On Thu, Feb 01, 2018 at 10:35:18AM +0100, Maxime Coquelin wrote:
On 01/29/2018 03:11 PM, Jens Freimann wrote:
Implement code to dequeue and process descriptors from
the vring if VIRTIO_F_PACKED is enabled.
Check if descriptor was made available by driver by looking at
VIRTIO_F_DESC_AVAIL flag in descriptor. If so dequeue and set
the used flag VIRTIO_F_DESC_USED to the current value of the
used wrap counter.
Used ring wrap counter needs to be toggled when last descriptor is
written out. This allows the host/guest to detect new descriptors even
after the ring has wrapped.
Signed-off-by: Jens Freimann <jfreim...@redhat.com>
---
lib/librte_vhost/vhost.c | 1 +
lib/librte_vhost/vhost.h | 1 +
lib/librte_vhost/virtio_net.c | 194 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 196 insertions(+)
diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index 78913912c..e5f58d9c8 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -191,6 +191,7 @@ init_vring_queue(struct virtio_net *dev, uint32_t vring_idx)
vq->kickfd = VIRTIO_UNINITIALIZED_EVENTFD;
vq->callfd = VIRTIO_UNINITIALIZED_EVENTFD;
+ vq->used_wrap_counter = 1;
vhost_user_iotlb_init(dev, vring_idx);
/* Backends are set to -1 indicating an inactive device. */
diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
index 8554d51d8..a3d4214b6 100644
--- a/lib/librte_vhost/vhost.h
+++ b/lib/librte_vhost/vhost.h
@@ -106,6 +106,7 @@ struct vhost_virtqueue {
struct batch_copy_elem *batch_copy_elems;
uint16_t batch_copy_nb_elems;
+ uint32_t used_wrap_counter;
rte_rwlock_t iotlb_lock;
rte_rwlock_t iotlb_pending_lock;
diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
index edfab3ba6..5d4cfe8cc 100644
--- a/lib/librte_vhost/virtio_net.c
+++ b/lib/librte_vhost/virtio_net.c
@@ -19,6 +19,7 @@
#include "iotlb.h"
#include "vhost.h"
+#include "virtio-1.1.h"
#define MAX_PKT_BURST 32
@@ -1111,6 +1112,199 @@ restore_mbuf(struct rte_mbuf *m)
}
}
+static inline uint16_t
+dequeue_desc(struct virtio_net *dev, struct vhost_virtqueue *vq,
+ struct rte_mempool *mbuf_pool, struct rte_mbuf *m,
+ struct vring_desc_1_1 *descs)
+{
+ struct vring_desc_1_1 *desc;
+ uint64_t desc_addr;
+ uint32_t desc_avail, desc_offset;
+ uint32_t mbuf_avail, mbuf_offset;
+ uint32_t cpy_len;
+ struct rte_mbuf *cur = m, *prev = m;
+ struct virtio_net_hdr *hdr = NULL;
+ uint16_t head_idx = vq->last_used_idx & (vq->size - 1);
+ int wrap_counter = vq->used_wrap_counter;
+
+ desc = &descs[vq->last_used_idx & (vq->size - 1)];
+ if (unlikely((desc->len < dev->vhost_hlen)) ||
+ (desc->flags & VRING_DESC_F_INDIRECT))
+ rte_panic("INDIRECT not supported yet");
Using rte_panic() may not be a good idea here, because a malicious guest
could make the vswitch to crash easily.
Good point. It was for debugging only, I will remove it.
+
+ desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
You should use vhost_iova_to_vva() here and everywhere else, otherwise
you break IOMMU support.
Yes, I'll change it.
+ if (unlikely(!desc_addr))
+ return -1;
+
+ if (virtio_net_with_host_offload(dev)) {
+ hdr = (struct virtio_net_hdr *)((uintptr_t)desc_addr);
+ rte_prefetch0(hdr);
+ }
+
+ /*
+ * A virtio driver normally uses at least 2 desc buffers
+ * for Tx: the first for storing the header, and others
+ * for storing the data.
+ */
+ if (likely((desc->len == dev->vhost_hlen) &&
+ (desc->flags & VRING_DESC_F_NEXT) != 0)) {
+ if ((++vq->last_used_idx & (vq->size - 1)) == 0)
+ toggle_wrap_counter(vq);
+
+ desc = &descs[vq->last_used_idx & (vq->size - 1)];
+
+ if (unlikely(desc->flags & VRING_DESC_F_INDIRECT))
+ rte_panic("INDIRECT not supported yet");
Ditto.
+
+ desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
+ if (unlikely(!desc_addr))
+ return -1;
+
+ desc_offset = 0;
+ desc_avail = desc->len;
+ } else {
+ desc_avail = desc->len - dev->vhost_hlen;
+ desc_offset = dev->vhost_hlen;
+ }
+
+ rte_prefetch0((void *)(uintptr_t)(desc_addr + desc_offset));
+
+ PRINT_PACKET(dev, (uintptr_t)(desc_addr + desc_offset), desc_avail, 0);
+
+ mbuf_offset = 0;
+ mbuf_avail = m->buf_len - RTE_PKTMBUF_HEADROOM;
+ while (1) {
+ uint64_t hpa;
+
+ cpy_len = RTE_MIN(desc_avail, mbuf_avail);
+
+ /*
+ * A desc buf might across two host physical pages that are
+ * not continuous. In such case (gpa_to_hpa returns 0), data
+ * will be copied even though zero copy is enabled.
+ */
+ if (unlikely(dev->dequeue_zero_copy && (hpa = gpa_to_hpa(dev,
+ desc->addr + desc_offset, cpy_len)))) {
+ cur->data_len = cpy_len;
+ cur->data_off = 0;
+ cur->buf_addr = (void *)(uintptr_t)desc_addr;
+ cur->buf_physaddr = hpa;
+
+ /*
+ * In zero copy mode, one mbuf can only reference data
+ * for one or partial of one desc buff.
+ */
+ mbuf_avail = cpy_len;
+ } else {
+ rte_memcpy(rte_pktmbuf_mtod_offset(cur, void *,
+ mbuf_offset),
+ (void *)((uintptr_t)(desc_addr + desc_offset)),
+ cpy_len);
+ }
+
+ mbuf_avail -= cpy_len;
+ mbuf_offset += cpy_len;
+ desc_avail -= cpy_len;
+ desc_offset += cpy_len;
+
+ /* This desc reaches to its end, get the next one */
+ if (desc_avail == 0) {
+ if ((desc->flags & VRING_DESC_F_NEXT) == 0)
+ break;
+
+ if ((++vq->last_used_idx & (vq->size - 1)) == 0)
+ toggle_wrap_counter(vq);
+
+ desc = &descs[vq->last_used_idx & (vq->size - 1)];
+ if (unlikely(desc->flags & VRING_DESC_F_INDIRECT))
+ rte_panic("INDIRECT not supported yet");
+
+ desc_addr = rte_vhost_gpa_to_vva(dev->mem, desc->addr);
+ if (unlikely(!desc_addr))
+ return -1;
+
+ rte_prefetch0((void *)(uintptr_t)desc_addr);
+
+ desc_offset = 0;
+ desc_avail = desc->len;
+
+ PRINT_PACKET(dev, (uintptr_t)desc_addr, desc->len, 0);
+ }
+
+ /*
+ * This mbuf reaches to its end, get a new one
+ * to hold more data.
+ */
+ if (mbuf_avail == 0) {
+ cur = rte_pktmbuf_alloc(mbuf_pool);
+ if (unlikely(cur == NULL)) {
+ RTE_LOG(ERR, VHOST_DATA, "Failed to "
+ "allocate memory for mbuf.\n");
+ return -1;
+ }
+
+ prev->next = cur;
+ prev->data_len = mbuf_offset;
+ m->nb_segs += 1;
+ m->pkt_len += mbuf_offset;
+ prev = cur;
+
+ mbuf_offset = 0;
+ mbuf_avail = cur->buf_len - RTE_PKTMBUF_HEADROOM;
+ }
+ }
+
+ if (hdr)
+ vhost_dequeue_offload(hdr, m);
+
+ if ((++vq->last_used_idx & (vq->size - 1)) == 0)
+ toggle_wrap_counter(vq);
+
+ rte_smp_wmb();
+ _set_desc_used(&descs[head_idx], wrap_counter);
+
+ prev->data_len = mbuf_offset;
+ m->pkt_len += mbuf_offset;
+
+ return 0;
+}
+
+static inline uint16_t
+vhost_dequeue_burst_1_1(struct virtio_net *dev, struct vhost_virtqueue *vq,
+ struct rte_mempool *mbuf_pool, struct rte_mbuf **pkts,
+ uint16_t count)
+{
+ uint16_t i;
+ uint16_t idx;
+ struct vring_desc_1_1 *desc = vq->desc_1_1;
+ int err;
+
+ count = RTE_MIN(MAX_PKT_BURST, count);
+ for (i = 0; i < count; i++) {
+ idx = vq->last_used_idx & (vq->size - 1);
+ if (!desc_is_avail(vq, &desc[idx]))
+ break;
+ rte_smp_rmb();
+
+ pkts[i] = rte_pktmbuf_alloc(mbuf_pool);
+ if (unlikely(pkts[i] == NULL)) {
+ RTE_LOG(ERR, VHOST_DATA,
+ "Failed to allocate memory for mbuf.\n");
+ break;
+ }
+
+ err = dequeue_desc(dev, vq, mbuf_pool, pkts[i], desc);
+ if (unlikely(err)) {
+ rte_pktmbuf_free(pkts[i]);
+ break;
+ }
+ }
+
+ rte_spinlock_unlock(&vq->access_lock);
Where is it locked? It looks unbalanced.
It is locked in the caller rte_vhost_dequeue_burst() and we return
immediately. But I could change it to lock and unlock right here.
Thanks for the review!
regards,
Jens
