Re: [Qemu-devel] [PATCH 2/2] tests: test rx recovery from cont

[Fam Zheng <famz@redhat.com>]

On Wed, 07/08 13:12, Jason Wang wrote:
> 
> 
> On 07/08/2015 11:22 AM, Fam Zheng wrote:
> > On Tue, 07/07 18:58, Jason Wang wrote:
> >> Rx should be recovered after cont.
> >>
> >> Signed-off-by: Jason Wang <jasowang@redhat.com>
> >> ---
> >>  tests/virtio-net-test.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
> >>  1 file changed, 48 insertions(+)
> >>
> >> diff --git a/tests/virtio-net-test.c b/tests/virtio-net-test.c
> >> index 97aa442..aeae80c 100644
> >> --- a/tests/virtio-net-test.c
> >> +++ b/tests/virtio-net-test.c
> >> @@ -138,6 +138,45 @@ static void tx_test(const QVirtioBus *bus, QVirtioDevice *dev,
> >>      g_assert_cmpstr(buffer, ==, "TEST");
> >>  }
> >>  
> >> +static void rx_stop_cont_test(const QVirtioBus *bus, QVirtioDevice *dev,
> >> +                              QGuestAllocator *alloc, QVirtQueue *vq,
> >> +                              int socket)
> >> +{
> >> +    uint64_t req_addr;
> >> +    uint32_t free_head;
> >> +    char test[] = "TEST";
> >> +    char buffer[64];
> >> +    int len = htonl(sizeof(test));
> >> +    struct iovec iov[] = {
> >> +        {
> >> +            .iov_base = &len,
> >> +            .iov_len = sizeof(len),
> >> +        }, {
> >> +            .iov_base = test,
> >> +            .iov_len = sizeof(test),
> >> +        },
> >> +    };
> >> +    int ret;
> >> +
> >> +    req_addr = guest_alloc(alloc, 64);
> >> +
> >> +    free_head = qvirtqueue_add(vq, req_addr, 64, true, false);
> >> +    qvirtqueue_kick(bus, dev, vq, free_head);
> >> +
> >> +    qmp("{ 'execute' : 'stop'}");
> >> +
> >> +    ret = iov_send(socket, iov, 2, 0, sizeof(len) + sizeof(test));
> >> +    g_assert_cmpint(ret, ==, sizeof(test) + sizeof(len));
> > Maybe add a small lag here? The next "cont" could be too early that is noticed
> > earlier than the packet.
> 
> I'm not sure I get the point of this. But at any case, rx should be
> recovered. (Btw, current qemu.git will fail in this case).

If 'cont' and the packet land in main loop in the same qemu_poll_ns(), it's
possible that the packet is processed before 'stop'.

A trick is using qmp commands as barriers:

    qmp("{ 'execute' : 'stop'}");

    ret = iov_send(socket, iov, 2, 0, sizeof(len) + sizeof(test));
    g_assert_cmpint(ret, ==, sizeof(test) + sizeof(len));

    /* We could check the status, but this command is more importantly to
     * ensure the packet data gets queued in QEMU, before we do 'cont'.
     */
    qmp("{ 'execute' : 'query-status'}");
    qmp("{ 'execute' : 'cont'}");

Fam

> 
> >
> >> +
> >> +    qmp("{ 'execute' : 'cont'}");
> >> +
> >> +    qvirtio_wait_queue_isr(bus, dev, vq, QVIRTIO_NET_TIMEOUT_US);
> >> +    memread(req_addr + 12, buffer, sizeof(test));
> >> +    g_assert_cmpstr(buffer, ==, "TEST");
> >> +
> >> +    guest_free(alloc, req_addr);
> >> +}
> >> +
> >>  static void send_recv_test(const QVirtioBus *bus, QVirtioDevice *dev,
> >>                             QGuestAllocator *alloc, QVirtQueue *rvq,
> >>                             QVirtQueue *tvq, int socket)
> >> @@ -146,6 +185,13 @@ static void send_recv_test(const QVirtioBus *bus, QVirtioDevice *dev,
> >>      tx_test(bus, dev, alloc, tvq, socket);
> >>  }
> >>  
> >> +static void stop_cont_test(const QVirtioBus *bus, QVirtioDevice *dev,
> >> +                           QGuestAllocator *alloc, QVirtQueue *rvq,
> >> +                           QVirtQueue *tvq, int socket)
> >> +{
> >> +    rx_stop_cont_test(bus, dev, alloc, rvq, socket);
> >> +}
> >> +
> >>  static void pci_basic(gconstpointer data)
> >>  {
> >>      QVirtioPCIDevice *dev;
> >> @@ -204,6 +250,8 @@ int main(int argc, char **argv)
> >>      g_test_init(&argc, &argv, NULL);
> >>  #ifndef _WIN32
> >>      qtest_add_data_func("/virtio/net/pci/basic", send_recv_test, pci_basic);
> >> +    qtest_add_data_func("/virtio/net/pci/rx_stop_cont",
> >> +                        stop_cont_test, pci_basic);
> >>  #endif
> >>      qtest_add_func("/virtio/net/pci/hotplug", hotplug);
> >>  
> >> -- 
> >> 2.1.4
> >>
>