+++ /dev/null
-/* Copyright 2012 Red Hat, Inc.
- * Copyright IBM, Corp. 2012
- *
- * Based on Linux 2.6.39 vhost code:
- * Copyright (C) 2009 Red Hat, Inc.
- * Copyright (C) 2006 Rusty Russell IBM Corporation
- *
- * Author: Michael S. Tsirkin <mst@redhat.com>
- * Stefan Hajnoczi <stefanha@redhat.com>
- *
- * Inspiration, some code, and most witty comments come from
- * Documentation/virtual/lguest/lguest.c, by Rusty Russell
- *
- * This work is licensed under the terms of the GNU GPL, version 2.
- */
-
-#include "trace.h"
-#include "hw/hw.h"
-#include "exec/memory.h"
-#include "exec/address-spaces.h"
-#include "hw/virtio/virtio-access.h"
-#include "hw/virtio/dataplane/vring.h"
-#include "hw/virtio/dataplane/vring-accessors.h"
-#include "qemu/error-report.h"
-
-/* vring_map can be coupled with vring_unmap or (if you still have the
- * value returned in *mr) memory_region_unref.
- */
-static void *vring_map(MemoryRegion **mr, hwaddr phys, hwaddr len,
- bool is_write)
-{
- MemoryRegionSection section = memory_region_find(get_system_memory(), phys, len);
-
- if (!section.mr || int128_get64(section.size) < len) {
- goto out;
- }
- if (is_write && section.readonly) {
- goto out;
- }
- if (!memory_region_is_ram(section.mr)) {
- goto out;
- }
-
- /* Ignore regions with dirty logging, we cannot mark them dirty */
- if (memory_region_get_dirty_log_mask(section.mr)) {
- goto out;
- }
-
- *mr = section.mr;
- return memory_region_get_ram_ptr(section.mr) + section.offset_within_region;
-
-out:
- memory_region_unref(section.mr);
- *mr = NULL;
- return NULL;
-}
-
-static void vring_unmap(void *buffer, bool is_write)
-{
- ram_addr_t addr;
- MemoryRegion *mr;
-
- mr = qemu_ram_addr_from_host(buffer, &addr);
- memory_region_unref(mr);
-}
-
-/* Map the guest's vring to host memory */
-bool vring_setup(Vring *vring, VirtIODevice *vdev, int n)
-{
- hwaddr vring_addr = virtio_queue_get_ring_addr(vdev, n);
- hwaddr vring_size = virtio_queue_get_ring_size(vdev, n);
- void *vring_ptr;
-
- vring->broken = false;
-
- vring_ptr = vring_map(&vring->mr, vring_addr, vring_size, true);
- if (!vring_ptr) {
- error_report("Failed to map vring "
- "addr %#" HWADDR_PRIx " size %" HWADDR_PRIu,
- vring_addr, vring_size);
- vring->broken = true;
- return false;
- }
-
- vring_init(&vring->vr, virtio_queue_get_num(vdev, n), vring_ptr, 4096);
-
- vring->last_avail_idx = virtio_queue_get_last_avail_idx(vdev, n);
- vring->last_used_idx = vring_get_used_idx(vdev, vring);
- vring->signalled_used = 0;
- vring->signalled_used_valid = false;
-
- trace_vring_setup(virtio_queue_get_ring_addr(vdev, n),
- vring->vr.desc, vring->vr.avail, vring->vr.used);
- return true;
-}
-
-void vring_teardown(Vring *vring, VirtIODevice *vdev, int n)
-{
- virtio_queue_set_last_avail_idx(vdev, n, vring->last_avail_idx);
- virtio_queue_invalidate_signalled_used(vdev, n);
-
- memory_region_unref(vring->mr);
-}
-
-/* Disable guest->host notifies */
-void vring_disable_notification(VirtIODevice *vdev, Vring *vring)
-{
- if (!virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
- vring_set_used_flags(vdev, vring, VRING_USED_F_NO_NOTIFY);
- }
-}
-
-/* Enable guest->host notifies
- *
- * Return true if the vring is empty, false if there are more requests.
- */
-bool vring_enable_notification(VirtIODevice *vdev, Vring *vring)
-{
- if (virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
- vring_avail_event(&vring->vr) = vring->vr.avail->idx;
- } else {
- vring_clear_used_flags(vdev, vring, VRING_USED_F_NO_NOTIFY);
- }
- smp_mb(); /* ensure update is seen before reading avail_idx */
- return !vring_more_avail(vdev, vring);
-}
-
-/* This is stolen from linux/drivers/vhost/vhost.c:vhost_notify() */
-bool vring_should_notify(VirtIODevice *vdev, Vring *vring)
-{
- uint16_t old, new;
- bool v;
- /* Flush out used index updates. This is paired
- * with the barrier that the Guest executes when enabling
- * interrupts. */
- smp_mb();
-
- if (virtio_has_feature(vdev, VIRTIO_F_NOTIFY_ON_EMPTY) &&
- unlikely(!vring_more_avail(vdev, vring))) {
- return true;
- }
-
- if (!virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
- return !(vring_get_avail_flags(vdev, vring) &
- VRING_AVAIL_F_NO_INTERRUPT);
- }
- old = vring->signalled_used;
- v = vring->signalled_used_valid;
- new = vring->signalled_used = vring->last_used_idx;
- vring->signalled_used_valid = true;
-
- if (unlikely(!v)) {
- return true;
- }
-
- return vring_need_event(virtio_tswap16(vdev, vring_used_event(&vring->vr)),
- new, old);
-}
-
-
-static int get_desc(Vring *vring, VirtQueueElement *elem,
- struct vring_desc *desc)
-{
- unsigned *num;
- struct iovec *iov;
- hwaddr *addr;
- MemoryRegion *mr;
-
- if (desc->flags & VRING_DESC_F_WRITE) {
- num = &elem->in_num;
- iov = &elem->in_sg[*num];
- addr = &elem->in_addr[*num];
- } else {
- num = &elem->out_num;
- iov = &elem->out_sg[*num];
- addr = &elem->out_addr[*num];
-
- /* If it's an output descriptor, they're all supposed
- * to come before any input descriptors. */
- if (unlikely(elem->in_num)) {
- error_report("Descriptor has out after in");
- return -EFAULT;
- }
- }
-
- /* Stop for now if there are not enough iovecs available. */
- if (*num >= VIRTQUEUE_MAX_SIZE) {
- error_report("Invalid SG num: %u", *num);
- return -EFAULT;
- }
-
- /* TODO handle non-contiguous memory across region boundaries */
- iov->iov_base = vring_map(&mr, desc->addr, desc->len,
- desc->flags & VRING_DESC_F_WRITE);
- if (!iov->iov_base) {
- error_report("Failed to map descriptor addr %#" PRIx64 " len %u",
- (uint64_t)desc->addr, desc->len);
- return -EFAULT;
- }
-
- /* The MemoryRegion is looked up again and unref'ed later, leave the
- * ref in place. */
- iov->iov_len = desc->len;
- *addr = desc->addr;
- *num += 1;
- return 0;
-}
-
-static void copy_in_vring_desc(VirtIODevice *vdev,
- const struct vring_desc *guest,
- struct vring_desc *host)
-{
- host->addr = virtio_ldq_p(vdev, &guest->addr);
- host->len = virtio_ldl_p(vdev, &guest->len);
- host->flags = virtio_lduw_p(vdev, &guest->flags);
- host->next = virtio_lduw_p(vdev, &guest->next);
-}
-
-/* This is stolen from linux/drivers/vhost/vhost.c. */
-static int get_indirect(VirtIODevice *vdev, Vring *vring,
- VirtQueueElement *elem, struct vring_desc *indirect)
-{
- struct vring_desc desc;
- unsigned int i = 0, count, found = 0;
- int ret;
-
- /* Sanity check */
- if (unlikely(indirect->len % sizeof(desc))) {
- error_report("Invalid length in indirect descriptor: "
- "len %#x not multiple of %#zx",
- indirect->len, sizeof(desc));
- vring->broken = true;
- return -EFAULT;
- }
-
- count = indirect->len / sizeof(desc);
- /* Buffers are chained via a 16 bit next field, so
- * we can have at most 2^16 of these. */
- if (unlikely(count > USHRT_MAX + 1)) {
- error_report("Indirect buffer length too big: %d", indirect->len);
- vring->broken = true;
- return -EFAULT;
- }
-
- do {
- struct vring_desc *desc_ptr;
- MemoryRegion *mr;
-
- /* Translate indirect descriptor */
- desc_ptr = vring_map(&mr,
- indirect->addr + found * sizeof(desc),
- sizeof(desc), false);
- if (!desc_ptr) {
- error_report("Failed to map indirect descriptor "
- "addr %#" PRIx64 " len %zu",
- (uint64_t)indirect->addr + found * sizeof(desc),
- sizeof(desc));
- vring->broken = true;
- return -EFAULT;
- }
- copy_in_vring_desc(vdev, desc_ptr, &desc);
- memory_region_unref(mr);
-
- /* Ensure descriptor has been loaded before accessing fields */
- barrier(); /* read_barrier_depends(); */
-
- if (unlikely(++found > count)) {
- error_report("Loop detected: last one at %u "
- "indirect size %u", i, count);
- vring->broken = true;
- return -EFAULT;
- }
-
- if (unlikely(desc.flags & VRING_DESC_F_INDIRECT)) {
- error_report("Nested indirect descriptor");
- vring->broken = true;
- return -EFAULT;
- }
-
- ret = get_desc(vring, elem, &desc);
- if (ret < 0) {
- vring->broken |= (ret == -EFAULT);
- return ret;
- }
- i = desc.next;
- } while (desc.flags & VRING_DESC_F_NEXT);
- return 0;
-}
-
-static void vring_unmap_element(VirtQueueElement *elem)
-{
- int i;
-
- /* This assumes that the iovecs, if changed, are never moved past
- * the end of the valid area. This is true if iovec manipulations
- * are done with iov_discard_front and iov_discard_back.
- */
- for (i = 0; i < elem->out_num; i++) {
- vring_unmap(elem->out_sg[i].iov_base, false);
- }
-
- for (i = 0; i < elem->in_num; i++) {
- vring_unmap(elem->in_sg[i].iov_base, true);
- }
-}
-
-/* This looks in the virtqueue and for the first available buffer, and converts
- * it to an iovec for convenient access. Since descriptors consist of some
- * number of output then some number of input descriptors, it's actually two
- * iovecs, but we pack them into one and note how many of each there were.
- *
- * This function returns the descriptor number found, or vq->num (which is
- * never a valid descriptor number) if none was found. A negative code is
- * returned on error.
- *
- * Stolen from linux/drivers/vhost/vhost.c.
- */
-int vring_pop(VirtIODevice *vdev, Vring *vring,
- VirtQueueElement *elem)
-{
- struct vring_desc desc;
- unsigned int i, head, found = 0, num = vring->vr.num;
- uint16_t avail_idx, last_avail_idx;
- int ret;
-
- /* Initialize elem so it can be safely unmapped */
- elem->in_num = elem->out_num = 0;
-
- /* If there was a fatal error then refuse operation */
- if (vring->broken) {
- ret = -EFAULT;
- goto out;
- }
-
- /* Check it isn't doing very strange things with descriptor numbers. */
- last_avail_idx = vring->last_avail_idx;
- avail_idx = vring_get_avail_idx(vdev, vring);
- barrier(); /* load indices now and not again later */
-
- if (unlikely((uint16_t)(avail_idx - last_avail_idx) > num)) {
- error_report("Guest moved used index from %u to %u",
- last_avail_idx, avail_idx);
- ret = -EFAULT;
- goto out;
- }
-
- /* If there's nothing new since last we looked. */
- if (avail_idx == last_avail_idx) {
- ret = -EAGAIN;
- goto out;
- }
-
- /* Only get avail ring entries after they have been exposed by guest. */
- smp_rmb();
-
- /* Grab the next descriptor number they're advertising, and increment
- * the index we've seen. */
- head = vring_get_avail_ring(vdev, vring, last_avail_idx % num);
-
- elem->index = head;
-
- /* If their number is silly, that's an error. */
- if (unlikely(head >= num)) {
- error_report("Guest says index %u > %u is available", head, num);
- ret = -EFAULT;
- goto out;
- }
-
- i = head;
- do {
- if (unlikely(i >= num)) {
- error_report("Desc index is %u > %u, head = %u", i, num, head);
- ret = -EFAULT;
- goto out;
- }
- if (unlikely(++found > num)) {
- error_report("Loop detected: last one at %u vq size %u head %u",
- i, num, head);
- ret = -EFAULT;
- goto out;
- }
- copy_in_vring_desc(vdev, &vring->vr.desc[i], &desc);
-
- /* Ensure descriptor is loaded before accessing fields */
- barrier();
-
- if (desc.flags & VRING_DESC_F_INDIRECT) {
- ret = get_indirect(vdev, vring, elem, &desc);
- if (ret < 0) {
- goto out;
- }
- continue;
- }
-
- ret = get_desc(vring, elem, &desc);
- if (ret < 0) {
- goto out;
- }
-
- i = desc.next;
- } while (desc.flags & VRING_DESC_F_NEXT);
-
- /* On success, increment avail index. */
- vring->last_avail_idx++;
- if (virtio_has_feature(vdev, VIRTIO_RING_F_EVENT_IDX)) {
- vring_avail_event(&vring->vr) =
- virtio_tswap16(vdev, vring->last_avail_idx);
- }
-
- return head;
-
-out:
- assert(ret < 0);
- if (ret == -EFAULT) {
- vring->broken = true;
- }
- vring_unmap_element(elem);
- return ret;
-}
-
-/* After we've used one of their buffers, we tell them about it.
- *
- * Stolen from linux/drivers/vhost/vhost.c.
- */
-void vring_push(VirtIODevice *vdev, Vring *vring, VirtQueueElement *elem,
- int len)
-{
- unsigned int head = elem->index;
- uint16_t new;
-
- vring_unmap_element(elem);
-
- /* Don't touch vring if a fatal error occurred */
- if (vring->broken) {
- return;
- }
-
- /* The virtqueue contains a ring of used buffers. Get a pointer to the
- * next entry in that used ring. */
- vring_set_used_ring_id(vdev, vring, vring->last_used_idx % vring->vr.num,
- head);
- vring_set_used_ring_len(vdev, vring, vring->last_used_idx % vring->vr.num,
- len);
-
- /* Make sure buffer is written before we update index. */
- smp_wmb();
-
- new = ++vring->last_used_idx;
- vring_set_used_idx(vdev, vring, new);
- if (unlikely((int16_t)(new - vring->signalled_used) < (uint16_t)1)) {
- vring->signalled_used_valid = false;
- }
-}
Code Review / kvmfornfv.git / blobdiff