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-rw-r--r--hw/dataplane/Makefile.objs2
-rw-r--r--hw/dataplane/vring.c362
-rw-r--r--hw/dataplane/vring.h62
-rw-r--r--trace-events3
4 files changed, 428 insertions, 1 deletions
diff --git a/hw/dataplane/Makefile.objs b/hw/dataplane/Makefile.objs
index 8c8dea1b21..34e6d579ec 100644
--- a/hw/dataplane/Makefile.objs
+++ b/hw/dataplane/Makefile.objs
@@ -1,3 +1,3 @@
ifeq ($(CONFIG_VIRTIO), y)
-common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o
+common-obj-$(CONFIG_VIRTIO_BLK_DATA_PLANE) += hostmem.o vring.o
endif
diff --git a/hw/dataplane/vring.c b/hw/dataplane/vring.c
new file mode 100644
index 0000000000..d5d4ef45d1
--- /dev/null
+++ b/hw/dataplane/vring.c
@@ -0,0 +1,362 @@
+/* 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/dataplane/vring.h"
+
+/* 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;
+
+ hostmem_init(&vring->hostmem);
+ vring_ptr = hostmem_lookup(&vring->hostmem, 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 = 0;
+ vring->last_used_idx = 0;
+ 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)
+{
+ hostmem_finalize(&vring->hostmem);
+}
+
+/* Disable guest->host notifies */
+void vring_disable_notification(VirtIODevice *vdev, Vring *vring)
+{
+ if (!(vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX))) {
+ vring->vr.used->flags |= 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 (vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) {
+ vring_avail_event(&vring->vr) = vring->vr.avail->idx;
+ } else {
+ vring->vr.used->flags &= ~VRING_USED_F_NO_NOTIFY;
+ }
+ smp_mb(); /* ensure update is seen before reading avail_idx */
+ return !vring_more_avail(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 ((vdev->guest_features & VIRTIO_F_NOTIFY_ON_EMPTY) &&
+ unlikely(vring->vr.avail->idx == vring->last_avail_idx)) {
+ return true;
+ }
+
+ if (!(vdev->guest_features & VIRTIO_RING_F_EVENT_IDX)) {
+ return !(vring->vr.avail->flags & 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(vring_used_event(&vring->vr), new, old);
+}
+
+/* This is stolen from linux/drivers/vhost/vhost.c. */
+static int get_indirect(Vring *vring,
+ struct iovec iov[], struct iovec *iov_end,
+ unsigned int *out_num, unsigned int *in_num,
+ struct vring_desc *indirect)
+{
+ struct vring_desc desc;
+ unsigned int i = 0, count, found = 0;
+
+ /* 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;
+
+ /* Translate indirect descriptor */
+ desc_ptr = hostmem_lookup(&vring->hostmem,
+ 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;
+ }
+ desc = *desc_ptr;
+
+ /* 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;
+ }
+
+ /* Stop for now if there are not enough iovecs available. */
+ if (iov >= iov_end) {
+ return -ENOBUFS;
+ }
+
+ iov->iov_base = hostmem_lookup(&vring->hostmem, desc.addr, desc.len,
+ desc.flags & VRING_DESC_F_WRITE);
+ if (!iov->iov_base) {
+ error_report("Failed to map indirect descriptor"
+ "addr %#" PRIx64 " len %u",
+ (uint64_t)desc.addr, desc.len);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ iov->iov_len = desc.len;
+ iov++;
+
+ /* If this is an input descriptor, increment that count. */
+ if (desc.flags & VRING_DESC_F_WRITE) {
+ *in_num += 1;
+ } else {
+ /* If it's an output descriptor, they're all supposed
+ * to come before any input descriptors. */
+ if (unlikely(*in_num)) {
+ error_report("Indirect descriptor "
+ "has out after in: idx %u", i);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ *out_num += 1;
+ }
+ i = desc.next;
+ } while (desc.flags & VRING_DESC_F_NEXT);
+ return 0;
+}
+
+/* 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,
+ struct iovec iov[], struct iovec *iov_end,
+ unsigned int *out_num, unsigned int *in_num)
+{
+ struct vring_desc desc;
+ unsigned int i, head, found = 0, num = vring->vr.num;
+ uint16_t avail_idx, last_avail_idx;
+
+ /* If there was a fatal error then refuse operation */
+ if (vring->broken) {
+ return -EFAULT;
+ }
+
+ /* Check it isn't doing very strange things with descriptor numbers. */
+ last_avail_idx = vring->last_avail_idx;
+ avail_idx = vring->vr.avail->idx;
+ 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);
+ vring->broken = true;
+ return -EFAULT;
+ }
+
+ /* If there's nothing new since last we looked. */
+ if (avail_idx == last_avail_idx) {
+ return -EAGAIN;
+ }
+
+ /* 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->vr.avail->ring[last_avail_idx % num];
+
+ /* If their number is silly, that's an error. */
+ if (unlikely(head >= num)) {
+ error_report("Guest says index %u > %u is available", head, num);
+ vring->broken = true;
+ return -EFAULT;
+ }
+
+ if (vdev->guest_features & (1 << VIRTIO_RING_F_EVENT_IDX)) {
+ vring_avail_event(&vring->vr) = vring->vr.avail->idx;
+ }
+
+ /* When we start there are none of either input nor output. */
+ *out_num = *in_num = 0;
+
+ i = head;
+ do {
+ if (unlikely(i >= num)) {
+ error_report("Desc index is %u > %u, head = %u", i, num, head);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ if (unlikely(++found > num)) {
+ error_report("Loop detected: last one at %u vq size %u head %u",
+ i, num, head);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ desc = vring->vr.desc[i];
+
+ /* Ensure descriptor is loaded before accessing fields */
+ barrier();
+
+ if (desc.flags & VRING_DESC_F_INDIRECT) {
+ int ret = get_indirect(vring, iov, iov_end, out_num, in_num, &desc);
+ if (ret < 0) {
+ return ret;
+ }
+ continue;
+ }
+
+ /* If there are not enough iovecs left, stop for now. The caller
+ * should check if there are more descs available once they have dealt
+ * with the current set.
+ */
+ if (iov >= iov_end) {
+ return -ENOBUFS;
+ }
+
+ /* TODO handle non-contiguous memory across region boundaries */
+ iov->iov_base = hostmem_lookup(&vring->hostmem, desc.addr, desc.len,
+ desc.flags & VRING_DESC_F_WRITE);
+ if (!iov->iov_base) {
+ error_report("Failed to map vring desc addr %#" PRIx64 " len %u",
+ (uint64_t)desc.addr, desc.len);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ iov->iov_len = desc.len;
+ iov++;
+
+ if (desc.flags & VRING_DESC_F_WRITE) {
+ /* If this is an input descriptor,
+ * increment that count. */
+ *in_num += 1;
+ } else {
+ /* If it's an output descriptor, they're all supposed
+ * to come before any input descriptors. */
+ if (unlikely(*in_num)) {
+ error_report("Descriptor has out after in: idx %d", i);
+ vring->broken = true;
+ return -EFAULT;
+ }
+ *out_num += 1;
+ }
+ i = desc.next;
+ } while (desc.flags & VRING_DESC_F_NEXT);
+
+ /* On success, increment avail index. */
+ vring->last_avail_idx++;
+ return head;
+}
+
+/* After we've used one of their buffers, we tell them about it.
+ *
+ * Stolen from linux/drivers/vhost/vhost.c.
+ */
+void vring_push(Vring *vring, unsigned int head, int len)
+{
+ struct vring_used_elem *used;
+ uint16_t new;
+
+ /* 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. */
+ used = &vring->vr.used->ring[vring->last_used_idx % vring->vr.num];
+ used->id = head;
+ used->len = len;
+
+ /* Make sure buffer is written before we update index. */
+ smp_wmb();
+
+ new = vring->vr.used->idx = ++vring->last_used_idx;
+ if (unlikely((int16_t)(new - vring->signalled_used) < (uint16_t)1)) {
+ vring->signalled_used_valid = false;
+ }
+}
diff --git a/hw/dataplane/vring.h b/hw/dataplane/vring.h
new file mode 100644
index 0000000000..3274f623f5
--- /dev/null
+++ b/hw/dataplane/vring.h
@@ -0,0 +1,62 @@
+/* Copyright 2012 Red Hat, Inc. and/or its affiliates
+ * 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.
+ */
+
+#ifndef VRING_H
+#define VRING_H
+
+#include <linux/virtio_ring.h>
+#include "qemu-common.h"
+#include "hw/dataplane/hostmem.h"
+#include "hw/virtio.h"
+
+typedef struct {
+ HostMem hostmem; /* guest memory mapper */
+ struct vring vr; /* virtqueue vring mapped to host memory */
+ uint16_t last_avail_idx; /* last processed avail ring index */
+ uint16_t last_used_idx; /* last processed used ring index */
+ uint16_t signalled_used; /* EVENT_IDX state */
+ bool signalled_used_valid;
+ bool broken; /* was there a fatal error? */
+} Vring;
+
+static inline unsigned int vring_get_num(Vring *vring)
+{
+ return vring->vr.num;
+}
+
+/* Are there more descriptors available? */
+static inline bool vring_more_avail(Vring *vring)
+{
+ return vring->vr.avail->idx != vring->last_avail_idx;
+}
+
+/* Fail future vring_pop() and vring_push() calls until reset */
+static inline void vring_set_broken(Vring *vring)
+{
+ vring->broken = true;
+}
+
+bool vring_setup(Vring *vring, VirtIODevice *vdev, int n);
+void vring_teardown(Vring *vring);
+void vring_disable_notification(VirtIODevice *vdev, Vring *vring);
+bool vring_enable_notification(VirtIODevice *vdev, Vring *vring);
+bool vring_should_notify(VirtIODevice *vdev, Vring *vring);
+int vring_pop(VirtIODevice *vdev, Vring *vring,
+ struct iovec iov[], struct iovec *iov_end,
+ unsigned int *out_num, unsigned int *in_num);
+void vring_push(Vring *vring, unsigned int head, int len);
+
+#endif /* VRING_H */
diff --git a/trace-events b/trace-events
index bb7621eeb6..167d776eff 100644
--- a/trace-events
+++ b/trace-events
@@ -98,6 +98,9 @@ virtio_blk_rw_complete(void *req, int ret) "req %p ret %d"
virtio_blk_handle_write(void *req, uint64_t sector, size_t nsectors) "req %p sector %"PRIu64" nsectors %zu"
virtio_blk_handle_read(void *req, uint64_t sector, size_t nsectors) "req %p sector %"PRIu64" nsectors %zu"
+# hw/dataplane/vring.c
+vring_setup(uint64_t physical, void *desc, void *avail, void *used) "vring physical %#"PRIx64" desc %p avail %p used %p"
+
# thread-pool.c
thread_pool_submit(void *req, void *opaque) "req %p opaque %p"
thread_pool_complete(void *req, void *opaque, int ret) "req %p opaque %p ret %d"
generated by cgit v1.2.3 (git 2.26.2) at 2024-12-04 07:33:17 +0000