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Diffstat (limited to 'virtio.c')
| -rw-r--r-- | virtio.c | 665 |
1 files changed, 665 insertions, 0 deletions
diff --git a/virtio.c b/virtio.c new file mode 100644 index 0000000..380590a --- /dev/null +++ b/virtio.c @@ -0,0 +1,665 @@ +// SPDX-License-Identifier: GPL-2.0-or-later AND BSD-3-Clause +/* + * virtio API, vring and virtqueue functions definition + * + * Copyright Red Hat + * Author: Laurent Vivier <lvivier@redhat.com> + */ + +/* Some parts copied from QEMU subprojects/libvhost-user/libvhost-user.c + * originally licensed under the following terms: + * + * -- + * + * Copyright IBM, Corp. 2007 + * Copyright (c) 2016 Red Hat, Inc. + * + * Authors: + * Anthony Liguori <aliguori@us.ibm.com> + * Marc-André Lureau <mlureau@redhat.com> + * Victor Kaplansky <victork@redhat.com> + * + * This work is licensed under the terms of the GNU GPL, version 2 or + * later. See the COPYING file in the top-level directory. + * + * Some parts copied from QEMU hw/virtio/virtio.c + * licensed under the following terms: + * + * Copyright IBM, Corp. 2007 + * + * Authors: + * Anthony Liguori <aliguori@us.ibm.com> + * + * This work is licensed under the terms of the GNU GPL, version 2. See + * the COPYING file in the top-level directory. + * + * -- + * + * virtq_used_event() and virtq_avail_event() from + * https://docs.oasis-open.org/virtio/virtio/v1.2/csd01/virtio-v1.2-csd01.html#x1-712000A + * licensed under the following terms: + * + * -- + * + * This header is BSD licensed so anyone can use the definitions + * to implement compatible drivers/servers. + * + * Copyright 2007, 2009, IBM Corporation + * Copyright 2011, Red Hat, Inc + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. Neither the name of IBM nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ‘‘AS IS’’ AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <stddef.h> +#include <endian.h> +#include <string.h> +#include <errno.h> +#include <sys/eventfd.h> +#include <sys/socket.h> + +#include "util.h" +#include "virtio.h" + +#define VIRTQUEUE_MAX_SIZE 1024 + +/** + * vu_gpa_to_va() - Translate guest physical address to our virtual address. + * @dev: Vhost-user device + * @plen: Physical length to map (input), capped to region (output) + * @guest_addr: Guest physical address + * + * Return: virtual address in our address space of the guest physical address + */ +static void *vu_gpa_to_va(struct vu_dev *dev, uint64_t *plen, uint64_t guest_addr) +{ + unsigned int i; + + if (*plen == 0) + return NULL; + + /* Find matching memory region. */ + for (i = 0; i < dev->nregions; i++) { + const struct vu_dev_region *r = &dev->regions[i]; + + if ((guest_addr >= r->gpa) && + (guest_addr < (r->gpa + r->size))) { + if ((guest_addr + *plen) > (r->gpa + r->size)) + *plen = r->gpa + r->size - guest_addr; + /* NOLINTNEXTLINE(performance-no-int-to-ptr) */ + return (void *)(guest_addr - r->gpa + r->mmap_addr + + r->mmap_offset); + } + } + + return NULL; +} + +/** + * vring_avail_flags() - Read the available ring flags + * @vq: Virtqueue + * + * Return: the available ring descriptor flags of the given virtqueue + */ +static inline uint16_t vring_avail_flags(const struct vu_virtq *vq) +{ + return le16toh(vq->vring.avail->flags); +} + +/** + * vring_avail_idx() - Read the available ring index + * @vq: Virtqueue + * + * Return: the available ring index of the given virtqueue + */ +static inline uint16_t vring_avail_idx(struct vu_virtq *vq) +{ + vq->shadow_avail_idx = le16toh(vq->vring.avail->idx); + + return vq->shadow_avail_idx; +} + +/** + * vring_avail_ring() - Read an available ring entry + * @vq: Virtqueue + * @i: Index of the entry to read + * + * Return: the ring entry content (head of the descriptor chain) + */ +static inline uint16_t vring_avail_ring(const struct vu_virtq *vq, int i) +{ + return le16toh(vq->vring.avail->ring[i]); +} + +/** + * virtq_used_event - Get location of used event indices + * (only with VIRTIO_F_EVENT_IDX) + * @vq Virtqueue + * + * Return: return the location of the used event index + */ +static inline uint16_t *virtq_used_event(const struct vu_virtq *vq) +{ + /* For backwards compat, used event index is at *end* of avail ring. */ + return &vq->vring.avail->ring[vq->vring.num]; +} + +/** + * vring_get_used_event() - Get the used event from the available ring + * @vq Virtqueue + * + * Return: the used event (available only if VIRTIO_RING_F_EVENT_IDX is set) + * used_event is a performant alternative where the driver + * specifies how far the device can progress before a notification + * is required. + */ +static inline uint16_t vring_get_used_event(const struct vu_virtq *vq) +{ + return le16toh(*virtq_used_event(vq)); +} + +/** + * virtqueue_get_head() - Get the head of the descriptor chain for a given + * index + * @vq: Virtqueue + * @idx: Available ring entry index + * @head: Head of the descriptor chain + */ +static void virtqueue_get_head(const struct vu_virtq *vq, + unsigned int idx, unsigned int *head) +{ + /* Grab the next descriptor number they're advertising, and increment + * the index we've seen. + */ + *head = vring_avail_ring(vq, idx % vq->vring.num); + + /* If their number is silly, that's a fatal mistake. */ + if (*head >= vq->vring.num) + die("vhost-user: Guest says index %u is available", *head); +} + +/** + * virtqueue_read_indirect_desc() - Copy virtio ring descriptors from guest + * memory + * @dev: Vhost-user device + * @desc: Destination address to copy the descriptors to + * @addr: Guest memory address to copy from + * @len: Length of memory to copy + * + * Return: -1 if there is an error, 0 otherwise + */ +static int virtqueue_read_indirect_desc(struct vu_dev *dev, struct vring_desc *desc, + uint64_t addr, size_t len) +{ + uint64_t read_len; + + if (len > (VIRTQUEUE_MAX_SIZE * sizeof(struct vring_desc))) + return -1; + + if (len == 0) + return -1; + + while (len) { + const struct vring_desc *orig_desc; + + read_len = len; + orig_desc = vu_gpa_to_va(dev, &read_len, addr); + if (!orig_desc) + return -1; + + memcpy(desc, orig_desc, read_len); + len -= read_len; + addr += read_len; + desc += read_len / sizeof(struct vring_desc); + } + + return 0; +} + +/** + * enum virtqueue_read_desc_state - State in the descriptor chain + * @VIRTQUEUE_READ_DESC_ERROR Found an invalid descriptor + * @VIRTQUEUE_READ_DESC_DONE No more descriptors in the chain + * @VIRTQUEUE_READ_DESC_MORE there are more descriptors in the chain + */ +enum virtqueue_read_desc_state { + VIRTQUEUE_READ_DESC_ERROR = -1, + VIRTQUEUE_READ_DESC_DONE = 0, /* end of chain */ + VIRTQUEUE_READ_DESC_MORE = 1, /* more buffers in chain */ +}; + +/** + * virtqueue_read_next_desc() - Read the the next descriptor in the chain + * @desc: Virtio ring descriptors + * @i: Index of the current descriptor + * @max: Maximum value of the descriptor index + * @next: Index of the next descriptor in the chain (output value) + * + * Return: current chain descriptor state (error, next, done) + */ +static int virtqueue_read_next_desc(const struct vring_desc *desc, + int i, unsigned int max, unsigned int *next) +{ + /* If this descriptor says it doesn't chain, we're done. */ + if (!(le16toh(desc[i].flags) & VRING_DESC_F_NEXT)) + return VIRTQUEUE_READ_DESC_DONE; + + /* Check they're not leading us off end of descriptors. */ + *next = le16toh(desc[i].next); + /* Make sure compiler knows to grab that: we don't want it changing! */ + smp_wmb(); + + if (*next >= max) + return VIRTQUEUE_READ_DESC_ERROR; + + return VIRTQUEUE_READ_DESC_MORE; +} + +/** + * vu_queue_empty() - Check if virtqueue is empty + * @vq: Virtqueue + * + * Return: true if the virtqueue is empty, false otherwise + */ +bool vu_queue_empty(struct vu_virtq *vq) +{ + if (!vq->vring.avail) + return true; + + if (vq->shadow_avail_idx != vq->last_avail_idx) + return false; + + return vring_avail_idx(vq) == vq->last_avail_idx; +} + +/** + * vring_can_notify() - Check if a notification can be sent + * @dev: Vhost-user device + * @vq: Virtqueue + * + * Return: true if notification can be sent + */ +static bool vring_can_notify(const struct vu_dev *dev, struct vu_virtq *vq) +{ + uint16_t old, new; + bool v; + + /* We need to expose used array entries before checking used event. */ + smp_mb(); + + /* Always notify when queue is empty (when feature acknowledge) */ + if (vu_has_feature(dev, VIRTIO_F_NOTIFY_ON_EMPTY) && + !vq->inuse && vu_queue_empty(vq)) + return true; + + if (!vu_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) + return !(vring_avail_flags(vq) & VRING_AVAIL_F_NO_INTERRUPT); + + v = vq->signalled_used_valid; + vq->signalled_used_valid = true; + old = vq->signalled_used; + new = vq->signalled_used = vq->used_idx; + return !v || vring_need_event(vring_get_used_event(vq), new, old); +} + +/** + * vu_queue_notify() - Send a notification to the given virtqueue + * @dev: Vhost-user device + * @vq: Virtqueue + */ +/* cppcheck-suppress unusedFunction */ +void vu_queue_notify(const struct vu_dev *dev, struct vu_virtq *vq) +{ + if (!vq->vring.avail) + return; + + if (!vring_can_notify(dev, vq)) { + debug("vhost-user: virtqueue can skip notify..."); + return; + } + + if (eventfd_write(vq->call_fd, 1) < 0) + die_perror("Error writing vhost-user queue eventfd"); +} + +/* virtq_avail_event() - Get location of available event indices + * (only with VIRTIO_F_EVENT_IDX) + * @vq: Virtqueue + * + * Return: return the location of the available event index + */ +static inline uint16_t *virtq_avail_event(const struct vu_virtq *vq) +{ + /* For backwards compat, avail event index is at *end* of used ring. */ + return (uint16_t *)&vq->vring.used->ring[vq->vring.num]; +} + +/** + * vring_set_avail_event() - Set avail_event + * @vq: Virtqueue + * @val: Value to set to avail_event + * avail_event is used in the same way the used_event is in the + * avail_ring. + * avail_event is used to advise the driver that notifications + * are unnecessary until the driver writes entry with an index + * specified by avail_event into the available ring. + */ +static inline void vring_set_avail_event(const struct vu_virtq *vq, + uint16_t val) +{ + uint16_t val_le = htole16(val); + + if (!vq->notification) + return; + + memcpy(virtq_avail_event(vq), &val_le, sizeof(val_le)); +} + +/** + * virtqueue_map_desc() - Translate descriptor ring physical address into our + * virtual address space + * @dev: Vhost-user device + * @p_num_sg: First iov entry to use (input), + * first iov entry not used (output) + * @iov: Iov array to use to store buffer virtual addresses + * @max_num_sg: Maximum number of iov entries + * @pa: Guest physical address of the buffer to map into our virtual + * address + * @sz: Size of the buffer + * + * Return: false on error, true otherwise + */ +static bool virtqueue_map_desc(struct vu_dev *dev, + unsigned int *p_num_sg, struct iovec *iov, + unsigned int max_num_sg, + uint64_t pa, size_t sz) +{ + unsigned int num_sg = *p_num_sg; + + ASSERT(num_sg < max_num_sg); + ASSERT(sz); + + while (sz) { + uint64_t len = sz; + + iov[num_sg].iov_base = vu_gpa_to_va(dev, &len, pa); + if (iov[num_sg].iov_base == NULL) + die("vhost-user: invalid address for buffers"); + iov[num_sg].iov_len = len; + num_sg++; + sz -= len; + pa += len; + } + + *p_num_sg = num_sg; + return true; +} + +/** + * vu_queue_map_desc - Map the virtqueue descriptor ring into our virtual + * address space + * @dev: Vhost-user device + * @vq: Virtqueue + * @idx: First descriptor ring entry to map + * @elem: Virtqueue element to store descriptor ring iov + * + * Return: -1 if there is an error, 0 otherwise + */ +static int vu_queue_map_desc(struct vu_dev *dev, struct vu_virtq *vq, unsigned int idx, + struct vu_virtq_element *elem) +{ + const struct vring_desc *desc = vq->vring.desc; + struct vring_desc desc_buf[VIRTQUEUE_MAX_SIZE]; + unsigned int out_num = 0, in_num = 0; + unsigned int max = vq->vring.num; + unsigned int i = idx; + uint64_t read_len; + int rc; + + if (le16toh(desc[i].flags) & VRING_DESC_F_INDIRECT) { + unsigned int desc_len; + uint64_t desc_addr; + + if (le32toh(desc[i].len) % sizeof(struct vring_desc)) + die("vhost-user: Invalid size for indirect buffer table"); + + /* loop over the indirect descriptor table */ + desc_addr = le64toh(desc[i].addr); + desc_len = le32toh(desc[i].len); + max = desc_len / sizeof(struct vring_desc); + read_len = desc_len; + desc = vu_gpa_to_va(dev, &read_len, desc_addr); + if (desc && read_len != desc_len) { + /* Failed to use zero copy */ + desc = NULL; + if (!virtqueue_read_indirect_desc(dev, desc_buf, desc_addr, desc_len)) + desc = desc_buf; + } + if (!desc) + die("vhost-user: Invalid indirect buffer table"); + i = 0; + } + + /* Collect all the descriptors */ + do { + if (le16toh(desc[i].flags) & VRING_DESC_F_WRITE) { + if (!virtqueue_map_desc(dev, &in_num, elem->in_sg, + elem->in_num, + le64toh(desc[i].addr), + le32toh(desc[i].len))) + return -1; + } else { + if (in_num) + die("Incorrect order for descriptors"); + if (!virtqueue_map_desc(dev, &out_num, elem->out_sg, + elem->out_num, + le64toh(desc[i].addr), + le32toh(desc[i].len))) { + return -1; + } + } + + /* If we've got too many, that implies a descriptor loop. */ + if ((in_num + out_num) > max) + die("vhost-user: Loop in queue descriptor list"); + rc = virtqueue_read_next_desc(desc, i, max, &i); + } while (rc == VIRTQUEUE_READ_DESC_MORE); + + if (rc == VIRTQUEUE_READ_DESC_ERROR) + die("vhost-user: Failed to read descriptor list"); + + elem->index = idx; + elem->in_num = in_num; + elem->out_num = out_num; + + return 0; +} + +/** + * vu_queue_pop() - Pop an entry from the virtqueue + * @dev: Vhost-user device + * @vq: Virtqueue + * @elem: Virtqueue element to file with the entry information + * + * Return: -1 if there is an error, 0 otherwise + */ +/* cppcheck-suppress unusedFunction */ +int vu_queue_pop(struct vu_dev *dev, struct vu_virtq *vq, struct vu_virtq_element *elem) +{ + unsigned int head; + int ret; + + if (!vq->vring.avail) + return -1; + + if (vu_queue_empty(vq)) + return -1; + + /* Needed after vu_queue_empty(), see comment in + * virtqueue_num_heads(). + */ + smp_rmb(); + + if (vq->inuse >= vq->vring.num) + die("vhost-user queue size exceeded"); + + virtqueue_get_head(vq, vq->last_avail_idx++, &head); + + if (vu_has_feature(dev, VIRTIO_RING_F_EVENT_IDX)) + vring_set_avail_event(vq, vq->last_avail_idx); + + ret = vu_queue_map_desc(dev, vq, head, elem); + + if (ret < 0) + return ret; + + vq->inuse++; + + return 0; +} + +/** + * vu_queue_detach_element() - Detach an element from the virqueue + * @vq: Virtqueue + */ +void vu_queue_detach_element(struct vu_virtq *vq) +{ + vq->inuse--; + /* unmap, when DMA support is added */ +} + +/** + * vu_queue_unpop() - Push back the previously popped element from the virqueue + * @vq: Virtqueue + */ +/* cppcheck-suppress unusedFunction */ +void vu_queue_unpop(struct vu_virtq *vq) +{ + vq->last_avail_idx--; + vu_queue_detach_element(vq); +} + +/** + * vu_queue_rewind() - Push back a given number of popped elements + * @vq: Virtqueue + * @num: Number of element to unpop + */ +/* cppcheck-suppress unusedFunction */ +bool vu_queue_rewind(struct vu_virtq *vq, unsigned int num) +{ + if (num > vq->inuse) + return false; + + vq->last_avail_idx -= num; + vq->inuse -= num; + return true; +} + +/** + * vring_used_write() - Write an entry in the used ring + * @vq: Virtqueue + * @uelem: Entry to write + * @i: Index of the entry in the used ring + */ +static inline void vring_used_write(struct vu_virtq *vq, + const struct vring_used_elem *uelem, int i) +{ + struct vring_used *used = vq->vring.used; + + used->ring[i] = *uelem; +} + +/** + * vu_queue_fill_by_index() - Update information of a descriptor ring entry + * in the used ring + * @vq: Virtqueue + * @index: Descriptor ring index + * @len: Size of the element + * @idx: Used ring entry index + */ +void vu_queue_fill_by_index(struct vu_virtq *vq, unsigned int index, + unsigned int len, unsigned int idx) +{ + struct vring_used_elem uelem; + + if (!vq->vring.avail) + return; + + idx = (idx + vq->used_idx) % vq->vring.num; + + uelem.id = htole32(index); + uelem.len = htole32(len); + vring_used_write(vq, &uelem, idx); +} + +/** + * vu_queue_fill() - Update information of a given element in the used ring + * @dev: Vhost-user device + * @vq: Virtqueue + * @elem: Element information to fill + * @len: Size of the element + * @idx: Used ring entry index + */ +/* cppcheck-suppress unusedFunction */ +void vu_queue_fill(struct vu_virtq *vq, const struct vu_virtq_element *elem, + unsigned int len, unsigned int idx) +{ + vu_queue_fill_by_index(vq, elem->index, len, idx); +} + +/** + * vring_used_idx_set() - Set the descriptor ring current index + * @vq: Virtqueue + * @val: Value to set in the index + */ +static inline void vring_used_idx_set(struct vu_virtq *vq, uint16_t val) +{ + vq->vring.used->idx = htole16(val); + + vq->used_idx = val; +} + +/** + * vu_queue_flush() - Flush the virtqueue + * @vq: Virtqueue + * @count: Number of entry to flush + */ +/* cppcheck-suppress unusedFunction */ +void vu_queue_flush(struct vu_virtq *vq, unsigned int count) +{ + uint16_t old, new; + + if (!vq->vring.avail) + return; + + /* Make sure buffer is written before we update index. */ + smp_wmb(); + + old = vq->used_idx; + new = old + count; + vring_used_idx_set(vq, new); + vq->inuse -= count; + if ((uint16_t)(new - vq->signalled_used) < (uint16_t)(new - old)) + vq->signalled_used_valid = false; +} |