc[head].addr = cpu_to_virtio64(_vq->vdev, addr); vq->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->vring.desc[head].next); else vq->free_head = i; /* Store token and indirect buffer state. */ vq->desc_state[head].data = data; if (indirect) vq->desc_state[head].indir_desc = desc; /* Put entry in available array (but don't update avail->idx until they * do sync). */ avail = vq->avail_idx_shadow & (vq->vring.num - 1); vq->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->avail_idx_shadow++; vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, vq->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; i = head; for (n = 0; n < total_sg; n++) { if (i == err_idx) break; vring_unmap_one(vq, &desc[i]); i = vq->vring.desc[i].next; } vq->vq.num_free += total_sg; if (indirect) kfree(desc); END_USE(vq); return -EIO; } /** * 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_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, 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, 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, gfp); } EXPORT_SYMBOL_GPL(virtqueue_add_inbuf); /** * virtqueue_kick_prepare - first half of split virtqueue_kick call. * @vq: the struct virtqueue * * Instead of virtqueue_kick(), you can do: * if (virtqueue_kick_prepare(vq)) * virtqueue_notify(vq); * * This is sometimes useful because the virtqueue_kick_prepare() needs * to be serialized, but the actual virtqueue_notify() call does not. */ bool virtqueue_kick_prepare(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); u16 new, old; bool needs_kick; START_USE(vq); /* We need to expose available array entries before checking avail * event. */ virtio_mb(vq->weak_barriers); old = vq->avail_idx_shadow - vq->num_added; new = vq->avail_idx_shadow; vq->num_added = 0; #ifdef DEBUG if (vq->last_add_time_valid) { WARN_ON(ktime_to_ms(ktime_sub(ktime_get(), vq->last_add_time)) > 100); } vq->last_add_time_valid = false; #endif if (vq->event) { needs_kick = vring_need_event(virtio16_to_cpu(_vq->vdev, vring_avail_event(&vq->vring)), new, old); } else { needs_kick = !(vq->vring.used->flags & cpu_to_virtio16(_vq->vdev, VRING_USED_F_NO_NOTIFY)); } END_USE(vq); return needs_kick; } EXPORT_SYMBOL_GPL(virtqueue_kick_prepare); /** * virtqueue_notify - second half of split virtqueue_kick call. * @vq: the struct virtqueue * * This does not need to be serialized. * * 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); static void detach_buf(struct vring_virtqueue *vq, unsigned int head) { unsigned int i, j; u16 nextflag = cpu_to_virtio16(vq->vq.vdev, VRING_DESC_F_NEXT); /* Clear data ptr. */ vq->desc_state[head].data = NULL; /* Put back on free list: unmap first-level descriptors and find end */ i = head; while (vq->vring.desc[i].flags & nextflag) { vring_unmap_one(vq, &vq->vring.desc[i]); i = virtio16_to_cpu(vq->vq.vdev, vq->vring.desc[i].next); vq->vq.num_free++; } vring_unmap_one(vq, &vq->vring.desc[i]); vq->vring.desc[i].next = cpu_to_virtio16(vq->vq.vdev, vq->free_head); vq->free_head = head; /* Plus final descriptor */ vq->vq.num_free++; /* Free the indirect table, if any, now that it's unmapped. */ if (vq->desc_state[head].indir_desc) { struct vring_desc *indir_desc = vq->desc_state[head].indir_desc; u32 len = virtio32_to_cpu(vq->vq.vdev, vq->vring.desc[head].len); BUG_ON(!(vq->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(vq, &indir_desc[j]); kfree(vq->desc_state[head].indir_desc); vq->desc_state[head].indir_desc = NULL; } } static inline bool more_used(const struct vring_virtqueue *vq) { return vq->last_used_idx != virtio16_to_cpu(vq->vq.vdev, vq->vring.used->idx); } /** * virtqueue_get_buf - get the next used buffer * @vq: the struct virtqueue we're talking about. * @len: the length written into the buffer * * If the driver wrote data into the buffer, @len will be set to the * amount written. This means you don't need to clear the buffer * beforehand to ensure there's no data leakage in the case of short * writes. * * Caller must ensure we don't call this with other virtqueue * operations at the same time (except where noted). * * Returns NULL if there are no used buffers, or the "data" token * handed to virtqueue_add_*(). */ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len) { struct vring_virtqueue *vq = to_vvq(_vq); void *ret; unsigned int i; u16 last_used; START_USE(vq); if (unlikely(vq->broken)) { END_USE(vq); return NULL; } if (!more_used(vq)) { pr_debug("No more buffers in queue\n"); END_USE(vq); return NULL; } /* Only get used array entries after they have been exposed by host. */ virtio_rmb(vq->weak_barriers); last_used = (vq->last_used_idx & (vq->vring.num - 1)); i = virtio32_to_cpu(_vq->vdev, vq->vring.used->ring[last_used].id); *len = virtio32_to_cpu(_vq->vdev, vq->vring.used->ring[last_used].len); if (unlikely(i >= vq->vring.num)) { BAD_RING(vq, "id %u out of range\n", i); return NULL; } if (unlikely(!vq->desc_state[i].data)) { BAD_RING(vq, "id %u is not a head!\n", i); return NULL; } /* detach_buf clears data, so grab it now. */ ret = vq->desc_state[i].data; detach_buf(vq, i); vq->last_used_idx++; /* If we expect an interrupt for the next entry, tell host * by writing event index and flush out the write before * the read in the next get_buf call. */ if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) virtio_store_mb(vq->weak_barriers, &vring_used_event(&vq->vring), cpu_to_virtio16(_vq->vdev, vq->last_used_idx)); #ifdef DEBUG vq->last_add_time_valid = false; #endif END_USE(vq); return ret; } EXPORT_SYMBOL_GPL(virtqueue_get_buf); /** * virtqueue_disable_cb - disable callbacks * @vq: the struct virtqueue we're talking about. * * Note that this is not necessarily synchronous, hence unreliable and only * useful as an optimization. * * Unlike other operations, this need not be serialized. */ void virtqueue_disable_cb(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) { vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT; vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow); } } EXPORT_SYMBOL_GPL(virtqueue_disable_cb); /** * virtqueue_enable_cb_prepare - restart callbacks after disable_cb * @vq: the struct virtqueue we're talking about. * * This re-enables callbacks; it returns current queue state * in an opaque unsigned value. This value should be later tested by * virtqueue_poll, to detect a possible race between the driver checking for * more work, and enabling callbacks. * * Caller must ensure we don't call this with other virtqueue * operations at the same time (except where noted). */ unsigned virtqueue_enable_cb_prepare(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); u16 last_used_idx; START_USE(vq); /* We optimistically turn back on interrupts, then check if there was * more to do. */ /* Depending on the VIRTIO_RING_F_EVENT_IDX feature, we need to * either clear the flags bit or point the event index at the next * entry. Always do both to keep code simple. */ if (vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) { vq->avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT; vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow); } vring_used_event(&vq->vring) = cpu_to_virtio16(_vq->vdev, last_used_idx = vq->last_used_idx); END_USE(vq); return last_used_idx; } EXPORT_SYMBOL_GPL(virtqueue_enable_cb_prepare); /** * virtqueue_poll - query pending used buffers * @vq: the struct virtqueue we're talking about. * @last_used_idx: virtqueue state (from call to virtqueue_enable_cb_prepare). * * Returns "true" if there are pending used buffers in the queue. * * This does not need to be serialized. */ bool virtqueue_poll(struct virtqueue *_vq, unsigned last_used_idx) { struct vring_virtqueue *vq = to_vvq(_vq); virtio_mb(vq->weak_barriers); return (u16)last_used_idx != virtio16_to_cpu(_vq->vdev, vq->vring.used->idx); } EXPORT_SYMBOL_GPL(virtqueue_poll); /** * virtqueue_enable_cb - restart callbacks after disable_cb. * @vq: the struct virtqueue we're talking about. * * This re-enables callbacks; it returns "false" if there are pending * buffers in the queue, to detect a possible race between the driver * checking for more work, and enabling callbacks. * * Caller must ensure we don't call this with other virtqueue * operations at the same time (except where noted). */ bool virtqueue_enable_cb(struct virtqueue *_vq) { unsigned last_used_idx = virtqueue_enable_cb_prepare(_vq); return !virtqueue_poll(_vq, last_used_idx); } EXPORT_SYMBOL_GPL(virtqueue_enable_cb); /** * virtqueue_enable_cb_delayed - restart callbacks after disable_cb. * @vq: the struct virtqueue we're talking about. * * This re-enables callbacks but hints to the other side to delay * interrupts until most of the available buffers have been processed; * it returns "false" if there are many pending buffers in the queue, * to detect a possible race between the driver checking for more work, * and enabling callbacks. * * Caller must ensure we don't call this with other virtqueue * operations at the same time (except where noted). */ bool virtqueue_enable_cb_delayed(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); u16 bufs; START_USE(vq); /* We optimistically turn back on interrupts, then check if there was * more to do. */ /* Depending on the VIRTIO_RING_F_USED_EVENT_IDX feature, we need to * either clear the flags bit or point the event index at the next * entry. Always do both to keep code simple. */ if (vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT) { vq->avail_flags_shadow &= ~VRING_AVAIL_F_NO_INTERRUPT; vq->vring.avail->flags = cpu_to_virtio16(_vq->vdev, vq->avail_flags_shadow); } /* TODO: tune this threshold */ bufs = (u16)(vq->avail_idx_shadow - vq->last_used_idx) * 3 / 4; virtio_store_mb(vq->weak_barriers, &vring_used_event(&vq->vring), cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs)); if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->vring.used->idx) - vq->last_used_idx) > bufs)) { END_USE(vq); return false; } END_USE(vq); return true; } EXPORT_SYMBOL_GPL(virtqueue_enable_cb_delayed); /** * virtqueue_detach_unused_buf - detach first unused buffer * @vq: the struct virtqueue we're talking about. * * Returns NULL or the "data" token handed to virtqueue_add_*(). * This is not valid on an active queue; it is useful only for device * shutdown. */ void *virtqueue_detach_unused_buf(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); unsigned int i; void *buf; START_USE(vq); for (i = 0; i < vq->vring.num; i++) { if (!vq->desc_state[i].data) continue; /* detach_buf clears data, so grab it now. */ buf = vq->desc_state[i].data; detach_buf(vq, i); vq->avail_idx_shadow--; vq->vring.avail->idx = cpu_to_virtio16(_vq->vdev, vq->avail_idx_shadow); END_USE(vq); return buf; } /* That should have freed everything. */ BUG_ON(vq->vq.num_free != vq->vring.num); END_USE(vq); return NULL; } EXPORT_SYMBOL_GPL(virtqueue_detach_unused_buf); irqreturn_t vring_interrupt(int irq, void *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); if (!more_used(vq)) { pr_debug("virtqueue interrupt with no work for %p\n", vq); return IRQ_NONE; } if (unlikely(vq->broken)) return IRQ_HANDLED; pr_debug("virtqueue callback for %p (%p)\n", vq, vq->vq.callback); if (vq->vq.callback) vq->vq.callback(&vq->vq); return IRQ_HANDLED; } EXPORT_SYMBOL_GPL(vring_interrupt); struct virtqueue *__vring_new_virtqueue(unsigned int index, struct vring vring, struct virtio_device *vdev, bool weak_barriers, bool (*notify)(struct virtqueue *), void (*callback)(struct virtqueue *), const char *name) { unsigned int i; struct vring_virtqueue *vq; vq = kmalloc(sizeof(*vq) + vring.num * sizeof(struct vring_desc_state), GFP_KERNEL); if (!vq) return NULL; vq->vring = vring; 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->queue_dma_addr = 0; vq->queue_size_in_bytes = 0; vq->notify = notify; vq->weak_barriers = weak_barriers; vq->broken = false; vq->last_used_idx = 0; vq->avail_flags_shadow = 0; vq->avail_idx_shadow = 0; vq->num_added = 0; list_add_tail(&vq->vq.list, &vdev->vqs); #ifdef DEBUG vq->in_use = false; vq->last_add_time_valid = false; #endif vq->indirect = virtio_has_feature(vdev, VIRTIO_RING_F_INDIRECT_DESC); vq->event = virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX); /* No callback? Tell other side not to bother us. */ if (!callback) { vq->avail_flags_shadow |= VRING_AVAIL_F_NO_INTERRUPT; vq->vring.avail->flags = cpu_to_virtio16(vdev, vq->avail_flags_shadow); } /* Put everything in free lists. */ vq->free_head = 0; for (i = 0; i < vring.num-1; i++) vq->vring.desc[i].next = cpu_to_virtio16(vdev, i + 1); memset(vq->desc_state, 0, vring.num * sizeof(struct vring_desc_state)); return &vq->vq; } EXPORT_SYMBOL_GPL(__vring_new_virtqueue); 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)); } } 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 (*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 (!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, notify, callback, name); if (!vq) { vring_free_queue(vdev, queue_size_in_bytes, queue, dma_addr); return NULL; } to_vvq(vq)->queue_dma_addr = dma_addr; to_vvq(vq)->queue_size_in_bytes = queue_size_in_bytes; to_vvq(vq)->we_own_ring = true; return vq; } EXPORT_SYMBOL_GPL(vring_create_virtqueue); struct virtqueue *vring_new_virtqueue(unsigned int index, unsigned int num, unsigned int vring_align, struct virtio_device *vdev, bool weak_barriers, void *pages, bool (*notify)(struct virtqueue *vq), void (*callback)(struct virtqueue *vq), const char *name) { struct vring vring; vring_init(&vring, num, pages, vring_align); return __vring_new_virtqueue(index, vring, vdev, weak_barriers, 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) { vring_free_queue(vq->vq.vdev, vq->queue_size_in_bytes, vq->vring.desc, vq->queue_dma_addr); } list_del(&_vq->list); kfree(vq); } EXPORT_SYMBOL_GPL(vring_del_virtqueue); /* Manipulates transport-specific feature bits. */ void vring_transport_features(struct virtio_device *vdev) { unsigned int i; for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++) { switch (i) { case VIRTIO_RING_F_INDIRECT_DESC: break; case VIRTIO_RING_F_EVENT_IDX: break; case VIRTIO_F_VERSION_1: break; case VIRTIO_F_IOMMU_PLATFORM: break; 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->vring.num; } EXPORT_SYMBOL_GPL(virtqueue_get_vring_size); bool virtqueue_is_broken(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); return vq->broken; } EXPORT_SYMBOL_GPL(virtqueue_is_broken); /* * This should prevent the device from being used, allowing drivers to * recover. You may need to grab appropriate locks to flush. */ void virtio_break_device(struct virtio_device *dev) { struct virtqueue *_vq; list_for_each_entry(_vq, &dev->vqs, list) { struct vring_virtqueue *vq = to_vvq(_vq); vq->broken = true; } } EXPORT_SYMBOL_GPL(virtio_break_device); dma_addr_t virtqueue_get_desc_addr(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); BUG_ON(!vq->we_own_ring); return vq->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); return vq->queue_dma_addr + ((char *)vq->vring.avail - (char *)vq->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); return vq->queue_dma_addr + ((char *)vq->vring.used - (char *)vq->vring.desc); } EXPORT_SYMBOL_GPL(virtqueue_get_used_addr); const struct vring *virtqueue_get_vring(struct virtqueue *vq) { return &to_vvq(vq)->vring; } EXPORT_SYMBOL_GPL(virtqueue_get_vring); MODULE_LICENSE("GPL");