Support mergable rx buffers for virtio-net. This helps reduce the amount
of memory the guest kernel has to allocate per rx vq.
Signed-off-by: Sasha Levin <sasha.le...@oracle.com>
---
tools/kvm/include/kvm/uip.h | 2 +-
tools/kvm/net/uip/core.c | 2 +-
tools/kvm/virtio/net.c | 42 ++++++++++++++++++++++++++++++++++++------
3 files changed, 38 insertions(+), 8 deletions(-)
diff --git a/tools/kvm/include/kvm/uip.h b/tools/kvm/include/kvm/uip.h
index cb79e94..4e63808 100644
--- a/tools/kvm/include/kvm/uip.h
+++ b/tools/kvm/include/kvm/uip.h
@@ -253,7 +253,7 @@ struct uip_tcp_socket {
};
struct uip_tx_arg {
- struct virtio_net_hdr *vnet;
+ void *vnet;
struct uip_info *info;
struct uip_eth *eth;
int vnet_len;
diff --git a/tools/kvm/net/uip/core.c b/tools/kvm/net/uip/core.c
index e31efc2..789b814 100644
--- a/tools/kvm/net/uip/core.c
+++ b/tools/kvm/net/uip/core.c
@@ -8,7 +8,7 @@
int uip_tx(struct iovec *iov, u16 out, struct uip_info *info)
{
- struct virtio_net_hdr *vnet;
+ void *vnet;
struct uip_tx_arg arg;
int eth_len, vnet_len;
struct uip_eth *eth;
diff --git a/tools/kvm/virtio/net.c b/tools/kvm/virtio/net.c
index 15dbde3..7855cfc 100644
--- a/tools/kvm/virtio/net.c
+++ b/tools/kvm/virtio/net.c
@@ -8,6 +8,7 @@
#include "kvm/irq.h"
#include "kvm/uip.h"
#include "kvm/guest_compat.h"
+#include "kvm/iovec.h"
#include <linux/vhost.h>
#include <linux/virtio_net.h>
@@ -65,6 +66,13 @@ struct net_dev {
static LIST_HEAD(ndevs);
static int compat_id = -1;
+#define MAX_PACKET_SIZE 65550
+
+static bool has_virtio_feature(struct net_dev *ndev, u32 feature)
+{
+ return ndev->features & (1 << feature);
+}
+
static void *virtio_net_rx_thread(void *p)
{
struct iovec iov[VIRTIO_NET_QUEUE_SIZE];
@@ -73,7 +81,7 @@ static void *virtio_net_rx_thread(void *p)
struct net_dev *ndev = p;
u16 out, in;
u16 head;
- int len;
+ size_t len, copied;
u32 id;
mutex_lock(&ndev->mutex);
@@ -92,10 +100,31 @@ static void *virtio_net_rx_thread(void *p)
mutex_unlock(&ndev->io_lock[id]);
while (virt_queue__available(vq)) {
+ unsigned char buffer[MAX_PACKET_SIZE + sizeof(struct
virtio_net_hdr_mrg_rxbuf)];
+ struct iovec dummy_iov = {
+ .iov_base = buffer,
+ .iov_len = sizeof(buffer),
+ };
+ struct virtio_net_hdr_mrg_rxbuf *hdr;
+
+ len = ndev->ops->rx(&dummy_iov, 1, ndev);
+ copied = 0;
head = virt_queue__get_iov(vq, iov, &out, &in, kvm);
- len = ndev->ops->rx(iov, in, ndev);
- virt_queue__set_used_elem(vq, head, len);
-
+ hdr = (void *)iov[0].iov_base;
+ while (copied < len) {
+ size_t iovsize = min(len - copied,
iov_size(iov, in));
+
+ memcpy_toiovecend(iov, buffer, copied, iovsize);
+ copied += iovsize;
+ if (has_virtio_feature(ndev,
VIRTIO_NET_F_MRG_RXBUF))
+ hdr->num_buffers++;
+ virt_queue__set_used_elem(vq, head, iovsize);
+ if (copied == len)
+ break;
+ while (!virt_queue__available(vq))
+ sleep(0);
+ head = virt_queue__get_iov(vq, iov, &out, &in,
kvm);
+ }
/* We should interrupt guest right now, otherwise
latency is huge. */
if (virtio_queue__should_signal(vq))
ndev->vdev.ops->signal_vq(kvm, &ndev->vdev, id);
@@ -243,7 +272,7 @@ static bool virtio_net__tap_init(struct net_dev *ndev)
goto fail;
}
- hdr_len = (ndev->features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
+ hdr_len = has_virtio_feature(ndev, VIRTIO_NET_F_MRG_RXBUF) ?
sizeof(struct virtio_net_hdr_mrg_rxbuf) :
sizeof(struct virtio_net_hdr);
if (ioctl(ndev->tap_fd, TUNSETVNETHDRSZ, &hdr_len) < 0)
@@ -351,6 +380,7 @@ static u32 get_host_features(struct kvm *kvm, void *dev)
| 1UL << VIRTIO_RING_F_EVENT_IDX
| 1UL << VIRTIO_RING_F_INDIRECT_DESC
| 1UL << VIRTIO_NET_F_CTRL_VQ
+ | 1UL << VIRTIO_NET_F_MRG_RXBUF
| 1UL << (ndev->queue_pairs > 1 ? VIRTIO_NET_F_MQ : 0);
}
@@ -711,7 +741,7 @@ static void notify_status(struct kvm *kvm, void *dev, u8
status)
if (!virtio_net__tap_init(ndev))
die_perror("You have requested a TAP device, but
creation of one has failed because");
} else {
- ndev->info.vnet_hdr_len = (ndev->features & (1 <<
VIRTIO_NET_F_MRG_RXBUF)) ?
+ ndev->info.vnet_hdr_len = has_virtio_feature(ndev,
VIRTIO_NET_F_MRG_RXBUF) ?
sizeof(struct
virtio_net_hdr_mrg_rxbuf) :
sizeof(struct virtio_net_hdr);
uip_init(&ndev->info);
--
1.8.2.1
--
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