kvm tools: Use ioeventfd in virtio-net

Use ioeventfds to receive notifications of IO events in virtio-net.
Doing so prevents an exit every time we receive/send a packet.

Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

diff --git a/tools/kvm/virtio/net.c b/tools/kvm/virtio/net.c
index 3064da612554bde2056a3b85dfdc2d0fee2bb899..5c39c437086c9534cab969adec6f9dd2ae7e3324 100644 (file)
--- a/tools/kvm/virtio/net.c
+++ b/tools/kvm/virtio/net.c
@@ -8,6 +8,7 @@
 #include "kvm/kvm.h"
 #include "kvm/pci.h"
 #include "kvm/irq.h"
+#include "kvm/ioeventfd.h"
 
 #include <linux/virtio_net.h>
 #include <linux/if_tun.h>
@@ -280,6 +281,11 @@ static bool virtio_net_pci_io_out(struct ioport *ioport, struct kvm *kvm, u16 po
        return ret;
 }
 
+static void ioevent_callback(struct kvm *kvm, void *param)
+{
+       virtio_net_handle_callback(kvm, (u64)param);
+}
+
 static struct ioport_operations virtio_net_io_ops = {
        .io_in  = virtio_net_pci_io_in,
        .io_out = virtio_net_pci_io_out,
@@ -388,6 +394,8 @@ void virtio_net__init(const struct virtio_net_parameters *params)
        if (virtio_net__tap_init(params)) {
                u8 dev, line, pin;
                u16 net_base_addr;
+               u64 i;
+               struct ioevent ioevent;
 
                if (irq__register_device(VIRTIO_ID_NET, &dev, &pin, &line) < 0)
                        return;
@@ -401,5 +409,19 @@ void virtio_net__init(const struct virtio_net_parameters *params)
                pci__register(&pci_header, dev);
 
                virtio_net__io_thread_init(params->kvm);
+
+               for (i = 0; i < VIRTIO_NET_NUM_QUEUES; i++) {
+                       ioevent = (struct ioevent) {
+                               .io_addr                = net_base_addr + VIRTIO_PCI_QUEUE_NOTIFY,
+                               .io_len                 = sizeof(u16),
+                               .fn                     = ioevent_callback,
+                               .datamatch              = i,
+                               .fn_ptr                 = (void *)i,
+                               .fn_kvm                 = params->kvm,
+                               .fd                     = eventfd(0, 0),
+                       };
+
+                       ioeventfd__add_event(&ioevent);
+               }
        }
 }