[Qemu-devel] [RFC PATCH 19/20] Insert do_event_tap() to virtio-{blk, net}, comment out assert() on cpu_single_env temporally.

[Yoshiaki Tamura]

do_event_tap() is inserted to functions which actually fire outputs.
By synchronizing VMs before outputs are fired, we can failover to the
receiver upon failure.  To save VM continuously, comment out assert()
on cpu_single_env temporally.

Signed-off-by: Yoshiaki Tamura <address@hidden>
---
 hw/virtio-blk.c |    2 ++
 hw/virtio-net.c |    2 ++
 qemu-kvm.c      |    7 ++++++-
 3 files changed, 10 insertions(+), 1 deletions(-)

diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index b80402d..1dd1c31 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -327,6 +327,8 @@ static void virtio_blk_handle_output(VirtIODevice *vdev, 
VirtQueue *vq)
         .old_bs = NULL,
     };
 
+    do_event_tap();
+
     while ((req = virtio_blk_get_request(s))) {
         virtio_blk_handle_request(req, &mrb);
     }
diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 5c0093e..1a32bf3 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -667,6 +667,8 @@ static void virtio_net_handle_tx(VirtIODevice *vdev, 
VirtQueue *vq)
 {
     VirtIONet *n = to_virtio_net(vdev);
 
+    do_event_tap();
+
     if (n->tx_timer_active) {
         virtio_queue_set_notification(vq, 1);
         qemu_del_timer(n->tx_timer);
diff --git a/qemu-kvm.c b/qemu-kvm.c
index 1414f49..769bc95 100644
--- a/qemu-kvm.c
+++ b/qemu-kvm.c
@@ -935,8 +935,12 @@ int kvm_run(CPUState *env)
 
     post_kvm_run(kvm, env);
 
+    /* TODO: we need to prevent tapping events that derived from the
+     * same VMEXIT. This needs more info from the kernel. */
 #if defined(KVM_CAP_COALESCED_MMIO)
     if (kvm_state->coalesced_mmio) {
+        /* prevent from tapping events while handling coalesced_mmio */
+        event_tap_suspend();
         struct kvm_coalesced_mmio_ring *ring =
             (void *) run + kvm_state->coalesced_mmio * PAGE_SIZE;
         while (ring->first != ring->last) {
@@ -946,6 +950,7 @@ int kvm_run(CPUState *env)
             smp_wmb();
             ring->first = (ring->first + 1) % KVM_COALESCED_MMIO_MAX;
         }
+        event_tap_resume();
     }
 #endif
 
@@ -1770,7 +1775,7 @@ static void resume_all_threads(void)
 {
     CPUState *penv = first_cpu;
 
-    assert(!cpu_single_env);
+    /* assert(!cpu_single_env); */
 
     while (penv) {
         penv->stop = 0;
-- 
1.7.0.31.g1df487