On Mon, Jul 28, 2014 at 01:25:14PM +0530, Amit Shah wrote:
> On (Mon) 28 Jul 2014 [15:32:42], Amos Kong wrote:
> > QEMU commandline:
> >
> > ./x86_64-softmmu/qemu-system-x86_64 --enable-kvm -m 2000 -drive file=/images/nolvm.qcow2 --kernel /home/devel/linux/arch/x86/boot/bzImage -append "ro root=/dev/sda1 console=ttyS0,115200" -monitor unix:/tmp/m,nowait,server -device virtio-net-pci,netdev=h0,vectors=17,mq=on,id=n0 -netdev tap,id=h0,queues=8 -device virtio-net-pci,netdev=h1,vectors=0,mq=on,id=n1 -netdev tap,id=h1,queues=8 -vnc :0 -mon chardev=qmp,mode=control,pretty=on -chardev socket,id=qmp,host=localhost,port=1234,server,nowait -serial stdio -object rng-random,filename=/dev/urandom,id=rng0 -device virtio-rng-pci,rng=rng0,id=h0 -object rng-random,filename=/dev/urandom,id=rng1 -device virtio-rng-pci,rng=rng1,id=h1
> >
> > It works when I only add one virtio-rng device. Did you touch this
> > problem?
> >
> > I'm using latest net-next/master (ac3d2e5a9ef2f4d8f57c50070c4883ecb7cec29f)
Hi Amit,
> <snip>
> > [ 0.223503] Non-volatile memory driver v1.3
> > [ 1.172293] tsc: Refined TSC clocksource calibration: 2893.436 MHz
> > qemu: terminating on signal 2 <---------- (I have to cancel QEMU process by Ctrl + C)
>
> This looks similar to what I saw when driver asks for randomness from the host
> before probe is completed.
>
> Does the following patch help?
This patch was already inclued in latest net-next/master
patch commit: e052dbf554610e2104c5a7518c4d8374bed701bb
> While the driver is setup (DRIVER_OK is set), the vqs aren't marked
> usable before the probe for the other device finishes as well. That's
> not a scenario I considered. We can try to put this patch in 3.16,
> but it won't be applicable for 3.17, where this is handled the proper
> way. Also, 3.15 isn't affected, since that doesn't have multi-device
> support.
>
> Also attaching a patch that enables traces in qemu so it's easier to
> see what's going on.
>
> diff --git a/drivers/char/hw_random/virtio-rng.c
> b/drivers/char/hw_random/virtio-rng.c
> index e9b15bc..124cac5 100644
> --- a/drivers/char/hw_random/virtio-rng.c
> +++ b/drivers/char/hw_random/virtio-rng.c
> @@ -34,12 +34,11 @@ struct virtrng_info {
> unsigned int data_avail;
> struct completion have_data;
> bool busy;
> + bool probe_done;
> char name[25];
> int index;
> };
>
> -static bool probe_done;
> -
> static void random_recv_done(struct virtqueue *vq)
> {
> struct virtrng_info *vi = vq->vdev->priv;
> @@ -73,7 +72,7 @@ static int virtio_read(struct hwrng *rng, void *buf,
> -size_t size, bool wait)
> * Don't ask host for data till we're setup. This call can
> * happen during hwrng_register(), after commit d9e7972619.
> */
> - if (unlikely(!probe_done))
> + if (unlikely(!vi->probe_done))
> return 0;
>
> if (!vi->busy) {
> @@ -146,7 +145,7 @@ static int probe_common(struct virtio_device
> *vdev)
> return err;
> }
>
> - probe_done = true;
> + vi->probe_done = true;
> return 0;
> }
>
>
> Amit
> >From ec1aa555b67628beefa0ac6902baa2cc2e156f58 Mon Sep 17 00:00:00 2001
> Message-Id: <ec1aa555b67628beefa0ac6902baa2cc2e156f58.1406533638.git.amit.shah@xxxxxxxxxx>
> From: Amit Shah <amit.shah@xxxxxxxxxx>
> Date: Mon, 21 Jul 2014 14:46:28 +0530
> Subject: [PATCH 1/1] virtio-rng: add some trace events
>
> Add some trace events to virtio-rng for easier debugging
>
> Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
> ---
> hw/virtio/virtio-rng.c | 7 +++++++
> trace-events | 5 +++++
> 2 files changed, 12 insertions(+)
>
> diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
> index 7c5a675..4a6472b 100644
> --- a/hw/virtio/virtio-rng.c
> +++ b/hw/virtio/virtio-rng.c
> @@ -16,6 +16,7 @@
> #include "hw/virtio/virtio-rng.h"
> #include "sysemu/rng.h"
> #include "qom/object_interfaces.h"
> +#include "trace.h"
>
> static bool is_guest_ready(VirtIORNG *vrng)
> {
> @@ -24,6 +25,7 @@ static bool is_guest_ready(VirtIORNG *vrng)
> && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> return true;
> }
> + trace_virtio_rng_guest_not_ready(vrng);
> return false;
> }
>
> @@ -62,6 +64,7 @@ static void chr_read(void *opaque, const void *buf, size_t size)
> offset += len;
>
> virtqueue_push(vrng->vq, &elem, len);
> + trace_virtio_rng_pushed(vrng, len);
> }
> virtio_notify(vdev, vrng->vq);
> }
> @@ -81,7 +84,11 @@ static void virtio_rng_process(VirtIORNG *vrng)
> quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX);
> }
> size = get_request_size(vrng->vq, quota);
> +
> + trace_virtio_rng_request(vrng, size, quota);
> +
> size = MIN(vrng->quota_remaining, size);
> +
> if (size) {
> rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);
> }
> diff --git a/trace-events b/trace-events
> index 11a17a8..99f39ac 100644
> --- a/trace-events
> +++ b/trace-events
> @@ -41,6 +41,11 @@ virtio_irq(void *vq) "vq %p"
> virtio_notify(void *vdev, void *vq) "vdev %p vq %p"
> virtio_set_status(void *vdev, uint8_t val) "vdev %p val %u"
>
> +# hw/virtio/virtio-rng.c
> +virtio_rng_guest_not_ready(void *rng) "rng %p: guest not ready"
> +virtio_rng_pushed(void *rng, size_t len) "rng %p: %zd bytes pushed"
> +virtio_rng_request(void *rng, size_t size, unsigned quota) "rng %p: %zd bytes requested, %u bytes quota left"
> +
> # hw/char/virtio-serial-bus.c
> virtio_serial_send_control_event(unsigned int port, uint16_t event, uint16_t value) "port %u, event %u, value %u"
> virtio_serial_throttle_port(unsigned int port, bool throttle) "port %u, throttle %d"
> --
> 1.9.3
>
--
Amos.
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